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WO2021238929A1 - 一种成像设备的状态检测方法和系统 - Google Patents

一种成像设备的状态检测方法和系统 Download PDF

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Publication number
WO2021238929A1
WO2021238929A1 PCT/CN2021/095840 CN2021095840W WO2021238929A1 WO 2021238929 A1 WO2021238929 A1 WO 2021238929A1 CN 2021095840 W CN2021095840 W CN 2021095840W WO 2021238929 A1 WO2021238929 A1 WO 2021238929A1
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WIPO (PCT)
Prior art keywords
energy
event
background
crystal
time
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Application number
PCT/CN2021/095840
Other languages
English (en)
French (fr)
Inventor
吕新宇
薛满泉
褚少平
王旭明
Original Assignee
上海联影医疗科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN202010448693.6A external-priority patent/CN111568452A/zh
Priority claimed from CN202010448695.5A external-priority patent/CN111568453A/zh
Priority claimed from CN202010604518.1A external-priority patent/CN111714147A/zh
Priority claimed from CN202010604531.7A external-priority patent/CN111685785B/zh
Priority claimed from CN202010626175.9A external-priority patent/CN111728625B/zh
Application filed by 上海联影医疗科技股份有限公司 filed Critical 上海联影医疗科技股份有限公司
Priority to JP2022572797A priority Critical patent/JP7512440B2/ja
Priority to EP21814520.9A priority patent/EP4144296A4/en
Publication of WO2021238929A1 publication Critical patent/WO2021238929A1/zh
Priority to US18/058,785 priority patent/US20230102139A1/en
Priority to JP2024102650A priority patent/JP2024125364A/ja

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
    • G01T1/2914—Measurement of spatial distribution of radiation
    • G01T1/2985—In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis)
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/0002—Inspection of images, e.g. flaw detection
    • G06T7/0012—Biomedical image inspection
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/10—Segmentation; Edge detection
    • G06T7/194—Segmentation; Edge detection involving foreground-background segmentation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/03—Computed tomography [CT]
    • A61B6/037—Emission tomography
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10072—Tomographic images
    • G06T2207/10081—Computed x-ray tomography [CT]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10072—Tomographic images
    • G06T2207/10104—Positron emission tomography [PET]

Definitions

  • This application relates to the field of imaging technology, and in particular to a method and system for detecting the state of an imaging device.
  • PET positron emission computed tomography
  • a certain substance in the target body generally a substance necessary for biological metabolism, such as glucose, protein, nucleic acid, fatty acid, etc.
  • a short-lived radionuclide Element such as F18, carbon 11, etc.
  • a positron After traveling a few tenths of a millimeter to a few millimeters, a positron encounters an electron and annihilates, resulting in a pair of photons with an energy of 511 keV in opposite directions.
  • the photon signal can be captured by a highly sensitive camera and corrected for scattering and random information by a computer.
  • a three-dimensional image reflecting the accumulation of radionuclides in the target object can be obtained, so as to achieve the purpose of diagnosis.
  • PET scanning has the characteristics of high sensitivity, high specificity, and good safety. Therefore, it is widely used in the medical field. In order to improve the accuracy of the data collected by the PET equipment and the quality of the PET image, the status of the PET equipment needs to be detected and/or corrected.
  • an imaging device for example, a PET imaging device.
  • An aspect of this specification provides a method for detecting the state of an imaging device.
  • the method includes: acquiring a first background event of a crystal of a detector of the imaging device, the first background event being related to the self-radiation particles of the crystal;
  • the crystal position look-up table is corrected; the energy state of the imaging device is corrected; the second background event of the crystal is obtained, and the second background event is related to the crystal's own radiation particles; based on the The first background event and the second background event are used to correct the flight time status of the detector.
  • the acquiring the first background event of the crystal of the detector of the imaging device includes: acquiring the first background event of the self-radiation particles of the crystal received by the detector according to a preset energy window. Background event; the correction of the crystal position look-up table based on the first background event includes: determining a single event image based on the first background event; The crystal position look-up table is used for correction.
  • the correcting the energy state of the imaging device includes: correcting the energy state of the imaging device based on the first background event.
  • the correcting the energy state of the imaging device includes: acquiring a third background event of the crystal, where the third background event is related to the self-radiation particles of the crystal, and The third background event includes the background single event or background coincidence event of the crystal's own radiation particles received by the detector; based on the third background event, the energy state of the imaging device is corrected .
  • the correcting the energy state of the imaging device includes: generating an energy spectrogram based on the energy information of the first background event or the third background event; determining the energy spectrum The peak position of the graph; determine the energy correction state of the imaging device according to the peak position of the energy spectrogram and the corrected peak position corresponding to the peak position; determine the energy correction state of the imaging device according to the energy correction state The status is corrected.
  • the correcting the energy state of the imaging device includes: determining at least two elements related to the nuclide decay of the crystal based on the first background event or the third background event. An energy peak value and an ADC value corresponding to the at least two energy peak values; and an energy scale curve of the imaging device is determined according to the at least two energy peak values and the ADC value corresponding to the at least two energy peak values.
  • the correcting the time-of-flight state of the probe based on the first background event and the second background event includes: according to the first background event and the second background event The second background event is to determine the measured flight time; the flight time of the detector is corrected according to the flight time state of the imaging device reflected by the measured flight time.
  • the method further includes: generating an event time spectrum according to the first background event and/or the second background event; and determining the correspondence between the TDC value and time according to the event time spectrum Relationship; according to the corresponding relationship, the TDC scale curve of the imaging device is determined.
  • the method further includes: obtaining a fourth background event of the crystal, the fourth background event being related to the crystal's own radiation particles; based on the fourth background event, generating Event time spectrum; according to the event time spectrum, determine the corresponding relationship between the TDC value and time; according to the corresponding relationship, determine the TDC calibration curve of the imaging device.
  • the method further includes: determining a measured flight time and a theoretical flight time based on the first background event and the second background event; and based on the measured flight time and the theoretical flight time , To synchronize the time of the detector module of the detector.
  • One aspect of this specification provides a method for correcting a crystal position look-up table.
  • the method includes: acquiring a background event of a crystal of a detector of an imaging device, the background event being related to the self-radiation particles of the crystal; determining a single event image based on the background event; and determining a single event image based on the single event Image to correct the crystal position look-up table of the imaging device.
  • the acquiring the background event of the crystal of the detector of the imaging device includes: determining the energy window of the detector of the imaging device; and acquiring the energy window received by the detector according to the energy window.
  • the background event of the crystal's own radiation particles includes: determining the energy window of the detector of the imaging device; and acquiring the energy window received by the detector according to the energy window.
  • the range of the energy window is within a clinical energy window threshold range of the imaging device.
  • the determining a single event image based on the background event includes: determining a single characteristic energy peak event based on the background event; generating the single event image based on the single characteristic energy peak event .
  • the single characteristic energy peak event includes an event of 597 keV photons received by the detector.
  • the correcting the crystal position lookup table of the imaging device according to the single event image includes: obtaining the position label of the crystal in the crystal position lookup table according to the single event image Corresponding pixel distribution in the single event image; and correcting the crystal position look-up table according to the corresponding pixel distribution of the crystal position label in the single event image.
  • the method further includes: determining whether the crystal position look-up table of the imaging device is shifted based on the background event.
  • One aspect of this specification provides an energy correction state detection method.
  • the method includes: acquiring a background event of a crystal of a detector of an imaging device, the background event being related to the self-radiation particles of the crystal; generating an energy spectrogram based on the energy information of the background event; determining the The peak position of the energy spectrogram; the energy correction state is determined according to the peak position of the energy spectrogram and the corrected peak position corresponding to the peak position of the energy spectrogram.
  • the acquiring the background event of the crystal of the detector of the imaging device includes: determining the event acquisition mode of the detector; and acquiring the detection received by the detector according to the event acquisition mode.
  • the background event of the self-radiation particles of the crystal of the device includes: determining the event acquisition mode of the detector; and acquiring the detection received by the detector according to the event acquisition mode.
  • the event collection mode includes a single event mode
  • the generating an energy spectrum based on the energy information of the background event includes: based on the background received by the detector in the single event mode.
  • the energy information of the event generates the energy spectrogram, wherein the energy spectrogram includes at least one of a universal peak-to-peak value or a single energy peak.
  • the event collection mode includes a coincidence event mode
  • the acquiring, according to the event collection mode, the background event of the self-radiation particles of the crystal of the detector received by the detector includes: A preset time window and/or a preset energy window are used to obtain the background event of the self-radiated particles of the crystal of the detector received by the detector in the coincidence event mode.
  • the generating an energy spectrogram based on the energy information of the background event includes: screening particle energy information according to the arrival time of the particles of the background event;
  • the energy spectrogram includes a single energy peak.
  • the range of the preset time window is not less than the clinical time window threshold range of the imaging device.
  • the determining the energy correction state according to the peak position of the energy spectrum diagram and the corrected peak position corresponding to the peak position of the energy spectrum diagram includes: determining the peak value of the energy spectrum diagram The ratio of the position to the corrected peak position; based on the ratio, it is determined whether the energy correction state of the imaging device is abnormal.
  • the peak position of the energy spectrogram includes at least one of an all-around peak-to-peak position or a single energy peak-to-peak position.
  • the corrected peak position corresponds to the peak position of the energy spectrum of the 511 keV photon.
  • One aspect of this specification provides a method for determining an energy calibration curve.
  • the method includes: acquiring a background event of a crystal of a detector of an imaging device, the background event being related to the self-radiation particles of the crystal; based on the background event, determining that it is related to the nuclide decay of the crystal Determine the energy calibration curve according to the at least two energy peaks and the ADC values corresponding to the at least two energy peaks.
  • the determining, based on the background event, at least two energy peaks related to the nuclide decay of the crystal and an ADC value corresponding to the at least two energy peaks includes: The bottom event is to determine the peak decay characteristic energy of the multiple nuclides of the crystal; perform analog-to-digital conversion on the peak decay characteristic energy of the multiple nuclides to obtain the ADC value corresponding to the peak decay characteristic energy; select all The at least two energy peaks in the decay characteristic energy peaks and ADC values corresponding to the at least two energy peaks.
  • the at least two energy peaks include 307 keV and 597 keV energy peaks; and the ADC values corresponding to the at least two energy peaks include ADC values corresponding to the 307 keV and 597 keV energy peaks.
  • the determining the energy calibration curve according to the at least two energy peaks and ADC values corresponding to the at least two energy peaks includes: by comparing the at least two energy peaks and the ADC values corresponding to the at least two energy peaks.
  • the ADC values corresponding to the at least two energy peaks are interpolated and fitted to determine the energy scale curve.
  • the method further includes: determining an ADC value corresponding to any energy peak value on the energy scale curve according to the energy scale curve.
  • the method further includes: determining the ADC value corresponding to the peak energy of 511 keV according to the energy calibration curve.
  • the method further includes: correcting the energy of the particles received by the detector according to the ADC value corresponding to the 511 keV energy peak.
  • the method includes: obtaining a background coincidence event of a crystal of a detector of an imaging device, the background coincidence event being related to the self-radiation particles of the crystal; determining the measurement flight time according to the information of the background coincidence event, and Theoretical flight time; according to the measured flight time and the theoretical flight time, time synchronization is performed on the detector.
  • the information of the background coincidence event includes: the arrival time of two particles in each background coincidence event of the background coincidence event to the detector and the corresponding crystal position; According to the information of the background coincidence event, determining the measured flight time and the theoretical flight time includes: determining each of the background coincidence events according to the arrival time of two particles of the background coincidence event And determining the theoretical flight time of each background coincidence event according to the crystal positions corresponding to the two particles of each background coincidence event.
  • the time synchronization of the detector according to the measured flight time and the theoretical flight time includes: determining a time difference based on the measured flight time and the theoretical flight time; Time difference, time synchronization of the detector.
  • the determining the time difference based on the measured flight time and the theoretical flight time includes: based on multiple measured flight times and multiple theoretical flights received by any pair of detector modules of the detector Time, determine the difference between the plurality of measured flight times and the plurality of theoretical flight times; determine that the mean value of the difference between the plurality of measured flight times and the plurality of theoretical flight times is the time difference.
  • the time synchronization of the detector according to the time difference includes: in response to the time difference being greater than or equal to one clock cycle, time synchronization of the detector module of the detector.
  • the time synchronization of the detector includes: adjusting the value of a counter of one of the detector modules of any pair of the detector, and adjusting the adjusted counter The value of is determined as the time reference standard.
  • the method further includes: determining any one of the detector modules in the any pair of detector modules after adjusting the calculator as a reference module, and comparing the detector modules in the detector based on the reference module Time synchronization of other detector modules except the pair of detector modules.
  • One aspect of this specification provides a time-of-flight status detection method.
  • the method includes: obtaining a background coincidence event of a crystal of a detector of an imaging device, the background coincidence event being related to the self-radiation particles of the crystal; determining the measurement flight time according to the information of the background coincidence event, and Theoretical flight time; according to the measured flight time and the theoretical flight time, the flight time state of the imaging device is determined, and the flight time state reflects whether the crystal drifts.
  • the acquiring the background coincidence event of the crystal of the detector of the imaging device includes: determining a time window and an energy window of the imaging device; and acquiring the time window and the energy window of the detector receiving The obtained background of the crystal's own radiation particles is consistent with the event and its related information.
  • the range of the time window is not less than the clinical time window threshold range of the imaging device; the range of the energy window is not less than the clinical energy window threshold range of the imaging device.
  • the information of the background coincidence event includes: the arrival time of two particles in each background coincidence event of the background coincidence event to the detector and the corresponding crystal position; According to the information of the background coincidence event, determining the measurement flight time and the theoretical flight time includes: determining the measurement of each background coincidence event according to the arrival time of the two particles of each background coincidence event Flight time; and determining the theoretical flight time of each background coincidence event according to the crystal positions corresponding to the two particles of each background coincidence event.
  • the determining the flight time status of the imaging device according to the measured flight time and the theoretical flight time includes: in response to the difference between the measured flight time and the theoretical flight time exceeding a threshold, It is determined that the crystal corresponding to the background coincidence event has drifted.
  • the method further includes: correcting the flight time of the detector according to the information of the background coincidence event to obtain the corrected flight time.
  • the correcting the flight time of the detector according to the information of the background coincidence event to obtain the corrected flight time includes: obtaining an energy-time mapping relationship, and the energy-time mapping The relationship reflects the corresponding relationship between the particle energy and the flight time offset; based on the energy-time mapping relationship, the flight corresponding to the energy of the two particles in the background coincidence event is determined Time offset; the flight time of the detector is corrected according to the flight time offset to obtain the corrected flight time.
  • the device includes: an acquisition module for acquiring a first background event and a second background event of the crystal of the detector of the imaging device, and the first background event and the second background event are related to each other The crystal’s own radiation particles are related; a correction module for correcting the crystal position look-up table based on the first background event; correcting the energy state of the imaging device; and based on the first book The bottom event and the second background event are used to correct the time-of-flight state of the detector.
  • Another aspect of this specification provides a computer device, including a memory, a processor, and a computer program stored on the memory and running on the processor, wherein the processor executes the computer program When implementing the method as described earlier.
  • Another aspect of this specification provides a computer-readable storage medium on which a computer program is stored, characterized in that, when the program is executed by a processor, the method as described above is implemented.
  • Fig. 1 is a schematic diagram of an application scenario of an exemplary imaging device state detection method according to some embodiments of the present application
  • Fig. 2 is a schematic diagram of exemplary hardware and/or software of a computing device according to some embodiments of the present application;
  • Fig. 3 is an exemplary block diagram of a state correction device of an imaging device according to some embodiments of the present application.
  • FIG. 4 is an exemplary flowchart of a method for detecting a state of an imaging device according to some embodiments of the present application
  • Fig. 5 is an exemplary schematic diagram of a PET device receiving particles according to some embodiments of the present application.
  • Fig. 6 is an exemplary block diagram of a crystal position look-up table correction device according to some embodiments of the present application.
  • FIG. 7 is an exemplary flowchart of a method for correcting a crystal position look-up table according to some embodiments of the present application.
  • FIGS. 8A-8C are exemplary schematic diagrams of a method for correcting a crystal position look-up table according to some embodiments of the present application.
  • Fig. 9 is an exemplary block diagram of an energy state detection device according to some embodiments of the present application.
  • Fig. 10 is an exemplary flowchart of an energy state detection method according to some embodiments of the present application.
  • FIG. 11 is a schematic diagram of an energy spectrogram formed in a single event mode according to some embodiments of the present application.
  • FIG. 12 is a schematic diagram of an energy spectrogram formed according to an event mode according to some embodiments of the present application.
  • FIG. 13 is an exemplary block diagram of a device for determining an energy scale curve according to some embodiments of the present application.
  • Fig. 14 is an exemplary flowchart of a method for determining an energy scale curve according to some embodiments of the present application.
  • Fig. 15 is an exemplary block diagram of a time synchronization device according to some embodiments of the present application.
  • Fig. 16 is an exemplary flowchart of a time synchronization method according to some embodiments of the present application.
  • FIG. 17 is a schematic diagram of the detector module according to some embodiments of the present application receiving photons
  • Fig. 18 is an exemplary block diagram of a time-of-flight state detection device according to some embodiments of the present application.
  • FIG. 19 is an exemplary flow chart of a method for detecting a time-of-flight state according to some embodiments of the present application.
  • FIG. 20 is an exemplary schematic diagram of an event time spectrum according to some embodiments of the present application.
  • FIG. 21 is an exemplary schematic diagram of the corresponding relationship between TDC value and time according to some embodiments of the present application.
  • system is a method for distinguishing different components, elements, parts, parts, or assemblies of different levels.
  • the words can be replaced by other expressions.
  • PET equipment can perform imaging by measuring a pair of gamma photons produced by positron annihilation.
  • the status of the PET device can be detected and corrected periodically or in real time, so as to improve the accuracy of the data collected by the PET device, the quality of the PET image, and the like.
  • a radioactive rod source (barrel source) can be used to detect the status of the PET device.
  • barrel source can be used to detect the status of the PET device.
  • active state detection due to the presence of radioactive sources, it will cause a certain degree of radiation damage to the user (for example, medical staff), increase the operator's radiation dose, and the operation method is complicated, which can only be applied For regular testing.
  • the method for detecting the state of the imaging device detects the state of the imaging device based on the inherent radioactive phenomenon of the crystal of the detector of the imaging device, which can be used without an additional radioactive rod source (barrel source). Detecting the status of PET equipment can simplify the detection process, reduce the radiation dose of the operator, save the cost of radioactive source procurement, and the method is simple to operate. In addition, this method can perform status detection when the PET equipment is in an idle state, can perform detection at any idle time, and can perform multiple detections repeatedly, which is convenient for increasing the frequency of detection and discovering the abnormal state of the equipment in time. Therefore, the flexibility of this method higher.
  • Fig. 1 is a schematic diagram of an application scenario of an exemplary imaging device state detection method according to some embodiments of the present application.
  • the imaging device state detection system 100 may include an imaging device 110, a network 120, a terminal device 130, a processing device 140 and a storage device 150.
  • the various components in the system 100 may be connected to each other through a network 120.
  • the imaging device 110 and the terminal device 130 may be connected or communicated through the network 120.
  • the imaging device 110 and the storage device 150 may be connected or communicated through the network 120.
  • the imaging device 110 may be used to scan a target object in the detection area to obtain scan data of the target object.
  • the target object may include biological objects and/or non-biological objects.
  • the target object may include a specific part of the body, such as the head, chest, abdomen, etc., or a combination thereof.
  • the target object may be animate or inanimate organic and/or inorganic substances.
  • the imaging device 110 may be a non-invasive biomedical imaging device used for disease diagnosis or research purposes.
  • the imaging device 110 may include a single-modality scanner and/or a multi-modality scanner.
  • Monomodal scanners can include, for example, ultrasound scanners, X-ray scanners, computed tomography (CT) scanners, magnetic resonance imaging (MRI) scanners, ultrasound scanners, positron emission computed tomography (PET) scanners , Optical Coherence Tomography (OCT) Scanner, Ultrasound (US) Scanner, Intravascular Ultrasound (IVUS) Scanner, Near Infrared Spectroscopy (NIRS) Scanner, Far Infrared (FIR) Scanner, etc., or any combination thereof.
  • CT computed tomography
  • MRI magnetic resonance imaging
  • PET positron emission computed tomography
  • OCT Optical Coherence Tomography
  • US Ultrasound
  • IVUS Intravascular Ultrasound
  • NIRS Near Infrared
  • Multimodal scanners may include, for example, X-ray imaging-magnetic resonance imaging (X-ray-MRI) scanners, positron emission tomography-X-ray imaging (PET-X-ray) scanners, single-photon emission computed tomography-nuclear magnetic Resonance imaging (SPECT-MRI) scanner, positron emission tomography-computed tomography (PET-CT) scanner, digital subtraction angiography-magnetic resonance imaging (DSA-MRI) scanner, etc.
  • X-ray imaging-magnetic resonance imaging X-ray-MRI
  • PET-X-ray positron emission tomography-X-ray imaging
  • SPECT-MRI single-photon emission computed tomography-nuclear magnetic Resonance imaging
  • PET-CT positron emission tomography-computed tomography
  • DSA-MRI digital subtraction angiography-magnetic resonance imaging
  • the term "imaging modality” or “modality” broadly refers to an imaging method or technique for collecting, generating, processing, and/or analyzing imaging information of a target object.
  • the imaging device 110 may be a positron emission computed tomography (PET) device.
  • PET positron emission computed tomography
  • the imaging device 110 may include modules and/or components for performing imaging and/or related analysis.
  • the imaging device 110 may include accessory components and imaging components.
  • accessory components refer to the various facilities that are designed to meet the needs of clinical diagnosis and treatment with imaging components.
  • they can include mechanical equipment such as examination beds, diagnostic beds, catheter beds, photography beds, etc., various supports, suspensions, etc.
  • the imaging component can have multiple forms.
  • the digital imaging component can include a detector, a computer system, and image processing software; other imaging components can include a fluorescent screen, a film cassette, an image intensifier, a video TV, etc. .
  • the detector may include a plurality of detector modules, and each detector module may include a plurality of detector units.
  • each detector module may include a photosensitive module and a readout circuit.
  • the photosensitive module can be used to collect the photon signal generated by the radionuclide injected by the target object and convert the collected photon signal into an electrical signal.
  • the readout circuit can be used to read the electrical signal in the photosensitive module and convert it into Digitize data so that it can be used to generate images.
  • the photosensitive module may include a crystal.
  • a crystal is a structure in which a large number of microscopic matter units (atoms, ions, molecules, etc.) are arranged in an orderly manner according to a certain rule, for example, crystalline Si (silicon), CdTe, GaAs, HgI2, and CdZnTe (CZT).
  • the photosensitive module may use scintillation crystals as the photosensitive substrate. Scintillation crystals refer to crystals that can convert the kinetic energy of high-energy particles into light energy under the impact of high-energy particles (for example, X-rays, gamma photons) to emit flashes.
  • the detector may include a semiconductor detector, a photovoltaic detector, etc., which is not limited in this specification.
  • the data acquired by the imaging device 110 may be transmitted to the processing device 140 for further analysis. Additionally or alternatively, the data acquired by the imaging device 110 may be sent to a terminal device (for example, the terminal device 130) for display and/or a storage device (for example, the storage device 150) for storage.
  • a terminal device for example, the terminal device 130
  • a storage device for example, the storage device 150
  • the network 120 may include any suitable network capable of facilitating the exchange of information and/or data of the system 100.
  • at least one component of the system 100 may exchange information and/or data with at least one other component of the system 100 via the network 120.
  • the processing device 140 may obtain a background single event, a background coincidence event, etc. from the detector of the imaging device 110 via the network 120.
  • the network 120 may include a public network (for example, the Internet), a private network (for example, a local area network (LAN)), a wired network, a wireless network (for example, an 802.11 network, a Wi-Fi network), a frame relay network, and a virtual private network.
  • the VPN may include a satellite network, a telephone network, routers, hubs, switches, fiber optic networks, telecommunications networks, intranets, wireless local area networks (WLAN), metropolitan area network (MAN), a public switched telephone network (PSTN), Bluetooth (TM) Network, ZigBee TM network, Near Field Communication (NFC) network, etc., or any combination thereof.
  • the network 120 may include at least one network access point.
  • the network 120 may include wired and/or wireless network access points, such as base stations and/or Internet exchange points, and at least one component of the system 100 may be connected to the network 120 through the access points to exchange data and/or information.
  • the terminal device 130 may communicate and/or connect with the imaging device 110, the processing device 140, and/or the storage device 150.
  • the user may interact with the imaging device 110 through the terminal device 130 to control one or more components of the imaging device 110.
  • the terminal device 130 may include a mobile device 131, a tablet computer 132, a laptop computer 133, etc., or any combination thereof.
  • the mobile device 131 may include a mobile control handle, a personal digital assistant (PDA), a smart phone, etc., or any combination thereof.
  • PDA personal digital assistant
  • the terminal device 130 may include an input device, an output device, and so on.
  • the input device may select keyboard input, touch screen (for example, with tactile or tactile feedback) input, voice input, eye tracking input, gesture tracking input, brain monitoring system input, image input, video input, or any other similar input mechanism.
  • the input information received through the input device can be transmitted to the processing device 140 via, for example, a bus, for further processing.
  • Other types of input devices may include cursor control devices, such as a mouse, trackball, or cursor direction keys.
  • an operator eg, a medical staff
  • the output device may include a display, a speaker, a printer, etc. or any combination thereof.
  • the output device may be used to output the image of the target object scanned by the imaging device 110, and/or the image determined by the processing device 140, and the like.
  • the terminal device 130 may be a part of the processing device 140.
  • the processing device 140 may process data and/or information obtained from the imaging device 110, the at least one terminal device 130, the storage device 150, or other components of the system 100.
  • the processing device 140 may obtain the first background event, the second background event, the third background event, the fourth background event, etc. from the imaging device 110, and perform analysis and processing on the imaging device 110. Status detection.
  • the processing device 140 may be a single server or a group of servers. Server groups can be centralized or distributed.
  • the processing device 140 may be local or remote.
  • the processing device 140 may access information and/or data from the imaging device 110, the at least one terminal device 130, and/or the storage device 150 through the network 120.
  • the processing device 140 may be directly connected to the imaging device 110, at least one terminal device 130, and/or the storage device 150 to access information and/or data.
  • the processing device 140 may be implemented on a cloud platform.
  • cloud platforms may include private clouds, public clouds, hybrid clouds, community clouds, distributed clouds, inter-cloud clouds, multi-clouds, etc., or any combination thereof.
  • the processing device 140 may include one or more processors (for example, a single-chip processor or a multi-chip processor).
  • the processing device 140 may include a central processing unit (CPU), an application specific integrated circuit (ASIC), an application specific instruction set processor (ASIP), an image processing unit (GPU), a physical operation processing unit (PPU), and digital signal processing.
  • Controller DSP
  • Field Programmable Gate Array FPGA
  • Programmable Logic Device PLD
  • Controller Microcontroller Unit, Reduced Instruction Set Computer (RISC), Microprocessor, etc. or any combination thereof.
  • the processing device 140 may be a part of the imaging device 110 or the terminal device 130.
  • the processing device 140 may be integrated in the imaging device 110 for detecting the state of the imaging device 110 based on a background single event or a background coincidence event.
  • the storage device 150 may store data, instructions, and/or any other information.
  • the storage device 150 may store background events and related information obtained by the imaging device 110.
  • the storage device 150 may store data obtained from the imaging device 110, the at least one terminal device 130, and/or the processing device 140.
  • the storage device 150 may store data and/or instructions used by the processing device 140 to execute or use to complete the exemplary methods described in this application.
  • the storage device 150 may include mass memory, removable memory, volatile read-write memory, read-only memory (ROM), etc., or any combination thereof.
  • the storage device 150 may be implemented on a cloud platform.
  • the storage device 150 may be connected to the network 120 to communicate with at least one other component in the system 100 (for example, the imaging device 110, the at least one terminal device 130, the processing device 140). At least one component in the system 100 can access data stored in the storage device 150 via the network 120 (for example, background single event information, background conforming event information, single event images, etc.). In some embodiments, the storage device 150 may be part of the processing device 140.
  • the storage device 150 may be a data storage device including a cloud computing platform (such as a public cloud, a private cloud, a community, and a hybrid cloud, etc.).
  • a cloud computing platform such as a public cloud, a private cloud, a community, and a hybrid cloud, etc.
  • Fig. 2 is a schematic diagram of exemplary hardware and/or software of a computing device according to some embodiments of the present application.
  • the computing device 200 may include a processor 210, a memory 220, an input/output interface 230, and a communication port 240.
  • the processor 210 can execute calculation instructions (program codes) and perform the functions of the imaging device state detection system 100 described in this application.
  • the calculation instructions may include programs, objects, components, data structures, procedures, modules, and functions (the functions refer to specific functions described in this application).
  • the processor 210 may process background event information obtained from any component of the system 100.
  • the processor 210 may include a microcontroller, a microprocessor, a reduced instruction set computer (RISC), an application specific integrated circuit (ASIC), an application specific instruction set processor (ASIP), a central processing unit (CPU) , Graphics processing unit (GPU), physical processing unit (PPU), microcontroller unit, digital signal processor (DSP), field programmable gate array (FPGA), advanced RISC machine (ARM), programmable logic device, and Any circuits, processors, etc., that perform one or more functions, or any combination thereof.
  • RISC reduced instruction set computer
  • ASIC application specific integrated circuit
  • ASIP application specific instruction set processor
  • CPU central processing unit
  • GPU Graphics processing unit
  • PPU physical processing unit
  • DSP digital signal processor
  • FPGA field programmable gate array
  • ARM advanced RISC machine
  • programmable logic device any circuits, processors, etc., that perform one or more functions, or any combination thereof.
  • the computing device 200 in FIG. 2 only describes one processor, but it should be noted that
  • the memory 220 may store data/information obtained from any other components of the system 100.
  • the memory 220 may include mass memory, removable memory, volatile read and write memory, read-only memory (ROM), etc., or any combination thereof.
  • Exemplary mass storage devices may include magnetic disks, optical disks, solid state drives, and the like.
  • Removable storage can include flash drives, floppy disks, optical disks, memory cards, compact disks, and magnetic tapes.
  • Volatile read and write memory may include random access memory (RAM).
  • RAM can include dynamic RAM (DRAM), double-rate synchronous dynamic RAM (DDR SDRAM), static RAM (SRAM), thyristor RAM (T-RAM), zero capacitance (Z-RAM), and so on.
  • ROM can include mask ROM (MROM), programmable ROM (PROM), erasable programmable ROM (PEROM), electrically erasable programmable ROM (EEPROM), compact disk ROM (CD-ROM) and digital universal disk ROM Wait.
  • MROM mask ROM
  • PROM programmable ROM
  • PEROM erasable programmable ROM
  • EEPROM electrically erasable programmable ROM
  • CD-ROM compact disk ROM
  • digital universal disk ROM Wait digital universal disk ROM Wait.
  • the input/output interface 230 may be used to input or output signals, data or information.
  • the input/output interface 230 may allow the user to communicate with components in the system 100 (for example, the imaging device 110).
  • the input/output interface 230 may include an input device and an output device.
  • An exemplary input device may include one or any combination of a keyboard, a mouse, a touch screen, a microphone, and the like.
  • Exemplary output devices may include display devices, speakers, printers, projectors, etc., or any combination thereof.
  • Exemplary display devices may include one or any combination of liquid crystal displays (LCD), light emitting diode (LED)-based displays, flat panel displays, curved displays, television equipment, cathode ray tubes (CRT), and the like.
  • the communication port 240 may be connected to a network for data communication.
  • the connection may be a wired connection, a wireless connection, or a combination of both.
  • Wired connections can include cables, optical cables, or telephone lines, etc., or any combination thereof.
  • the wireless connection may include one or any combination of Bluetooth, Wi-Fi, WiMax, WLAN, ZigBee, mobile network (for example, 3G, 4G, or 5G, etc.).
  • the communication port 240 may be a standardized port, such as RS232, RS485, and so on. In some embodiments, the communication port 240 may be a specially designed port. For example, the communication port 240 may be designed according to the Digital Imaging and Medical Communication Protocol (DICOM).
  • DICOM Digital Imaging and Medical Communication Protocol
  • Fig. 3 is an exemplary block diagram of a state correction device of an imaging device according to some embodiments of the present application.
  • the apparatus 300 for correcting the state of the imaging device may include an acquiring module 310, an image generating module 320, a determining module 330, and a correcting module 340.
  • the obtaining module 310 may be used to obtain data and/or information.
  • the acquisition module 310 may be used to acquire the background event information related to the self-radiation particles of its crystal received by the detector of the imaging device 110.
  • the acquisition module 310 may be used to acquire background single events and/or background coincidence events of the crystal of the detector of the imaging device 110 (for example, the first background event and the second background event described in FIG. 4). Background event, third background event, fourth background event, fifth background event, and sixth background event).
  • the obtaining module 310 may be used to obtain information of a background event (for example, a first background event) of the crystal of the detector of the imaging device 110 in response to the abnormal state of the crystal position look-up table of the imaging device 110.
  • the acquisition module 310 may be used to acquire the background event of the crystal of the detector of the imaging device 110 (for example, the second background event or the first Three background events) information.
  • the image generation module 320 may be used to generate images related to background events. For example, the image generation module 320 may be used to generate a single event image based on a background event (for example, a first background event). In some embodiments, the image generation module 320 may be used to generate an energy spectrogram based on energy information of a background event (for example, a first background event or a third background event). In some embodiments, the image generation module 320 may be used to generate an event time spectrum based on information of a background event (e.g., a first background event and/or a second background event, or a fourth background event). In some embodiments, the image generation module 320 may also be used to generate other related images, for example, an image of a target object, etc., which is not limited in this specification.
  • a background event for example, a first background event
  • the image generation module 320 may be used to generate an energy spectrogram based on energy information of a background event (for example, a first background event or
  • the determining module 330 may be used to determine Time of Flight (TOF, Time of Flight). In some embodiments, the determining module 330 may be used to determine a background coincidence event based on a background event (for example, a background coincidence event filtered from a first background event and a second background event, or the fourth background event in FIG. 4). ) Information to calculate the measured flight time and theoretical flight time. In some embodiments, the determining module 330 may also be used to determine the peak position of the energy spectrogram according to the energy spectrogram. In some embodiments, the determining module 330 may also be used to determine the correspondence between a time-to-digital converter (TDC, Time-to-Digital Converter) value and time.
  • TDC Time-to-digital converter
  • the determining module 330 may further include a peak position determining unit 332 and a time determining unit 334.
  • the peak position determining unit 332 may be used to calculate the peak position of the energy spectrum.
  • the time determination unit 334 may be used to calculate event-related time information, for example, measured flight time, theoretical flight time, and so on.
  • the correction module 340 may be used to correct the state of the imaging device.
  • the status of the imaging device may refer to the status of its software and/or hardware, and the accuracy status of system data.
  • the state of the imaging device that the calibration module 340 can be used to calibrate may include: crystal position look-up table state, energy calibration status, energy calibration status, time synchronization status between detector modules, flight time status, TDC calibration status, system failure, etc. , Or any combination thereof.
  • the correction module 340 may be used to correct the crystal position look-up table of the imaging device based on the information of the background event (for example, the first background event).
  • the correction module 340 may be used to correct the energy state of the imaging device based on information of a background event (for example, a first background event or a third background event).
  • the correction module 340 may be configured to perform time correction on the detector of the imaging device based on the information of the background coincidence event (for example, the background coincidence event obtained based on the first background event and the second background event).
  • the correction module 340 may further include a LUT correction unit 342, an energy state correction unit 344, a time synchronization unit 346, and a time-of-flight state correction unit 348.
  • the LUT correction unit 342 may be used to correct the crystal position look-up table of the imaging device.
  • the LUT correction unit 342 may determine (for example, before correcting the crystal position look-up table) whether the state of the crystal position look-up table is abnormal. Whether the state of the crystal position look-up table of the imaging device is abnormal can indicate the event detected by the detector, and the calculated response position of each crystal of the detector to the event is consistent with the actual position of the crystal.
  • the LUT correction unit 342 in response to the abnormal state of the crystal position look-up table, may correct the crystal position look-up table based on the information of the background event (for example, the first background event).
  • the energy state correction unit 344 may be used to correct the energy state of the imaging device. In some embodiments, the energy state correction unit 344 may determine (for example, before correcting the energy state) whether the energy state is abnormal.
  • the energy state of an imaging device may refer to the matching state of energy values obtained when each detector channel thereof receives particles of the same energy. Whether the energy state is abnormal can refer to whether the energy values obtained by each detector channel receiving particles of the same energy are the same.
  • the energy scale curve may shift accordingly.
  • the energy scale curve maps the ADC value that refers to particle energy to actual energy.
  • the accuracy of the energy scale curve is related to the image resolution of the PET equipment.
  • ADC Analog-to-Digital Converter
  • ADC value refers to a sampled value of the analog-to-digital converter.
  • the energy state correction unit 344 may correct the energy state based on the information of the background event (for example, the first background event or the third background event). For example, the energy state correction unit 344 may determine at least two energy peaks related to the nuclide decay of the crystal and ADC values corresponding to the at least two energy peaks based on the information of the third background event; The at least two energy peaks and ADC values corresponding to the at least two energy peaks determine the energy calibration curve of the imaging device.
  • the time synchronization unit 346 may be used to synchronize the time of each detector module of the detector of the imaging device. In some embodiments, the time synchronization unit 346 can determine (for example, before or at the same time when the time of the detector module is corrected) whether the time of the detector module is synchronized. In some embodiments, in response to the time synchronization of the detector module, the time synchronization unit 346 may synchronize the time of the detector module based on the background coincidence event information. For example, the time synchronization unit 346 may synchronize the time of each detector module of the detector according to the measured flight time and the theoretical flight time.
  • the time-of-flight state correction unit 348 may be used to correct the time-of-flight state of the imaging device.
  • the time-of-flight status correction unit 348 may determine (for example, before correcting the time-of-flight status) whether the time-of-flight status is abnormal.
  • the time-of-flight state may refer to the state of the time when the detector receives the particle. Whether the flight time status is abnormal can refer to whether the flight time drifts.
  • the flight time state correction unit 348 in response to an abnormal state of flight time (for example, the difference between the measured flight time of the background coincidence event and the theoretical flight time exceeds a threshold), the flight time state correction unit 348 may perform detection based on the information of the background coincidence event. The flight time of the aircraft is corrected.
  • the time-of-flight state correction unit 348 may also determine the TDC calibration curve of the imaging device according to the corresponding relationship between the TDC value and time.
  • the above description of the state correction device 300 of the imaging device and its modules is only for convenience of description, and does not limit the present application within the scope of the embodiments mentioned. It can be understood that for those skilled in the art, after understanding the principle of the system, it is possible to arbitrarily combine various modules, or form a subsystem to connect with other modules without departing from this principle.
  • the different modules in the acquisition module 310, the image generation module 320, the determination module 330, and the correction module 340 for example, the processing device 140 disclosed in FIG.
  • each module may have its own storage module.
  • each module can share a storage module. Such deformations are all within the protection scope of this application.
  • Fig. 4 is an exemplary flowchart of a method for detecting a state of an imaging device according to some embodiments of the present application.
  • the method 400 for detecting the state of an imaging device may be executed by the state detecting system 100 (such as the processing device 140) or the state correcting device 300 of the imaging device.
  • the state detection method 400 of an imaging device can be stored in a storage device (such as the storage device 150) in the form of a program or instruction.
  • the state detection system 100 such as the processing device 140
  • executes the program or instruction the imaging device can be implemented.
  • the state detection method 400 The operation schematic diagram of the state detection method 400 presented below is illustrative. In some embodiments, one or more undescribed additional operations and/or one or more undiscussed operations may be utilized to complete the process. In addition, the order of operations of the state detection method 400 shown in FIG. 4 and described below is not intended to be limiting.
  • step 410 the processing device 140 may obtain the first background event of the crystal of the detector of the imaging device. In some embodiments, step 410 may be performed by the obtaining module 310.
  • the detector of the imaging device may include multiple detector crystals, and a pair of gamma photons generated by positron annihilation may be received by the crystals of two different detectors.
  • ⁇ photons When ⁇ photons are incident on the detector of the imaging device, a large number of photons are generated on the crystal. The photons are received by the detector and converted into electrical signals.
  • the action position of the ⁇ photons can be calculated.
  • the image has pincushion or barrel distortion, and the actual calculated position may not be the actual position of the gamma photon.
  • the detector needs to use the flood field source to illuminate, and the obtained flood field image is segmented to obtain the response position of each crystal, which is used as a look-up table (LUT) for the position of the crystal of the detector.
  • LUT look-up table
  • the crystal that interacts with the gamma photon can be determined according to the calculated gamma photon's position and the crystal position look-up table, and the actual physical position of the crystal in the system is used as the gamma photon's position to determine the gamma photon's position.
  • the incident position is used to use the flood field source to illuminate, and the obtained flood field image is segmented to obtain the response position of each crystal, which is used as a look-up table (LUT) for the position of the crystal of the detector.
  • the crystal that interacts with the gamma photon can be determined according to the calculated gamma photon's position and the crystal position look-up table, and the actual physical position of the crystal in the system is used as the
  • the accuracy of the crystal position look-up table is related to the accuracy of the detection of the incident position of the gamma photon, and the accuracy of the detection of the incident position of the gamma photon can ensure the image resolution of the imaging device.
  • the crystal position look-up table may be deviated due to unclear flood field images and other reasons, so it needs to be corrected.
  • the crystal of the detector of the imaging device may include scintillation crystals such as sodium iodide (NaI), bismuth germanate (BGO), lutetium silicate (LSO), and yttrium lutetium silicate (LYSO).
  • the yttrium lutetium silicate (LYSO) scintillation crystal detector will be mainly used as an example for description.
  • the processing device 140 may periodically detect the status of the crystal position look-up table of the imaging device 110 based on a preset time interval (eg, one hour, one day, one week, five days, etc.). In some embodiments, the processing device 140 may detect the status of the crystal position look-up table of the imaging device 110 in real time (for example, when the imaging device is idle). For example, the processing device 140 may detect whether the state of the crystal position look-up table of the imaging device 110 is abnormal before the imaging device 110 scans the target object.
  • a preset time interval eg, one hour, one day, one week, five days, etc.
  • the processing device 140 may detect the status of the crystal position look-up table of the imaging device 110 in real time (for example, when the imaging device is idle). For example, the processing device 140 may detect whether the state of the crystal position look-up table of the imaging device 110 is abnormal before the imaging device 110 scans the target object.
  • the background events described in this application are related to the self-radiation particles of the crystal of the detector of the imaging device.
  • the detector crystal as a scintillation crystal of yttrium lutetium silicate (LYSO) as an example, because of the presence of Lu176 in LYSO, the crystal has an inherent radiation phenomenon, which can also be called a background radiation phenomenon.
  • LYSO yttrium lutetium silicate
  • the beta particles produced have a short range, and their energy is mainly deposited in the decayed crystal; the generated gamma photons have high penetrating power and can not only be detected in the decayed crystal. It may also escape being detected by other crystals.
  • the event when the detector receives beta particles and/or gamma photons is called a background event.
  • the background event may include a background single event or a background coincidence event.
  • a particle produced by the decay of Lu176 is only detected in the same crystal, and the event that the detector corresponding to the crystal receives the particle can be called a background single event; the escape of gamma photons produced by the decay is detected by other crystals.
  • the connection between the detector corresponding to the crystal receiving ⁇ particles and the detector corresponding to the crystal receiving ⁇ photons can be called response lines, and the event that the detector receives ⁇ particles and ⁇ photons can be called background coincidence events .
  • the data of beta particles and/or gamma photons received by the detector may be referred to as background event information.
  • the detector of the imaging device may include a crystal array A and a crystal array B.
  • a ⁇ event is generated in the crystal array A, and a corresponding ⁇ event is received in the corresponding crystal array B.
  • the crystal array A couples the light sensor and the front-end circuit, the front-end circuit includes an amplifier, and records beta event information;
  • the crystal array B couples the light sensor and the front-end circuit, and the front-end circuit includes an amplifier, and records the gamma event information.
  • the information of the background coincidence event can be the time information Ta of the ⁇ event received by the crystal array A and the position in the crystal array A of the crystal that received the ⁇ event; the time information Tb of the ⁇ event received by the crystal array B and the reception of ⁇ The position in the crystal array B of the event.
  • the position may be the coordinate position corresponding to the corresponding crystal obtained by establishing a direct coordinate system with the entire detector.
  • the processing device 140 may obtain the first background event of the self-radiated particles of the crystal received by the detector according to a preset energy window.
  • the first background event may be a single background event.
  • the range of the energy window is within a clinical energy window threshold range of the imaging device.
  • the processing device 140 may obtain the first background event of the self-radiation particles of the crystal received by the detector according to a preset time window.
  • the energy window please refer to the related description in FIG. 7, and for more information about the time window, please refer to the related description in FIG. 10, which will not be repeated here.
  • step 420 the processing device 140 may correct the crystal position look-up table based on the first background event.
  • step 420 may be performed by the correction module 340 (such as the LUT correction unit 342).
  • the processing device 140 may determine a single event image based on the first background event; and/or correct the crystal position look-up table based on the single event image.
  • the processing device 140 may determine a single event image based on the first background event; and/or correct the crystal position look-up table based on the single event image.
  • step 430 the processing device 140 may correct the energy state of the imaging device.
  • step 430 may be performed by the correction module 340 (such as the energy state correction unit 344).
  • the digital processing part of the detector can convert the incident gamma photons into electrical signals to obtain information such as their energy, location and time, and then determine the location of the response line where the background event is located through the energy coincidence calculation, and reconstruct it through two-dimensional or three-dimensional tomography
  • the algorithm obtains the distribution of positron nuclides in the target object, thereby observing the physiological and/or biochemical processes in the target object in vitro.
  • the energy calculation of each detector module is performed on the data of the detector module. Therefore, when the detector is determined, the energy calculations between the detection modules are independent of each other. However, there may be differences between the multiple crystals and photoelectric conversion devices used by the detector of the imaging device, and between the circuits.
  • the energy value corresponding to the count peak value detected by each crystal has a certain deviation from the energy value corresponding to the theoretical count peak value. Therefore, imaging is required The energy status of the equipment is corrected.
  • the processing device 140 may periodically perform energy state correction on the imaging device 110 based on a preset time interval (eg, 5 hours, 10 hours, 3 days, 5 days, 1 month, etc.). In some embodiments, the processing device 140 may perform energy state correction on the imaging device when it is in normal use or when the imaging device is idle. In some embodiments, the processing device 140 may perform energy state correction on the detector module of the imaging device after replacement (for example, after one or more detection modules of the imaging device fails and is replaced). In some embodiments, the processing device 140 may perform energy state correction on the imaging device after performing the crystal position look-up table correction on the imaging device. In some embodiments, the processing device 140 may perform energy state correction on the imaging device in response to the abnormal energy state of the imaging device.
  • a preset time interval eg, 5 hours, 10 hours, 3 days, 5 days, 1 month, etc.
  • the processing device 140 may correct the energy state of the imaging device based on the first background event. In some embodiments, the processing device 140 may obtain the third background event of the crystal of the detector of the imaging device, and correct the energy state of the imaging device based on the third background event.
  • the third background event is related to the self-radiation particles of the crystal of the detector of the imaging device, and the third background event may include the background of the self-radiation particles of the crystal received by the detector of the imaging device.
  • Single event or background coincidence event For example, if the event collection mode is a single event mode (correspondingly, the first background event is the background single event), the processing device 140 may first perform a detection of the crystal of the detector of the imaging device 110 based on the background single event in 420.
  • the position look-up table is corrected, and then in 430, based on the background single event, the energy state of the imaging device 110 is corrected.
  • the single event mode may refer to the event collection mode corresponding to the detector of the imaging device when collecting background single events.
  • the processing device 140 may obtain a third background event of the crystal after calibrating the crystal position look-up table of the detector of the imaging device 110 based on the first background event, and perform a correction on the imaging device 110 based on the third background event.
  • the energy state is corrected.
  • the processing device 140 may determine whether the energy state of the imaging device 110 is abnormal. Specifically, the processing device 140 may generate an energy spectrogram based on the energy information of the first background event or the third background event, and determine the peak position of the energy spectrogram; according to the peak value of the energy spectrogram The position, and the corrected peak position corresponding to the peak position, determine the energy correction state of the imaging device; in response to the abnormality of the energy correction state, correct the energy state of the imaging device. In some embodiments, the processing device 140 may directly correct the energy state of the imaging device 110 without determining whether the energy state of the imaging device 110 is abnormal.
  • the third background event may be a background single event
  • the processing device 140 may generate the energy spectrogram based on the energy information of the background single event.
  • the processing device 140 may, according to a preset time window and/or a preset energy window, be based on the particle arrival time of the third background event (that is, the first Three background events (background coincidence events), particle energy information is screened; and the energy spectrogram is generated according to the screened particle energy information.
  • the energy spectrum diagram may include at least one of an all-around peak-to-peak value or a single energy peak.
  • the coincidence event mode may refer to the mode in which the background coincidence event is obtained through coincidence processing after the detector of the imaging device receives the background event.
  • the coincidence event mode may refer to the mode in which the background coincidence event is obtained through coincidence processing after the detector of the imaging device receives the background event.
  • the processing device 140 may determine, based on the first background event or the third background event, at least two energy peaks related to the nuclide decay of the crystal and the at least two energy peaks related to the nuclide decay of the crystal.
  • the ADC value corresponding to the energy peak; and the energy calibration curve of the imaging device is determined according to the at least two energy peaks and the ADC value corresponding to the at least two energy peaks.
  • step 440 the processing device 140 may obtain a second background event of the crystal.
  • step 440 may be performed by the acquisition module 310.
  • the second background event is related to the self-radiating particles of the crystal, and the second background event may be a single background event.
  • the processing device 140 may obtain the second background event after completing the energy state correction of the imaging device, or obtain the second background event before the energy state correction or the crystal position look-up table correction. , This manual does not limit this.
  • the processing device 140 may obtain the second background event of the self-radiated particles of the crystal received by the detector according to a preset energy window.
  • the range of the energy window is within a clinical energy window threshold range of the imaging device.
  • the processing device 140 may obtain the second background event of the crystal's own radiation particles received by the detector according to a preset time window.
  • the range of the time window is within the clinical time window threshold range of the imaging device.
  • step 450 the processing device 140 may correct the flight time state of the probe based on the first background event and the second background event.
  • step 450 may be performed by the correction module 340 (such as the time-of-flight status correction unit 348).
  • the processing device 140 may determine the measured flight time based on the first background event and the second background event, and perform an evaluation of the flight time status of the imaging device as reflected by the measured flight time.
  • the flight time of the detector of the imaging device is corrected.
  • the processing device 140 may obtain a background coincidence event by performing coincidence processing on the first background event and the second background event, and determine the measured flight time and the theoretical flight time based on the information of the background coincidence event;
  • the information of the background coincidence event corrects the flight time of the probe.
  • the background event information may include the arrival time of the particles in the background event to the detector of the imaging device and the corresponding crystal position.
  • the processing device 140 may determine whether the flight time state is abnormal. For more information about flight time correction, please refer to other parts of this manual, for example, Figure 19 and its related description, which will not be repeated here.
  • the processing device 140 may generate an event time spectrum based on the first background event and the second background event; determine the corresponding relationship between the TDC value and time according to the event time spectrum; Relationship to determine the TDC calibration curve of the imaging device.
  • the processing device 140 may obtain the fourth background event of the crystal, and determine the TDC calibration curve of the imaging device based on the fourth background event.
  • the fourth background event is related to the self-radiating particles of the crystal.
  • the fourth background event can include a background single event or a background coincident event.
  • the processing device 140 may generate an event time spectrum based on the fourth background event; determine the corresponding relationship between the TDC value and time based on the event time spectrum; determine the imaging based on the corresponding relationship TDC calibration curve of the device.
  • the processing device 140 may determine the background corresponding to each TDC value based on the background single event or background coincidence event (for example, the fourth background event) of the self-radiation particles of the crystal of the detector received by the detector.
  • the detector of the imaging device can record the arrival time of the particles in the background event to the detector, and convert the arrival time into a corresponding electrical signal (ie, the number of channels).
  • the signal generates the event time spectrum.
  • the greater the total number of collected background events the smaller the error, and the higher the accuracy of the corresponding TDC calibration curve.
  • the processing device 140 may determine the reference TDC value and the reference time corresponding to the reference TDC value based on the event time spectrum. For example, as shown in FIG. 20, the processing device 140 can set the TDC value 60 (the channel value corresponding to the position of the vertical dashed line in FIG. 20) that can make the total number of background events corresponding to the TDC values on the left and right sides of the event time spectrum substantially equal It is determined as the reference TDC value, and it is recorded as i 0 . Then, let the time corresponding to the reference TDC value be T/2 as the reference time, where T represents the clock period of the TDC.
  • T represents the clock period of the TDC.
  • TDC values may be selected as the reference TDC value (for example, the TDC value with a TDC value of 0 in the event time spectrum), and the reference time may be It is an arbitrary time value in [0,T], which is not limited in this manual.
  • the form of the TDC calibration curve may include a curve, a function relationship, a look-up table, etc., which are not limited in this specification.
  • the processing device 140 may determine the time corresponding to any TDC value on the TDC calibration curve based on the TDC calibration curve.
  • the processing device 140 may determine the time corresponding to any TDC value on the TDC scale curve based on the TDC scale curve, and perform flight time correction or time synchronization correction based on the determined time.
  • the processing device 140 may determine the measured flight time and the theoretical flight time according to the first background event and the second background event; according to the measured flight time and the theoretical flight time, the The detector module of the detector performs time synchronization. In some embodiments, the processing device 140 may perform time synchronization on the detector of the imaging device based on the fourth background event.
  • the fourth background event may include the background coincidence event of the crystal's own radiation particles received by the detector of the imaging device 110, and the processing device 140 may determine the measured flight time and the theoretical flight time based on the background coincidence event information. ; In response to the difference between the measured flight time and the theoretical flight time exceeding a threshold, time synchronization is performed on the detector module.
  • the processing device 140 may determine whether the time of the detector module is synchronized. For more information about time synchronization, please refer to other parts of this manual, for example, Figures 16-17 and related descriptions, which will not be repeated here.
  • the processing device 140 may correct the crystal position look-up table and the energy state of the imaging device 110 based on the background single event (for example, the first background event or the second background event) collected at the same time. In some embodiments, the processing device 140 may detect and/or correct and determine the energy correction state of the imaging device 110 based on a single background event or a background coincidence event (for example, a third background event) collected at the same time. Energy scale curve. In some embodiments, the processing device 140 may be based on the background coincidence event collected at the same time (for example, the first background event and the second background event are processed in accordance with the background coincidence event, the third background event, or the first background event).
  • the processing device 140 may determine the TDC calibration curve of the imaging device 110 based on a background single event or a background coincidence event (for example, a third background event or a fourth background event).
  • the processing device 140 may be corrected in response to the crystal position look-up table of the imaging device 110, and perform energy state correction, time synchronization of the detector module, and/or time-of-flight state correction on the imaging device. In some embodiments, the processing device 140 may perform the time synchronization of the detector module and the time-of-flight state correction on the imaging device in response to the energy state of the imaging device 110 being corrected.
  • any operation of energy state detection and/or correction, energy calibration curve determination, time synchronization of the detector module, time-of-flight state correction, and TDC calibration curve determination can be performed separately (that is, the system 100 can target For each state detection or correction, a background event is collected separately, and the same background event data is not shared between various state detection or correction).
  • the processing device 140 may obtain the first background event in response to the abnormal energy state of the imaging device 110, and correct the energy state of the imaging device 110 based on the first background event.
  • the processing device 140 may obtain the first background event and the second background event in response to the abnormal state of the flight time of the imaging device 110, and perform imaging based on the first background event and the second background event. The time-of-flight status of the device 110 is corrected.
  • these amendments and changes are still within the scope of this application.
  • the correspondence between the physical position of the crystal array of the detector receiving the annihilation effect gamma photon and the position decoded on the image can be a linear relationship.
  • the correspondence between the two can be in a nonlinear relationship.
  • the accuracy of detecting the incident position of gamma photons can ensure the image resolution of an imaging device (such as a PET device). Therefore, in order to find the correspondence between the crystal and the image, a crystal position look-up table can be established, and the accurate receiving position of the gamma photon can be determined by the look-up table.
  • LYSO scintillation crystals can be used as the scintillation crystals of the detector of imaging equipment because of its high light output, fast luminescence decay, large effective atomic number, high density, stable physical and chemical properties and high detection efficiency of gamma rays.
  • the Lu176 present in LYSO can release three energy gamma photons with energies of 88keV, 202keV and 307keV and beta particles with a random energy range of 0keV ⁇ 597keV during the decay process.
  • the embodiment of this specification provides a method for correcting the crystal position look-up table, which can couple a crystal array with a certain regular arrangement and a photodetector to form a detector module, under the condition of no radioactive source, using the crystal of the detector.
  • Intrinsic radiation phenomenon collecting background events in a fixed energy interval to form a single-event image, and calibrating and correcting the crystal position look-up table through the single-event image.
  • Fig. 6 is an exemplary block diagram of a crystal position look-up table correction device according to some embodiments of the present application.
  • the crystal position look-up table correction device 600 may include: an acquisition module 610, an image generation module 620, and a correction module 630.
  • the acquisition module 610 and the acquisition module 310 may be modules with the same structure and/or function
  • the image generation module 620 and the image generation module 320 may be modules with the same structure and/or function
  • the LUT correction unit 342 in the module 340 may be a module with the same structure and/or function.
  • the acquiring module 610 may be used to acquire the background event (for example, the first background event) of the self-radiation particles from the crystal of the detector received by the detector of the imaging device.
  • the image generation module 620 may be used to determine a single event image according to the background event.
  • the correction module 630 may be used to correct the crystal position lookup table of the imaging device according to the single event image. For more details about each module of the crystal position look-up table correction device 600, please refer to FIG. 7 and related descriptions, which will not be repeated here.
  • Fig. 7 is an exemplary flow chart of a method for correcting a crystal position look-up table according to some embodiments of the present application.
  • the method 700 for correcting the crystal position look-up table of the imaging device can be executed by the state detection system 100 (such as the processing device 140) of the imaging device, the state correcting device 300 of the imaging device, or the crystal position look-up table correcting device 600.
  • the crystal position look-up table correction method 700 can be stored in a storage device (such as the storage device 150) in the form of a program or instruction.
  • the state detection system 100 such as the processing device 140
  • executes the program or instruction the imaging device can be implemented.
  • Method 700 for the correction of the crystal position look-up table The operation schematic diagram of the crystal position look-up table correction method 700 presented below is illustrative.
  • one or more undescribed additional operations and/or one or more undiscussed operations may be utilized to complete the process.
  • the order of operations of the crystal position look-up table correction method 700 shown in FIG. 7 and described below is not intended to be limiting. As shown in FIG. 7, the method 700 for correcting the crystal position look-up table may include the following steps:
  • Step 710 Acquire the background event of the crystal of the detector of the imaging device.
  • step 710 may be performed by the processing device 140, or the obtaining module 310, or the obtaining module 610.
  • the background event is related to the self-radiating particles of the crystal.
  • the crystal of the detector is a LYSO scintillation crystal
  • the ⁇ particles produced during decay can be absorbed immediately in the crystal of the decayed detector, and the ⁇ photons can reach the opposite crystal through the entire field of view. It is absorbed by the crystal of the corresponding detector.
  • the detector crystal After receiving the ⁇ particle or ⁇ photon, the detector crystal can record the corresponding particle arrival time or photon arrival time, particle energy or photon energy and the corresponding crystal position, that is, the background event information.
  • the processing device 140 may preset the energy window of the detector, and obtain the crystal from the detector received by the detector according to the preset energy window.
  • the background event of the self-radiating particle for example, the first background event.
  • the energy window of the detector can be determined based on the energy resolution. The higher the energy resolution, the smaller the value of the corresponding energy window.
  • a suitable energy window can be set to filter out the received low-energy background radiation particles.
  • the range of the energy window may be within the clinical energy window threshold range of the imaging device (eg, PET device).
  • the processing device 140 may obtain the background event (for example, the first background event) according to the energy window.
  • Step 720 Determine a single event image according to the background event.
  • step 720 may be performed by the processing device 140, or the image generation module 320, or the image generation module 620.
  • the processing device 140 may obtain a single characteristic energy peak event according to the background event; and generate the single event image according to the single characteristic energy peak event. Specifically, the processing device 140 may form a corresponding energy spectrum according to the particle energy or photon energy recorded after the detector receives the beta particle or the gamma photon in the background event. Among them, because Lu176 will release three energies of 88keV, 202keV, and 307keV during the attenuation process, as well as ⁇ particles with a random energy range of 0keV to 597keV, energy superposition can be generated between the three kinds of ⁇ photons and ⁇ particles.
  • a single characteristic energy peak event in the generated energy spectrum may include a characteristic energy peak event formed by the superposition of 88 keV photons and ⁇ particles, a characteristic energy peak event formed by the superposition of 202 keV and ⁇ particles, The characteristic energy peak event formed by the superposition of 307 keV photons and beta particles, the characteristic energy peak event of 597 keV and/or the characteristic energy peak events formed by the superposition of 597 keV photons and beta particles, etc.
  • the single characteristic energy peak event used in this embodiment may include a background event of 597 keV photons received by the detector.
  • the processing device 140 may generate a single event image according to a single characteristic energy peak event of 597 keV photons received by the detector of the imaging device 110.
  • the characteristic energy peak event of 597 keV photons can be used to construct a single event image.
  • the processing device 140 may generate a single event image based on the characteristic energy peak event of the 597 keV photon and the characteristic energy peak event of the photon in a certain energy range around the characteristic energy peak event of the 597 keV photon when constructing the single event image.
  • Step 730 Correct the crystal position lookup table of the imaging device according to the single event image.
  • step 730 may be performed by the processing device 140, the correction module 340, or the correction module 630.
  • the processing device 140 may obtain the pixel distribution corresponding to the position label of the crystal in the crystal position look-up table in the single event image according to the single event image; and/or according to the position label of the crystal
  • the corresponding pixel distribution in the single event image is corrected, and the crystal position look-up table is corrected.
  • the single event image can represent the image formed by photon deposition of fixed energy received by the crystal array of the detector, for example, as shown in FIG. 8A, FIG. 8A is an exemplary single event image, and each of the single event images shown in FIG. 8A A cluster of bright spots represents the mapping position of a detector's crystal in the image.
  • Each crystal of the detector corresponds to a crystal position label according to its position in the detector, that is, each bright spot cluster in a single event image corresponds to a crystal position label. Therefore, according to the single event image, the correspondence between each group of pixel points (ie bright spot clusters) and the crystal position numbers in the single event image can be obtained. According to the correspondence between each group of pixels in the single event image and the crystal position number, the crystal position look-up table of the imaging device can be corrected. For example, the processing device 140 may determine the corresponding number of columns shown in FIG. 8B and the corresponding number of rows shown in FIG. 8C based on the number and/or position of bright spot clusters in the single event image shown in FIG. The number of rows and columns corresponding to each bright spot cluster determines the corresponding crystal position index, so as to correct the crystal position look-up table.
  • the detector crystal of the imaging device 110 can obtain the background coincidence event generated by the background event according to the corrected crystal position look-up table, and the processing device 140 can form the background event energy information including the background event based on the background coincidence event.
  • the lens position look-up table of the imaging device 110 is secondarily corrected according to the coincidence event image to obtain the second-corrected crystal position look-up table.
  • the second-corrected crystal position look-up table can be positioned more accurately The position of the crystal of the detector that receives the background coincidence event.
  • the processing device 140 may determine whether the crystal position lookup table of the imaging device has shifted based on the background event. In some embodiments, the processing device 140 may correct the crystal position look-up table based on the background event in response to an offset of the crystal position look-up table of the imaging device (that is, the state of the crystal position look-up table is abnormal). In some embodiments, the processing device 140 may acquire a single event image, and correct the crystal position look-up table of the imaging device based on the single event image.
  • crystal position look-up table correction method can effectively avoid the use of radioactive sources in daily correction operations, simplify the correction process, effectively use the background event data of the imaging device without patient scanning, and increase the correction frequency to make the imaging device It can adaptively perform iterative correction optimization to improve the performance of imaging equipment.
  • low-energy background events can be filtered out by a limited energy window, and single event data of the detector can be collected to obtain the characteristic peak of 597 keV photons produced by the natural decay of crystal Lu176 Single event image of the event.
  • single-event image of the characteristic peak event of 511keV photon obtained by the Na-22 radiation source it basically presents a similar peak-valley distribution.
  • the crystal position look-up table is corrected, and the corrected crystal position look-up table is used to collect coincident events of the detector of the imaging device, which can improve the imaging resolution of the imaging device.
  • the corrected crystal position look-up table can be directly written into the imaging device, so that during subsequent scanning and imaging, the crystal position look-up table can be used directly without further correction of the crystal position look-up table.
  • the corrected crystal position look-up table can be stored in a storage device (for example, the storage device 150), so that subsequent scan imaging or image reconstruction can be performed based on the crystal position look-up table. .
  • Imaging equipment such as PET equipment
  • This embodiment provides an energy correction state (or energy state) detection method, which can use the background inherent radiation phenomenon of the crystal of the detector under the condition of no radioactive source to collect background events in a fixed energy interval to achieve the Energy status detection.
  • Fig. 9 is an exemplary block diagram of an energy state detection device according to some embodiments of the present application.
  • the energy state detection device 900 may include: an acquisition module 910, a peak position determination module 920, and a state determination module 930.
  • the acquisition module 910 and the acquisition module 310 may be modules with the same structure and/or function
  • the peak position determination module 920 and the peak position determination unit 332 may be modules with the same structure and/or function
  • the state determination module 930 The energy state correction unit 344 may be a module with the same structure and/or function.
  • the acquiring module 910 may be a module having the functions of the acquiring module 310 and the image generating module 320 at the same time.
  • the acquiring module 910 may be used to acquire a background event (for example, the first background event or the third background event) of the crystal of the detector of the imaging device 110 and related information. In some embodiments, the acquisition module 910 may be used to form an energy spectrogram based on the energy information of the background event. In some embodiments, the acquisition module 910 may be used to acquire the event acquisition mode of the detector. For example, the acquisition module 910 may acquire the event acquisition mode of the detector from an input device (for example, the input device of the terminal device 130). In some embodiments, the acquisition module 910 may be used to acquire the energy information of the background event of the self-radiated particles of the crystal of the detector received by the detector according to the event acquisition mode, and form an energy spectrum.
  • a background event for example, the first background event or the third background event
  • the acquisition module 910 may be used to form an energy spectrogram based on the energy information of the background event.
  • the acquisition module 910 may be used to acquire the event acquisition mode of the detector. For example
  • the acquisition module 910 may send the acquired background events and related information to other modules (for example, the image generation module 320), and the other modules generate an energy spectrogram.
  • the peak position determining module 920 can be used to determine the peak position of the energy spectrum.
  • the peak position determining module 920 can obtain at least two peak positions of the energy spectrum according to the energy spectrum.
  • the state determination module 930 may be configured to determine the energy correction state according to the peak position of the energy spectrogram and the corrected peak position corresponding to the peak position of the energy spectrogram.
  • the energy state detection device 900 may further include a correction module (for example, the correction module 340) for correcting the energy state of the imaging device after determining that the energy correction state of the imaging device is abnormal.
  • a correction module for example, the correction module 340
  • FIG. 10 and related descriptions which will not be repeated here.
  • Fig. 10 is an exemplary flowchart of a method for detecting an energy state according to some embodiments of the present application.
  • the method 1000 for detecting the energy state of the imaging device may be executed by the state detection system 100 (such as the processing device 140), the energy state correction unit 344, or the energy state detection device 900 of the imaging device.
  • the energy state detection method 1000 may be stored in a storage device (such as the storage device 150) in the form of a program or instruction.
  • the state detection system 100 such as the processing device 140
  • executes the program or instruction the energy of the imaging device can be realized.
  • State detection method 1000 The operation schematic diagram of the energy state detection method 1000 of the imaging device presented below is illustrative. In some embodiments, one or more undescribed additional operations and/or one or more undiscussed operations may be utilized to complete the process. In addition, the order of operations of the energy state detection method 1000 shown in FIG. 10 and described below is not intended to be limiting. As shown in FIG. 10, the energy state detection method 1000 may include the following steps:
  • Step 1010 Acquire the background event of the crystal of the detector of the imaging device.
  • step 1010 may be performed by the processing device 140, or the obtaining module 310, or the obtaining module 910.
  • the processing device 140 may obtain the background event of the self-radiation particles of the crystal of the detector received by the detector of the imaging device, for example, the first background event or the third background event.
  • the processing device 140 may determine the event collection mode of the detector; according to the event collection mode, obtain the background event of the self-radiation particles of the crystal of the detector received by the detector. In some embodiments, the processing device 140 may determine the detector's event collection mode based on user input. Among them, the event collection mode can include a single event mode and a coincident event mode.
  • Step 1020 Generate an energy spectrogram based on the energy information of the background event.
  • step 1020 may be performed by the processing device 140, or the image generation module 320, or the acquisition module 910.
  • the processing device 140 may generate a corresponding energy spectrum based on the obtained particle energy or photon energy recorded after the detector of the imaging device receives the beta particle or the gamma photon.
  • the energy spectrogram refers to the corresponding relationship between the energy of a particle and the number of corresponding background events.
  • the abscissa is energy, and the ordinate is the number of background events corresponding to the energy.
  • Step 1030 Determine the peak position of the energy spectrum.
  • step 1030 may be performed by the processing device 140, or the peak position determination unit 332, or the peak position determination module 920.
  • the processing device 140 may obtain at least two peak positions of the energy spectrum according to the energy spectrum.
  • the peak position of the energy spectrogram may include at least one of an all-around peak-to-peak position or a single energy peak position.
  • the peak-to-peak position of the almighty energy can be the peak energy position of 597 keV formed by the superposition of gamma photons of three energies.
  • the single energy peak position is the energy peak position formed by the superposition of gamma photons and beta particles.
  • the energy peak position formed by the superposition of 88 keV photons and ⁇ particles For example: the energy peak position formed by the superposition of 88 keV photons and ⁇ particles, the energy peak position formed by the superposition of 202 keV and ⁇ particles, and/or the energy peak positions formed by the superposition of 307 keV photons and ⁇ particles.
  • the omnipotent peak-to-peak position and the single energy peak position can be obtained.
  • the at least two peak positions of the energy spectrum can be the energy peak position of 597 keV, the energy peak position formed by the superposition of 88 keV photons and beta particles, the energy peak position formed by the superposition of 202 keV and beta particles, and/or the photon and 307 keV. At least two of the energy peak positions formed by the superposition of ⁇ particles. If the energy information of the background conforming to the event pattern is used to form an energy spectrogram, a single energy peak position can be obtained.
  • the at least two peak positions of the energy spectrum can be the energy peak position formed by the superposition of 88 keV photons and beta particles, the energy peak position formed by the superposition of 202 keV and beta particles, and/or the energy peak positions formed by the superposition of 307 keV photons and beta particles. At least two of the energy peak positions.
  • Step 1040 Determine the energy correction state according to the peak position of the energy spectrogram and the corrected peak position corresponding to the peak position of the energy spectrogram.
  • step 1040 may be performed by the processing device 140, or the energy state correction unit 344, or the state determination module 930.
  • the processing device 140 may first obtain the corrected peak position corresponding to the peak position of the current energy spectrum before determining the energy correction state of the imaging device.
  • the corrected peak position can correspond to the peak position of the energy spectrum formed by the 511 keV photon.
  • Correction peak position can refer to the traditional imaging equipment (for example, PET equipment) correction method, using radioactive sources such as FDG (fluorodeoxyglucose), Ge68 (germanium-68) and the like emitted by the energy of 511keV gamma photons The peak position of the formed energy spectrum.
  • the processing device 140 may calculate the ratio of the peak position of the energy spectrum to the corrected peak position; compare the ratio with a preset threshold, and if the ratio is not the same as the preset threshold, determine the imaging
  • the energy calibration status of the device is abnormal.
  • the ratio of the peak position of the energy spectrum to the corrected peak position can have a stable relationship. This relationship can be expressed as a fixed value, or as a look-up table in which the energy peak position is related to the ratio.
  • the energy peak position of the background event energy spectrum can change. Further, the ratio between the peak position of the energy spectrum and the corrected peak position can change, so the energy spectrum can be changed.
  • the ratio relationship between the peak position and the corrected peak position is used to judge the energy state, that is, the energy drift. More specifically, a large amount of data can be counted in advance to obtain the ratio relationship between the peak position of the current imaging device's energy spectrum and the corrected peak position; according to a large amount of ratio relationship data, the different peak positions and corrected peak values corresponding to the corresponding imaging device can be obtained. Threshold of the ratio between locations.
  • the peak position of the energy spectrum can be compared with the corrected peak position to obtain the ratio; and then the ratio threshold value of the peak position of the energy spectrum corresponding to the ratio can be obtained. The calculated actual ratio can be compared with the ratio threshold.
  • the ratio is not the same as the corresponding ratio threshold, it is judged that the energy state is abnormal, that is, the current imaging device has energy drift; if the ratio is the same as the corresponding ratio threshold, the energy is judged The state is normal, that is, the energy of the current imaging device has not drifted.
  • background events can be collected through passive detection and the energy state of the imaging device can be detected, which can reduce the radiation dose received by the operator and reduce the hospital’s use cost.
  • active detection its operation is simple. Can be tested at any time.
  • the processing device 140 may adjust the system parameters of the imaging device in response to the abnormality of the energy correction state of the imaging device, so as to correct the energy state of the imaging device. In some embodiments, the processing device 140 may send a prompt message to the user in response to the abnormality of the energy correction state of the imaging device.
  • the event collection mode is a single event mode
  • the processing device 140 can obtain the energy information of the background single event received by the detector and form an energy spectrum; the energy spectrum can include the all-around peak-to-peak value or At least one of a single energy peak.
  • the energy spectrum formed by the energy information of the background single event received by the detector may include the energy peak position of 597 keV, the energy peak position formed by the superposition of 88 keV photons and beta particles, and 202 keV.
  • FIG. 11 is an exemplary energy spectrum generated in the single-event mode. With superposition effect, the actual energy value at this location is greater than 597 keV, which is about 635 keV.
  • the energy correction state of the imaging device (for example, PET device) can be determined.
  • the peak position of the energy of the all-power peak 597 keV is used as an example.
  • the peak position of the energy formed by the superposition of 88 keV photons and ⁇ particles can also be obtained, and the peak position of the energy formed by the superposition of 202 keV and ⁇ particles can also be obtained.
  • the peak position of the formed energy and/or the peak position of the energy formed by the superposition of 307 keV photons and beta particles determines the energy correction state, which is not limited in this specification.
  • the event collection mode is a coincident event mode; the processing device 140 can obtain the information received by the crystal of each detector according to a preset time window; the information can include energy information of particles and/or photons, and The arrival time of particles and/or photons; the processing device 140 may filter the photon energy information according to the arrival time of the photons; generate the energy spectrogram according to the filtered photon energy information, and the energy spectrogram may include a single energy peak .
  • the time window can be used to reflect the sensitivity of an imaging device (for example, a PET device).
  • the range of the time window may not be less than the clinical time window threshold range of the imaging device.
  • the processing device 140 may determine the range of the time window according to the time resolution.
  • the value of the time window may be greater than the value of the time resolution, such as being determined by 1/10 of the height and width of the time distribution curve.
  • the time resolution can refer to the full width at half maximum of the corresponding time difference distribution of the two relative detectors in the known background coincidence event.
  • a suitable time window can be set.
  • the particles received by the crystal of each detector can include beta particles or gamma photons.
  • the absorption time can be expressed as Ta, and ⁇ photons can be detected by absorption through the entire field of view to the opposite detector crystal, and the absorption time can be expressed as Tb, so the detection time of ⁇ events is longer than The detection time of ⁇ event is late, that is, Ta ⁇ Tb.
  • the gamma events in the crystal can be screened out.
  • the photon energy information is screened, that is, the gamma event is screened out.
  • an energy spectrum can be formed according to the filtered photon energy information.
  • Fig. 12 is an energy spectrum diagram generated in a coincident event mode in an embodiment.
  • the peak of the selected gamma photon energy spectrum is relatively clear, and the energy corresponding to the peak position is 307keV.
  • the peak position of the energy spectrum formed by three energy gamma photons with photon energy of 88 keV, 202 keV and/or 307 keV can also be screened out.
  • the energy spectrograms in different event acquisition modes can be obtained according to different event acquisition modes, and furthermore accurate energy peak positions can be obtained.
  • the single event Based on the single event mode acquisition, the single event can be directly detected.
  • the position of the almighty peak of 597 keV in the crystal energy spectrum of the event but the present invention is not limited to the almighty peak.
  • the peak position of the 307keV energy or the peak position of the remaining energy can be detected, so that the subsequent determination of the energy state can be more accurate.
  • the energy scale may refer to the conversion operation of mapping the ADC value of the particle energy collected by the imaging device (for example, the PET device) to the actual energy.
  • the imaging device for example, the PET device
  • the detector of the imaging device After the detector of the imaging device receives the photons, it can excite visible light photons. These photons can be converted into corresponding electrical signals by a photomultiplier tube (PMT) or silicon photomultiplier (SiPM), which can undergo analog-to-digital conversion Generate ADC value.
  • PMT photomultiplier tube
  • SiPM silicon photomultiplier
  • the energy calibration can be completed and the energy calibration curve can be obtained.
  • the ADC value may be a value obtained after analog-to-digital conversion of the collected electrical signal.
  • the method for determining the energy calibration curve provided in this embodiment can collect the background event of gamma photons through the inherent radiation phenomenon of the crystal of the detector, and obtain the characteristic energy peak of 307keV and the characteristic energy of 597keV in the background event energy spectrum obtained by the crystal. At least two characteristic energy peaks such as peaks are used to interpolate and fit the 511 keV characteristic energy peak in practical applications from the at least two characteristic energy peaks to obtain the corresponding relationship between the ADC value and the actual photon energy.
  • Fig. 13 is an exemplary block diagram of a device for determining an energy scale curve according to some embodiments of the present application.
  • the energy calibration curve determination device 1300 may include: an acquisition module 1310, an event screening module 1320, and a curve determination module 1330.
  • the acquisition module 1310 and the acquisition module 310 may be modules with the same structure and/or function, and the energy state correction unit 344 may have the functions of the event screening module 1320 and the curve determination module 1330 at the same time.
  • the acquiring module 1310 may be used to acquire the background event (for example, the third background event) of the radiation particles from the crystal itself received by the detector.
  • the event screening module 1320 can be used to screen the background event and determine at least two energy peaks related to the nuclide decay of the crystal and ADC values corresponding to the at least two energy peaks.
  • the curve determination module 1330 may be configured to determine the energy scale curve according to the at least two energy peaks and ADC values corresponding to the at least two energy peaks.
  • the energy calibration curve determination device 1300 may further include an extraction module. The extraction module may be used to determine the ADC value corresponding to any energy peak value on the energy scale curve according to the energy scale curve.
  • the extraction module can also be used to determine the ADC value corresponding to the peak energy of 511 keV according to the energy calibration curve.
  • the extraction module can also be used to determine the ADC value corresponding to the peak energy of 511 keV according to the energy calibration curve.
  • Fig. 14 is an exemplary flowchart of a method for determining an energy scale curve according to some embodiments of the present application.
  • the method 1400 for determining the energy scale curve of the imaging device may be executed by the state detection system 100 (such as the processing device 140) of the imaging device, the energy state correction unit 344, or the device 1300 for determining the energy scale curve.
  • the energy calibration curve determination method 1400 can be stored in a storage device (such as the storage device 150) in the form of a program or instruction.
  • the state detection system 100 such as the processing device 140
  • the energy calibration curve can be implemented. Determine method 1400.
  • the operation schematic diagram of the energy calibration curve determination method 1400 presented below is illustrative. In some embodiments, one or more undescribed additional operations and/or one or more undiscussed operations may be utilized to complete the process.
  • the order of operations of the energy scale curve determination method 1400 shown in FIG. 14 and described below is not intended to be limiting. As shown in FIG. 14, the method 1400 for determining an energy calibration curve may include the following steps:
  • Step 1410 Acquire the background event of the crystal of the detector of the imaging device.
  • step 1410 may be performed by the processing device 140, or the obtaining module 310, or the obtaining module 1310.
  • the processing device 140 may obtain the background event (for example, the first background event or the third background event) related to the self-radiation particles of the crystal of the detector received by the detector.
  • the imaging equipment collects background events in the passive state during idle time. Since the proportion of various scattering events in the background is relatively high, it is easy to reduce the signal-to-noise ratio of the ⁇ characteristic energy peak of the background energy spectrum. In theory, the longer the collection time of the event, the better.
  • the collection time of background events can be in the range of 0.1-20 hours. For example, the collection time may not be less than 30 minutes.
  • the time window and the energy window of the imaging device may be preset; and the background event is acquired based on the time window and the energy window.
  • the energy window please refer to the related description in FIG. 7, and for more information about the time window, please refer to the related description in FIG. 10, which will not be repeated here.
  • Step 1420 Based on the background event, determine at least two energy peaks related to the nuclide decay of the crystal and ADC values corresponding to the at least two energy peaks.
  • step 1420 may be performed by the processing device 140, the event screening module 1320, or the energy state correction unit 344.
  • the processing device can determine the gamma decay characteristic energy peak value of the crystal nuclide based on the background event; perform analog-to-digital conversion on the gamma decay characteristic energy peak value of the nuclide to obtain the corresponding characteristic energy ADC value corresponding to the peak value; selecting the at least two energy peak values and the ADC value corresponding to the at least two energy peak values in the gamma decay characteristic energy peak value.
  • the processing device 140 may generate a corresponding energy spectrogram according to the background event, and by performing energy screening on the energy spectrogram, the characteristic energy peak of gamma decay of the nuclide can be obtained.
  • the nuclide may include radioactive nuclide present in the crystal of a detector such as Lu176.
  • the characteristic gamma decay energy peak corresponding to Lu176 can include: gamma decay characteristic energy peak of 88keV photon, gamma decay characteristic energy peak of 202keV photon, gamma decay characteristic energy peak of 307keV photon, 597keV photon
  • the ADC value of the corresponding ⁇ decay characteristic energy peak can be obtained by performing analog-to-digital conversion on the acquired ⁇ decay characteristic energy peak.
  • part of the gamma decay characteristic energy peaks and their corresponding ADC values can be selected from them.
  • at least two characteristic energy peaks for example, 0 keV, 307 keV, 597 keV, etc.
  • the ADC values corresponding to the corresponding ⁇ characteristic energy peaks can be selected.
  • Step 1430 Determine the energy scale curve according to the at least two energy peaks and ADC values corresponding to the at least two energy peaks.
  • step 1430 may be performed by the processing device 140, the curve determination module 1330, or the energy state correction unit 344.
  • the processing device 140 may determine the energy calibration curve through interpolation fitting. Specifically, the processing device 140 may perform interpolation fitting on the multiple ADC values and corresponding ⁇ characteristic energy peaks to obtain an energy calibration curve. For example, the processing device 140 may perform interpolation fitting according to the selected three ⁇ characteristic energy peaks of 0 keV, 307 keV, and 597 keV and the ADC value corresponding to the ⁇ characteristic energy peak to obtain an energy calibration curve.
  • the energy scale curve can cover all energy ranges, for example, the energy range can be 0 to 2000 keV.
  • the energy calibration curve can be used to determine the corresponding energy peak value on the energy calibration curve.
  • ADC value that is, according to the energy calibration curve, all energy peaks and corresponding ADC values can be obtained.
  • various drugs with various characteristic peak nuclides
  • photons of corresponding energy can be detected. Therefore, it is necessary to obtain all the characteristics in advance. Energy peak value and corresponding ADC value.
  • the ADC value corresponding to the 511 keV energy peak may be determined according to the energy calibration curve.
  • the peak energy of 511 keV is a characteristic peak produced by the more commonly used radionuclide injections. Therefore, the ADC value corresponding to the peak energy of 511 keV can be obtained according to the energy calibration curve in advance.
  • the above method for determining the energy calibration curve can avoid the use of radioactive sources, improve the safety and feasibility of the operation, and effectively use the background event data of the PET imaging equipment without patient scanning, which can be more effective and timely.
  • the energy calibration curve of the detector is updated.
  • a method for calibrating the energy of the crystal of the detector of the imaging device is also provided.
  • the ADC value corresponding to the peak energy of 511 keV can be determined according to the energy calibration curve, so as to calibrate the photon energy received by the detector.
  • the detector can distinguish the received energy more accurately, and further improve the imaging accuracy of the imaging device.
  • the detector of an imaging device (such as a PET device) receives a pair of gamma photons generated by positron annihilation
  • the corresponding detector module needs to measure the time when the gamma photons reach the detector crystal.
  • the detector needs to be The time of the module is aligned.
  • a cable can be used for time synchronization, and each detector module is connected by the cable, and pulses are sent to each detector module through the cable at the same time.
  • the detector module can set the local clock to zero according to the pulse, thereby completing clock synchronization.
  • This application provides a time synchronization method, which can use the background inherent radiation phenomenon of the detector's crystal under the condition of no radioactive source to collect the corresponding background event, and determine the measurement flight time and theoretical flight based on the information of the background event Time, according to the measured flight time and the theoretical flight time, time synchronization is performed on the detector module of the detector.
  • Fig. 15 is an exemplary block diagram of a time synchronization device according to some embodiments of the present application.
  • the time synchronization apparatus 1500 may include an acquisition module 1510, a time determination module 1520, and a time synchronization module 1530.
  • the acquisition module 1510 and the acquisition module 310 may be modules with the same structure and/or function
  • the time determination module 1520 and the time determination unit 334 may be modules with the same structure and/or function
  • the time synchronization module 1530 and The time synchronization unit 346 may be a module with the same structure and/or function.
  • the acquisition module 1510 may be used to acquire a background coincidence event of a crystal of a detector of an imaging device and related information, where the background coincidence event is related to the self-radiation particles of the crystal.
  • the time determination module 1520 may be used to calculate the measured flight time and the theoretical flight time according to the information of the background coincidence event.
  • the time synchronization module 1530 may be used to synchronize the time of the probe according to the measured flight time and the theoretical flight time. For more content of each module of the time synchronization device 1500, please refer to FIG. 16 and related descriptions, which will not be repeated here.
  • Fig. 16 is an exemplary flowchart of a time synchronization method according to some embodiments of the present application.
  • the time synchronization method 1600 of the imaging device may be executed by the state detection system 100 (such as the processing device 140) or the time synchronization apparatus 1500 of the imaging device.
  • the time synchronization method 1600 may be stored in a storage device (such as the storage device 150) in the form of a program or instruction.
  • the state detection system 100 such as the processing device 140
  • the time synchronization method 1600 may be implemented.
  • the schematic operation of the time synchronization method 1600 presented below is illustrative. In some embodiments, one or more undescribed additional operations and/or one or more undiscussed operations may be utilized to complete the process.
  • the order of operations of the time synchronization method 1600 shown in FIG. 16 and described below is not intended to be limiting. As shown in FIG. 16, the time synchronization method 1600 may include the following steps:
  • Step 1610 Obtain the background coincidence event of the crystal of the detector of the imaging device.
  • step 1610 may be performed by the processing device 140, or the obtaining module 310, or the obtaining module 1510.
  • the processing device 140 may obtain the background coincidence events related to the self-radiation particles of the crystal of the detector received by the detector of the imaging device (for example, the coincidence processing based on the first background event and the second background event)
  • the obtained background conforms to the information of the event, or the third background event, or the fourth background event).
  • Step 1620 Determine the measured flight time and the theoretical flight time according to the information of the background coincidence event.
  • step 1620 may be performed by the processing device 140, or the time determining unit 334, or the time determining module 1520.
  • the processing device 140 can obtain the corresponding background coincidence event according to the time when the two particles in each background coincidence event are detected by the crystal in the detector module (that is, the arrival time of the detector). Measured flight time; According to the crystal positions of the two particles in each background coincidence event, the theoretical flight time of the corresponding background coincidence event is obtained.
  • Figure 17 is a schematic diagram of an exemplary detector module receiving photons. Just as an example, as shown in Figure 17, if a crystal in one of the detector modules of the detector receives the first particle (for example, beta particles) for T1, a crystal in the other detector module receives The time of the second particle (for example, gamma photon) is T2.
  • the time T1 of receiving the first particle can be subtracted from the time T2 of receiving the second particle to obtain the measured flight time of the corresponding coincident event. If the detector crystal that receives the first particle is A and the detector crystal that receives the second particle is B, then the linear distance L between the detector crystal A and the detector crystal B can be obtained, and then use the straight line Divide the distance L by the speed of light C to get the theoretical flight time.
  • Step 1630 Perform time synchronization on the detector according to the measured flight time and the theoretical flight time.
  • step 1630 may be performed by the processing device 140, or the time synchronization unit 346, or the time synchronization module 1530.
  • the processing device 140 may respond to the difference between the measured flight time and the theoretical flight time of the corresponding background coincidence event (for example, the difference between the measured flight time and the theoretical flight time is greater than a threshold), and determine the imaging device's The time between the detector modules is not synchronized; in response to the measured flight time being the same as the theoretical flight time of the corresponding background coincidence event (for example, the difference between the measured flight time and the theoretical flight time is not greater than the threshold), the imaging is determined The time between the detector modules of the device is synchronized.
  • the threshold may be the clock period of the detector module.
  • the processing device 140 can perform the processing on each detector module of the detector of the imaging device according to the measured flight time and the corresponding theoretical flight time. Time synchronization.
  • the processing device 140 may determine the time difference according to the measured flight time and the theoretical flight time; and perform time synchronization on each detector module of the imaging device according to the time difference. For example, the processing device 140 may obtain the time difference by subtracting the theoretical flight time from the measured flight time (or obtain the time difference by subtracting the measured flight time from the theoretical flight time), and synchronize the time of each detector module of the imaging device according to the absolute value of the time difference.
  • the processing device 140 may calculate the multiple measured flight times and the multiple theoretical flight times received by any pair of detector modules of the imaging device’s detector.
  • the difference between multiple measured flight times and multiple theoretical flight times can be calculated for the same pair of detector modules, that is, first obtain multiple background coincidence events detected by the same pair of detector modules For each background coincidence event, the time when two particles in the information of the background coincidence event are detected by the crystal in the detector module (that is, the time when the two particles reach the detector module) and the detection of the background coincidence Calculate the measured flight time and theoretical flight time of the crystal position in the detector module of the event, and then calculate the difference between the measured flight time and the theoretical flight time of the corresponding background coincidence event; by comparing the difference between multiple background coincidence events The value is averaged to determine the time difference, and then the crystals of each detector module of the imaging device are time synchronized through the time difference. This method can make time synchronization more accurate.
  • the time difference may be greater than or equal to one clock cycle.
  • Each detector module of the detector of the imaging device includes a counter, which can be used as a clock of all detector crystals in the corresponding detector module to record the current time. That is, the detector crystals belonging to the same detector module use the same clock. After each cycle, the counter will increase by 1.
  • the process of clock synchronization can be a process of counter alignment. Synchronize the clocks of each detector crystal, that is, synchronize the clocks of the corresponding detector modules (for example, the counters of each detector module can be aligned).
  • the processing device 140 may adjust the value of the counter of one of the pair of detector modules, and determine the value of the adjusted counter as Time reference standard. In some embodiments, if the time difference is less than one clock cycle, there is no need to adjust the corresponding counter; if the time difference is greater than or equal to one clock cycle, adjust the counter of any detector module in a pair of detector module counters, for example , Add 1 or subtract 1 to the counter to make it the same as the value of the counter of the other detector module in the pair of detector modules. After the adjustment is completed, you can continue to obtain information about the background coincidence event of the detector crystal's own radiation particles, and then calculate the time difference based on the background coincidence event information. If the time difference is less than one clock cycle, the clock synchronization is completed; if the time difference is greater than or equal to One clock cycle, continue to adjust the counter until the detected time difference is less than one clock cycle.
  • one of the detector modules in any pair of detector modules can be used as the reference module, and the other detector modules except the pair of detector modules in the imaging device can be time-synchronized until all the detector modules are detected.
  • the time difference between the device modules is less than one clock cycle.
  • the clocks of any pair of detector modules in the detector can be synchronized first, and after the synchronization is completed, any detector module of the pair of detector modules that has been synchronized can be used as The reference module then synchronizes the time of all other detector modules in sequence until the time difference between all the detector modules is less than one clock cycle.
  • the imaging device may include a control module, and the control module may output a control signal according to the comparison result of the time difference and a clock period. If the time difference is greater than or equal to a clock period, the control module will generate an adjustment signal to adjust each detector module Counter to achieve clock alignment; if the time difference is less than one clock cycle, no adjustment signal is generated.
  • the inherent radiation phenomenon of the detector crystal background is used to synchronize the clock between the detector modules, and the synchronization status is monitored in real time, which can simplify the structure of the imaging device, increase the reliability of the device, and avoid the clock caused by cables and other reasons. Synchronization failure problem.
  • the embodiment of the application provides a method for detecting the time-of-flight state. Under the condition of no radioactive source, the background inherent radiation phenomenon of the crystal of the detector is used to collect background coincidence events, and based on the background coincidence event information, the imaging equipment Correction of the flight time status can solve the problems of high radiation dose to the operator, high hospital cost and complicated operation.
  • Fig. 18 is an exemplary block diagram of a time-of-flight state detection device according to some embodiments of the present application.
  • the time-of-flight status detection device 1800 may include an acquisition module 1810, a time-of-flight determination module 1820, and a status determination module 1830.
  • the acquisition module 1810 and the acquisition module 310 may be modules with the same structure and/or function
  • the flight time determination module 1820 and the time determination unit 334 may be modules with the same structure and/or function
  • the state determination module 1830 The time-of-flight state correction unit 348 may be a module with the same structure and/or function.
  • the obtaining module 1810 may be used to obtain background coincidence events (for example, the third background event or the fourth background event) and related information.
  • the acquisition module 1810 may also be used to determine a time window and an energy window of the imaging device; and to acquire a background coincidence event based on the time window and the energy window.
  • the flight time determination module 1820 may be used to calculate the measured flight time and the theoretical flight time according to the information of the background coincidence event.
  • the state determination module 1830 may be used to determine the flight time state of the imaging device according to the measured flight time and the theoretical flight time.
  • the time-of-flight status detection device 1800 may further include a correction module.
  • the correction module may be used to perform correction according to the flight time of the imaging device to obtain the corrected flight time.
  • the correction module may also be used to obtain the energy-time mapping relationship; the energy-time mapping relationship reflects the mapping relationship between the particle energy and the time-of-flight offset; and the background conforms to the two events in the event. The energy of each particle and the energy-time mapping relationship are obtained to obtain the flight time offset of the corresponding background coincidence event; the flight time of the imaging device is corrected according to the flight time offset to obtain the corrected flight time.
  • Fig. 19 is an exemplary flow chart of a time-of-flight state detection method according to some embodiments of the present application.
  • the method 1900 for detecting the time of flight state (ie, TOF state) of the imaging device may be executed by the state detection system 100 (such as the processing device 140) or the time of flight state detection device 1800 of the imaging device.
  • the time-of-flight state detection method 1900 may be stored in a storage device (such as the storage device 150) in the form of a program or instruction.
  • the state detection system 100 such as the processing device 140
  • the time-of-flight state can be realized.
  • Detection method 1900 The operational schematic diagram of the time-of-flight state detection method 1900 presented below is illustrative.
  • a method 1900 for detecting a time-of-flight state may include:
  • Step 1910 Obtain the background coincidence event of the crystal of the detector of the imaging device.
  • step 1910 may be performed by the processing device 140, or the obtaining module 310, or the obtaining module 1810.
  • the processing device 140 may obtain the background coincidence event (for example, the third background event or the fourth background event) related to the self-radiation particles of the crystal of the detector received by the detector of the imaging device.
  • the processing device 140 may determine the time window and the energy window of the imaging device; based on the time window and the energy window, obtain the background coincidence event of the crystal's own radiation particles received by the detector and its Related Information. For more information about each module of the energy calibration curve determination device 1300, please refer to FIG. 14 and related descriptions, which will not be repeated here.
  • the processing device 140 may obtain a background coincidence event through coincidence processing based on two different sets of background single events (for example, a first background event and a second background event).
  • Step 1920 Determine the measured flight time and the theoretical flight time according to the information of the background coincidence event.
  • step 1920 may be performed by the processing device 140, the time determination unit 334, or the flight time determination module 1820.
  • the processing device 140 can obtain the measured flight time of the corresponding background coincidence event according to the arrival time of the two particles in the background coincidence event; according to the background coincidence event, the measured flight time of the two particles in the background coincidence event The position of the crystal is obtained, and the theoretical flight time of the corresponding background coincidence event is obtained.
  • measuring flight time and theoretical flight time please refer to Figure 16 and its related descriptions, which will not be repeated here.
  • Step 1930 Determine a time-of-flight state of the imaging device according to the measured time-of-flight and the theoretical time-of-flight, and the time-of-flight state can reflect whether the detector crystal drifts.
  • step 1930 may be performed by the processing device 140, the time-of-flight state correction unit, or the state determination module 1830.
  • the processing device 140 may compare the difference between the measured flight time and the theoretical flight time. In response to the difference between the measured flight time and the theoretical flight time exceeding a threshold, the processing device 140 may determine that the crystal corresponding to the background coincidence event has drifted, that is, the flight time state is abnormal.
  • the detector corresponding to the background coincidence event can be determined If the measured flight time is the same as the theoretical flight time of the corresponding background coincidence event (for example, the difference between the measured flight time and the theoretical flight time is not greater than a threshold), it can be considered that the background coincidence event corresponds to The crystal of the detector is normal and there is no drift.
  • the TOF correction state ie, TOF state
  • the measured flight time and the theoretical flight time can be equal, that is, the difference between them is close to zero.
  • the processing device 140 may calculate the difference between the measured flight time and the theoretical flight time of all background coincidence events on the crystal of each detector, based on the average value of the difference between all background coincidence events, or Whether the expected value after Gaussian fitting exceeds the threshold, confirm whether the corresponding crystal is shifted.
  • the processing device 140 may correct the flight time of the detector according to the background coincidence event information to obtain the corrected flight time.
  • the processing device 140 may obtain the energy-time mapping relationship.
  • the energy-time mapping relationship may reflect the corresponding relationship between particle energy and flight time offset.
  • the flight time offset of the corresponding background coincidence event can be obtained according to the energy of the two particles in each of the background coincidence events and the energy-time mapping relationship.
  • the flight time of the detector can be corrected according to the flight time offset to obtain the corrected flight time.
  • the background coincidence event information may include the energy of two particles.
  • the crystal array A and the crystal array B are respectively coupled with the light sensor, the output signal is amplified by the amplifier, and the time information Ta of the ⁇ event and the time information Tb of the ⁇ event are obtained, and the energy information Ea and Ea of the two events are obtained by integration.
  • the energy-time mapping relationship can be established in advance. Specifically, according to an imaging device (for example, a PET device) that has completed flight time correction, count the flight time offsets corresponding to a large number of background coincident events with two particles of different energies, and establish the energy and flight time of the two particles. The corresponding relationship between the time offsets, that is, the energy-time mapping relationship. In actual use, you can first obtain the pre-established energy-time mapping relationship, and then obtain the background energies of the two particles in the event. Find the energy-time mapping relationship based on the energy of the two particles in the background coincidence event, determine the flight time offset corresponding to the energy of the two particles, and correct the flight time of the detector based on the flight time offset, and get the corrected Flight time.
  • an imaging device for example, a PET device
  • the flight time offsets that is, the energy and flight time of the two particles.
  • the corresponding relationship between the time offsets that is, the energy-time mapping relationship.
  • the time-of-flight status detection method can obtain multiple sets of background coincidence events through different time windows based on the inherent radioactive phenomenon of the LYSO background. According to the different absorption characteristics of ⁇ and ⁇ particles, a correction is made for each pair of background coincidence events. Through multiple sets of background coincidence events, the TOF state of all detector crystals can be measured, and the flight time of the imaging device can be corrected through the energy-time mapping relationship, so as to obtain more accurate TOF information. Using the above flight time correction method can save correction time and improve the accuracy of flight time correction.
  • the modules of the above-mentioned devices may be functional modules or program modules. , It can be realized by software or hardware.
  • the foregoing modules may be located in the same processor (for example, the processing device 140); or the foregoing modules may also be located in different processors in any combination.
  • this application uses specific words to describe the embodiments of this application.
  • “one embodiment”, “an embodiment”, and/or “some embodiments” mean a certain feature, structure, or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that “one embodiment” or “one embodiment” or “an alternative embodiment” mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. .
  • certain features, structures, or characteristics in one or more embodiments of the present application can be appropriately combined.
  • a computer storage medium may contain a propagated data signal containing a computer program code, for example on a baseband or as part of a carrier wave.
  • the propagated signal may have multiple manifestations, including electromagnetic forms, optical forms, etc., or suitable combinations.
  • the computer storage medium may be any computer readable medium other than the computer readable storage medium, and the medium may be connected to an instruction execution system, device, or device to realize communication, dissemination, or transmission of the program for use.
  • the program code located on the computer storage medium can be transmitted through any suitable medium, including radio, cable, fiber optic cable, RF, or similar medium, or any combination of the above medium.
  • the computer program codes required for the operation of each part of this application can be written in any one or more programming languages, including object-oriented programming languages such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python Etc., conventional programming languages such as C language, Visual Basic, Fortran 2003, Perl, COBOL 2002, PHP, ABAP, dynamic programming languages such as Python, Ruby and Groovy, or other programming languages.
  • the program code can run entirely on the user's computer, or run as an independent software package on the user's computer, or partly run on the user's computer and partly run on a remote computer, or run entirely on the remote computer or server.
  • the remote computer can be connected to the user's computer through any network form, such as a local area network (LAN) or a wide area network (WAN), or connected to an external computer (for example, via the Internet), or in a cloud computing environment, or as a service Use software as a service (SaaS).
  • LAN local area network
  • WAN wide area network
  • SaaS service Use software as a service
  • numbers describing the number of ingredients and attributes are used. It should be understood that such numbers used in the description of the embodiments use the modifiers "approximately”, “approximately” or “substantially” in some examples. Retouch. Unless otherwise stated, “approximately”, “approximately” or “substantially” indicates that the number is allowed to vary by ⁇ 20%.
  • the numerical parameters used in the specification and claims are approximate values, and the approximate values can be changed according to the required characteristics of individual embodiments. In some embodiments, the numerical parameter should consider the prescribed effective digits and adopt the method of general digit retention. Although the numerical ranges and parameters used to confirm the breadth of the range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values is as accurate as possible within the feasible range.

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Abstract

本说明书实施例提供一种成像设备的状态检测方法和系统。所述方法包括：获取所述成像设备的探测器的晶体的第一本底事件，所述第一本底事件与所述晶体的自身辐射粒子有关；基于所述第一本底事件，对所述晶体位置查找表进行校正；对所述成像设备的能量状态进行校正；获取所述晶体的第二本底事件，所述第二本底事件与所述晶体的自身辐射粒子有关；基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正。

Description

一种成像设备的状态检测方法和系统
交叉引用
本申请要求2020年5月25日提交的中国申请号202010448695.5的优先权，2020年5月25日提交的中国申请号202010448693.6的优先权，2020年6月29日提交的中国申请号202010604518.1的优先权，2020年6月29日提交的中国申请号202010604531.7的优先权，2020年7月2日提交的中国申请号202010626175.9的优先权，全部内容通过引用并入本文。
技术领域
本申请涉及成像技术领域，特别涉及一种成像设备的状态检测方法和系统。
背景技术
成像技术已广泛应用于生物检测、医学诊断等领域。以正电子发射计算机断层扫描为例，正电子发射计算机断层扫描(Positron Emission Computed Tomography，PET)是核医学领域比较先进的临床检查影像技术。PET成像中，将放射性核素注射到目标对象体内，使得目标对象体内某种物质(一般是生物生命代谢中必须的物质，例如：葡萄糖、蛋白质、核酸、脂肪酸等)标记上短寿命的放射性核素(如F18，碳11等)。注入人体后，放射性核素在衰变过程中释放出正电子，一个正电子在行进十分之几毫米到几毫米后遇到一个电子后发生湮灭，从而产生方向相反的一对能量为511keV的光子。光子信号可通过高度灵敏的照相机捕捉，并经计算机进行散射和随机信息的校正。经过对不同的正电子进行相同的分析处理，可以得到反映放射性核素在目标对象体内聚集情况的三维图像，从而达到诊断的目的。PET扫描具有灵敏度高、特异性高以及安全性好等特点，因此，在医疗领域被广泛应用。为提高PET设备采集数据的准确性、PET图像质量，需要对PET设备的状态进行检测和/或校正。
因此，希望提供一种成像设备(例如PET成像设备)的状态检测方法和系统。
发明内容
本说明书的一方面提供一种成像设备的状态检测方法。所述方法包括：获取所述成像设备的探测器的晶体的第一本底事件，所述第一本底事件与所述晶体的自身辐射粒子有关；基于所述第一本底事件，对所述晶体位置查找表进行校正；对所述成像设备的能量状态进行校正；获取所述晶体的第二本底事件，所述第二本底事件与所述晶体的自身辐射粒子有关；基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正。
在一些实施例中，所述获取所述成像设备的探测器的晶体的第一本底事件包括：根据预设能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的第一本底事件；所述基于 所述第一本底事件，对所述晶体位置查找表进行校正包括：基于所述第一本底事件，确定单事件图像；根据所述单事件图像，对所述晶体位置查找表进行校正。
在一些实施例中，所述对所述成像设备的能量状态进行校正包括：基于所述第一本底事件，对所述成像设备的能量状态进行校正。
在一些实施例中，所述对所述成像设备的能量状态进行校正包括：获取所述晶体的第三本底事件，所述第三本底事件与所述晶体的自身辐射粒子有关，所述第三本底事件包括所述探测器接收到的所述晶体的自身辐射粒子的本底单事件或本底符合事件；基于所述第三本底事件，对所述成像设备的能量状态进行校正。
在一些实施例中，所述对所述成像设备的能量状态进行校正，包括：基于所述第一本底事件或所述第三本底事件的能量信息生成能谱图；确定所述能谱图的峰值位置；根据所述能谱图的峰值位置，以及与所述峰值位置对应的校正峰值位置，确定所述成像设备的能量校正状态；根据所述能量校正状态对所述成像设备的能量状态进行校正。
在一些实施例中，所述对所述成像设备的能量状态进行校正包括：基于所述第一本底事件或所述第三本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值；根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述成像设备的能量刻度曲线。
在一些实施例中，所述基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正包括：根据所述第一本底事件和所述第二本底事件，确定测量飞行时间；根据所述测量飞行时间所反映的所述成像设备的飞行时间状态对所述探测器的飞行时间进行校正。
在一些实施例中，所述方法还包括：根据所述第一本底事件和/或所述第二本底事件，生成事件时刻谱；根据所述事件时刻谱，确定TDC值与时间的对应关系；根据所述对应关系，确定所述成像设备的TDC刻度曲线。
在一些实施例中，所述方法还包括：获取所述晶体的第四本底事件，所述第四本底事件与所述晶体的自身辐射粒子有关；基于所述第四本底事件，生成事件时刻谱；根据所述事件时刻谱，确定TDC值与时间的对应关系；根据所述对应关系，确定所述成像设备的TDC刻度曲线。
在一些实施例中，所述方法还包括：根据所述第一本底事件和所述第二本底事件，确定测量飞行时间以及理论飞行时间；根据所述测量飞行时间以及所述理论飞行时间，对所述探测器的探测器模块进行时间同步。
本说明书的一方面提供一种晶体位置查找表校正方法。所述方法包括：获取成像设备的探测器的晶体的本底事件，所述本底事件与所述晶体的自身辐射粒子有关；基于所述本底事件，确定单事件图像；根据所述单事件图像，对所述成像设备的晶体位置查找表进行校正。
在一些实施例中，所述获取成像设备的探测器的晶体的本底事件包括：确定所述成像设备的探测器的能量窗；根据所述能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的本底事件。
在一些实施例中，所述能量窗的范围在所述成像设备的临床能量窗阈值范围之内。
在一些实施例中，所述基于所述本底事件，确定单事件图像包括：基于所述本底事件，确定单一特征能峰事件；根据所述单一特征能峰事件，生成所述单事件图像。
在一些实施例中，所述单一特征能峰事件包括所述探测器接收到的597keV光子的事件。
在一些实施例中，所述根据所述单事件图像，对所述成像设备的晶体位置查找表进行校正包括：根据所述单事件图像，获取所述晶体位置查找表中所述晶体的位置标号在所述单事件图像中的对应像素分布；根据所述晶体的位置标号在所述单事件图像中的对应像素分布，校正所述晶体位置查找表。
在一些实施例中，所述方法进一步包括：基于所述本底事件，确定所述成像设备的晶体位置查找表是否发生偏移。
本说明书的一方面提供一种能量校正状态检测方法。所述方法包括：获取成像设备的探测器的晶体的本底事件，所述本底事件与所述晶体的自身辐射粒子有关；基于所述本底事件的能量信息生成能谱图；确定所述能谱图的峰值位置；根据所述能谱图的峰值位置，以及与所述能谱图的峰值位置对应的校正峰值位置，确定所述能量校正状态。
在一些实施例中，所述获取成像设备的探测器的晶体的本底事件包括：确定所述探测器的事件采集模式；根据所述事件采集模式，获取所述探测器接收到的所述探测器的晶体的自身辐射粒子的本底事件。
在一些实施例中，所述事件采集模式包括单事件模式，所述基于所述本底事件的能量信息生成能谱图包括：基于所述探测器在所述单事件模式下接收到的本底事件的能量信息生成所述能谱图，其中，所述能谱图包括全能峰峰值或单一能量峰值中的至少一种。
在一些实施例中，所述事件采集模式包括符合事件模式，所述根据所述事件采集模式，获取所述探测器接收到的所述探测器的晶体的自身辐射粒子的本底事件包括：根据预设时间窗和/或预设能量窗，获取所述探测器在所述符合事件模式下接收到的所述探测器的晶体的自 身辐射粒子的本底事件。
在一些实施例中，所述基于所述本底事件的能量信息生成能谱图包括：根据所述本底事件的粒子到达时间，筛选粒子能量信息；根据筛选后的所述粒子能量信息生成所述能谱图，所述能谱图包括单一能量峰值。
在一些实施例中，所述预设时间窗的范围不小于所述成像设备的临床时间窗阈值范围。
在一些实施例中，所述根据所述能谱图的峰值位置，以及与所述能谱图的峰值位置对应的校正峰值位置，确定所述能量校正状态包括：确定所述能谱图的峰值位置与所述校正峰值位置的比值；基于所述比值，确定所述成像设备的能量校正状态是否异常。
在一些实施例中，所述能谱图的峰值位置包括全能峰峰值位置或单一能量峰峰值位置中的至少一种。
在一些实施例中，所述校正峰值位置对应511keV光子的能谱图的峰值位置。
本说明书的一方面提供一种能量刻度曲线确定方法。所述方法包括：获取成像设备的探测器的晶体的本底事件，所述本底事件与所述晶体的自身辐射粒子有关；基于所述本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值；根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述能量刻度曲线。
在一些实施例中，所述基于所述本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值包括：根据所述本底事件，确定所述晶体的多种核素的衰变特征能峰值；对所述多种核素的衰变特征能峰值进行模数转换，得到与所述衰变特征能峰值对应的ADC值；选取所述衰变特征能峰值中的所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值。
在一些实施例中，所述至少两个能峰值包括307keV和597keV能峰值；以及与所述至少两个能峰值对应的ADC值包括与所述307keV和597keV能峰值对应的ADC值。
在一些实施例中，所述根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述能量刻度曲线包括：通过对所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值进行插值拟合，确定所述能量刻度曲线。
在一些实施例中，所述方法还包括：根据所述能量刻度曲线，确定与所述能量刻度曲线上任意能峰值对应的ADC值。
在一些实施例中，所述方法还包括：根据所述能量刻度曲线，确定511keV能峰值对应的ADC值。
在一些实施例中，所述方法还包括：根据所述511keV能峰值对应的ADC值，对所述探测器接收到的粒子的能量进行校正。
本说明书的一方面提供一种时间同步方法。所述方法包括：获取成像设备的探测器的晶体的本底符合事件，所述本底符合事件与所述晶体的自身辐射粒子有关；根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间；根据所述测量飞行时间以及所述理论飞行时间，对所述探测器进行时间同步。
在一些实施例中，所述本底符合事件的信息包括：所述本底符合事件的每一个本底符合事件中的两个粒子到达所述探测器的到达时间以及相应的晶体位置；所述根据所述本底符合事件的信息，确定测量飞行时间以及所述理论飞行时间包括：根据所述每一个本底符合事件的两个粒子的所述到达时间，确定所述每一个本底符合事件的测量飞行时间；以及根据所述每一个本底符合事件的两个粒子对应的所述晶体位置，确定所述每一个本底符合事件的理论飞行时间。
在一些实施例中，所述根据所述测量飞行时间以及所述理论飞行时间，对所述探测器进行时间同步包括：基于所述测量飞行时间以及所述理论飞行时间，确定时间差；根据所述时间差，对所述探测器进行时间同步。
在一些实施例中，所述基于所述测量飞行时间以及所述理论飞行时间，确定时间差包括：基于所述探测器的任意一对探测器模块接收到的多个测量飞行时间以及多个理论飞行时间，确定所述多个测量飞行时间以及所述多个理论飞行时间的差值；确定所述多个测量飞行时间以及所述多个理论飞行时间的差值的均值为所述时间差。
在一些实施例中，所述根据所述时间差，对所述探测器进行时间同步包括：响应于所述时间差大于或等于一个时钟周期，对所述探测器的探测器模块进行时间同步。
在一些实施例中，所述对所述探测器进行时间同步包括：对所述探测器的任意一对探测器模块中的其中一个探测器模块的计数器的值进行调整，并将调整后的计数器的值确定为时间参考标准。
在一些实施例中，所述方法还包括：将调整计算器后的所述任意一对探测器模块中的任意一个探测器模块确定为基准模块，并基于所述基准模块对所述探测器中除该对探测器模块外的其它探测器模块进行时间同步。
本说明书的一方面提供一种飞行时间状态检测方法。所述方法包括：获取成像设备的探测器的晶体的本底符合事件，所述本底符合事件与所述晶体的自身辐射粒子有关；根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间；根据所述测量飞行时间以及 所述理论飞行时间，确定所述成像设备的飞行时间状态，所述飞行时间状态反映了所述晶体是否产生漂移。
在一些实施例中，所述获取成像设备的探测器的晶体的本底符合事件包括：确定所述成像设备的时间窗和能量窗；根据所述时间窗和能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的本底符合事件及其相关信息。
在一些实施例中，所述时间窗的范围不小于所述成像设备的临床时间窗阈值范围；所述能量窗的范围不小于所述成像设备的临床能量窗阈值范围。
在一些实施例中，所述本底符合事件的信息包括：所述本底符合事件的每一个本底符合事件中的两个粒子到达所述探测器的到达时间以及相应的晶体位置；所述根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间包括：根据所述每一个本底符合事件的两个粒子的所述到达时间，确定所述每一个本底符合事件的测量飞行时间；以及根据所述每一个本底符合事件的两个粒子对应的所述晶体位置，确定所述每一个本底符合事件的理论飞行时间。
在一些实施例中，所述根据所述测量飞行时间以及所述理论飞行时间，确定所述成像设备的飞行时间状态包括：响应于所述测量飞行时间与所述理论飞行时间的差异超过阈值，确定与所述本底符合事件对应的晶体产生漂移。
在一些实施例中，所述方法还包括：根据所述本底符合事件的信息对所述探测器的飞行时间进行校正，以得到校正后的飞行时间。
在一些实施例中，所述根据所述本底符合事件的信息对所述探测器的飞行时间进行校正，以得到校正后的飞行时间包括：获取能量-时间映射关系，所述能量-时间映射关系反映粒子能量与飞行时间偏移量之间的对应关系；基于所述能量-时间映射关系，确定与所述本底符合事件的每一个本底符合事件中的两个粒子的能量对应的飞行时间偏移量；根据所述飞行时间偏移量对所述探测器的飞行时间进行校正，以得到所述校正后的飞行时间。
本说明书的另一方面提供一种成像设备的状态检测装置。所述装置包括：获取模块，用于获取所述成像设备的探测器的晶体的第一本底事件以及第二本底事件，所述第一本底事件和所述第二本底事件与所述晶体的自身辐射粒子有关；校正模块，用于基于所述第一本底事件，对所述晶体位置查找表进行校正；对所述成像设备的能量状态进行校正；以及基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正。
本说明书的另一方面提供一种计算机设备，包括存储器、处理器以及存储在所述存储器上并可在所述处理器上运行的计算机程序，其特征在于，所述处理器执行所述计算机程序 时实现如前所述的方法。
本说明书的另一方面提供一种计算机可读存储介质，其上存储有计算机程序，其特征在于，该程序被处理器执行时实现如前所述的方法。
附图说明
本申请将以示例性实施例的方式进一步说明，这些示例性实施例将通过附图进行详细描述。这些实施例并非限制性的，在这些实施例中，相同的编号表示相同的结构，其中：
图1是根据本申请的一些实施例所示的示例性成像设备的状态检测方法的应用场景示意图；
图2是根据本申请的一些实施例所示的计算设备的示例性硬件和/或软件的示意图；
图3是根据本申请的一些实施例所示的成像设备的状态校正装置的示例性框图；
图4是根据本申请的一些实施例所示的成像设备的状态检测方法的示例性流程图；
图5是根据本申请的一些实施例所示的PET设备接收粒子的示例性示意图；
图6是根据本申请的一些实施例所示的晶体位置查找表校正装置的示例性框图；
图7是根据本申请的一些实施例所示的晶体位置查找表校正方法的示例性流程图；
图8A-8C是根据本申请的一些实施例所示的晶体位置查找表校正方法的示例性示意图；
图9是根据本申请的一些实施例所示的能量状态检测装置的示例性框图；
图10是根据本申请的一些实施例所示的能量状态检测方法的示例性流程图；
图11是根据本申请的一些实施例所示的单事件模式形成的能谱图的示意图；
图12是根据本申请的一些实施例所示的符合事件模式形成的能谱图的示意图；
图13是根据本申请的一些实施例所示的能量刻度曲线确定装置的示例性框图；
图14是根据本申请的一些实施例所示的能量刻度曲线确定方法的示例性流程图；
图15是根据本申请的一些实施例所示的时间同步装置的示例性框图；
图16是根据本申请的一些实施例所示的时间同步方法的示例性流程图；
图17是根据本申请的一些实施例所示的探测器模块接收光子的示意图；
图18是根据本申请的一些实施例所示的飞行时间状态检测装置的示例性框图；
图19是根据本申请的一些实施例所示的飞行时间状态检测方法的示例性流程图；
图20是根据本申请的一些实施例所示的事件时刻谱的示例性示意图；
图21是根据本申请的一些实施例所示的TDC值与时间的对应关系的示例性示意图。
具体实施方式
为了更清楚地说明本申请实施例的技术方案，下面将对实施例描述中所需要使用的附图作简单的介绍。显而易见地，下面描述中的附图仅仅是本申请的一些示例或实施例，对于本领域的普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图将本申请应用于其它类似情景。除非从语言环境中显而易见或另做说明，图中相同标号代表相同结构或操作。
应当理解，本文使用的“系统”、“装置”、“单元”和/或“模组”是用于区分不同级别的不同组件、元件、部件、部分或装配的一种方法。然而，如果其他词语可实现相同的目的，则可通过其他表达来替换所述词语。
如本申请和权利要求书中所示，除非上下文明确提示例外情形，“一”、“一个”、“一种”和/或“该”等词并非特指单数，也可包括复数。一般说来，术语“包括”与“包含”仅提示包括已明确标识的步骤和元素，而这些步骤和元素不构成一个排它性的罗列，方法或者设备也可能包含其它的步骤或元素。
本申请中使用了流程图用来说明根据本申请的实施例的系统所执行的操作。应当理解的是，前面或后面操作不一定按照顺序来精确地执行。相反，可以按照倒序或同时处理各个步骤。同时，也可以将其他操作添加到这些过程中，或从这些过程移除某一步或数步操作。
PET设备可以通过测量正电子湮灭产生的一对γ光子进行成像。在一些实施例中，可以通过定期或实时的对PET设备的状态进行检测、校正，提高PET设备采集数据的准确性、PET图像质量等。在一些实施例中，可以采用放射性棒源(桶源)实现对PET设备的状态检测。但是，在有源的情况下进行状态检测，由于存在放射源，会对用户(例如，医护人员)造成一定程度的放射伤害，增加了操作者受辐射的剂量，并且操作方法复杂，只能适用于定期检测。
本说明书实施例提供的成像设备的状态检测方法，基于成像设备的探测器的晶体的本底固有的放射性现象对成像设备的状态进行检测，可以在没有额外放射性棒源(桶源)的情况下检测PET设备的状态，可以简化检测流程，减少操作人员的受辐射剂量，节省放射源采购成本，且该方法操作简单。此外，该方法可以在PET设备处于闲置状态时进行状态检测，可以在任意空闲时间进行检测，可以反复进行多次检测，方便提高检测的频率，及时发现设备的异常状态，因此该方法的灵活性更高。
图1是根据本申请一些实施例所示的示例性成像设备的状态检测方法的应用场景示意图。
如图1所示，成像设备的状态检测系统100中可以包括成像设备110、网络120、终端设备130、处理设备140以及存储设备150。该系统100中的各个组件之间可以通过网络120互相连接。例如，成像设备110和终端设备130可以通过网络120连接或通信。又例如，成像设备110和存储设备150可以通过网络120连接或通信。
成像设备110可以用于对检测区域内的目标对象进行扫描，得到该目标对象的扫描数据。在一些实施例中，目标对象可以包括生物对象和/或非生物对象。例如，目标对象可以包括身体的特定部分，例如头部、胸部、腹部等，或其组合。又例如，目标对象可以是有生命或无生命的有机和/或无机物质。
在一些实施例中，成像设备110可以是用于疾病诊断或研究目的的非侵入性生物医学成像装置。例如，成像设备110可以包括单模态扫描仪和/或多模态扫描仪。单模态扫描仪可以包括例如超声波扫描仪、X射线扫描仪、计算机断层扫描(CT)扫描仪、核磁共振成像(MRI)扫描仪、超声检查仪、正电子发射计算机断层扫描(PET)扫描仪、光学相干断层扫描(OCT)扫描仪、超声(US)扫描仪、血管内超声(IVUS)扫描仪、近红外光谱(NIRS)扫描仪、远红外(FIR)扫描仪等，或其任意组合。多模态扫描仪可以包括例如X射线成像-核磁共振成像(X射线-MRI)扫描仪、正电子发射断层扫描-X射线成像(PET-X射线)扫描仪、单光子发射计算机断层扫描-核磁共振成像(SPECT-MRI)扫描仪、正电子发射断层扫描-计算机断层摄影(PET-CT)扫描仪、数字减影血管造影-核磁共振成像(DSA-MRI)扫描仪等。上面提供的扫描仪仅用于说明目的，而无意限制本申请的范围。如本文所用，术语“成像模态”或“模态”广泛地是指收集、生成、处理和/或分析目标对象的成像信息的成像方法或技术。本说明书实施例中，成像设备110可以为正电子发射计算机断层扫描(PET)设备。
在一些实施例中，成像设备110可以包括用于执行成像和/或相关分析的模块和/或组件。在一些实施例中，成像设备110可以包括附属组件和成像组件。其中，附属组件是指为满足临床诊疗的需要而设计的各种与成像组件配套的设施，例如，可以包括机械设备如检查床、诊断床、导管床、摄影床等、各种支撑、悬吊组件、制动组件、保持组件、滤线栅、滤过板、遮线器等。在一些实施例中，成像组件可以有多种形式，例如，数字成像组件可以包括探测器、计算机系统及图像处理软件等；其他成像组件可以包括荧光屏、胶片暗匣、影像增强器、影像电视等。
在一些实施例中，探测器可以包括多个探测器模块，每个探测器模块可以包括多个探测器单元。在一些实施例中，每个探测器模块可以包括感光模块与读出电路。其中，感光模块可以用于采集目标对象注射的放射性核素产生的光子信号，并将采集到的光子信号转换为 电信号，读出电路可以用于读出感光模块中电信号并将其转化为数字化数据，以便用于生成图像。在一些实施例中，感光模块可以包括晶体。晶体(crystal)是由大量微观物质单位(原子、离子、分子等)按一定规则有序排列的结构，例如，晶体Si(硅)、CdTe、GaAs、HgI2和CdZnTe(CZT)等。在一些实施例中，感光模块可以使用闪烁晶体作为感光基底。闪烁晶体是指在高能粒子(例如，X射线，γ光子)的撞击下，能将高能粒子的动能转变为光能而发出闪光的晶体。在一些实施例中，探测器可以包括半导体探测器、光伏型探测器等，本说明书对此不做限制。
在一些实施例中，由成像设备110获取的数据(如，目标对象的扫描数据)可以被传送到处理设备140以供进一步分析。附加地或替代地，由成像设备110获取的数据可以被发送到终端设备(例如，终端设备130)用于显示和/或存储设备(例如，存储设备150)用于存储。
网络120可以包括能够促进系统100的信息和/或数据交换的任何合适的网络。在一些实施例中，系统100的至少一个组件(例如，成像设备110、终端设备130、处理设备140、存储设备150)可以通过网络120与系统100中至少一个其他组件交换信息和/或数据。例如，处理设备140可以通过网络120从成像设备110的探测器获得本底单事件、本底符合事件等。网络120可以包括公共网络(例如，因特网)、专用网络(例如，局部区域网络(LAN))、有线网络、无线网络(例如，802.11网络、Wi-Fi网络)、帧中继网络、虚拟专用网络(VPN)、卫星网络、电话网络、路由器、集线器、交换机、光纤网络、电信网络、内联网、无线局部区域网络(WLAN)、城域网(MAN)、公共电话交换网络(PSTN)、蓝牙 TM网络、ZigBee TM网络、近场通信(NFC)网络等，或其任意组合。在一些实施例中，网络120可以包括至少一个网络接入点。例如，网络120可以包括有线和/或无线网络接入点，例如基站和/或互联网交换点，系统100的至少一个组件可以通过接入点连接到网络120以交换数据和/或信息。
终端设备130可以与成像设备110、处理设备140和/或存储设备150通信和/或连接。例如，用户可以通过终端设备130与成像设备110进行交互，以控制成像设备110的一个或多个部件。在一些实施例中，终端设备130可以包括移动设备131、平板计算机132、膝上型计算机133等，或其任意组合。例如，移动设备131可以包括移动控制手柄、个人数字助理(PDA)、智能手机等，或其任意组合。
在一些实施例中，终端设备130可以包括输入设备、输出设备等。输入设备可以选用键盘输入、触摸屏(例如，具有触觉或触觉反馈)输入、语音输入、眼睛跟踪输入、手势跟踪输入、大脑监测系统输入、图像输入、视频输入或任何其他类似的输入机制。通过输入设备 接收的输入信息可以通过如总线传输到处理设备140，以进行进一步处理。其他类型的输入设备可以包括光标控制装置，例如，鼠标、轨迹球或光标方向键等。在一些实施例中，操作者(如，医护人员)可以通过输入设备输入扫描目标对象的指令、检测成像设备110的状态的指令等。输出设备可以包括显示器、扬声器、打印机等或其任意组合。输出设备可以用于输出成像设备110扫描的目标对象的图像，和/或处理设备140确定的图像等。在一些实施例中，终端设备130可以是处理设备140的一部分。
处理设备140可以处理从成像设备110、至少一个终端设备130、存储设备150或系统100的其他组件获得的数据和/或信息。例如，处理设备140可以从成像设备110中获取第一本底事件、第二本底事件、第三本底事件、第四本底事件等，并对其进行分析处理，以对成像设备110进行状态检测。在一些实施例中，处理设备140可以是单一服务器或服务器组。服务器组可以是集中式的或分布式的。在一些实施例中，处理设备140可以是本地或远程的。例如，处理设备140可以通过网络120从成像设备110、至少一个终端设备130和/或存储设备150访问信息和/或数据。又例如，处理设备140可以直接连接到成像设备110、至少一个终端设备130和/或存储设备150以访问信息和/或数据。在一些实施例中，处理设备140可以在云平台上实现。例如，云平台可以包括私有云、公共云、混合云、社区云、分布式云、云间云、多云等或其任意组合。
在一些实施例中，处理设备140可以包括一个或以上处理器(例如，单芯片处理器或多芯片处理器)。仅作为示例，处理设备140可以包括中央处理单元(CPU)、专用集成电路(ASIC)、专用指令集处理器(ASIP)、图像处理单元(GPU)、物理运算处理单元(PPU)、数字信号处理器(DSP)、现场可编程门阵列(FPGA)、可编程逻辑器件(PLD)、控制器、微控制器单元、精简指令集计算机(RISC)、微处理器等或其任意组合。在一些实施例中，处理设备140可以为成像设备110或终端设备130的一部分。例如，处理设备140可以集成在成像设备110内，用于基于本底单事件或本底符合事件对成像设备110的状态进行检测。
存储设备150可以存储数据、指令和/或任何其他信息。例如，存储设备150可以存储成像设备110获取的本底事件及其相关信息等。在一些实施例中，存储设备150可以存储从成像设备110、至少一个终端设备130和/或处理设备140获得的数据。在一些实施例中，存储设备150可以存储处理设备140用来执行或使用来完成本申请中描述的示例性方法的数据和/或指令。在一些实施例中，存储设备150可以包括大容量存储器、可移动存储器、易失性读写存储器、只读存储器(ROM)等或其任意组合。在一些实施例中，存储设备150可以在云平台上实现。
在一些实施例中，存储设备150可以连接到网络120以与系统100中的至少一个其他组件(例如，成像设备110、至少一个终端设备130、处理设备140)通信。系统100中的至少一个组件可以通过网络120访问存储设备150中存储的数据(例如，本底单事件的信息、本底符合事件的信息、单事件图像等)。在一些实施例中，存储设备150可以是处理设备140的一部分。
应该注意的是，上述描述仅出于说明性目的而提供，并不旨在限制本申请的范围。对于本领域普通技术人员而言，在本申请内容的指导下，可做出多种变化和修改。可以以各种方式组合本申请描述的示例性实施例的特征、结构、方法和其他特征，以获得另外的和/或替代的示例性实施例。例如，存储设备150可以是包括云计算平台(例如公共云、私有云、社区和混合云等)的数据存储设备。然而，这些变化与修改不会背离本申请的范围。
图2是根据本申请的一些实施例所示的计算设备的示例性硬件和/或软件的示意图。
如图2所示，计算设备200可以包括处理器210、存储器220、输入/输出接口230和通信端口240。
处理器210可以执行计算指令(程序代码)并执行本申请描述的成像设备的状态检测系统100的功能。所述计算指令可以包括程序、对象、组件、数据结构、过程、模块和功能(所述功能指本申请中描述的特定功能)。例如，处理器210可以处理从系统100的任何组件获得的本底事件的信息。在一些实施例中，处理器210可以包括微控制器、微处理器、精简指令集计算机(RISC)、专用集成电路(ASIC)、应用特定指令集处理器(ASIP)、中央处理器(CPU)、图形处理单元(GPU)、物理处理单元(PPU)、微控制器单元、数字信号处理器(DSP)、现场可编程门阵列(FPGA)、高级RISC机(ARM)、可编程逻辑器件以及能够执行一个或多个功能的任何电路和处理器等，或其任意组合。仅为了说明，图2中的计算设备200只描述了一个处理器，但需要注意的是本申请中的计算设备200还可以包括多个处理器。
存储器220可以存储从系统100的任何其他组件获得的数据/信息。在一些实施例中，存储器220可以包括大容量存储器、可移动存储器、易失性读取和写入存储器和只读存储器(ROM)等，或其任意组合。示例性大容量存储器可以包括磁盘、光盘和固态驱动器等。可移动存储器可以包括闪存驱动器、软盘、光盘、存储卡、压缩盘和磁带等。易失性读取和写入存储器可以包括随机存取存储器(RAM)。RAM可以包括动态RAM(DRAM)、双倍速率同步动态RAM(DDR SDRAM)、静态RAM(SRAM)、晶闸管RAM(T-RAM)和零电容(Z-RAM)等。ROM可以包括掩模ROM(MROM)、可编程ROM(PROM)、可擦除可 编程ROM(PEROM)、电可擦除可编程ROM(EEPROM)、光盘ROM(CD-ROM)和数字通用盘ROM等。
输入/输出接口230可以用于输入或输出信号、数据或信息。在一些实施例中，输入/输出接口230可以使用户与系统100中的组件(例如，成像设备110)进行联系。在一些实施例中，输入/输出接口230可以包括输入装置和输出装置。示例性输入装置可以包括键盘、鼠标、触摸屏和麦克风等中的一种或以上任意组合。示例性输出设备可以包括显示设备、扬声器、打印机、投影仪等，或其任意组合。示例性显示装置可以包括液晶显示器(LCD)、基于发光二极管(LED)的显示器、平板显示器、曲面显示器、电视设备、阴极射线管(CRT)等中的一种或以上任意组合。通信端口240可以连接到网络以便数据通信。所述连接可以是有线连接、无线连接或两者的组合。有线连接可以包括电缆、光缆或电话线等，或其任意组合。无线连接可以包括蓝牙、Wi-Fi、WiMax、WLAN、ZigBee、移动网络(例如，3G、4G或5G等)等中的一种或以上任意组合。在一些实施例中，通信端口240可以是标准化端口，如RS232、RS485等。在一些实施例中，通信端口240可以是专门设计的端口。例如，通信端口240可以根据数字成像和医学通信协议(DICOM)进行设计。
图3是根据本申请的一些实施例所示的成像设备的状态校正装置的示例性框图。
如图3所示，在一些实施例中，成像设备的状态校正装置300可以包括获取模块310、图像生成模块320、确定模块330以及校正模块340。
获取模块310可以用于获取数据和/或信息。例如，获取模块310可以用于获取成像设备110的探测器接收到的与其晶体的自身辐射粒子有关的本底事件的信息。在一些实施例中，获取模块310可以用于获取成像设备110的探测器的晶体的本底单事件和/或本底符合事件(例如，图4所描述的第一本底事件、第二本底事件、第三本底事件、第四本底事件、第五本底事件以及第六本底事件)。在一些实施例中，获取模块310可以用于响应于成像设备110的晶体位置查找表状态异常，获取成像设备110的探测器的晶体的本底事件(例如，第一本底事件)的信息。在一些实施例中，获取模块310可以用于响应于对成像设备110的晶体位置查找表进行了校正，获取成像设备110的探测器的晶体的本底事件(例如，第二本底事件或第三本底事件)的信息。
图像生成模块320可以用于生成与本底事件相关的图像。例如，图像生成模块320可以用于基于本底事件(例如，第一本底事件)，生成单事件图像。在一些实施例中，图像生成模块320可以用于基于本底事件(例如，第一本底事件、或第三本底事件)的能量信息生成能谱图。在一些实施例中，图像生成模块320可以用于基于本底事件(例如，第一本底事 件和/或第二本底事件、或第四本底事件)的信息，生成事件时刻谱。在一些实施例中，图像生成模块320还可以用于生成其他相关的图像，例如，目标对象的图像等，本说明书对此不做限制。
确定模块330可以用于确定飞行时间(TOF，Time of flight)。在一些实施例中，确定模块330可以用于基于本底符合事件(例如，从第一本底事件和第二本底事件中筛选的本底符合事件、或图4中的第四本底事件)的信息，计算测量飞行时间与理论飞行时间。在一些实施例中，确定模块330还可以用于根据所述能谱图，确定能谱图的峰值位置。在一些实施例中，确定模块330还可以用于确定时间数字转换(TDC，Time-to-Digital Converter)值与时间的对应关系。
在一些实施例中，确定模块330可以进一步包括峰值位置确定单元332以及时间确定单元334。峰值位置确定单元332可以用于计算能谱图的峰值位置。时间确定单元334可以用于计算事件相关的时间信息，例如，测量飞行时间、理论飞行时间等。
校正模块340可以用于校正成像设备的状态。成像设备的状态可以指其软件和/或硬件的状态，以及系统数据的准确性状态等。校正模块340可以用于校正的成像设备的状态可以包括：晶体位置查找表状态、能量刻度状态、能量校正状态、探测器模块之间的时间同步状态、飞行时间状态、TDC刻度状态、系统故障等，或其任意组合。例如，校正模块340可以用于基于本底事件(例如，第一本底事件)的信息，对成像设备的所述晶体位置查找表进行校正。又如，校正模块340可以用于基于本底事件(例如，第一本底事件或第三本底事件)的信息，对成像设备的能量状态进行校正。再如，校正模块340可以用于基于本底符合事件(例如，基于第一本底事件和第二本底事件得到的本底符合事件)的信息，对成像设备的探测器进行时间校正。
在一些实施例中，校正模块340可以进一步包括LUT校正单元342、能量状态校正单元344、时间同步单元346、飞行时间状态校正单元348。
LUT校正单元342可以用于对成像设备的所述晶体位置查找表进行校正。在一些实施例中，LUT校正单元342可以判断(例如，在校正晶体位置查找表之前)晶体位置查找表状态是否异常。成像设备的晶体位置查找表状态是否异常可以指针对探测器检测到的事件，计算获得的探测器的各个晶体对事件的响应位置是否与该晶体的实际位置相符。在一些实施例中，响应于晶体位置查找表状态异常，LUT校正单元342可以基于本底事件(例如，第一本底事件)的信息对晶体位置查找表进行校正。
能量状态校正单元344可以用于对成像设备的能量状态进行校正。在一些实施例中， 能量状态校正单元344可以判断(例如，在校正能量状态之前)能量状态是否异常。成像设备的能量状态可以指其各探测器通道接收相同能量的粒子时得到的能量值的匹配状态。能量状态是否异常可以指各探测器通道接收相同能量的粒子得到的能量值是否相同。在一些实施例中，如果成像设备的能量状态异常，相应地，能量刻度曲线可能发生偏移。能量刻度曲线将指代粒子能量的ADC值映射为实际能量。能量刻度曲线的准确性关系到PET设备图像分辨率的高低。其中，ADC(Analog-to-Digital Converter，模数转换器)，是指将连续变化的模拟信号转换成离散的数字信号的器件；ADC值是指模数转换器的采样值。在一些实施例中，能量状态校正单元344可以基于本底事件(例如，第一本底事件或第三本底事件)的信息对能量状态进行校正。例如，能量状态校正单元344可以基于所述第三本底事件的信息，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值；根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述成像设备的能量刻度曲线。
时间同步单元346可以用于对成像设备的探测器的各探测器模块进行时间同步。在一些实施例中，时间同步单元346可以判断(例如，在校正探测器模块的时间之前或同时)探测器模块的时间是否同步。在一些实施例中，响应于探测器模块的时间不同步，时间同步单元346可以基于本底符合事件的信息，对探测器模块的时间进行同步。例如，时间同步单元346可以根据所述测量飞行时间以及所述理论飞行时间，对探测器的各探测器模块的时间进行同步。
飞行时间状态校正单元348可以用于对成像设备的飞行时间状态进行校正。在一些实施例中，飞行时间状态校正单元348可以判断(例如，在校正飞行时间状态之前)飞行时间状态是否异常。飞行时间状态可以指探测器接收到粒子的时间的状态。飞行时间状态是否异常可以指飞行时间是否发生漂移。在一些实施例中，响应于飞行时间状态异常(例如，本底符合事件的测量飞行时间与理论飞行时间的差异超过阈值)，飞行时间状态校正单元348可以根据该本底符合事件的信息对探测器的飞行时间进行校正。在一些实施例中，飞行时间状态校正单元348还可以根据所述TDC值与时间的对应关系，确定成像设备的TDC刻度曲线。
需要注意的是，以上对于成像设备的状态校正装置300及其模块的描述，仅为描述方便，并不能把本申请限制在所举实施例范围之内。可以理解，对于本领域的技术人员来说，在了解该系统的原理后，可能在不背离这一原理的情况下，对各个模块进行任意组合，或者构成子系统与其他模块连接。例如，在一些实施例中，例如，图3中披露的获取模块310、图像生成模块320、确定模块330以及校正模块340(例如，处理设备140)中的不同模块，也 可以是一个模块实现上述的两个或两个以上模块的功能。又例如，各个模块可以分别具有各自的存储模块。再例如，各个模块可以共用一个存储模块。诸如此类的变形，均在本申请的保护范围之内。
图4是根据本申请的一些实施例所示的成像设备的状态检测方法的示例性流程图。
在一些实施例中，成像设备(例如PET设备)的状态检测方法400可以由成像设备的状态检测系统100(如处理设备140)或状态校正装置300执行。例如，成像设备的状态检测方法400可以以程序或指令的形式存储在存储装置(如存储设备150)中，当状态检测系统100(如处理设备140)执行该程序或指令时，可以实现成像设备的状态检测方法400。下面呈现的状态检测方法400的操作示意图是说明性的。在一些实施例中，可以利用一个或以上未描述的附加操作和/或未讨论的一个或以上操作来完成该过程。另外，图4中示出的和下面描述的状态检测方法400的操作的顺序不旨在是限制性的。
在步骤410中，处理设备140可以获取成像设备的探测器的晶体的第一本底事件。在一些实施例中，步骤410可以由获取模块310执行。
在一些实施例中，成像设备的探测器可以包含多个探测器晶体，正电子湮灭产生的一对γ光子可以被两个不同的探测器的晶体接收。当γ光子入射到成像设备的探测器在晶体上产生大量光子，光子被探测器接收并转换为电信号，通过对多个探测器产生的信号进行加权，可以计算γ光子的作用位置。但是，由于探测器实际设计及算法本身问题等导致图像发生枕形或桶形失真，实际计算位置可能并非γ光子的真实作用位置。因此，探测器需要利用泛场源进行照射，对获得的泛场图像进行分割获得各个晶体的响应位置，并作为探测器的晶体的位置查找表(look-up table，LUT)。在实际采集时，可以根据计算的γ光子的作用位置和晶体位置查找表判定与γ光子作用的晶体，利用所述晶体在系统中的实际物理位置作为γ光子的作用位置，从而确定γ光子的入射位置。因此，晶体位置查找表的准确性关系到γ光子入射位置探测的准确性，而γ光子入射位置探测的准确性可以保证成像设备图像分辨率。但是，晶体位置查找表可能会因泛场图像不清晰等原因而发生偏差，因此，需要对其进行校正。在一些实施例中，成像设备的探测器的晶体可以包括碘化钠(NaI)、锗酸铋(BGO)、硅酸镥(LSO)、硅酸钇镥(LYSO)等闪烁晶体。本说明书实施例中，将主要以硅酸钇镥(LYSO)闪烁晶体探测器为例进行说明。
在一些实施例中，处理设备140可以基于预设时间间隔(如，一小时、一天、一周、五天等)定期检测成像设备110的晶体位置查找表的状态。在一些实施例中，处理设备140可以实时(例如，在成像设备空闲时)检测成像设备110的晶体位置查找表的状态。例如， 处理设备140可以在成像设备110扫描目标对象之前，检测成像设备110的晶体位置查找表的状态是否异常。
本申请所述的本底事件(例如，第一本底事件、第二本底事件、第三本底事件、第四本底事件等)与成像设备的探测器的晶体的自身辐射粒子有关。以探测器的晶体是硅酸钇镥(LYSO)闪烁晶体为例，由于LYSO中存在Lu176，因此，该晶体具有固有放射现象，也可称为本底辐射现象。在Lu176衰变时，将产生β粒子以及γ光子，产生的β粒子射程较短，其能量主要沉积在发生衰变的晶体中；产生的γ光子穿透本领高，不仅可以在发生衰变的晶体中探测到，也可能逃逸被其他晶体探测到。探测器接收到β粒子和/或γ光子的事件称为本底事件。在一些实施例中，本底事件可以包括本底单事件或本底符合事件。仅作为示例，一个Lu176衰变产生的粒子只在同一个晶体中探测到，则晶体对应的探测器接收到粒子的事件可以称为本底单事件；衰变产生的γ光子逃逸被其他的晶体探测到，则接收β粒子的晶体对应的探测器和接收γ光子的晶体对应的探测器之间的连线可以称为响应线，探测器接收到β粒子和γ光子的事件可以称为本底符合事件。在一些实施例中，探测器接收到β粒子和/或γ光子的数据可以称为本底事件的信息。
如图5所示，成像设备的探测器可以包括晶体阵列A以及晶体阵列B，在晶体阵列A中产生β事件，在对应的晶体阵列B中接收到相应的γ事件。晶体阵列A耦合光传感器以及前端电路，前端电路包括放大器，记录β事件信息；晶体阵列B耦合光传感器以及前端电路，前端电路包括放大器，记录γ事件信息。本底符合事件的信息可以为，晶体阵列A接收到β事件的时间信息Ta以及接收到β事件的晶体在晶体阵列A中的位置；晶体阵列B接收到γ事件的时间信息Tb以及接收到γ事件的晶体阵列B中的位置。其中，位置可以为以整个探测器建立直接坐标系，得到的相应晶体对应的坐标位置。
在一些实施例中，处理设备140可以根据预设的能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的第一本底事件。所述第一本底事件可以为本底单事件。在一些实施例中，所述能量窗的范围在成像设备的临床能量窗阈值范围之内。在一些实施例中，处理设备140可以根据预设的时间窗，获取所述探测器接收到的所述晶体的自身辐射粒子的第一本底事件。关于能量窗的更多内容可以参见图7中相关描述，关于时间窗的更多内容可以参见图10中相关描述，此处不再赘述。
在步骤420中，处理设备140可以基于所述第一本底事件，对所述晶体位置查找表进行校正。在一些实施例中，步骤420可以由校正模块340(如LUT校正单元342)执行。
在一些实施例中，处理设备140可以基于所述第一本底事件，确定单事件图像；和/或 根据所述单事件图像，对所述晶体位置查找表进行校正。更多关于校正晶体位置查找表的内容可以参见本说明书其他部分，例如，图7及其相关描述，此处不再赘述。
在步骤430中，处理设备140可以对所述成像设备的能量状态进行校正。在一些实施例中，步骤430可以由校正模块340(如能量状态校正单元344)执行。
探测器的数字化处理部分可以将入射的γ光子转换为电信号，获得其能量、位置和时间等信息，然后通过能量符合计算确定本底事件所在响应线的位置，并通过二维或三维断层重建算法获得正电子核素在目标对象体中的分布，从而在体外观测目标对象体内的生理和/或生化过程。在进行能量符合计算时，各探测器模块的能量计算是针对该探测器模块的数据进行。因此，当探测器确定后，其各个探测模块间的能量计算是相互独立的，但是由于成像设备的探测器使用的多个晶体和光电转换器件之间、以及各电路之间可能会存在差别，使用相同的方法对晶体接收到的相同能量的γ光子进行能量计算后，各个晶体探测的计数峰值所对应的能量值与理论计数峰值所对应的能量值有一定的偏移，因此，需要对成像设备的能量状态进行校正。
在一些实施例中，处理设备140可以基于预设时间间隔(如，5小时、10小时、3天、5天、1个月等)定期对成像设备110进行能量状态校正。在一些实施例中，处理设备140可以在成像设备正常使用时或在成像设备空闲时，对其进行能量状态校正。在一些实施例中，处理设备140可以在成像设备的探测器模块更换后(例如，成像设备的一个或多个探测模块发生故障并被更换之后)，对其进行能量状态校正。在一些实施例中，处理设备140可以在对成像设备进行晶体位置查找表校正后，对其进行能量状态校正。在一些实施例中，处理设备140可以响应于成像设备的能量状态异常对其进行能量状态校正。
在一些实施例中，处理设备140可以基于所述第一本底事件，对所述成像设备的能量状态进行校正。在一些实施例中，处理设备140可以获取所述成像设备的探测器的晶体的第三本底事件，基于所述第三本底事件对所述成像设备的能量状态进行校正。其中，所述第三本底事件与成像设备的探测器的晶体的自身辐射粒子有关，所述第三本底事件可以包括成像设备的探测器接收到的所述晶体的自身辐射粒子的本底单事件或本底符合事件。例如，如果事件采集模式为单事件模式(相应地，第一本底事件为本底单事件)，处理设备140可以在420中基于该本底单事件，先对成像设备110的探测器的晶体位置查找表进行校正，然后在430中，基于该本底单事件，对成像设备110的能量状态进行校正。其中，单事件模式可以指成像设备的探测器在采集本底单事件时对应的事件采集模式。又例如，处理设备140可以在基于第一本底事件对成像设备110的探测器的晶体位置查找表进行校正后，获取晶体的第三 本底事件，基于该第三本底事件对成像设备110的能量状态进行校正。
在一些实施例中，处理设备140可以判断成像设备110的能量状态是否异常。具体地，处理设备140可以基于所述第一本底事件或所述第三本底事件的能量信息生成能谱图，并确定所述能谱图的峰值位置；根据所述能谱图的峰值位置，以及与所述峰值位置对应的校正峰值位置，确定所述成像设备的能量校正状态；响应于所述能量校正状态异常，对所述成像设备的能量状态进行校正。在一些实施例中，处理设备140可以不判断成像设备110的能量状态是否异常，直接对成像设备110的能量状态进行校正。在一些实施例中，第三本底事件可以为本底单事件，处理设备140可以基于所述本底单事件的能量信息生成所述能谱图。在一些实施例中，处理设备140可以根据预设时间窗和/或预设能量窗，基于成像设备110的探测器在符合事件模式下接收到的第三本底事件的粒子到达时间(即第三本底事件为本底符合事件)，筛选粒子能量信息；并根据筛选后的粒子能量信息生成所述能谱图。在一些实施例中，所述能谱图可以包括全能峰峰值或单一能量峰值中的至少一种。其中，符合事件模式可以指成像设备的探测器接收到本底事件后，通过符合处理获得本底符合事件的模式。更多关于校正能量状态的内容可以参见本说明书其他部分，例如，图10-12及其相关描述，此处不再赘述。
在一些实施例中，处理设备140可以基于所述第一本底事件或所述第三本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值；并根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述成像设备的能量刻度曲线。更多关于确定能量刻度曲线相关的内容，可以参见本说明书其他部分，例如，图14及其相关描述，此处不再赘述。
在步骤440中，处理设备140可以获取所述晶体的第二本底事件。在一些实施例中，步骤440可以由获取模块310执行。
所述第二本底事件与所述晶体的自身辐射粒子有关，所述第二本底事件可以为本底单事件。在一些实施例中，处理设备140可以在完成所述成像设备的能量状态校正后获取所述第二本底事件，或者在能量状态校正或晶体位置查找表校正前获取所述第二本底事件，本说明书对此不作限制。在一些实施例中，处理设备140可以根据预设的能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的第二本底事件。在一些实施例中，所述能量窗的范围在成像设备的临床能量窗阈值范围之内。在一些实施例中，处理设备140可以根据预设的时间窗，获取所述探测器接收到的所述晶体的自身辐射粒子的第二本底事件。在一些实施例中，所述时间窗的范围在成像设备的临床时间窗阈值范围之内。
在步骤450中，处理设备140可以基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正。在一些实施例中，步骤450可以由校正模块340(如飞行时间状态校正单元348)执行。
在一些实施例中，处理设备140可以基于所述第一本底事件和第二本底事件确定测量飞行时间，并根据所述测量飞行时间所反映的所述成像设备的飞行时间状态，对所述成像设备的探测器的飞行时间进行校正。具体地，处理设备140可以通过对所述第一本底事件和第二本底事件进行符合处理，得到本底符合事件，基于该本底符合事件的信息确定测量飞行时间以及理论飞行时间；根据该本底符合事件的信息对所述探测器的飞行时间进行校正。在一些实施例中，本底事件的信息可以包括本底事件中粒子到达成像设备的探测器的到达时间以及相应的晶体位置。在一些实施例中，在对飞行时间状态进行校正之前，处理设备140可以判断飞行时间状态是否异常。更多关于飞行时间校正的内容可以参见本说明书其他部分，例如，图19及其相关描述，此处不再赘述。
在一些实施例中，处理设备140可以基于所述第一本底事件和第二本底事件，生成事件时刻谱；根据所述事件时刻谱，确定TDC值与时间的对应关系；根据所述对应关系，确定所述成像设备的TDC刻度曲线。在一些实施例中，处理设备140可以获取所述晶体的第四本底事件，基于所述第四本底事件确定成像设备的TDC刻度曲线。其中，所述第四本底事件与所述晶体的自身辐射粒子有关。第四本底事件可以包括本底单事件或本底符合事件。在一些实施例中，处理设备140可以基于所述第四本底事件，生成事件时刻谱；根据所述事件时刻谱，确定TDC值与时间的对应关系；根据所述对应关系，确定所述成像设备的TDC刻度曲线。
仅作为示例，处理设备140可以基于探测器接收的探测器的晶体的自身辐射粒子的本底单事件或本底符合事件(例如，第四本底事件)，确定每个TDC值对应的本底事件数N i，即事件时刻谱，其中，i表示TDC值，i＝0,1,2,…。具体地，在成像设备的探测器接收到本底事件后，可以记录本底事件中的粒子到达探测器的到达时间，并将该到达时间转换为相应的电信号(即通道数)，根据电信号生成所述事件时刻谱。在一些实施例中，采集的本底事件总数越多，误差越小，对应得到的TDC刻度曲线的准确性越高。例如，为减小统计误差，可以使得TDC值对应的N i平均值大于1000。进一步，处理设备140可以基于所述事件时刻谱，确定基准TDC值以及与其对应的参考时间。例如，图20中所示，处理设备140可以将能够使得事件时刻谱中左右两边的TDC值对应的本底事件总数大体相等的TDC值60(即图20中竖直虚线对应位置的channel值)确定为所述基准TDC值，将其记为i 0。然后，令所述 基准TDC值对应的时间为T/2，作为所述参考时间，其中，T表示TDC的时钟周期。进一步地，可以通过数学式：T I-1＝T I–N I*(T/ΣN I)进行递归计算，确定所述事件时刻谱中所述基准TDC值左边的TDC值与时间的对应关系，其中，I＝i 0,i 0-1,i 0-2,…,i start。可以通过数学式：T I+1＝T I+NI*(T/ΣN I)进行递归计算，确定所述事件时刻谱中所述基准TDC值右边的TDC值与时间的对应关系，其中，I＝i 0,i 0+1,i 0+2,…,i end,其中T I＝i0＝T/2。处理设备140可以基于上述基准TDC值左边的TDC值与时间的对应关系以及右边的TDC值与时间的对应关系，得到TDC值与时间的对应关系T(i),i＝0,1,2,…，进而得到TDC刻度曲线(如图21所示)。可以理解，上述参考时间位置仅作为示例，在一些替代性实施例中，可以选择其他的TDC值作为基准TDC值(例如，事件时刻谱中TDC值为0的TDC值)，所述参考时间可以为[0,T]中的任意时间值，本说明书对此不做限制。在一些实施例中，TDC刻度曲线的形式可以包括曲线、函数关系、查找表等形式，本说明书对此不做限制。在一些实施例中，在得到TDC刻度曲线后，处理设备140可以基于该TDC刻度曲线确定TDC刻度曲线上任意TDC值对应的时间。在一些实施例中，处理设备140可以基于该TDC刻度曲线确定TDC刻度曲线上任意TDC值对应的时间，基于确定的时间进行飞行时间校正或时间同步校正等。
在一些实施例中，处理设备140可以根据所述第一本底事件和第二本底事件，确定测量飞行时间以及理论飞行时间；根据所述测量飞行时间以及所述理论飞行时间，对所述探测器的探测器模块进行时间同步。在一些实施例中，处理设备140可以基于所述第四本底事件，对成像设备的探测器进行时间同步。例如，第四本底事件可以包括成像设备110的探测器接收到的晶体的自身辐射粒子的本底符合事件，处理设备140可以根据该本底符合事件的信息，确定测量飞行时间以及理论飞行时间；响应于所述测量飞行时间与所述理论飞行时间的差异超过阈值，对探测器模块进行时间同步。在一些实施例中，在对探测器模块进行时间同步之前，处理设备140可以判断探测器模块的时间是否同步。更多关于时间同步的内容可以参见本说明书其他部分，例如，图16-17及其相关描述，此处不再赘述。
在一些实施例中，处理设备140可以基于同一次采集的本底单事件(例如，第一本底事件或第二本底事件)，对成像设备110的晶体位置查找表以及能量状态进行校正。在一些实施例中，处理设备140可以基于同一次采集的本底单事件或本底符合事件(例如，第三本底事件)，对成像设备110的能量校正状态进行检测和/或校正以及确定能量刻度曲线。在一些实施例中，处理设备140可以基于同一次采集的本底符合事件(例如，第一本底事件和第二本底事件进行符合处理得到的本底符合事件、第三本底事件或第四本底事件)，对成像设备110的飞行时间状态进行校正、时间同步和/或确定TDC刻度曲线。在一些实施例中，处 理设备140可以基于本底单事件或本底符合事件(例如，第三本底事件或第四本底事件)确定成像设备110的TDC刻度曲线。
在一些实施例中，处理设备140可以响应于成像设备110的晶体位置查找表被校正，对成像设备进行能量状态校正、探测器模块的时间同步和/或飞行时间状态校正等。在一些实施例中，处理设备140可以响应于成像设备110能量状态被校正，对成像设备进行探测器模块的时间同步以及飞行时间状态校正。在一些实施例中，能量状态检测和/或校正、能量刻度曲线确定、探测器模块的时间同步、飞行时间状态校正、TDC刻度曲线确定中的任一操作可以单独执行(即，系统100可以针对每一种状态检测或校正，单独进行一次本底事件的采集，各种状态检测或校正之间不共用相同的本底事件数据)。
应当注意的是，上述有关方法400的描述仅仅是为了示例和说明，而不限定本申请的适用范围。对于本领域技术人员来说，在本申请的指导下可以对方法400进行各种修正和改变。例如，处理设备140可以响应于成像设备110的能量状态异常，获取所述第一本底事件，并基于所述第一本底事件对成像设备110的能量状态进行校正。又例如，处理设备140可以响应于成像设备110的飞行时间状态异常，获取所述第一本底事件和第二本底事件，并基于所述第一本底事件和第二本底事件对成像设备110的飞行时间状态进行校正。然而，这些修正和改变仍在本申请的范围之内。
理想的情况下，接收湮灭效应γ光子的探测器的晶体阵列的物理位置和解码到图像上位置的对应关系可以是线性关系。但是，由于编码过程中的康普顿散射效应、各晶体的物理材质不均一以及相关电子元器件的非线性响应等原因，导致两者的对应可以呈非线性关系。γ光子入射位置探测的准确性可以保证成像设备(例如PET设备)的图像分辨率。因此，为了找到晶体与图像之间的对应关系，可以建立晶体位置查找表，通过该查找表确定γ光子的准确接收位置。
LYSO闪烁晶体以其高光输出、快发光衰减、有效原子序数多、密度大、物化性质稳定以及对γ射线探测效率高等特点，可以被用作成像设备的探测器的闪烁晶体。LYSO中存在的Lu176在衰变过程中可以释放出能量分别为88keV、202keV和307keV的三种能量的γ光子以及能量随机范围为0keV～597keV的β粒子。
本说明书实施例提供一种晶体位置查找表的校正方法，可以对具有一定规则排列的晶体阵列和光感探测器耦合形成的探测器模块，在无放射源的条件下，利用探测器的晶体的本底固有放射现象，采集固定能量区间的本底事件，形成单事件图像，通过单事件图像对晶体位置查找表进行标定校正。
图6是根据本申请的一些实施例所示的晶体位置查找表校正装置的示例性框图。
如图6所示，晶体位置查找表校正装置600可以包括：获取模块610、图像生成模块620以及校正模块630。在一些实施例中，获取模块610与获取模块310可以为相同结构和/或功能的模块，图像生成模块620与图像生成模块320可以为相同结构和/或功能的模块，以及校正模块630与校正模块340中LUT校正单元342可以为相同结构和/或功能的模块。
获取模块610可以用于获取成像设备的探测器接收到的来自于探测器的晶体的自身辐射粒子的本底事件(例如，第一本底事件)。图像生成模块620可以用于根据所述本底事件确定单事件图像。校正模块630可以用于根据所述单事件图像对所述成像设备的晶体位置查找表进行校正。关于晶体位置查找表校正装置600的各个模块的更多内容可以参见图7及其相关描述，此处不再赘述。
图7是根据本申请的一些实施例所示的晶体位置查找表校正方法的示例性流程图。
在一些实施例中，成像设备的晶体位置查找表校正方法700可以由成像设备的状态检测系统100(如处理设备140)、成像设备的状态校正装置300或晶体位置查找表校正装置600执行。例如，晶体位置查找表校正方法700可以以程序或指令的形式存储在存储装置(如存储设备150)中，当状态检测系统100(如处理设备140)执行该程序或指令时，可以实现成像设备的晶体位置查找表校正方法700。下面呈现的晶体位置查找表校正方法700的操作示意图是说明性的。在一些实施例中，可以利用一个或以上未描述的附加操作和/或未讨论的一个或以上操作来完成该过程。另外，图7中示出的和下面描述的晶体位置查找表校正方法700的操作的顺序不旨在是限制性的。如图7所示，晶体位置查找表校正方法700可以包括如下步骤：
步骤710，获取成像设备的探测器的晶体的本底事件。在一些实施例中，步骤710可以由处理设备140、或获取模块310、或获取模块610执行。
在一些实施例中，所述本底事件与所述晶体的自身辐射粒子有关。具体地，如果探测器的晶体为LYSO闪烁晶体，由于LYSO中存在的Lu176，衰变时产生的β粒子可以在发生衰变的探测器的晶体被立即吸收，而γ光子可以通过整个视野到达对面的晶体被相应的探测器的晶体吸收，探测器晶体在接收到β粒子或γ光子之后，可以记录相应的粒子到达时间或光子到达时间、粒子能量或光子能量以及相应的晶体位置，即本底事件的信息。
在一些实施例中，在获取探测器晶体自身辐射粒子的本底事件之前，处理设备140可以预先设置探测器的能量窗，根据预先设置的能量窗获取探测器接收到的来自于探测器的晶体的自身辐射粒子的本底事件(例如，第一本底事件)。在一些实施例中，可以基于能量分 辨率确定探测器的能量窗，能量分辨率越高其对应的能量窗的值可以越小。在一些实施例中，为了更好地适应LYSO本底固有的放射性现象，可以通过设置合适的能量窗，以滤除掉接收到的低能量的本底辐射粒子。在一些实施例中，所述能量窗的范围可以在成像设备(例如，PET设备)的临床能量窗阈值范围之内。仅作为示例，可以首先获取在PET设备实际应用过程中，不同地区的不同医院的PET设备的能量窗阈值的大量数据，通过大量数据统计得到的PET设备的临床能量窗阈值范围；预先设置的探测器的能量窗的范围可以在相应PET设备的临床能量窗阈值范围之内，以保证基于获取的本底事件确定的数据可以与临床数据相匹配。在一些实施例中，在确定成像设备的能量窗之后，处理设备140可以根据能量窗获取本底事件(例如，第一本底事件)。
步骤720，根据所述本底事件确定单事件图像。在一些实施例中，步骤720可以由处理设备140、或图像生成模块320、或图像生成模块620执行。
在一些实施例中，处理设备140可以根据所述本底事件得到单一特征能峰事件；根据所述单一特征能峰事件生成所述单事件图像。具体地，处理设备140可以根据本底事件中探测器接收β粒子或γ光子之后所记录的粒子能量或光子能量，形成相应的能谱图。其中，由于Lu176在衰减的过程中会释放出88keV、202keV和307keV的三种能量的γ光子以及能量随机范围为0keV～597keV的β粒子，三种γ光子以及β粒子之间可以产生能量叠加。因此，在一些实施例中，生成的能谱图中的单一特征能峰事件可以包括88keV的光子与β粒子叠加后形成的特征能峰事件、202keV与β粒子叠加后形成的特征能峰事件、307keV的光子与β粒子叠加后形成的特征能峰事件、597keV的特征能峰事件和/或597keV的光子与β粒子叠加后形成的特征能峰事件等。优选的，本实施例使用的单一特征能峰事件可以包括探测器接收到的597keV光子的本底事件。在一些实施例中，处理设备140可以根据成像设备110的探测器接收到的597keV光子的单一特征能峰事件生成单事件图像。
理论上可以采用597keV的光子的特征能峰事件构建单事件图像，但是由于光子的散射以及电子学测量造成的误差等原因，使得实际测量得到的数据具备一定展宽的高斯分布。因此，处理设备140可以在构建单事件图像时，根据597keV的光子的特征能峰事件以及597keV的光子的特征能峰事件周围一定能量范围的光子的特征能峰事件生成单事件图像。
步骤730，根据所述单事件图像，对所述成像设备的晶体位置查找表进行校正。在一些实施例中，步骤730可以由处理设备140、或校正模块340、或校正模块630执行。
在一些实施例中，处理设备140可以根据所述单事件图像，获取晶体位置查找表中晶体的位置标号在所述单事件图像中对应的像素分布；和/或根据所述晶体的位置标号在所述单 事件图像中对应的像素分布，校正所述晶体位置查找表。单事件图像可以表示探测器的晶体阵列接收到的固定能量的光子沉积形成的图像，例如，图8A所示，图8A为示例性的单事件图像，图8A所示的单事件图像中的每个亮点簇表示一个探测器的晶体在图像中的映射位置。探测器的每个晶体根据其在探测器中所在的位置，都对应有一个晶体位置标号，即单事件图像中的每一个亮点簇都对应有一个晶体位置标号。因此，根据单事件图像，能够得到单事件图像中每一组像素点(即亮点簇)与晶体位置编号的对应关系。根据单事件图像中每组像素点与晶体位置编号的对应关系，即可对成像设备的晶体位置查找表进行校正。例如，处理设备140可以基于图8A所示的单事件图像中亮点簇的数量和/或位置确定图8B中所示相应的列数与图8C中所示相应行数，并基于单事件图像中每个亮点簇对应的行数和列数，确定相应的晶体位置标号，从而对晶体位置查找表进行校正。
在一些实施例中，成像设备110的探测器晶体可以根据校正后的晶体位置查找表获得由本底事件产生的本底符合事件，处理设备140可以基于该本底符合事件形成包含本底事件能量信息的符合事件图像，根据所述符合事件图像对成像设备110的晶体位置查找表进行二次校正，获得二次校正后的晶体位置查找表，二次校正后的晶体位置查找表可以更准确地定位接收本底符合事件的探测器的晶体的位置。
在一些实施例中，处理设备140可以基于所述本底事件，确定成像设备的晶体位置查找表是否发生偏移。在一些实施例中，处理设备140可以响应于成像设备的晶体位置查找表发生偏移(即晶体位置查找表的状态异常)，基于所述本底事件校正晶体位置查找表。在一些实施例中，处理设备140可以获取单事件图像，基于单事件图像对成像设备的晶体位置查找表进行校正。
使用上述晶体位置查找表校正方法，可以有效避免日常校正操作中放射源的使用，并能够简化校正流程，有效地利用无患者扫描情况下成像设备的本底事件数据，提高校正频率，使得成像设备能够自适应地进行迭代校正优化，提高成像设备的性能。
根据本申请一些实施例所提供的晶体位置查找表的校正方法，可以通过限定能量窗滤除低能量本底事件，采集探测器的单事件数据，得到晶体Lu176自然衰变产生的597keV光子的特征峰事件的单事件图像。与Na-22放射源所得的511keV光子的特征峰事件的单事件图像相比，基本呈现相似的峰谷分布。依据相似的单事件图像，对晶体位置查找表进行校正，并利用校正后的晶体位置查找表进行成像设备的探测器的符合事件采数，能够提高成像设备的成像分辨率。
在一些实施例中，可以将校正后的晶体位置查找表直接写入成像设备中，以便后续扫 描成像时，可以直接使用该晶体位置查找表而不需要再进行晶体位置查找表校正。在一些实施例中，可以将校正后的晶体位置查找表存入存储设备(例如，存储设备150)中，以便后续在扫描成像或图像重建时，可以基于该晶体位置查找表进行晶体位置的校正。
成像设备(例如PET设备)由于元器件的老化和/或环境的变化，可能导致其能量增益状态出现漂移，严重时会影响图像的质量。本实施例提供一种能量校正状态(或称能量状态)检测方法，可以在无放射源的条件下，利用探测器的晶体的本底固有放射现象，采集固定能量区间的本底事件，实现对能量状态的检测。
图9是根据本申请的一些实施例所示的能量状态检测装置的示例性框图。
如图9所示，能量状态检测装置900可以包括：获取模块910、峰值位置确定模块920以及状态确定模块930。在一些实施例中，获取模块910与获取模块310可以为相同结构和/或功能的模块，峰值位置确定模块920与峰值位置确定单元332可以为相同结构和/或功能的模块，状态确定模块930与能量状态校正单元344可可以为相同结构和/或功能的模块。在一些实施例中，获取模块910可以为同时具有获取模块310和图像生成模块320具备的功能的模块。
获取模块910可以用于获取成像设备110的探测器的晶体的本底事件(例如，第一本底事件、或第三本底事件)及其相关信息。在一些实施例中，获取模块910可以用于基于本底事件的能量信息形成能谱图。在一些实施例中，获取模块910可以用于获取探测器的事件采集模式。例如，获取模块910可以从输入装置(例如，终端设备130的输入装置)获取探测器的事件采集模式。在一些实施例中，获取模块910可以用于根据所述事件采集模式，获取探测器接收到的所述探测器的晶体的自身辐射粒子的本底事件的能量信息并形成能谱图。在一些实施例中，获取模块910可以将获取的本底事件及其相关信息发送给其他模块(例如，图像生成模块320)，由其他模块生成能谱图。峰值位置确定模块920可以用于根据确定能谱图的峰值位置。例如，峰值位置确定模块920可以根据所述能谱图，得到能谱图的至少两个峰值位置。状态确定模块930可以用于根据所述能谱图的峰值位置以及与所述能谱图的峰值位置对应的校正峰值位置，确定能量校正状态。在一些实施例中，能量状态检测装置900还可以包括校正模块(例如，校正模块340)，用于确定成像设备的能量校正状态异常后，对成像设备的能量状态进行校正。关于能量状态检测装置900的各个模块的更多内容可以参见图10及其相关描述，此处不再赘述。
图10是根据本申请的一些实施例所示的能量状态检测方法的示例性流程图。
在一些实施例中，成像设备的能量状态检测方法1000可以由成像设备的状态检测系 统100(如处理设备140)、能量状态校正单元344、或能量状态检测装置900执行。例如，能量状态检测方法1000可以以程序或指令的形式存储在存储装置(如存储设备150)中，当状态检测系统100(如处理设备140)执行该程序或指令时，可以实现成像设备的能量状态检测方法1000。下面呈现的成像设备的能量状态检测方法1000的操作示意图是说明性的。在一些实施例中，可以利用一个或以上未描述的附加操作和/或未讨论的一个或以上操作来完成该过程。另外，图10中示出的和下面描述的能量状态检测方法1000的操作的顺序不旨在是限制性的。如图10所示，能量状态检测方法1000可以包括如下步骤：
步骤1010，获取成像设备的探测器的晶体的本底事件。在一些实施例中，步骤1010可以由处理设备140、或获取模块310、或获取模块910执行。
在一些实施例中，处理设备140可以获取成像设备的探测器接收到的探测器的晶体的自身辐射粒子的本底事件，例如，第一本底事件、或第三本底事件。
在一些实施例中，处理设备140可以确定所述探测器的事件采集模式；根据所述事件采集模式，获取所述探测器接收到的所述探测器的晶体的自身辐射粒子的本底事件。在一些实施例中，处理设备140可以基于用户输入确定探测器的事件采集模式。其中，事件采集模式可以包括单事件模式和符合事件模式。
步骤1020，基于所述本底事件的能量信息生成能谱图。在一些实施例中，步骤1020可以由处理设备140、或图像生成模块320、或获取模块910执行。
在一些实施例中，处理设备140可以基于获取的成像设备的探测器接收β粒子或γ光子之后所记录的粒子能量或光子能量，生成相应的能谱图。能谱图是指粒子的能量与对应本底事件数量的对应关系，其横坐标为能量，纵坐标为该能量对应的本底事件数量。
步骤1030，确定所述能谱图的峰值位置。在一些实施例中，步骤1030可以由处理设备140、或峰值位置确定单元332、或峰值位置确定模块920执行。
在一些实施例中，处理设备140可以根据所述能谱图，得到能谱图的至少两个峰值位置。具体地，能谱图的峰值位置可以包括全能峰峰值位置或单一能量峰值位置中的至少一种。全能峰峰值位置可以为三种能量的γ光子叠加后形成的597keV的能量峰值位置。单一能量峰值位置为γ光子与β粒子叠加后形成的能量峰值位置。例如：88keV的光子与β粒子叠加后形成的能量峰值位置、202keV与β粒子叠加后形成的能量峰值位置、和/或307keV的光子与β粒子叠加后形成的能量峰值位置。
更具体的，若通过单事件模式的本底单事件的能量信息形成能谱图，可以得到全能峰峰值位置以及单一能量峰值位置。能谱图的至少两个峰值位置可以为597keV的能量峰值位 置、88keV的光子与β粒子叠加后形成的能量峰值位置、202keV与β粒子叠加后形成的能量峰值位置、和/或307keV的光子与β粒子叠加后形成的能量峰值位置中的至少两个。若通过符合事件模式的本底符合事件的能量信息形成能谱图，可以得到单一能量峰值位置。能谱图的至少两个峰值位置可以为88keV的光子与β粒子叠加后形成的能量峰值位置、202keV与β粒子叠加后形成的能量峰值位置、和/或307keV的光子与β粒子叠加后形成的能量峰值位置中的至少两个。
步骤1040，根据所述能谱图的峰值位置，以及与所述能谱图的峰值位置对应的校正峰值位置，确定所述能量校正状态。在一些实施例中，步骤1040可以由处理设备140、或能量状态校正单元344、或状态确定模块930执行。
具体地，在一些实施例中，处理设备140可以在确定成像设备的能量校正状态之前，首先获取与当前能谱图的峰值位置对应的校正峰值位置。校正峰值位置可以对应511keV的光子所形成的能谱图的峰值位置。校正峰值位置可以指传统的成像设备(例如，PET设备)校正方法中，利用的如FDG(氟代脱氧葡萄糖)、Ge68(锗-68)之类的放射源发出的能量为511keV的γ光子所形成的能谱图的峰值位置。
在一些实施例中，处理设备140可以计算所述能谱图的峰值位置与校正峰值位置的比值；将该比值与预设阈值进行比较，若所述比值与预设阈值不相同，则确定成像设备的能量校正状态异常。在成像设备的能量不变的情况下，能谱图的峰值位置与校正峰值位置的比值可以是一个稳定的关系。该关系可以表示为一个固定值，也可以表示为一个能量峰值位置与所述比值相关的查找表。当成像设备的能量发生变化时，本底事件能谱图的能峰值位置可以发生变化，进一步地能谱图的峰值位置与校正峰值位置之间比值关系可以发生变化，因此可以通过能谱图的峰值位置与校正峰值位置之间的比值关系，来判断能量状态，也即能量的漂移情况。更具体地，可以预先统计大量数据，获取当前成像设备的能谱图的峰值位置与校正峰值位置之间的比值关系；根据大量的比值关系数据，得到相应成像设备对应的不同峰值位置与校正峰值位置之间的比值阈值。在实际应用过程中，可以将能谱图的峰值位置与校正峰值位置做比，得到比值；再获取该比值对应的能谱图的峰值位置的比值阈值。可以将计算得到的实际比值与比值阈值进行比较，若比值与对应的比值阈值不相同，则判断能量状态异常，即当前成像设备存在能量漂移情况；若比值与对应的比值阈值相同，则判断能量状态正常，即当前成像设备能量未发生漂移。
根据上述方法，可以通过无源检测采集本底事件并对成像设备的能量状态进行检测，可以减少操作者收受到辐射的剂量，降低医院的使用成本，并且相对于有源检测，其操作简 单，可以在任何时期进行检测。
在一些实施例中，处理设备140可以响应于成像设备的能量校正状态异常，调整所述成像设备的系统参数，以对所述成像设备的能量状态进行校正。在一些实施例中，处理设备140可以响应于成像设备的能量校正状态异常，向用户发出提示信息。
在一些实施例中，所述事件采集模式为单事件模式，处理设备140可以获取探测器接收到的本底单事件的能量信息并形成能谱图；所述能谱图可以包括全能峰峰值或单一能量峰值中的至少一种。
具体地，在单事件模式下，探测器接收到的本底单事件的能量信息形成的能谱图中可以包括597keV的能量峰值位置、88keV的光子与β粒子叠加后形成的能量峰值位置、202keV与β粒子叠加后形成的能量峰值位置、和/或307keV的光子与β粒子叠加后形成的能量峰值位置。更具体地，在单事件模式下，如图11所示，图11为单事件模式下生成的示例性的能谱图，峰值位置处为全能峰597keV的能量的峰值位置，但是由于β粒子的叠加效应，该位置的实际能量值大于597keV，约为635keV。通过该全能峰的峰值位置与校正峰值位置之比的变化，可以确定成像设备(例如，PET设备)的能量校正状态。本实施例中，以全能峰597keV的能量的峰值位置进行举例说明，在一些替代性实施例中，也可以获取88keV的光子与β粒子叠加后形成的能量的峰值位置、202keV与β粒子叠加后形成的能量的峰值位置、和/或307keV的光子与β粒子叠加后形成的能量的峰值位置，确定能量校正状态，本说明书对此不作限制。
在一些实施例中，所述事件采集模式为符合事件模式；处理设备140可以根据预设时间窗获取每个探测器的晶体接收的信息；所述信息可以包括粒子和/或光子的能量信息以及粒子和/或光子的到达时间；处理设备140可以根据所述光子的到达时间，筛选光子能量信息；根据筛选后的光子能量信息生成所述能谱图，所述能谱图可以包括单一能量峰值。
所述时间窗可以用于体现成像设备(例如，PET设备)的灵敏度。优选地，时间窗的范围可以不小于成像设备的临床时间窗阈值范围。在一些实施例中，处理设备140可以依据时间分辨率确定时间窗的范围。例如，时间窗的值可以大于时间分辨率的值，如以时间分布曲线的1/10高宽确定。时间分辨率可以指对已知本底符合事件中相对的两个探测器相应的时间差分布的半高全宽。为了更好地适应LYSO本底固有的放射性现象，可以设置合适的时间窗。每个探测器的晶体接收的粒子可以包括β粒子，也可以包括γ光子。由于β粒子在产生后即被吸收，吸收时间可以表示为Ta，而γ光子可以通过整个视野到达对面探测器的晶体被吸收检测到，吸收时间可以表示为Tb，因此γ事件的检测时间要比β事件的检测时间晚，即 Ta<Tb。根据这个原理，可以筛选出晶体中的γ事件。根据所述光子到达时间，筛选光子能量信息，也即筛选出γ事件。然后，可以根据筛选出来的光子能量信息形成能谱图。图12为一个实施例中符合事件模式下生成的能谱图。如图12所示，筛选出的γ光子的能谱图的峰值比较清晰，该峰值位置对应的能量为307keV，通过分析该307kev能量的峰值位置和511keV校正能量的峰值位置的比值的变化，即可得到当前成像设备的能量状态。在一些实施例中，也可以筛选出光子能量为88keV、202keV和/或307keV的三种能量的γ光子形成的能谱图的峰值位置。
根据上述生成能谱图的方法，可以根据不同事件采集模式，分别获取不同事件采集模式下的能谱图，进一步地能够得到更为准确的能量峰值位置，基于单事件模式采集，可以直接检测单事件的晶体能谱中的全能峰597keV的位置，但本发明不限于全能峰。符合事件模式中，可以检测307keV能量的峰值位置或其余能量的峰值位置，使得后续在确定能量状态时，确定结果更为精准。
能量刻度，可以指成像设备(例如PET设备)采集到的指代粒子能量的ADC值映射为实际能量的转换操作。成像设备的探测器在接收到光子之后，可以激发出可见光光子，这些光子可以通过光电倍增管(PMT)或硅光电倍增器(SiPM)转换为相应的电信号，该电信号可以经过模数转换生成ADC值。通过对已知能量与相应ADC值进行映射，可以完成能量刻度，得到能量刻度曲线。其中，ADC值可以为采集到的电信号进行模数转换后得到的数值。
本实施例提供的能量刻度曲线确定方法，可以通过探测器的晶体的固有放射现象，采集γ光子的本底事件，在晶体所得到的本底事件能谱中得到307keV特征能峰、597keV特征能峰等至少两个特征能峰，由所述至少两个特征能峰对实际应用中的511keV特征能峰进行插值拟合，得到ADC值与实际光子能量的对应关系。
图13是根据本申请的一些实施例所示的能量刻度曲线确定装置的示例性框图。
如图13所示，能量刻度曲线确定装置1300可以包括：获取模块1310、事件筛选模块1320以及曲线确定模块1330。在一些实施例中，获取模块1310与获取模块310可以为相同结构和/或功能的模块，能量状态校正单元344可以同时具备事件筛选模块1320与曲线确定模块1330两个模块的功能。
获取模块1310可以用于获取探测器接收到的来自于探测器的晶体自身辐射粒子的本底事件(例如，第三本底事件)。事件筛选模块1320可以用于对所述本底事件进行筛选，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值。曲线确定模块1330可以用于根据所述至少两个能峰值以及与所述至少两个能峰值对应的 ADC值，确定所述能量刻度曲线。在一些实施例中，能量刻度曲线确定装置1300还可以包括提取模块。提取模块可以用于根据所述能量刻度曲线，确定与所述能量刻度曲线上任意能峰值对应的ADC值。在一些实施例中，提取模块还可以用于根据所述能量刻度曲线，确定511keV能峰值对应的ADC值。关于能量刻度曲线确定装置1300的各个模块的更多内容可以参见图14及其相关描述，此处不再赘述。
图14是根据本申请的一些实施例所示的能量刻度曲线确定方法的示例性流程图。
在一些实施例中，成像设备的能量刻度曲线确定方法1400可以由成像设备的状态检测系统100(如处理设备140)、能量状态校正单元344、或能量刻度曲线确定装置1300执行。例如，能量刻度曲线确定方法1400可以以程序或指令的形式存储在存储装置(如存储设备150)中，当状态检测系统100(如处理设备140)执行该程序或指令时，可以实现能量刻度曲线确定方法1400。下面呈现的能量刻度曲线确定方法1400的操作示意图是说明性的。在一些实施例中，可以利用一个或以上未描述的附加操作和/或未讨论的一个或以上操作来完成该过程。另外，图14中示出的和下面描述的能量刻度曲线确定方法1400的操作的顺序不旨在是限制性的。如图14所示，能量刻度曲线确定方法1400可以包括如下步骤：
步骤1410，获取成像设备的探测器的晶体的本底事件。在一些实施例中，步骤1410可以由处理设备140、或获取模块310、或获取模块1310执行。
在一些实施例中，处理设备140可以获取探测器接收到的与探测器的晶体的自身辐射粒子有关的本底事件(例如，第一本底事件或第三本底事件)。成像设备在空闲时间，采集无源状态下的本底事件，由于本底中各类散射事件的比例较高，很容易降低本底能谱γ特征能峰的信噪比，因此，对于本底事件理论上采集的时间越长越好。本底事件的采集时间可以在0.1～20小时范围内。例如，采集时长可以不小于30分钟。
在一些实施例中，可以预先设置成像设备的时间窗和能量窗；基于所述时间窗和能量窗获取本底事件。关于能量窗的更多内容可以参见图7中相关描述，关于时间窗的更多内容可以参见图10中相关描述，此处不再赘述。
步骤1420，基于所述本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值。在一些实施例中，步骤1420可以由处理设备140、或事件筛选模块1320、或能量状态校正单元344执行。
在一些实施例中，处理设备可以根据所述本底事件，确定所述晶体的核素的γ衰变特征能峰值；对所述核素的γ衰变特征能峰值进行模数转换，得到相应特征能峰值对应的ADC值；选取所述γ衰变特征能峰值中的所述至少两个能峰值以及与所述至少两个能峰值对应的 ADC值。具体地，处理设备140可以根据所述本底事件生成相应的能谱图，通过对该能谱图进行能量筛选，即可得到核素的γ衰变特征能峰值。在一些实施例中，该核素可以包括Lu176等探测器的晶体中存在的具有放射性的核素。以核素为Lu176为例进行说明，Lu176对应的γ衰变特征能峰可以包括：88keV光子的γ衰变特征能峰、202keV光子的γ衰变特征能峰、307keV光子的γ衰变特征能峰、597keV光子的γ衰变特征能峰以及各种能量值对应的γ衰变特征能峰。通过对获取到的γ衰变特征能峰值进行模数转换，即可得到相应γ衰变特征能峰值的ADC值。在得到所有γ衰变特征能峰以及相应γ衰变特征能峰的ADC值之后，可以从中选取部分γ衰变特征能峰以及与其对应的ADC值。在能量刻度的过程中，越多的γ衰变特征能峰和与其对应ADC值被标定出来，得到的能量刻度越准确。在一些实施例中，优选的，可以选取至少两个特征能峰值(例如，0keV、307keV、597keV等)以及相应γ特征能峰值对应的ADC值。
步骤1430，根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述能量刻度曲线。在一些实施例中，步骤1430可以由处理设备140、或曲线确定模块1330、或能量状态校正单元344执行。
在一些实施例中，处理设备140可以通过插值拟合，确定能量刻度曲线。具体地，处理设备140可以对所述多个ADC值以及对应的γ特征能峰值进行插值拟合，得到能量刻度曲线。例如，处理设备140可以根据选取的0keV、307keV和597keV三个γ特征能峰值以及所述γ特征能峰值对应的ADC值，进行插值拟合，得到能量刻度曲线。该能量刻度曲线能够覆盖所有能量范围，例如，其能量范围可以为0到2000keV。
在一些实施例中，在根据所述多个ADC值以及对应的核素的γ衰变特征能峰值，得到能量刻度曲线之后，可以根据所述能量刻度曲线，确定能量刻度曲线上任意能峰值对应的ADC值。即可以根据能量刻度曲线，得到所有能峰值以及对应的ADC值。在实际使用过程中，在成像设备的实际使用中可能会用到各种药物(具有各种特征峰核素)，相应地，可以检测到对应能量的光子，因此，有必要提前获取所有的特征能峰值以及对应的ADC值。例如，在根据所述多个ADC值以及对应的核素的γ衰变特征能峰值，得到能量刻度曲线之后，可以根据所述能量刻度曲线，确定511keV能峰值对应的ADC值。在一些实施例中，511keV的能峰值是比较常用的放射性核素注射剂所产生的特征峰，因此，可以提前根据能量刻度曲线，得到511keV能峰值对应的ADC值。
上述能量刻度曲线确定方法可以避免对放射源的使用，提高了操作的安全性和可行性，有效的地利用无患者扫描情况下PET成像设备的本底事件数据，可以更有效、及时的地对探 测器的能量刻度曲线进行更新。
在一些实施例中，还提供了一种成像设备的探测器的晶体的能量校正方法，可以根据能量刻度曲线，确定511keV能峰值对应的ADC值，从而对探测器接收到的光子能量进行校正，使探测器对接收到的能量判别更加准确，进一步提高成像设备的成像精准度。
成像设备(例如PET设备)的探测器在接收正电子湮灭产生的一对γ光子时，相应的探测器模块需要测量γ光子到达探测器晶体的时间，为了确保时间的一致性，需要对探测器模块的时间进行对齐。此外，在时间对齐之后，也可能存在时钟失同步的问题。因此，有必要对探测器模块的时间进行同步。
在传统技术中，可以采用线缆进行时间同步，利用线缆连接各个探测器模块，并同时通过线缆向各个探测器模块发送脉冲。探测器模块可以根据脉冲，将本地时钟置零，从而完成时钟同步。上述传统技术，无法对时钟同步状态进行检测，并且当线缆发生老化或接口松动后，可以造成时钟同步失败的问题。
本申请提供一种时间同步方法，可以在无放射源的条件下，利用探测器的晶体的本底固有放射现象，采集对应的本底事件，基于本底事件的信息确定测量飞行时间和理论飞行时间，根据所述测量飞行时间以及所述理论飞行时间，对探测器的探测器模块进行时间同步。
图15是根据本申请的一些实施例所示的时间同步装置的示例性框图。
如图15所示，时间同步装置1500可以包括获取模块1510、时间确定模块1520以及时间同步模块1530。在一些实施例中，获取模块1510与获取模块310可以为相同结构和/或功能的模块，时间确定模块1520与时间确定单元334可以为相同结构和/或功能的模块，以及时间同步模块1530与时间同步单元346可以为相同结构和/或功能的模块。
获取模块1510可以用于获取成像设备的探测器的晶体的本底符合事件及其相关信息，所述本底符合事件与所述晶体的自身辐射粒子有关。时间确定模块1520可以用于根据所述本底符合事件的信息，计算测量飞行时间以及理论飞行时间。时间同步模块1530可以用于根据所述测量飞行时间以及所述理论飞行时间，对所述探测器进行时间同步。关于时间同步装置1500的各个模块的更多内容可以参见图16及其相关描述，此处不再赘述。
图16是根据本申请的一些实施例所示的时间同步方法的示例性流程图。
在一些实施例中，成像设备的时间同步方法1600可以由成像设备的状态检测系统100(如处理设备140)或时间同步装置1500执行。例如，时间同步方法1600可以以程序或指令的形式存储在存储装置(如存储设备150)中，当状态检测系统100(如处理设备140)执行该程序或指令时，可以实现时间同步方法1600。下面呈现的时间同步方法1600的操作示 意图是说明性的。在一些实施例中，可以利用一个或以上未描述的附加操作和/或未讨论的一个或以上操作来完成该过程。另外，图16中示出的和下面描述的时间同步方法1600的操作的顺序不旨在是限制性的。如图16所示，时间同步方法1600可以包括如下步骤：
步骤1610，获取成像设备的探测器的晶体的本底符合事件。在一些实施例中，步骤1610可以由处理设备140、或获取模块310、或获取模块1510执行。
在一些实施例中，处理设备140可以获取成像设备的探测器接收到的探测器的晶体的自身辐射粒子有关的本底符合事件(例如，基于第一本底事件和第二本底事件符合处理得到的本底符合事件、或第三本底事件、或第四本底事件)的信息。
步骤1620，根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间。在一些实施例中，步骤1620可以由处理设备140、或时间确定单元334、或时间确定模块1520执行。
在一些实施例中，处理设备140可以根据每一个本底符合事件中的两个粒子被探测器模块内晶体探测到的时间(即到达所述探测器的到达时间)，得到相应本底符合事件的测量飞行时间；根据所述每一个本底符合事件中两个粒子的所述晶体位置，得到相应本底符合事件的理论飞行时间。图17为示例性的探测器模块接收光子的示意图。仅作为示例，如图17所示，如果探测器的其中一个探测器模块中的一个晶体接收到第一个粒子(例如β粒子)的时间为T1，另一个探测器模块中的一个晶体接收到第二个粒子(例如，γ光子)的时间为T2。可以将接收到第一个粒子的时间T1减去接收到第二个粒子的时间T2得到相应符合事件的测量飞行时间。如果接收到第一个粒子的探测器晶体为A，接收到第二个粒子的探测器晶体为B，那么可以获取探测器晶体A与探测器晶体B之间的直线距离L，再用该直线距离L除以光速C，即可得到理论飞行时间。
步骤1630，根据所述测量飞行时间以及所述理论飞行时间，对所述探测器进行时间同步。在一些实施例中，步骤1630可以由处理设备140、或时间同步单元346、或时间同步模块1530执行。
在一些实施例中，处理设备140可以响应于所述测量飞行时间与相应本底符合事件的理论飞行时间不相同(例如，测量飞行时间与理论飞行时间的差异大于一个阈值)，确定成像设备的各探测器模块之间的时间未同步；响应于所述测量飞行时间与相应本底符合事件的理论飞行时间相同(例如，测量飞行时间与理论飞行时间的差异不大于所述阈值)，确定成像设备的各探测器模块之间的时间是同步的。在一些实施例中，所述阈值可以为探测器模块的时钟周期。在一些实施例中，若成像设备的各探测器模块之间的时间未同步，处理设备140 可以根据所述测量飞行时间以及对应的理论飞行时间，对成像设备的探测器的各探测器模块进行时间同步。
在一些实施例中，处理设备140可以根据所述测量飞行时间以及理论飞行时间，确定时间差；根据所述时间差对成像设备的各探测器模块进行时间同步。例如，处理设备140可以通过测量飞行时间减去理论飞行时间得到时间差(或通过理论飞行时间减去测量飞行时间得到时间差)，根据时间差的绝对值对成像设备的各探测器模块进行时间同步。
在一些实施例中，处理设备140可以根据成像设备的探测器的任意一对探测器模块接收到的多个测量飞行时间以及多个理论飞行时间，计算所述多个测量飞行时间以及所述多个理论飞行时间的差值；根据多个差值，计算差值的均值，将所述均值确定为所述时间差。具体地，为了保证数据的可靠性，可以针对同一对探测器模块计算多个测量飞行时间与多个理论飞行时间的差值，即先获取同一对探测器模块探测到得多个本底符合事件的信息，对每一个本底符合事件的信息中的两个粒子被探测器模块内的晶体探测到的时间(即两个粒子到达所述探测器模块的到达时间)以及探测到该本底符合事件的探测器模块内的晶体位置，计算测量飞行时间以及理论飞行时间，再计算相应本底符合事件的测量飞行时间与理论飞行时间的差值；通过对多个本底符合事件的所述差值取平均值确定所述时间差，再通过所述时间差对成像设备的各探测器模块的晶体进行时间同步。通过该方法能够使时间同步更加的精准。
在一些实施例中，所述时间差可以大于或等于一个时钟周期。成像设备的探测器的每个探测器模块都包括一个计数器，该计数器可以作为相应探测器模块内所有探测器晶体的时钟，来记录当前的时间。即属于同一个探测器模块的探测器晶体使用同一个时钟。每经过一个周期，计数器将加1。时钟同步的过程可以是计数器对准的过程。将各个探测器晶体的时钟同步，即将相应探测器模块的时钟进行同步(例如，可以将各个探测器模块的计数器对齐)。具体地，若所述时间差大于或等于一个时钟周期，处理设备140可以对所述一对探测器模块中的其中一个探测器模块的计数器的值进行调整，并将调整后的计数器的值确定为时间参考标准。在一些实施例中，若时间差小于一个时钟周期，则不需要调整相应的计数器；若时间差大于或等于一个时钟周期，则在一对探测器模块的计数器中调整任意一个探测器模块的计数器，例如，对该计数器进行加1或减1使其与该对探测器模块中另一个探测器模块的计数器的值相同。调整完成之后，可以继续获取探测器晶体的自身辐射粒子的本底符合事件的信息，再根据本底符合事件的信息计算时间差，若时间差小于一个时钟周期，则时钟同步完成；若时间差大于或等于一个时钟周期，则继续调整计数器，直至检测得到的时间差小于一个时钟周期。
在一些实施例中，可以以所述任意一对探测器模块中的其中一个探测器模块为基准模块，对成像设备中除该对探测器模块外的其他探测器模块进行时间同步，直至所有探测器模块间的时间差均小于一个时钟周期。具体地，在一次时钟同步的过程中，可以首先对探测器中的任意一对探测器模块的时钟进行同步，同步完之后，将已经同步的该对探测器模块中的任意一个探测器模块作为基准模块，再依次对其余所有探测器模块进行时间同步，直至所有探测器模块间的时间差均小于一个时钟周期。
在一些实施例中，成像设备可以包括控制模块，控制模块可以根据时间差与一个时钟周期的比较结果输出控制信号，若时间差大于或等于一个时钟周期，控制模块将产生调整信号，调整各个探测器模块的计数器，以实现时钟对齐；若时间差小于一个时钟周期，则不产生调整信号。该方法中利用探测器晶体本底固有放射现象进行探测器模块之间的时钟同步，并实时进行同步状态监测，可以简化成像设备的结构，增加设备可靠性，避免由于线缆等原因造成的时钟同步失败问题。
成像设备(例如PET设备)由于硬件固有的特性，随着时间的变化，其飞行时间状态可能会出现漂移，严重时会影响成像质量。本申请实施例提供了一种飞行时间状态检测方法，在无放射源的条件下，利用探测器的晶体的本底固有放射现象，采集本底符合事件，基于本底符合事件的信息对成像设备的飞行时间状态进行校正，可以解决操作者受辐射剂量高、医院成本高以及操作复杂的问题。
图18是根据本申请的一些实施例所示的飞行时间状态检测装置的示例性框图。
如图18所示，飞行时间状态检测装置1800可以包括获取模块1810、飞行时间确定模块1820以及状态确定模块1830。在一些实施例中，获取模块1810与获取模块310可以为相同结构和/或功能的模块，飞行时间确定模块1820与时间确定单元334可以为相同结构和/或功能的模块，以及状态确定模块1830与飞行时间状态校正单元348可以为相同结构和/或功能的模块。
获取模块1810可以用于获取本底符合事件(例如，第三本底事件或第四本底事件)及其相关信息。在一些实施例中，获取模块1810还可以用于确定成像设备的时间窗和能量窗；以及基于所述时间窗和能量窗获取本底符合事件。飞行时间确定模块1820可以用于根据所述本底符合事件的信息，计算测量飞行时间以及理论飞行时间。状态确定模块1830可以用于根据所述测量飞行时间以及理论飞行时间，确定成像设备的飞行时间状态。
在一些实施例中，飞行时间状态检测装置1800还可以包括校正模块。校正模块可以用于根据所述成像设备的飞行时间进行校正，得到校正后的飞行时间。在一些实施例中，校 正模块还可以用于获取能量-时间映射关系；所述能量-时间映射关系反映粒子能量与飞行时间偏移量之间的映射关系；根据所述本底符合事件中两个粒子的能量以及能量-时间映射关系，获取相应本底符合事件的飞行时间偏移量；根据所述飞行时间偏移量对成像设备的飞行时间进行校正，得到校正后的飞行时间。
图19是根据本申请的一些实施例所示的飞行时间状态检测方法的示例性流程图。
在一些实施例中，成像设备的飞行时间状态(即，TOF状态)检测方法1900可以由成像设备的状态检测系统100(如处理设备140)或飞行时间状态检测装置1800执行。例如，飞行时间状态检测方法1900可以以程序或指令的形式存储在存储装置(如存储设备150)中，当状态检测系统100(如处理设备140)执行该程序或指令时，可以实现飞行时间状态检测方法1900。下面呈现的飞行时间状态检测方法1900的操作示意图是说明性的。在一些实施例中，可以利用一个或以上未描述的附加操作和/或未讨论的一个或以上操作来完成该过程。另外，图19中示出的和下面描述的飞行时间状态检测方法1900的操作的顺序不旨在是限制性的。如图19所示，飞行时间状态检测方法1900可以包括：
步骤1910，获取成像设备的探测器的晶体的本底符合事件。在一些实施例中，步骤1910可以由处理设备140、或获取模块310、或获取模块1810执行。
在一些实施例中，处理设备140可以获取成像设备的探测器接收到的探测器的晶体的自身辐射粒子相关的本底符合事件(例如，第三本底事件或第四本底事件)。在一些实施例中，处理设备140可以确定成像设备的时间窗和能量窗；基于所述时间窗和能量窗获取所述探测器接收到的所述晶体的自身辐射粒子的本底符合事件及其相关信息。关于能量刻度曲线确定装置1300的各个模块的更多内容可以参见图14及其相关描述，此处不再赘述。在一些实施例中，处理设备140可以基于两组不同的本底单事件(例如，第一本底事件和第二本底事件)通过符合处理获得本底符合事件。
步骤1920，根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间。在一些实施例中，步骤1920可以由处理设备140、或时间确定单元334、或飞行时间确定模块1820执行。
在一些实施例中，处理设备140可以根据本底符合事件中的两个粒子的所述到达时间，得到相应本底符合事件的测量飞行时间；根据本底符合事件中的两个粒子的所述晶体位置，得到相应本底符合事件的理论飞行时间。关于测量飞行时间以及理论飞行时间的更多内容可以参见图16及其相关描述，此处不再赘述。
步骤1930，根据所述测量飞行时间以及所述理论飞行时间，确定所述成像设备的飞行 时间状态，所述飞行时间状态可以反映探测器的晶体是否产生漂移。在一些实施例中，步骤1930可以由处理设备140、或飞行时间状态校正单元、或状态确定模块1830执行。
在一些实施例中，处理设备140可以比较所述测量飞行时间以及所述理论飞行时间的差异。响应于所述测量飞行时间与所述理论飞行时间的差异超过阈值，处理设备140可以确定与所述本底符合事件对应的晶体产生漂移，即飞行时间状态异常。具体地，若所述测量飞行时间与相应本底符合事件的理论飞行时间不相同(例如，测量飞行时间与理论飞行时间的差异大于一个阈值)，则可以确定该本底符合事件对应的探测器的晶体产生漂移；若所述测量飞行时间与相应本底符合事件的理论飞行时间相同(例如，测量飞行时间与理论飞行时间的差异不大于一个阈值)，则可以认为该本底符合事件对应的探测器的晶体正常，未产生漂移。理论上，在成像设备的TOF校正状态(即TOF状态)正常的情况下，测量飞行时间与理论飞行时间可以相等，即它们之间的差值接近于零。在一些实施例中，处理设备140可以通过计算每个探测器的晶体上的所有本底符合事件的测量飞行时间与理论飞行时间的差值，基于所有本底符合事件的差值的平均值或者高斯拟合后的期望值是否超过阈值，确认相应晶体是否发生偏移。
在一些实施例中，处理设备140可以在确定飞行时间状态异常之后，根据所述本底符合事件的信息对探测器的飞行时间进行校正，得到校正后的飞行时间。
具体地，处理设备140可以获取能量-时间映射关系。所述能量-时间映射关系可以反映粒子能量与飞行时间偏移量之间的对应关系。可以根据所述本底符合事件中的每一个本底符合事件中的两个粒子的能量以及所述能量-时间映射关系，获取相应本底符合事件的飞行时间偏移量。可以根据所述飞行时间偏移量对探测器的飞行时间进行校正，以得到校正后的飞行时间。在一些实施例中，本底符合事件的信息可以包括两个粒子的能量。结合图5，晶体阵列A和晶体阵列B分别耦合光传感器，将输出信号通过放大器放大，得到β事件的时间信息Ta和γ事件的时间信息Tb，并通过积分得到两个事件的能量信息Ea和Eb，也即得到两个粒子的能量。在进行校正之前，可以预先建立能量-时间映射关系。具体地，可以根据已经完成飞行时间校正的成像设备(例如，PET设备)，统计大量本底符合事件的两个不同能量的粒子对应的飞行时间偏移量，并建立两个粒子的能量与飞行时间偏移量之间的对应关系，也即能量-时间映射关系。在实际使用时，可以首先获取预先建立完成的能量-时间映射关系，再获取本底符合事件中两个粒子的能量。通过本底符合事件中两个粒子的能量查找能量-时间映射关系，确定与两个粒子能量对应的飞行时间偏移量，基于飞行时间偏移量对探测器的飞行时间进行校正，得到校正后的飞行时间。
本申请实施例提供的飞行时间状态检测方法，可以基于LYSO本底固有的放射性现象，通过不同的时间窗，获取多组本底符合事件。根据β和γ粒子不同的吸收特性，针对每对本底符合事件做出修正。可以通过多组本底符合事件，测量所有探测器晶体的TOF状态，并通过能量-时间映射关系，对成像设备的飞行时间进行校正，从而得到更为精准的TOF信息。利用上述飞行时间校正方法，可以节省校正时间，并提高飞行时间校正的精确度。
需要说明的是，在上述方法(例如，成像设备的晶体位置查找表校正方法700、能量状态检测方法1000、能量刻度曲线确定方法1400、时间同步方法1600以及飞行时间状态检测方法1900)中或者附图(例如，附图7、附图10、附图14、附图16以及附图19)的流程图中示出的步骤可以在诸如一组计算机可执行指令的计算机系统中执行，并且，虽然在流程图中示出了逻辑顺序，但是在某些情况下，可以以不同于此处的顺序执行所示出或描述的步骤。上述装置(例如，晶体位置查找表校正装置600、能量状态检测装置900、能量刻度曲线确定装置1300、时间同步装置1500以及飞行时间状态检测装置1800)的各个模块可以是功能模块也可以是程序模块，既可以通过软件来实现，也可以通过硬件来实现。对于通过硬件来实现的模块而言，上述各个模块可以位于同一处理器(例如，处理设备140)中；或者上述各个模块还可以按照任意组合的形式分别位于不同的处理器中。
上文已对基本概念做了描述，显然，对于本领域技术人员来说，上述详细披露仅仅作为示例，而并不构成对本申请的限定。虽然此处并没有明确说明，本领域技术人员可能会对本申请进行各种修改、改进和修正。该类修改、改进和修正在本申请中被建议，所以该类修改、改进、修正仍属于本申请示范实施例的精神和范围。
同时，本申请使用了特定词语来描述本申请的实施例。如“一个实施例”、“一实施例”、和/或“一些实施例”意指与本申请至少一个实施例相关的某一特征、结构或特点。因此，应强调并注意的是，本说明书中在不同位置两次或多次提及的“一实施例”或“一个实施例”或“一个替代性实施例”并不一定是指同一实施例。此外，本申请的一个或多个实施例中的某些特征、结构或特点可以进行适当的组合。
此外，本领域技术人员可以理解，本申请的各方面可以通过若干具有可专利性的种类或情况进行说明和描述，包括任何新的和有用的工序、机器、产品或物质的组合，或对他们的任何新的和有用的改进。相应地，本申请的各个方面可以完全由硬件执行、可以完全由软件(包括固件、常驻软件、微码等)执行、也可以由硬件和软件组合执行。以上硬件或软件均可被称为“数据块”、“模块”、“引擎”、“单元”、“组件”或“系统”。此外，本申请的各方面可能表现为位于一个或多个计算机可读介质中的计算机产品，该产品包括计算机 可读程序编码。
计算机存储介质可能包含一个内含有计算机程序编码的传播数据信号，例如在基带上或作为载波的一部分。该传播信号可能有多种表现形式，包括电磁形式、光形式等，或合适的组合形式。计算机存储介质可以是除计算机可读存储介质之外的任何计算机可读介质，该介质可以通过连接至一个指令执行系统、装置或设备以实现通讯、传播或传输供使用的程序。位于计算机存储介质上的程序编码可以通过任何合适的介质进行传播，包括无线电、电缆、光纤电缆、RF、或类似介质，或任何上述介质的组合。
本申请各部分操作所需的计算机程序编码可以用任意一种或多种程序语言编写，包括面向对象编程语言如Java、Scala、Smalltalk、Eiffel、JADE、Emerald、C++、C#、VB.NET、Python等，常规程序化编程语言如C语言、Visual Basic、Fortran 2003、Perl、COBOL 2002、PHP、ABAP，动态编程语言如Python、Ruby和Groovy，或其他编程语言等。该程序编码可以完全在用户计算机上运行、或作为独立的软件包在用户计算机上运行、或部分在用户计算机上运行部分在远程计算机运行、或完全在远程计算机或服务器上运行。在后种情况下，远程计算机可以通过任何网络形式与用户计算机连接，比如局域网(LAN)或广域网(WAN)，或连接至外部计算机(例如通过因特网)，或在云计算环境中，或作为服务使用如软件即服务(SaaS)。
此外，除非权利要求中明确说明，本申请所述处理元素和序列的顺序、数字字母的使用、或其他名称的使用，并非用于限定本申请流程和方法的顺序。尽管上述披露中通过各种示例讨论了一些目前认为有用的发明实施例，但应当理解的是，该类细节仅起到说明的目的，附加的权利要求并不仅限于披露的实施例，相反，权利要求旨在覆盖所有符合本申请实施例实质和范围的修正和等价组合。例如，虽然以上所描述的系统组件可以通过硬件设备实现，但是也可以只通过软件的解决方案得以实现，如在现有的服务器或移动设备上安装所描述的系统。
同理，应当注意的是，为了简化本申请披露的表述，从而帮助对一个或多个发明实施例的理解，前文对本申请实施例的描述中，有时会将多种特征归并至一个实施例、附图或对其的描述中。但是，这种披露方法并不意味着本申请对象所需要的特征比权利要求中提及的特征多。实际上，实施例的特征要少于上述披露的单个实施例的全部特征。
一些实施例中使用了描述成分、属性数量的数字，应当理解的是，此类用于实施例描述的数字，在一些示例中使用了修饰词“大约”、“近似”或“大体上”来修饰。除非另外说明，“大约”、“近似”或“大体上”表明所述数字允许有±20％的变化。相应地，在一些实 施例中，说明书和权利要求中使用的数值参数均为近似值，该近似值根据个别实施例所需特点可以发生改变。在一些实施例中，数值参数应考虑规定的有效数位并采用一般位数保留的方法。尽管本申请一些实施例中用于确认其范围广度的数值域和参数为近似值，在具体实施例中，此类数值的设定在可行范围内尽可能精确。
针对本申请引用的每个专利、专利申请、专利申请公开物和其他材料，如文章、书籍、说明书、出版物、文档等，特此将其全部内容并入本申请作为参考。与本申请内容不一致或产生冲突的申请历史文件除外，对本申请权利要求最广范围有限制的文件(当前或之后附加于本申请中的)也除外。需要说明的是，如果本申请附属材料中的描述、定义、和/或术语的使用与本申请所述内容有不一致或冲突的地方，以本申请的描述、定义和/或术语的使用为准。
最后，应当理解的是，本申请中所述实施例仅用以说明本申请实施例的原则。其他的变形也可能属于本申请的范围。因此，作为示例而非限制，本申请实施例的替代配置可视为与本申请的教导一致。相应地，本申请的实施例不仅限于本申请明确介绍和描述的实施例。

Claims (38)

  1. 一种成像设备的状态检测方法，其特征在于，包括：
    获取所述成像设备的探测器的晶体的第一本底事件，所述第一本底事件与所述晶体的自身辐射粒子有关；
    基于所述第一本底事件，对所述晶体位置查找表进行校正；
    对所述成像设备的能量状态进行校正；
    获取所述晶体的第二本底事件，所述第二本底事件与所述晶体的自身辐射粒子有关；
    基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正。
  2. 根据权利要求1所述的方法，其特征在于，
    所述获取所述成像设备的探测器的晶体的第一本底事件包括：根据预设能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的第一本底事件；
    所述基于所述第一本底事件，对所述晶体位置查找表进行校正包括：
    基于所述第一本底事件，确定单事件图像；
    根据所述单事件图像，对所述晶体位置查找表进行校正。
  3. 根据权利要求1所述的方法，其特征在于，所述对所述成像设备的能量状态进行校正包括：
    基于所述第一本底事件，对所述成像设备的能量状态进行校正。
  4. 根据权利要求1所述的方法，其特征在于，所述对所述成像设备的能量状态进行校正包括：
    获取所述晶体的第三本底事件，所述第三本底事件与所述晶体的自身辐射粒子有关，所述第三本底事件包括所述探测器接收到的所述晶体的自身辐射粒子的本底单事件或本底符合事件；
    基于所述第三本底事件，对所述成像设备的能量状态进行校正。
  5. 根据权利要求3或4所述的方法，其特征在于，所述对所述成像设备的能量状态进行校正，包括：
    基于所述第一本底事件或所述第三本底事件的能量信息生成能谱图；
    确定所述能谱图的峰值位置；
    根据所述能谱图的峰值位置，以及与所述峰值位置对应的校正峰值位置，确定所述成像设备的能量校正状态；
    根据所述能量校正状态对所述成像设备的能量状态进行校正。
  6. 根据权利要求3或4所述的方法，其特征在于，所述对所述成像设备的能量状态进行校正包括：
    基于所述第一本底事件或所述第三本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值；
    根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述成像设备的能量刻度曲线。
  7. 根据权利要求1所述的方法，其特征在于，所述基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正包括：
    根据所述第一本底事件和所述第二本底事件，确定测量飞行时间；
    根据所述测量飞行时间所反映的所述成像设备的飞行时间状态对所述探测器的飞行时间进行校正。
  8. 根据权利要求1所述的方法，其特征在于，所述方法还包括：
    根据所述第一本底事件和/或所述第二本底事件，生成事件时刻谱；
    根据所述事件时刻谱，确定TDC值与时间的对应关系；
    根据所述对应关系，确定所述成像设备的TDC刻度曲线。
  9. 根据权利要求1所述的方法，其特征在于，所述方法还包括：
    获取所述晶体的第四本底事件，所述第四本底事件与所述晶体的自身辐射粒子有关；
    基于所述第四本底事件，生成事件时刻谱；
    根据所述事件时刻谱，确定TDC值与时间的对应关系；
    根据所述对应关系，确定所述成像设备的TDC刻度曲线。
  10. 根据权利要求1所述的方法，其特征在于，所述方法还包括：
    根据所述第一本底事件和所述第二本底事件，确定测量飞行时间以及理论飞行时间；
    根据所述测量飞行时间以及所述理论飞行时间，对所述探测器的探测器模块进行时间同步。
  11. 一种晶体位置查找表校正方法，其特征在于，所述方法包括：
    获取成像设备的探测器的晶体的本底事件，所述本底事件与所述晶体的自身辐射粒子有关；
    基于所述本底事件，确定单事件图像；
    根据所述单事件图像，对所述成像设备的晶体位置查找表进行校正。
  12. 根据权利要求11所述的方法，其特征在于，所述获取成像设备的探测器的晶体的本底事件包括：
    确定所述成像设备的探测器的能量窗，所述能量窗的范围在所述成像设备的临床能量窗阈值范围之内；
    根据所述能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的本底事件。
  13. 根据权利要求11所述的方法，其特征在于，所述基于所述本底事件，确定单事件图像包括：
    基于所述本底事件，确定单一特征能峰事件；所述单一特征能峰事件包括所述探测器接收到的597keV光子的事件；
    根据所述单一特征能峰事件，生成所述单事件图像。
  14. 根据权利要求11所述的方法，其特征在于，所述根据所述单事件图像，对所述成像设备的晶体位置查找表进行校正包括：
    根据所述单事件图像，获取所述晶体位置查找表中所述晶体的位置标号在所述单事件图像中的对应像素分布；
    根据所述晶体的位置标号在所述单事件图像中的对应像素分布，校正所述晶体位置查找表。
  15. 根据权利要求11所述的方法，其特征在于，所述方法进一步包括：
    基于所述本底事件，确定所述成像设备的晶体位置查找表是否发生偏移。
  16. 一种能量校正状态检测方法，其特征在于，包括：
    获取成像设备的探测器的晶体的本底事件，所述本底事件与所述晶体的自身辐射粒子有关；
    基于所述本底事件的能量信息生成能谱图；
    确定所述能谱图的峰值位置；
    根据所述能谱图的峰值位置，以及与所述能谱图的峰值位置对应的校正峰值位置，确定所述能量校正状态。
  17. 根据权利要求16所述的方法，其特征在于，所述基于所述本底事件的能量信息生成能谱图包括：
    基于所述探测器在所述单事件模式下接收到的本底事件的能量信息生成所述能谱图，其中，所述能谱图包括全能峰峰值或单一能量峰值中的至少一种。
  18. 根据权利要求16所述的方法，其特征在于，所述基于所述本底事件的能量信息生成能谱图包括：
    根据预设时间窗和/或预设能量窗，获取所述探测器在所述符合事件模式下接收到的所述探测器的晶体的自身辐射粒子的本底事件；所述预设时间窗的范围不小于所述成像设备的临床时间窗阈值范围；
    根据所述本底事件的粒子到达时间，筛选粒子能量信息；
    根据筛选后的所述粒子能量信息生成所述能谱图，所述能谱图包括单一能量峰值。
  19. 根据权利要求16所述的方法，其特征在于，
    所述能谱图的峰值位置包括全能峰峰值位置或单一能量峰峰值位置中的至少一种；
    所述根据所述能谱图的峰值位置，以及与所述能谱图的峰值位置对应的校正峰值位置，确定所述能量校正状态包括：
    确定所述能谱图的峰值位置与所述校正峰值位置的比值；
    基于所述比值，确定所述成像设备的能量校正状态是否异常。
  20. 根据权利要求16所述的方法，其特征在于，所述校正峰值位置对应511keV光子的能谱图的峰值位置。
  21. 一种能量刻度曲线确定方法，其特征在于，包括：
    获取成像设备的探测器的晶体的本底事件，所述本底事件与所述晶体的自身辐射粒子有关；
    基于所述本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值；
    根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述能量刻度曲线。
  22. 根据权利要求21所述的方法，其特征在于，所述基于所述本底事件，确定与所述晶体的核素衰变相关的至少两个能峰值以及与所述至少两个能峰值对应的ADC值包括：
    根据所述本底事件，确定所述晶体的核素的衰变特征能峰值；
    对所述核素的衰变特征能峰值进行模数转换，得到与所述衰变特征能峰值对应的ADC值；
    选取所述衰变特征能峰值中的所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值。
  23. 根据权利要求21所述的方法，其特征在于，
    所述至少两个能峰值包括307keV和597keV能峰值；以及
    与所述至少两个能峰值对应的ADC值包括与所述307keV和597keV能峰值对应的ADC值。
  24. 根据权利要求21所述的方法，其特征在于，所述根据所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值，确定所述能量刻度曲线包括：
    通过对所述至少两个能峰值以及与所述至少两个能峰值对应的ADC值进行插值拟合，确定所述能量刻度曲线。
  25. 根据权利要求21所述的方法，其特征在于，所述方法还包括：
    根据所述能量刻度曲线，确定511keV能峰值对应的ADC值；
    根据所述511keV能峰值对应的ADC值，对所述探测器接收到的粒子的能量进行校正。
  26. 一种时间同步方法，其特征在于，包括：
    获取成像设备的探测器的晶体的本底符合事件，所述本底符合事件与所述晶体的自身辐射粒子有关；
    根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间；
    根据所述测量飞行时间以及所述理论飞行时间，对所述探测器进行时间同步。
  27. 根据权利要求26所述的方法，其特征在于，
    所述本底符合事件的信息包括：所述本底符合事件的每一个本底符合事件中的两个粒子到达所述探测器的到达时间以及相应的晶体位置；
    所述根据所述本底符合事件的信息，确定测量飞行时间以及所述理论飞行时间包括：
    根据所述每一个本底符合事件的两个粒子的所述到达时间，确定所述每一个本底符合事件的测量飞行时间；以及
    根据所述每一个本底符合事件的两个粒子对应的所述晶体位置，确定所述每一个本底符合事件的理论飞行时间。
  28. 根据权利要求27所述的方法，其特征在于，所述根据所述测量飞行时间以及所述理论飞行时间，对所述探测器进行时间同步包括：
    基于所述测量飞行时间以及所述理论飞行时间，确定时间差；
    根据所述时间差，对所述探测器进行时间同步。
  29. 根据权利要求28所述的方法，其特征在于，所述基于所述测量飞行时间以及所述理论飞行时间，确定时间差包括：
    基于所述探测器的任意一对探测器模块接收到的多个测量飞行时间以及多个理论飞行时间，确定所述多个测量飞行时间以及所述多个理论飞行时间的差值；
    确定所述多个测量飞行时间以及所述多个理论飞行时间的差值的均值为所述时间差。
  30. 根据权利要求28或29所述的方法，其特征在于，所述根据所述时间差，对所述探测器进行时间同步包括：
    响应于所述时间差大于或等于一个时钟周期，对所述探测器的任意一对探测器模块中的其中一个探测器模块的计数器的值进行调整，并将调整后的计数器的值确定为时间参考标准；以及
    将调整计数器后的所述任意一对探测器模块中的任意一个探测器模块确定为基准模块，并基于所述基准模块对所述探测器中除该对探测器模块外的其它探测器模块进行时间同步。
  31. 一种飞行时间状态检测方法，其特征在于，包括：
    获取成像设备的探测器的晶体的本底符合事件，所述本底符合事件与所述晶体的自身辐射粒子有关；
    根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间；
    根据所述测量飞行时间以及所述理论飞行时间，确定所述成像设备的飞行时间状态，所述飞行时间状态反映了所述晶体是否产生漂移。
  32. 根据权利要求31所述的方法，其特征在于，所述获取成像设备的探测器的晶体的本底符合事件包括：
    确定所述成像设备的时间窗和能量窗；
    根据所述时间窗和能量窗，获取所述探测器接收到的所述晶体的自身辐射粒子的本底符合事件及其相关信息；
    其中，所述时间窗的范围不小于所述成像设备的临床时间窗阈值范围；所述能量窗的范围不小于所述成像设备的临床能量窗阈值范围。
  33. 根据权利要求31所述的方法，其特征在于，
    所述本底符合事件的信息包括：所述本底符合事件的每一个本底符合事件中的两个粒子 到达所述探测器的到达时间以及相应的晶体位置；
    所述根据所述本底符合事件的信息，确定测量飞行时间以及理论飞行时间包括：
    根据所述每一个本底符合事件的两个粒子的所述到达时间，确定所述每一个本底符合事件的测量飞行时间；以及
    根据所述每一个本底符合事件的两个粒子对应的所述晶体位置，确定所述每一个本底符合事件的理论飞行时间。
  34. 根据权利要求31所述的方法，其特征在于，所述根据所述测量飞行时间以及所述理论飞行时间，确定所述成像设备的飞行时间状态包括：
    响应于所述测量飞行时间与所述理论飞行时间的差异超过阈值，确定与所述本底符合事件对应的晶体产生漂移；以及
    根据所述本底符合事件的信息对所述探测器的飞行时间进行校正，以得到校正后的飞行时间。
  35. 根据权利要求34所述的方法，其特征在于，所述根据所述本底符合事件的信息对所述探测器的飞行时间进行校正，以得到校正后的飞行时间包括：
    获取能量-时间映射关系，所述能量-时间映射关系反映粒子能量与飞行时间偏移量之间的对应关系；
    基于所述能量-时间映射关系，确定与所述本底符合事件的每一个本底符合事件中的两个粒子的能量对应的飞行时间偏移量；
    根据所述飞行时间偏移量对所述探测器的飞行时间进行校正，以得到校正后的飞行时间。
  36. 一种成像设备的状态校正装置，其特征在于，包括：
    获取模块，用于获取所述成像设备的探测器的晶体的第一本底事件以及第二本底事件，所述第一本底事件和所述第二本底事件与所述晶体的自身辐射粒子有关；
    校正模块，用于基于所述第一本底事件，对所述晶体位置查找表进行校正；对所述成像设备的能量状态进行校正；以及基于所述第一本底事件和所述第二本底事件，对所述探测器的飞行时间状态进行校正。
  37. 一种计算机设备，包括存储器、处理器以及存储在所述存储器上并可在所述处理器上运行的计算机程序，其特征在于，所述处理器执行所述计算机程序时实现如权利要求1-35中任一项所述的方法。
  38. 一种计算机可读存储介质，其上存储有计算机程序，其特征在于，该程序被处理器执行时实现如权利要求1-35中任一项所述的方法。
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