KR101684448B1 - Radiation detector, tomography imaging apparatus thereof, and x-ray imaging apparatus thereof - Google Patents

Abstract

A radiation detector comprising a plurality of pixels for sensing radiation is disclosed.
Each of the plurality of pixels comprising: a radiation absorbing layer for converting incident photons into a first electrical signal; And a photon processing unit including a plurality of storage units for counting and storing the number of photons based on the first electrical signal. At least one storage unit of the plurality of storage units compares the first electrical signal with a first reference value, and based on a third electrical signal obtained by comparing the second electrical signal with a second reference value, , The number of photons is counted and stored.

Description

TECHNICAL FIELD [0001] The present invention relates to a radiation detector, a tomographic imaging apparatus, and an X-ray imaging apparatus,

The present invention relates to a radiation detector for counting incident photons, a tomography apparatus therefor, and an X-ray imaging apparatus.

More particularly, the present invention relates to a radiation detector for classifying and counting incident radiation photons in a plurality of energy bands, a tomography apparatus and an X-ray imaging apparatus.

The medical imaging device is a device for acquiring the internal structure of an object as an image. The medical image processing apparatus is a non-invasive examination apparatus, which captures and processes structural details in the body, internal tissues and fluid flow, and displays them to the user. A user such as a doctor can diagnose the health condition and disease of the patient by using the medical image outputted from the medical image processing apparatus.

As a device for irradiating a patient with radiation and photographing an object, there are typically a computed tomography (CT) apparatus and an x-ray apparatus.

A CT (Computerized Tomography) device of a medical image processing apparatus can provide a cross-sectional image of a target object and can represent the internal structure of the target object (for example, elongation, lung, etc.) It has advantages and is widely used for precise diagnosis of diseases.

An X-ray apparatus is a medical imaging apparatus that transmits an X-ray to a human body and acquires an internal structure of the human body as an image. The X-ray apparatus is advantageous in comparison with other medical imaging apparatuses including an MRI apparatus and a CT apparatus, and can acquire a medical image of a subject within a short time. Therefore, X-ray apparatus is widely used for simple chest radiography, simple abdominal radiography, simple skeleton radiography, simple sinus radiography, neck soft tissue radiography, and mammography.

In a medical imaging apparatus for photographing a target by irradiating radiation such as a computer tomography apparatus or an X-ray apparatus, a radiation detector for sensing radiation passing through the target must be provided. The radiation detector must accurately detect the radiation passing through the object so that the medical image of the object can be accurately reconstructed.

A radiographic detector for multiple energy measurement capable of increasing the number of distinctive energy bands while minimizing the size of a pixel, a tomographic imaging apparatus therefor, and an X-ray imaging apparatus.

It is also an object of the present invention to provide a radiation detector for multiple energy measurement capable of classifying and counting photons more accurately for each energy band, a tomography apparatus therefor, and an X-ray imaging apparatus.

A radiation detector according to an embodiment of the present invention includes a plurality of pixels for sensing radiation. Wherein each of the plurality of pixels includes a radiation absorbing layer that converts incident photons into a first electrical signal and a photon processing unit that includes a plurality of storage units that store and store the number of the photons based on the first electrical signal . At least one storage unit of the plurality of storage units compares the first electrical signal with a first reference value, and based on a third electrical signal that is a result of comparing the second electrical signal as a result of the comparison with a second reference value, , The number of photons is counted and stored.

At least one of the first and second reference values may be set to a first value in at least one of the plurality of pixels, and at least one of the plurality of pixels may be set to a second value different from the first value. .

The at least one storage unit may include a first comparator that outputs the second electrical signal corresponding to a difference between the first electrical signal and the first reference value when the first electrical signal is equal to or greater than the first reference value, A second comparator that compares the second electrical signal with the second reference value and outputs the third electrical signal, and a first counter that counts and stores the number of photons based on the third electrical signal .

The first electrical signal may be a voltage signal corresponding to the energy of the incident photon, the first reference value may have a voltage value, and the second reference value may have a current value.

The at least one storage unit may further include a second counter for counting and storing the number of photons when the first electrical signal is greater than or equal to the first reference value, based on the second comparison signal.

In addition, at least one of the first reference value and the second reference value may be set to a different value for each pixel in a pixel group including a plurality of adjacent pixels.

The second reference value used in the at least one storage unit may be set to a different value in a first pixel of the plurality of pixels and a second pixel adjacent to the first pixel.

The second reference value applied to the first pixel may have a value greater than or less than the second reference value applied to the second pixel.

The first reference value used in the at least one storage unit may be set to a different value in a first pixel of the plurality of pixels and a second pixel adjacent to the first pixel.

The at least one storage unit may be sized based on at least one of the first reference value and the second reference value.

The at least one storage unit may have a first bit depth if the energy band of the photons to be counted is a low energy band and a second bit depth if the energy band of the photons to be counted is a high energy band higher than the low energy band. It can have two bit depths.

Also, the radiation detector may be a direct radiation detector for generating a CT image based on the counted photons.

The radiation absorbing layer may be disposed on a front surface of the radiation detector, and the photon processing unit may be disposed on a rear surface of the radiation detector.

Further, the radiation absorbing layer may be formed of cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe).

A radiation detector according to another embodiment of the present invention includes a plurality of pixels for sensing radiation. Each of the plurality of pixels comprising a plurality of sub-pixels, each of the plurality of sub-pixels comprising a radiation absorbing layer for converting incident photons into a first electrical signal, And a photon processing unit including a plurality of storage units for counting and storing the numbers. At least one storage unit of the plurality of storage units compares the first electrical signal with a first reference value, and based on a third electrical signal that is a result of comparing the second electrical signal as a result of the comparison with a second reference value, , The number of photons is counted and stored.

At least one of the first and second reference values

Wherein at least one of the plurality of subpixels is set to a first value and at least one of the plurality of pixels is set to a second value different from the first value.

The at least one storage unit may include a first comparator that outputs the second electrical signal corresponding to the difference between the first electrical signal and the first reference value when the first electrical signal is greater than or equal to the first reference value. A second comparator for comparing the second electrical signal with the second reference value and outputting the third electrical signal; And a first counter for counting and storing the number of photons based on the third electrical signal.

The first electrical signal is a voltage signal corresponding to the energy of the incident photon, the first reference value has a first voltage value, and the second reference value has a first current value.

The at least one storage unit may further include a second counter for counting and storing the number of photons when the first electrical signal is greater than or equal to the first reference value, based on the second comparison signal.

At least one of the first reference value and the second reference value may be set to a different value for each subpixel in a subpixel group including a plurality of adjacent subpixels.

In addition, the second reference value used in the at least one storage unit may be set to a different value in a first sub-pixel among the plurality of sub-pixels and a second sub-pixel adjacent to the first sub-pixel.

In addition, the second reference value applied to the first subpixel may have a value larger than the second reference value applied to the second subpixel.

The first reference value used in the at least one storage unit may be set to a different value in a first subpixel of the plurality of subpixels and a second subpixel adjacent to the first subpixel.

The at least one storage unit may be sized based on at least one of the first reference value and the second reference value.

The at least one storage unit may have a first bit depth if the energy band of the photons to be counted is a low energy band and a second bit depth if the energy band of the photons to be counted is a high energy band higher than the low energy band. It can have two bit depths.

The radiation detector may also be attached to the gantry and emit from a rotating X-ray source to sense the radiation passing through the object.

In addition, the radiation detector may be a direct radiation detector for generating multi-energy CT images based on the counted photons.

The radiation detector may also be attached to a mobile device and emit from a position adjustable X-ray source to sense the radiation passing through the object.

Further, it can be a radiation detector used for generating a multi-energy X-ray image.

According to another aspect of the present invention, there is provided a detector for detecting radiation, the detector comprising at least one coefficient pixel and including a plurality of image pixels for reconstructing an image. The coefficient pixel comprising: a radiation absorbing layer for converting incident photons into an electrical signal; A plurality of comparators for comparing the electrical signal with a plurality of reference values to classify the photons into a plurality of energy bands; And a plurality of counters for counting and storing the number of photons classified into each of the plurality of energy bands. At least one of the plurality of reference values in the first coefficient pixel included in the image pixel is different from at least one of the plurality of reference values in the second coefficient pixel included in the image pixel.

A tomography apparatus according to another embodiment of the present invention includes a radiation detector, wherein the radiation detector includes at least one coefficient pixel and includes a plurality of image pixels for reconstructing an image. The coefficient pixel comprising: a radiation absorbing layer for converting incident photons into an electrical signal; A plurality of comparators for comparing the electrical signal with a plurality of reference values to classify the photons into a plurality of energy bands; And

And a plurality of counters for counting and storing the number of photons classified into each of the plurality of energy bands. At least one of the plurality of reference values in the first coefficient pixel included in the image pixel is different from at least one of the plurality of reference values in the second coefficient pixel included in the image pixel.

The tomographic apparatus may further include an input / output unit for outputting a user interface screen for setting the plurality of reference values from a user.

The tomography apparatus may further include a power unit for generating a plurality of voltages corresponding to the plurality of reference values input through the user interface screen and supplying the plurality of voltages to the plurality of comparators.

Also, the tomographic apparatus may include a digital-to-analog converter for generating a current corresponding to the plurality of reference values input through the user interface screen and supplying the generated current to the plurality of comparators.

Also, at least one of the plurality of reference values used in the first coefficient pixel may have the same value as at least one of the plurality of reference values used in the second coefficient pixel.

The reference value used to classify the low energy band among the plurality of reference values used for the first coefficient pixel may be a reference value used for classifying the low energy band among the plurality of reference values used in the second coefficient pixel, Can have the same value.

Further, the first coefficient pixel may be adjacent to the second coefficient pixel.

In addition, the coefficient pixel may have a size less than or equal to one square millimeter.

In addition, each of the plurality of counters may vary in size according to the plurality of reference values.

The plurality of comparators further includes: a first comparator for comparing the first electrical signal with a first reference value; A second comparator for comparing the first electrical signal with a second reference value; And a third comparator for comparing the first electrical signal with a third reference value, wherein at least one of the first to third reference values used in the first coefficient pixel is a first To the third reference value by a predetermined offset.

Further, the tomographic apparatus may further include a first reference value used for the first coefficient pixel from the user, the first reference value used for the second coefficient pixel, and a second reference value used for the predetermined offset And an input / output unit for outputting a user interface screen for setting at least one.

A tomographic apparatus according to another embodiment of the present invention includes a radiation detector including a plurality of pixels for sensing radiation; And an image processor for reconstructing the CT image based on the photon amount detected by the radiation detector. Each of the plurality of pixels comprising: a radiation absorbing layer for converting incident photons into a first electrical signal; And a photon processing unit including a plurality of storage units for counting and storing the number of photons based on the first electrical signal. Wherein at least one storage unit of the plurality of storage units compares the first electrical signal with a first reference value, and based on a third electrical signal that is a result of comparing the second electrical signal as a result of the comparison with a second reference value, The number of photons is counted and stored.

An X-ray photographing apparatus according to an embodiment of the present invention includes an X-ray photographing apparatus including a radiation detector, wherein the radiation detector includes at least one coefficient pixel and includes a plurality of image pixels for reconstructing an image. The coefficient pixel comprising: a radiation absorbing layer for converting incident photons into an electrical signal; A plurality of comparators for comparing the electrical signal with a plurality of reference values to classify the photons into a plurality of energy bands; And a plurality of counters for counting and storing the number of photons classified into each of the plurality of energy bands. At least one of the plurality of reference values in the first coefficient pixel included in the image pixel is different from at least one of the plurality of reference values in the second coefficient pixel included in the image pixel.

1A is a schematic diagram of a typical CT system 20.
1B is a diagram illustrating the structure of a CT system 20 according to an embodiment of the present invention.
2 is a diagram showing a configuration of a communication unit.
Fig. 3A is a diagram showing a configuration of the X-ray system 200. Fig.
FIG. 3B is a view showing the fixed X-ray apparatus 200. FIG.
3C is a diagram showing a mobile X-ray apparatus 300. Fig.
4 is a view showing a radiation detector according to an embodiment of the present invention.
FIG. 5A is a view for explaining one pixel in FIG. 4; FIG.
5B is a diagram for explaining spectrum modeling.
6 is a view for explaining the energy distribution of photons incident on the radiation detector.
7A is another view showing a radiation detector according to an embodiment of the present invention.
7B is a view showing a radiation detector according to another embodiment of the present invention.
7C is a view showing a radiation detector according to another embodiment of the present invention.
8 is a view for explaining a radiation detector according to an embodiment of the present invention.
9 is another view for explaining a radiation detector according to an embodiment of the present invention.
10 is another view for explaining a radiation detector according to an embodiment of the present invention.
11 is another view for explaining a radiation detector according to an embodiment of the present invention.
12 is a view for explaining a general radiation detector.
13 is a view showing a radiation detector according to another embodiment of the present invention.
14 is another view showing a radiation detector according to another embodiment of the present invention.
15 is a view showing a computer tomography apparatus according to an embodiment of the present invention.
16 is a view showing a user interface screen output from a computer tomography apparatus according to an embodiment of the present invention.
FIG. 17 is another diagram showing a user interface screen output from a computer tomography apparatus according to an embodiment of the present invention. FIG.
18 is a view showing a computer tomography apparatus according to another embodiment of the present invention.
19 is a view for explaining generation of an image pixel value of a CT image.

Brief Description of the Drawings The advantages and features of the present invention, and how to accomplish them, will become apparent with reference to the embodiments described hereinafter with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

The terms used in this specification will be briefly described and the present invention will be described in detail.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term, not on the name of a simple term, but on the entire contents of the present invention.

When an element is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements as well, without departing from the spirit or scope of the present invention. Also, as used herein, the term "part " refers to a hardware component such as software, FPGA or ASIC, and" part " However, 'minus' is not limited to software or hardware. The " part " may be configured to be in an addressable storage medium and configured to play back one or more processors. Thus, by way of example, and not limitation, "part (s) " refers to components such as software components, object oriented software components, class components and task components, and processes, Subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays and variables. The functions provided in the components and "parts " may be combined into a smaller number of components and" parts " or further separated into additional components and "parts ".

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly explain the present invention in the drawings, parts not related to the description will be omitted.

As used herein, the term "image" may refer to multi-dimensional data composed of discrete image elements (e.g., pixels in a two-dimensional image and voxels in a three-dimensional image). For example, the image may include a medical image or the like of the object obtained by the CT photographing apparatus.

Herein, the term " tomography image " means an image obtained by performing tomographic imaging of a target object in a tomography apparatus or tomography system, irradiating a light beam such as an x-ray to a target object, can do. In the present specification, the term "CT (Computed Tomography) image" may mean a composite image of a plurality of x-ray images obtained by photographing an object while rotating around at least one axis of the object.

As used herein, an " object "may be a person or an animal, or part or all of a person or an animal. For example, the subject may comprise at least one of the following: liver, heart, uterus, brain, breast, organs such as the abdomen, and blood vessels. The "object" may also be a phantom. A phantom is a material that has a volume that is very close to the density of the organism and the effective atomic number, and can include a spheric phantom that has body-like properties.

As used herein, the term "user" may be a doctor, a nurse, a clinical pathologist, a medical imaging specialist, or the like, and may be a technician repairing a medical device.

A CT system or the like can provide a cross-sectional image to a target object. Therefore, the advantage of being able to express the internal structure of a target object (for example, elongation, lung, etc.) have.

Specifically, the tomography system can include all tomography devices such as computed tomography (CT), optical coherence tomography (OCT) or positron emission tomography (PET) -T device, single photon emission computed tomography have.

Hereinafter, a tomography system for acquiring a tomographic image will be described by taking the CT system 20 as an example.

The CT system can obtain a relatively accurate sectional image with respect to a target object by, for example, acquiring image data of 2 mm or less in thickness at several tens or hundreds of times per second. Conventionally, there has been a problem that only the horizontal section of the object is expressed, but it has been overcome by the appearance of the following various image reconstruction techniques. Three-dimensional reconstruction imaging techniques include the following techniques.

- SSD (Shade surface display): A technique to represent only voxels having a certain HU value by the initial 3D image technique.

- MIP (maximum intensity projection) / MinIP (minimum intensity projection): A 3D technique that represents only those with the highest or lowest HU value among the voxels that make up the image.

- VR (volume rendering): A technique that can control the color and transparency of voxels constituting an image according to a region of interest.

- Virtual endoscopy: A technique capable of endoscopic observation on reconstructed 3-D images using VR or SSD techniques.

- MPR (multi planar reformation): An image technique that reconstructs into other sectional images. It is possible to reconstruct the free direction in the direction desired by the user.

- Editing: Several techniques for organizing surrounding voxels to more easily observe the region of interest in the VR.

- VOI (voxel of interest): A technique that expresses only the selected region by VR.

A computed tomography (CT) system 20 according to an embodiment of the present invention may be described with reference to FIGS. 1A and 1B. The CT system 20 according to an embodiment of the present invention may include various types of devices.

1A is a schematic diagram of a CT system 20. 1A, a CT system 20 may include a gantry 172, a table 175, an X-ray generator 176, and an X-ray detector 188.

The gantry 172 may include an X-ray generating unit 176 and an X-ray detecting unit 188.

The object 10 can be placed on the table 175. [

The table 175 can be moved in a predetermined direction (e.g., at least one of up, down, left, and right) in the CT photographing process. In addition, the table 175 may be tilted or rotated by a predetermined angle in a predetermined direction.

Also, the gantry 172 can be inclined by a predetermined angle in a predetermined direction.

1B is a diagram showing the structure of a CT system 20 according to an embodiment of the present invention.

The CT system 20 according to the embodiment of the present invention includes a gantry 172, a table 175, a control unit 188, a storage unit 194, an image processing unit 196, an input unit 198, a display unit 191, , And a communication unit (192).

As described above, the object 10 can be located on the table 175. [ The table 175 according to the embodiment of the present invention can be moved in a predetermined direction (e.g., at least one of up, down, left, and right) and the movement can be controlled by the control unit 188. [

The gantry 172 according to the embodiment of the present invention includes a rotation frame 104, an X-ray generation unit 176, an X-ray detection unit 188, a rotation drive unit 180, a data acquisition circuit 186, (190).

The gantry 172 according to an embodiment of the present invention may include a rotating frame 104 in the form of a ring that is rotatable based on a predetermined rotation axis RA. The rotating frame 104 may also be in the form of a disk.

The rotation frame 104 may include an X-ray generation unit 176 and an X-ray detection unit 188 disposed to face each other with a predetermined field of view (FOV). In addition, the rotating frame 104 may include an anti-scatter grid 114. Scattering prevention grid 114 may be positioned between the X-ray generating unit 176 and the X-ray detecting unit 188.

 In medical imaging systems, X-ray radiation reaching the detector (or photosensitive film) includes attenuated primary radiation, which forms useful images, as well as scattered radiation, which degrades the quality of the image . An anti-scatter grid may be placed between the patient and the detector (or photosensitive film) to transmit the majority of the radiation and attenuate the scattered radiation.

For example, the anti-scatter grid may include strips of lead foil, solid polymer material, solid polymer and fiber composite material, etc. And the interspace material of the interlayer material may be alternately stacked. However, the form of the scattering prevention grid is not necessarily limited thereto.

The rotation frame 104 receives the drive signal from the rotation drive unit 180 and can rotate the X-ray generation unit 176 and the X-ray detection unit 188 at a predetermined rotation speed. The rotary frame 104 can receive a driving signal and power from the rotary driving unit 180 through a slip ring (not shown) in a contact manner. In addition, the rotation frame 104 can receive a driving signal and power from the rotation driving unit 180 through wireless communication.

 The X-ray generator 176 receives voltage and current from a power distribution unit (PDU) (not shown) through a slip ring (not shown) through a high voltage generator . When the high voltage generating section applies a predetermined voltage (hereinafter referred to as a tube voltage), the X-ray generating section 176 can generate X-rays having a plurality of energy spectra corresponding to this predetermined tube voltage .

The X-ray generated by the X-ray generator 176 may be emitted in a predetermined form by a collimator 112.

The X-ray detector 188 may be positioned to face the X-ray generator 176. The X-ray detector 188 may include a plurality of X-ray detecting elements. The single X-ray detecting element can form a single channel, but is not necessarily limited thereto.

The X-ray detector 188 senses X-rays generated from the X-ray generator 176 and transmitted through the object 10, and can generate an electric signal corresponding to the intensity of the sensed X-rays.

The X-ray detector 188 may include an indirect method for converting radiation into light and detecting the radiation, and a direct method detector for converting the radiation into direct charge and detecting the radiation. An indirect X-ray detector can use a Scintillator. In addition, a direct-type X-ray detector can use a photon counting detector. A Data Acquisition System (DAS) 186 may be coupled to the X-ray detector 188. The electrical signal generated by the X-ray detector 188 may be collected at the DAS 186. The electric signal generated by the X-ray detector 188 may be collected by the DAS 186 either wired or wirelessly. The electric signal generated by the X-ray detector 188 may be amplified by an amplifier (not shown) To an analog / digital converter (not shown).

Only some data collected from the X-ray detector 188 may be provided to the image processor 196 or only some data may be selected by the image processor 196 depending on the slice thickness or the number of slices.

The digital signal may be provided to the image processing unit 196 through the data transmission unit 190. The digital signal may be transmitted to the image processing unit 196 through a data transmission unit 190 in a wired or wireless manner.

The controller 188 according to an embodiment of the present invention can control the operation of each module of the CT system 20. [ For example, the control unit 188 includes a table 175, a rotation driving unit 180, a collimator 182, a DAS 186, a storage unit 194, an image processing unit 196, an input unit 198, 191), the communication unit 192, and the like.

The image processing unit 196 may receive the data acquired from the DAS 186 (for example, raw data) through the data transmitting unit 190 and perform a process of pre-processing .

The preprocessing may include, for example, a process of non-uniformity of sensitivity correction between channels, a sharp decrease in signal intensity or a process of correcting loss of signal due to an X-ray absorber such as a metal.

The output data of the image processing unit 196 may be referred to as raw data or projection data. Such projection data can be stored in the storage unit 194 together with shooting conditions (e.g., tube voltage, shooting angle, etc.) at the time of data acquisition.

The projection data may be a set of data values corresponding to the intensity of the X-rays passing through the object. For convenience of explanation, a set of projection data simultaneously obtained with the same shooting angle for all the channels is referred to as a projection data set.

The storage unit 194 may be a flash memory type, a hard disk type, a multimedia card micro type, a card type memory (SD, XD memory, etc.), a RAM (Random Access Memory) SRAM (Static Random Access Memory), ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), PROM (Programmable Read-Only Memory) And may include at least one type of storage medium.

Also, the image processing unit 196 can reconstruct the cross-sectional image of the object using the acquired projection data set. Such a cross-sectional image may be a three-dimensional image. In other words, the image processing unit 196 may generate a three-dimensional image of a target object by using a cone beam reconstruction method or the like based on the obtained projection data set.

External inputs for X-ray tomography conditions, image processing conditions and the like can be received through the input unit 198. For example, the X-ray tomography conditions include a plurality of tube voltages, energy value setting of a plurality of X rays, selection of a photography protocol, selection of an image reconstruction method, FOV area setting, number of slices, slice thickness, Processing parameter setting, and the like. The image processing condition may include resolution of the image, setting of the attenuation coefficient for the image, and setting of the combination ratio of the image.

The input unit 198 may include a device or the like for receiving a predetermined input from the outside. For example, the input unit 198 may include a microphone, a keyboard, a mouse, a joystick, a touch pad, a touch pan, a voice, a gesture recognition device, and the like.

The display unit 191 can display an X-ray photographed image reconstructed by the image processing unit 196.

Transmission and reception of data, power, etc. between the above-described elements can be performed using at least one of wired, wireless, and optical communication.

The communication unit 192 can perform communication with an external device, an external medical device, or the like through the server 193 or the like. This will be described later with reference to Fig.

2 is a diagram showing a configuration of a communication unit.

The communication unit 192 may be connected to the network 15 by wire or wireless and may communicate with the external server 193, the medical device 164, or the portable device 166. The communication unit 192 can exchange data with other medical devices in a hospital server or a hospital connected through a PACS (Picture Archiving and Communication System).

In addition, the communication unit 192 may perform data communication with the portable device 166 or the like according to a DICOM (Digital Imaging and Communications in Medicine) standard.

The communication unit 192 can transmit and receive data related to the diagnosis of the object through the network 15. [ In addition, the communication unit 192 can transmit and receive medical images and the like acquired by the medical device 164 such as an MRI apparatus and an X-ray apparatus.

Further, the communication unit 192 may receive the diagnosis history or the treatment schedule of the patient from the server 193, and may utilize it for clinical diagnosis of the patient. The communication unit 192 may perform data communication with the user or the patient portable device 166 as well as the server 193 and the medical device 164 in the hospital.

In addition, information on the abnormality of the equipment and the quality management status information can be transmitted to the system administrator or the service person through the network, and the feedback can be received.

Fig. 3A is a diagram showing a configuration of the X-ray system 101. Fig.

Referring to FIG. 3A, an X-ray system 101 includes an X-ray apparatus 100 and a workstation 110. FIG. The X-ray apparatus 100 shown in FIG. 3A can be a fixed X-ray apparatus or a mobile X-ray apparatus. The X-ray apparatus 100 may include an X-ray irradiating unit 120, a high voltage generating unit 121, a detecting unit 130, an operating unit 140, and a controller 150. The control unit 150 can control the overall operation of the X-ray apparatus 100.

The high-voltage generating unit 121 generates a high voltage for generating X-rays and applies the generated high voltage to the X-ray source 122.

The X-ray irradiating unit 120 guides the path of the X-rays irradiated from the X-ray source 122 and the X-ray source 122, which receives the high voltage generated from the high voltage generating unit 121 to generate and irradiate X- And a collimator 123 for adjusting the irradiation area of the line.

The X-ray source 122 may include an X-ray tube, and the X-ray tube may be a bipolar tube composed of an anode and a cathode. The inside of the X-ray tube is made into a high-vacuum state of about 10 mmHg, and the filament of the cathode is heated to a high temperature to generate a thermal electron. As the filament, a tungsten filament can be used and the filament can be heated by applying a voltage of 10V and a current of about 3-5A to the electric wire connected to the filament.

When a high voltage of about 10-300 kVp is applied between the cathode and the anode, the thermoelectron accelerates and generates X-rays while colliding against the target material of the anode. The generated X-rays are irradiated to the outside through the window, and a beryllium thin film can be used as the material of the window. At this time, most of the energy of electrons impinging on the target material is consumed as heat, and the remaining energy consumed as heat is converted into X-rays.

The anode is mainly made of copper, and the target material is disposed on the side facing the cathode. High-resistance materials such as Cr, Fe, Co, Ni, W and Mo can be used as the target material. The target material can be rotated by a rotating field, and when the target material is rotated, the electron impact area is increased and the heat accumulation rate can be increased 10 times or more per unit area as compared with the case where the target material is fixed.

The voltage applied between the cathode and the anode of the X-ray tube is referred to as a tube voltage, which is applied by the high voltage generator 121, and its size can be expressed as a peak value kVp. As the tube voltage increases, the speed of the thermoelectrons increases and consequently the energy of the X-rays (energy of photons) generated by collision with the target material increases. The current flowing through the X-ray tube is referred to as a tube current and can be expressed as an average value mA. As the tube current increases, the number of thermoelectrons emitted from the filament increases. As a result, the dose of X- .

Therefore, the energy of the X-ray can be controlled by the tube voltage, and the intensity or dose of the X-ray can be controlled by the tube current and the X-ray exposure time.

The detection unit 130 detects X-rays that are irradiated from the X-ray irradiating unit 120 and transmitted through the object. The detection unit 130 may be a digital detection unit. The detection unit 130 may be implemented using a TFT, or may be implemented using a CCD. Although the detecting unit 130 is shown as being included in the X-ray apparatus 100 in FIG. 3A, the detecting unit 130 may be an X-ray detector that is a separate device that can be connected to and detached from the X-ray apparatus 100.

The X-ray apparatus 100 may further include an operation unit 140 that provides an interface for operating the X-ray apparatus 100. The operation unit 140 may include an output unit 141 and an input unit 142. The input unit 142 can receive a command for operating the X-ray apparatus 300 from the user and various information related to the X-ray imaging. The control unit 150 can control or manipulate the X-ray apparatus 100 based on the information input to the input unit 142. The output unit 141 can output a sound indicating irradiation related information such as X-ray irradiation under the control of the control unit 150. [

The work station 110 and the X-ray apparatus 100 may be connected to each other wirelessly or wired, and may further include a device (not shown) for synchronizing clocks when wirelessly connected. The workstation 110 may be in a physically separate space with the X-ray machine 100.

The workstation 110 may include an output unit 111, an input unit 112, and a control unit 113. The output unit 111 and the input unit 112 provide an interface for operation of the workstation 110 and the X-ray apparatus 100 to the user. The control unit 113 can control the work station 110 and the X-ray apparatus 100. [

The X-ray apparatus 100 may be controlled through the work station 110 and may also be controlled by the controller 150 included in the X-ray apparatus 100. The user controls the X-ray apparatus 100 through the work station 110 or controls the X-ray apparatus 100 through the operation unit 140 and the control unit 150 included in the X-ray apparatus 100 It is possible. In other words, the user may control the X-ray apparatus 100 remotely through the workstation 110, or may directly control the X-ray apparatus 100.

In FIG. 3A, the control unit 113 of the work station 110 and the control unit 150 of the X-ray apparatus 100 are shown separately, but FIG. 3A is only an example. In another example, the controllers 113 and 150 may be implemented as one integrated controller, and the integrated controller may be included only in one of the workstation 110 and the X-ray apparatus 100. [ Hereinafter, the control units 113 and 150 refer to at least one of the control unit 113 of the work station 110 and the control unit 150 of the X-ray apparatus 100.

The output unit 111 and the input unit 112 of the work station 110 and the output unit 141 and the input unit 142 of the X-ray apparatus 100 respectively provide the user with an interface for operating the X-ray apparatus 100 . 3A, each of the work station 110 and the X-ray apparatus 100 includes the output units 111 and 141 and the input units 112 and 142. However, the present invention is not limited thereto. The output or input may be implemented only in one of the workstation 110 and the X-ray machine 100.

The input units 112 and 142 mean at least one of the input unit 112 of the work station 110 and the input unit 142 of the X-ray apparatus 100. The output units 111 and 141 are connected to the work station 110 The output unit 111 of the X-ray apparatus 100 and the output unit 141 of the X-ray apparatus 100, respectively.

Examples of the input units 112 and 142 may include a keyboard, a mouse, a touch screen, a voice recognizer, a fingerprint recognizer, an iris recognizer, and the like, and may include input devices that are obvious to those skilled in the art. The user may input a command for X-ray irradiation through the input units 112 and 142, and the input units 112 and 142 may be provided with switches for inputting such commands. The switch must be pushed twice to set the irradiation command for X-ray irradiation to be inputted.

That is, when the user presses a switch, the switch can have a structure in which a preparation command for preheating for X-ray irradiation is input, and a probe command for inputting substantial X-ray irradiation is input by pressing the switch deeper in this state. When the user operates the switch as described above, the control units 113 and 150 generate a high voltage for generating X-rays by generating a signal corresponding to a command input through the switch operation, that is, .

The high voltage generating unit 121 receives the ready signal transmitted from the control units 113 and 150 and starts preheating. When the preheating is completed, the high voltage generating unit 121 transmits a ready signal to the control units 113 and 150. The control unit 113 and the control unit 150 detect the X-ray transmitted through the object by the detection unit 130 together with the preheating of the high-voltage generating unit 121 And transmits the ready signal to the detector 130 so that the ready signal can be prepared. Upon receipt of the ready signal, the detector 130 prepares for detecting the X-ray. When the preparation for detection is completed, the detector 130 transmits a detection ready signal to the controllers 113 and 150.

The controller 113 and 150 transmit the irradiation signal to the high voltage generating unit 121 and the high voltage generating unit 121 Generates a high voltage to be applied to the X-ray source 122, and the X-ray source 122 irradiates the X-ray.

The control units 113 and 150 transmit a sound output signal to the output units 111 and 141 so that a predetermined sound is output from the output units 111 and 141 so that the object can recognize the X- can do. In addition, the output units 111 and 141 can output sound indicating other imaging related information other than X-ray irradiation. The output section 141 or the output section 141 may be disposed at a position different from the position at which the operating section 140 is located Can be located at a point. For example, it may be located on the wall of the photographing room where X-ray photography of the object is performed.

The control units 113 and 150 control the positions of the X-ray irradiating unit 120 and the detecting unit 130, the imaging timing, and the imaging conditions according to the imaging conditions set by the user.

Specifically, the control units 113 and 150 control the high-voltage generating unit 121 and the detecting unit 130 according to an instruction input through the input units 112 and 142 to control the X-ray irradiation timing, the intensity of the X- And so on. The control units 113 and 150 adjust the position of the detection unit 130 and control the operation timing of the detection unit 130 according to a predetermined photographing condition.

In addition, the control units 113 and 150 generate a medical image for the target object using the image data received through the detection unit 130. [ Specifically, the control units 113 and 150 receive the image data from the detection unit 130, remove the noise of the image data, and adjust the dynamic range and interleaving to generate a medical image of the object .

The output units 111 and 141 can output the medical images generated by the control units 113 and 150. [ The output units 111 and 141 may output information necessary for a user to operate the X-ray apparatus 100, such as a UI (user interface), user information, or object information. Examples of the output units 111 and 141 include a speaker, a printer, a CRT display, an LCD display, a PDP display, an OLED display, a FED display, an LED display, a VFD display, a DLP display, an FPD display, a 3D display, And may include a variety of output devices within the scope as would be apparent to those skilled in the art.

The workstation 110 shown in FIG. 3A may further include a communication unit (not shown) that can be connected to the server 162, the medical device 164, the portable terminal 166, and the like via the network 15.

The communication unit may be connected to the network 15 by wired or wireless communication with the server 162, the medical device 164, or the portable terminal 166. The communication unit can transmit and receive data related to the diagnosis of the object through the network 15 and transmit and receive medical images taken by other medical devices 164 such as CT, MRI and X-ray apparatus. Further, the communication unit may receive the diagnosis history or the treatment schedule of the patient from the server 162 and utilize it for diagnosis of the object. The communication unit may perform data communication with not only the server 162 in the hospital or the medical device 164 but also with the portable terminal 166 such as a doctor, a customer's mobile phone, a PDA, or a notebook computer.

The communication unit may include one or more components that enable communication with an external device, and may include, for example, a local communication module, a wired communication module, and a wireless communication module.

The short-range communication module means a module for performing short-range communication with a device located within a predetermined distance. Examples of the local area communication technology according to an exemplary embodiment of the present invention include wireless LAN, Wi-Fi, Bluetooth, ZigBee, Wi-Fi Direct, UWB, But is not limited to, IrDA (Infrared Data Association), BLE (Bluetooth Low Energy), NFC (Near Field Communication), and the like.

The wired communication module refers to a module for communication using an electric signal or an optical signal. Examples of the wired communication technology include a wired communication technology using a pair cable, a coaxial cable, an optical fiber cable, etc., Self-evident wired communications technology may be included.

The wireless communication module transmits and receives a radio signal with at least one of a base station, an external device, and a server on a mobile communication network. Here, examples of the wireless signal may include various types of data according to a voice call signal, a video call signal, or a text / multimedia message transmission / reception.

The X-ray apparatus 100 shown in Fig. 3A is applicable to a variety of digital signal processing apparatuses (DSP), microcomputer processing apparatuses and special purpose applications (for example, high speed A / D conversion, fast Fourier transform, ) Processing circuit and the like.

Communication between the work station 110 and the X-ray apparatus 100 may be performed using a high-speed digital interface such as LVDS (Low Voltage Differential Signaling), asynchronous serial communication such as UART (universal asynchronous receiver transmitter) A CAN (Controller Area Network), or the like can be used, and various communication methods can be used within a range that is obvious to a person skilled in the art.

3B is a perspective view showing the fixed X-ray apparatus 200. FIG. The X-ray apparatus 200 of FIG. 3B may be an embodiment of the X-ray apparatus 100 of FIG. 3A. 3A, the same reference numerals as those in FIG. 3A are used for the same components as those in FIG. 3A, and redundant explanations are omitted.

3B, the X-ray apparatus 200 includes an operation unit 140 for providing an interface for operating the X-ray apparatus 200, an X-ray irradiating unit 120 for irradiating the object with X-rays, Second, and third motors 211, 212, and 213 for providing a driving force for moving the X-ray irradiating unit 120, first, second, and third motors 211 A moving carriage 230 and a post frame 240 provided to move the X-ray irradiating unit 120 by the driving force of the X-ray irradiating unit 120, 212, 213.

The guide rail 220 includes a first guide rail 221 and a second guide rail 222 installed at predetermined angles with respect to each other. It is preferable that the first guide rail 221 and the second guide rail 222 extend in directions perpendicular to each other.

The first guide rail 221 is installed on the ceiling of the examination room where the X-ray apparatus 200 is disposed.

The second guide rail 222 is positioned below the first guide rail 221 and is slidably mounted on the first guide rail 221. A roller (not shown) which can be moved along the first guide rail 221 may be installed on the first guide rail 221. The second guide rail 222 is connected to the roller (not shown) and is movable along the first guide rail 221.

A first direction D1 is defined in a direction in which the first guide rail 221 extends and a second direction D2 is defined in a direction in which the second guide rail 222 extends. Therefore, the first direction D1 and the second direction D2 may be orthogonal to each other and parallel to the ceiling of the examination room.

The movable carriage 230 is disposed below the second guide rail 222 so as to be movable along the second guide rail 222. The moving carriage 230 may be provided with a roller (not shown) provided to move along the second guide rail 222.

Accordingly, the movable carriage 230 is movable in the first direction D1 together with the second guide rail 222, and is movable along the second guide rail 222 in the second direction D2.

The post frame 240 is fixed to the movable carriage 230 and is located below the movable carriage 230. The post frame 240 may have a plurality of posts 241, 242, 243, 244, 245.

The length of the post frame 240 in the up-and-down direction can be increased or decreased while the post frame 240 is fixed to the moving carriage 230. As shown in FIG.

A third direction D3 is defined in a direction in which the length of the post frame 240 increases or decreases. Therefore, the third direction D3 can be orthogonal to the first direction D1 and the second direction D2.

The detection unit 130 detects X-rays transmitted through the object, and may be coupled to the table-type receptor 290 or the stand-type receptor 280. [

A rotary joint 250 is disposed between the X-ray irradiating unit 120 and the post frame 240. The rotary joint 250 couples the X-ray irradiating part 120 to the post frame 240 and supports a load acting on the X-ray irradiating part 120. [

The X-ray irradiator 120 connected to the rotary joint 250 can rotate on a plane perpendicular to the third direction D3. At this time, the rotational direction of the X-ray irradiating unit 120 can be defined as the fourth direction D4.

The X-ray irradiating unit 120 is rotatable on a plane perpendicular to the ceiling of the examination room. The X-ray irradiating unit 120 can rotate about the rotational joint 250 in the fifth direction D5, which is the rotational direction about the axis parallel to the first direction D1 or the second direction D2 .

The first, second and third motors 211, 212 and 213 may be provided to move the X-ray irradiating unit 120 in the first direction D1 to the third direction D3. The first, second, and third motors 211, 212, and 213 may be electrically driven motors, and the motor may include an encoder.

The first, second, and third motors 211, 212, and 213 may be disposed at various positions in consideration of design convenience. For example, the first motor 211 for moving the second guide rail 222 in the first direction D1 is disposed around the first guide rail 221 and moves the movable carriage 230 in the second direction The second motor 212 that moves the post frame 240 to the first direction D2 is disposed around the second guide rail 222 and the third motor 213 that increases or decreases the length of the post frame 240 in the third direction D3 May be disposed within the mobile carriage 230. As another example, the first, second and third motors 211, 212 and 213 may be connected to power transmission means (not shown) so as to linearly move the X-ray irradiating unit 120 in the first direction D1 to the third direction D3 . The power transmission means (not shown) may be a commonly used belt and pulley, chain and sprocket, shaft or the like.

As another example, in order to rotate the X-ray irradiating unit 120 in the fourth direction D4 and the fifth direction D5, the rotating joint 250 and the post frame 240, and the rotating joint 250 and the X- A motor may be provided between the motor and the motor.

An operation unit 140 may be provided on one side of the X-ray irradiating unit 120.

FIG. 3B illustrates a stationary X-ray apparatus 200 connected to a ceiling of a laboratory. However, the X-ray apparatus 200 shown in FIG. 3B is merely for convenience of understanding, The X-ray apparatus may include various types of X-ray apparatuses, such as a C-arm type X-ray apparatus and an angiography X-ray apparatus, as well as the stationary X-ray apparatus 200 shown in FIG. Device.

FIG. 3C shows a mobile X-ray apparatus 300 capable of performing X-ray imaging regardless of the location of the radiography. The X-ray apparatus 300 of FIG. 3C may be an embodiment of the X-ray apparatus 100 of FIG. 3A. Among the components included in the X-ray apparatus 300 of FIG. 3C, the same reference numerals as those of FIG. 3A are used for the same components as those of FIG. 3A, and redundant explanations are omitted.

The X-ray apparatus 300 shown in FIG. 3C includes a moving unit 370 provided with a wheel for moving the X-ray apparatus 300, a manipulating unit 140 for providing an interface for manipulating the X- A main unit 305 including a high voltage generating unit 121 for generating a high voltage applied to the X-ray source 122 and a control unit 150 for controlling the overall operation of the X-ray apparatus 300, And an X-ray irradiating unit 120 including a collimator 123 for guiding the path of the X-ray generated and irradiated by the X-ray source 122 and adjusting the irradiated area of the X-ray, And a detection unit 130 that is irradiated by the pre-irradiation unit 120 and detects X-rays transmitted through the object 10.

3C is shown coupled to the table-type receptor 390, it is obvious that the detector 130 can be coupled to the stand-type receptor.

3C, the operation unit 140 is included in the main unit 305, but the present invention is not limited thereto. For example, as shown in FIG. 3B, the operation unit 140 of the X-ray apparatus 300 may be provided on one side of the X-ray irradiating unit 120.

A radiation detector according to an embodiment of the present invention is a device for detecting radiation, and detects an incident radiation photon by a direct method. Thus, a radiation detector according to an embodiment of the present invention can be used in all electronic devices that sense radiation photons.

Specifically, the radiation detector according to the embodiment of the present invention may be any tomographic detector such as a CT (computed tomography) apparatus, an OCT (Optical Coherence Tomography) or a PET (positron emission tomography) -CT apparatus, a SPECT (single photon emission computed tomography) And can be applied to a photographing apparatus.

Specifically, the radiation detector according to the embodiment of the present invention may correspond to the X-ray detecting unit 178 described in FIGS. 1A and 1B, and may be the same as the X-ray detecting unit 178 described in the tomography system 20 described with reference to FIGS. 1A and 1B . Specifically, the radiation detector according to the embodiment of the present invention may be a radiation detector used for generating a tomography image. Specifically, the radiation detector according to the embodiment of the present invention may be a radiation detector used for CT (computed tomography) image generation. In detail, the radiation detector according to the embodiment of the present invention is installed in the gantry 172 shown in FIGS. 1A and 1B and is emitted from an X-ray generator 176, which is an X- It can detect radiation.

The radiation detector according to the embodiment of the present invention may correspond to the detector 130 described with reference to FIGS. 3A, 3B, and 3C and may include the X-ray system described with reference to FIGS. 3A, 3B, 101, or an X-ray apparatus 100, 200, 300, respectively. Specifically, the radiation detector according to an embodiment of the present invention may be a radiation detector used for generating an X-ray image. In particular, a radiation detector according to an embodiment of the present invention may be attached to a mobile device and emit from a position-adjustable X-ray source to sense the radiation passing through the object. Here, the mobile device to which the X-ray source is attached may include at least one of the guide rail 220, the moving carriage 230, and the post frame 240 described with reference to FIG. 3B. In addition, the mobile device may include the moving part 370 described in Fig. 3C.

In addition, the radiation detector according to the embodiment of the present invention can be a radiation detector that can detect incident radiation according to a plurality of energy bands. For example, the radiation detector according to an embodiment of the present invention may be a radiation detector for obtaining a dual energy tomographic image. Also, the radiation detector according to an embodiment of the present invention may be a radiation detector for obtaining a dual energy X-ray image.

The radiation detector according to an embodiment of the present invention will be described in detail below with reference to FIGS. 4 to 19. FIG.

4 is a view showing a radiation detector according to an embodiment of the present invention.

The radiation detector 400 according to an embodiment of the present invention is a coefficient type detector that detects radiation by a direct method that directly converts incident radiation into electric charge. Specifically, it is a photon counting detector that converts incident photons into electrical signals and counts the number of photons incident using the converted electrical signals. Also, the radiation detector 400 according to an embodiment of the present invention is a radiation detector for multiple energy measurement.

The radiation detector for multiple energy measurement classifies one photon into a plurality of bands according to energy level and restores the medical image using the number of photons classified by energy band. In detail, the radiation detector 400 according to the embodiment of the present invention may be a radiation detector for reconstructing a multi-energy radiation image. For example, the radiation detector may be a radiation detector for obtaining a dual energy CT image or a dual energy X-ray image. Referring to FIG. 4, a radiation detector according to an embodiment of the present invention includes a plurality of pixels 401, 402 for sensing radiation. Here, the pixel may refer to a unit detector that detects radiation and classifies it by energy band.

Specifically, the radiation detector 400 may be a radiation detector used for generating a tomographic image. For example, the radiation detector 400 may be the same device as the X-ray detector 178 of FIG. 1A used to generate a CT image. Also, the radiation detector 400 may be a device corresponding to the detection unit 130 of FIG. 3A, FIG. 3B, or FIG. 3C used to generate an X-ray image.

Specifically, the radiation absorber 410 converts the radiation photons into electrical signals in a direct manner, and may be composed of cadmium telluride (CdTe). Cadmium telluride (CdTe) is a semi-conductor material, and a photon processing unit (not shown) disposed on the rear surface 420 of the radiation absorbing unit 410 may also be formed of a semiconductor material. The photon processing unit (not shown) disposed on the rear surface 420 may be formed of cadmium telluride (CdTe), which is the same material as the radiation absorbing unit 410, and may be formed of other kinds of semiconductor materials.

In addition, the above-described 'front surface' or 'rear surface' is a relative concept, a surface arranged to face the radiation source emitting radiation and receiving the radiation is referred to as a front surface, and an opposite surface not facing the radiation source is referred to as a rear surface.

The plurality of pixels 401 and 402 may be arranged in a lattice form as shown and may have a tetrahedron structure having the same size. In FIG. 4, 16 * 16 = 256 pixels are included in the radiation detector 400 as an example.

In each of the plurality of pixels 401 and 402, a radiation absorbing layer 410 may be disposed on the front surface, and a photon processing unit (not shown) may be disposed on the rear surface 420. Specifically, the photon processing unit (not shown) may be arranged with a plurality of comparators and at least one counter for counting the radiation incident on the radiation absorbing layer 410 and for storing the counted number of radiation photons.

Specifically, the radiation transmitted through the object is incident on the front surface 440 of the radiation detector 400, and the radiation absorbed by the radiation absorbing layer 410 disposed on the front surface is absorbed.

Further, the radiation absorbing layer 410 may be formed on at least one portion of the surface facing the X-ray light source. Specifically, the radiation absorbing layer 410 may be formed on the front surface of the radiation detector 400 facing the X-ray light source, the sides of the surface facing the X-ray light source, or the radiation detector 400, At least a part of the rear surface of the base 400 may be formed. 4 shows an example in which the radiation absorbing layer 410 is formed to have a uniform thickness on the entire surface of the radiation detector 400 facing the X-ray light source.

Although FIG. 5A illustrates the case where subpixels are arranged in a square lattice form, the subpixels included in one pixel may have various shapes such as a honeycomb shape, a triangle shape, and a diamond shape. In addition, the number of subpixels included in one pixel may be variously formed in addition to the above-described 4 * 6 = 24, 5 * 5 = 25, or 6 * 6 = 36 examples.

의 크기를 가질 수 있다. 구체적으로, 하나의 픽셀(401)에서 한 변의 길이는 0.9mm 내지 1.1 mm 가 될 수 있다. 바람직하게, 픽셀 사이즈(pixel size)는 1 제곱 미리미터 이하의 사이즈를 가질 수 있어서, 전면 면적이 1

이하의 크기를 가질 수 있다. Further, the front surface of one pixel (e.g., 401) is approximately 1 mm * 1 mm = 1

. ≪ / RTI > Specifically, the length of one side of one pixel 401 may be 0.9 mm to 1.1 mm. Preferably, the pixel size can have a size less than or equal to one square millimeter,

Or less.

FIG. 5A is a view for explaining one pixel in FIG. 4; FIG. The pixel 540 shown in FIG. 5A corresponds to one pixel 401, 402 shown in FIG. Specifically, the radiation absorbing layer 510 disposed on the front surface of the pixel 540 and the rear surface 520 on which the photon processing section (not shown) is disposed are respectively disposed on the radiation absorbing layer 410 and the rear surface 420 shown in FIG. 4, The description corresponding to FIG. 4 is omitted.

Referring to FIG. 5A, one pixel 540 may include a plurality of sub-pixels. When the pixel 540 includes a plurality of subpixels, one unit detector for sensing and processing radiation may be a subpixel.

For example, one pixel 500 may include 4 * 6 = 24, 5 * 5 = 25, or 6 * 6 = 36 subpixels.

인 하나의 픽셀에서 흡수되어 계수되어야 하는 광자의 개수는 이하의 스펙트럼 모델링(spectrum modeling)에 따라서 결정될 수 있다. The radiation detector included in the CT system must absorb a predetermined number of photons when photographing under a predetermined photographing condition. Unit area is 1

The number of photons that should be absorbed and counted in one pixel can be determined according to the following spectrum modeling.

The photon counting detector included in the CT system of the high-grade type or higher includes a tube voltage of 120 kVp, a tube current of at least 200 mA and a filter condition. : Aluminum equivalent thickness can be set to approximately 5.6mm.

Under the above described imaging conditions, the number of photons that one pixel 600 should absorb and count can be calculated according to spectral modeling of the x-ray based TASMIP (Tungsten Anode Spectral Model).

의 단위 면적을 가질 수 있다. Specifically, the number of photons that one pixel has to absorb per second can be approximately 200 to 500 million. Here, one pixel is approximately 1

Lt; / RTI >

5B is a diagram for explaining spectrum modeling.

Referring to FIG. 5B, spectral modeling may be designed with the values shown in FIG. 5B.

을 통과하여 입사되는 플루엔스(Fluence)는 1m 거리에서 측정하였을 때 2004955 photons/

/mAs 가 된다. In spectral modeling, the mean photon energy is 60.605 keV (kilo electron volt) and the first half value layer is 6.886 mm Al. Exposure is 7,739 mR / mAs when measured at a distance of 1 m, and 67,799 uGy / mAs when measured at a distance of 1 m from the air kerma. Under the above-described modeling conditions,

(Fluence), which is incident through the photodiode, is measured at a distance of 1 meter,

/ mAs.

/mAs 로, 대략 2Mega photons/

/mAs 이 된다. 이하에서는, 백만의 단위로 M(mega)을 사용한다. According to spectral modeling, the number of photons generated when 1mA of x-rays occurred is 2004955 photons /

/ mAs, approximately 2 mega photons /

/ mAs. In the following, M (mega) is used in units of one million.

로 입사되는 광자의 개수는 200 * 2004955 photons/

/mAs 으로 대략 400 M photons/

/mAs이 될 수 있다. 또한, 50%의 선량 저감을 고려하여 100 mA 의 선량으로 동작할 때, 단위 면적 1

로 입사되는 광자의 개수는 100 * 2004955 photons/

/mAs 으로 대략 200 M photons/

/mAs이 될 수 있다. For a detector with a dose of 200 mA, the unit area 1

Lt; RTI ID = 0.0 > 200 * 2004955 < / RTI > photons /

/ mAs to about 400 M photons /

/ mAs. Also, considering the dose reduction of 50%, when operating at a dose of 100 mA, the unit area 1

Lt; RTI ID = 0.0 > 100 * 2004955 < / RTI > photons /

/ mAs to about 200 M photons /

/ mAs.

을 갖는 하나의 픽셀(500)은 1 초당 대략 200 M 개 이상의 광자를 흡수하여 계수할 수 있다. Thus, if the unit area is approximately 1

Can be counted by absorbing at least about 200 < RTI ID = 0.0 > M < / RTI > photons per second.

Referring to FIG. 5A, the pixel 500 may include 6 * 6 = 36 subpixels, as in 541. FIG. That is, the front surface 540 of the pixel 500 may correspond to 541. As described above, if the pixel 500 absorbs and counts about 200 M photons per second and includes 36 subpixels, then one subpixel 560 will have 200/36 M = 5.56 M photons It can be absorbed and counted per second.

5A, the pixel 500 may include 6 * 4 = 24 subpixels as in 542. [ That is, the front surface 540 of the pixel 500 may correspond to 542. As described above, if the pixel 500 absorbs and counts about 200 M photons per second and includes 24 subpixels, one subpixel will absorb 200/24 M = 8.33 M photons per second Can be counted.

Also, the pixel 500 may include 5 * 5 = 25 sub-pixels. As described above, if the pixel 500 absorbs and counts about 200 M photons per second and includes 25 subpixels, then one subpixel 570 will be about 200/25 M = 8 M per second The number of photons can be absorbed and counted.

As in the above example, the number of photons to be counted for a predetermined period of time can be set according to specifications of a specific product to which the radiation detector is applied, for example, an X-ray apparatus, a tomographic apparatus, or each condition of spectral modeling have. The number and size of subpixels included in one pixel can be adjusted according to the number of the set photons. For example, the size of the counter included in the photon processing unit can be adjusted according to the number of photons set.

Also, the counting operation of the incident photons is performed independently for each subpixel (e.g., 560), and thus the subpixel 560 may be referred to as a counting pixel. Hereinafter, a subpixel which is a partial pixel included in the pixel 540 is referred to as a 'counting pixel'. In addition, since one pixel value of an image to be reconstructed can be determined based on the number of photons counted in at least one coefficient pixel, the at least one coefficient pixel group including the coefficient pixel can be referred to as an image pixel . For example, when one pixel value of an image is obtained based on the number of photons counted in all the coefficient pixels included in the pixel 540, the image pixel becomes a pixel 540. As another example, when one pixel value of an image is obtained based on the number of photons counted in all four adjacent coefficient pixels, the image pixel can be a coefficient pixel group including four coefficient pixels. Thus, the number and size of the coefficient pixel groups may be the same as the number and size of image pixels.

For example, when one pixel is formed as in 541 and includes 36 coefficient pixels, if one pixel value of the image is obtained based on the number of photons counted in all of the 36 coefficient pixels, Can be a single image pixel. Also, when one pixel is formed as in 541 and includes 36 coefficient pixels, if one pixel value of the image is obtained based on the number of photons counted in the adjacent nine coefficient pixels, The group of coefficient pixels 551, 552, 553, or 554 may be an image pixel.

Here, the number of image pixels included in the radiation detector 400 is smaller than the number of coefficient pixels. In addition, the size of the image pixel included in the radiation detector 400 is larger than the size of the coefficient pixel.

Specifically, the coefficient pixel counts the number of photons less than the number of photons incident on the image pixel.

Specifically, the image pixel corresponds to one pixel value forming the image, and one pixel value in the image is calculated based on the total number of photons counted in one image pixel. Specifically, the image pixel may include a plurality of coefficient pixels, and one pixel value in the image may be calculated based on the total number of photons counted in the coefficient pixel group including the plurality of coefficient pixels. When a plurality of coefficient pixels included in one pixel 540 are formed into one coefficient pixel group, one pixel 540 can be one image pixel. In addition, when a plurality of coefficient pixels included in the pixel 540 form a plurality of coefficient pixel groups, the pixel 410 corresponds to one image pixel of one coefficient pixel group, so that the pixel 410 may include a plurality of image pixels have.

6 is a view for explaining the energy distribution of photons incident on the radiation detector. In FIG. 6, the x-axis represents the energy magnitude of the photon, and the y-axis represents the number of photons incident on the radiation detector at a predetermined area. For example, a photon having an energy value of a is incident on a predetermined area of b number of photons. For example, the graph shown in Fig. 6 can be an energy spectrum of a photon.

An X-ray source for emitting X-rays, for example, an X-ray generator 106 shown in FIG. 1 receives a voltage and an electric current through a high voltage generator (not shown) . Here, the emitted X-rays may have various sizes of energy as shown in FIG.

The radiation detector 400 classifies incident photons by classifying them according to the energy level of the photons.

7A is another view showing a radiation detector according to an embodiment of the present invention. Specifically, FIG. 7A shows a configuration of a unit detector 700 that detects radiation and classifies and counts the radiation according to energy bands.

In addition, the unit detector 700 may correspond to the pixel 401 or the subpixel 560 described with reference to Figs. 4 to 5A. That is, the pixel 401 may be the unit detector 700. Also, the subpixel 560 may be the unit detector 700. That is, the radiation detector 400 may include a plurality of unit detectors 700. In addition, since one subpixel 560 corresponds to one coefficient pixel, one unit detector 700 can correspond to one coefficient pixel.

Referring to FIG. 7A, the unit detector 700 includes a radiation absorbing layer 710 and a photon processing unit 720.

The radiation absorbing layer 710 converts the incident radiation photons into an electrical signal S1. Specifically, the radiation absorbing layer 710 converts an incident X-ray photon into an electrical signal. Specifically, the radiation absorbing layer 710 can convert the photons into hole-electron pairs and generate an electrical signal S1 corresponding to the energy of the incident photons. Further, the electric signal S1 may be a voltage signal or a current signal. Hereinafter, the case where the electric signal S1 is a voltage signal will be described as an example.

The radiation absorbing layer 710 transmits the converted electrical signal S1 to the photon processing unit 720 including a plurality of storage units 730, 740, and 750 connected to a subsequent stage.

Specifically, the radiation absorbing layer 710 converts the radiation into an electrical signal S1 in a direct manner. The radiation absorbing layer 710 may be composed of cadmium telluride (CdTe). Further, the radiation absorbing layer 710 may be composed of cadmium zinc telluride (CdZnTe).

인 경우, 방사선 흡수층(710)은 전술한 바와 같이 1

면적으로 1초 동안 대략 200M 개의 광자를 흡수할 수 있다. 또한, 도 7a에 도시된 단위 디텍터(700)가, 하나의 서브 픽셀 내에 포함되며 하나의 픽셀이 m 개의 서브 픽셀을 포함하는 경우, 방사선 흡수층(710)은 전술한 바와 같이 1초 동안 대략 (200/m) M개의 광자를 흡수할 수 있다. Further, in the radiation absorbing layer 710, the front surface area on which the radiation is incident is approximately 1

, The radiation absorbing layer 710 is made of a material having a composition of 1

The area can absorb approximately 200M photons for one second. 7A is included in one subpixel, and one pixel includes m subpixels, the radiation absorbing layer 710 is arranged in the order of 200 / m) can absorb M photons.

The photon processing unit 720 includes a plurality of storage units for counting and storing the number of photons based on the first electrical signal. In detail, the photon processing unit 720 includes a plurality of storage units 730, 740, and 750 according to the number of energy bands to be distinguished. The photon processing unit 720 also counts the number of photons based on the electric signal generated by the radiation absorbing unit 710, in accordance with a direct method of converting the incident photons into direct charges and detecting them.

Each of the plurality of storage units 730, 740, and 750 compares the first electrical signal with a first reference value, and based on the third electrical signal that is a result of comparing the second electrical signal as a comparison result with a second reference value, And stores the number.

Specifically, the plurality of storage units 730, 740, and 750 classify the photons absorbed in the radiation absorbing layer 710 according to the energy level. More specifically, the plurality of storage units 730, 740 and 750 compares the electric signal S1 transmitted from the radiation absorbing layer 710 with a plurality of reference values ref1, ref3 and ref5, respectively, A plurality of energy bands may be classified into a plurality of energy bands, and subsequently, a plurality of photons may be classified into a plurality of energy bands.

That is, the coefficient pixel 700, which is the unit detector 700, includes a radiation absorbing layer 710 for converting the incident photons into an electric signal S1, a plurality of electric signals S1 for dividing the photons into a plurality of energy bands A plurality of comparators 731 and 732, 741 and 742, 751 and 752 for comparing with the reference values ref1 and ref2, ref3 and ref4, ref5 and ref6, and a plurality of photons classified into a plurality of energy bands, And a plurality of counters 733, 743, and 753 for storing the data. At least one of the plurality of reference values in the first coefficient pixel included in the image pixel is set to a value different from at least one of the plurality of reference values in the second coefficient pixel included in the image pixel. The setting of different reference values in the first coefficient pixel and the second coefficient pixel will be described in detail below with reference to FIG.

7A, a case where the photon processing unit 720 includes three storage units 730, 740, and 750 will be described as an example.

For example, the first storage unit 730 may compare the first electrical signal S1 with the first reference value ref1, compare the second electrical signal S12 with the second reference value ref2 Based on the resultant third electrical signal S13, the number of photons is counted.

The second storage unit 740 compares the first electrical signal S1 with the first reference value ref3 and compares the second electrical signal S22 with the second reference value ref4, Based on the third electrical signal S23, the number of photons is counted.

The third storage unit 750 compares the first electrical signal S1 with the first reference value ref5 and compares the second electrical signal S32 with the second reference value ref6, Based on the third electrical signal S33, the number of photons is counted.

Specifically, at least one of the first reference values ref1, ref3, and ref5 and the second reference values ref2, ref4, and ref6 may be set differently in at least one unit detector among the plurality of unit detectors.

Here, the unit detector may correspond to a pixel or a subpixel. Therefore, at least one of the first reference values ref1, ref3, ref5 and the second reference values ref2, ref4, ref6 may be set differently in at least one of the plurality of pixels. Also, when the pixel included in the radiation detector 400 includes a plurality of sub-pixels, at least one of the first reference values ref1, ref3, ref5 and the second reference values ref2, ref4, May be set differently in at least one of the pixels.

The setting of the first reference values ref1, ref3, ref5 and the second reference values ref2, ref4, ref6 will be described below in detail with reference to Figs. 8 to 10. Fig.

 The storage (e.g., 730) may include a first comparator 731, a second comparator 732, and a counter 733.

The first comparator 731 of the first storage unit 730 stores the difference between the first electrical signal S1 and the first reference value ref1 when the first electrical signal S1 is equal to or greater than the first reference value ref1, And outputs a second electric signal S12 corresponding to the value of the second electric signal S12.

The second comparator 732 compares the second electrical signal S12 with the second reference value ref2 and outputs a third electrical signal S13.

The first counter 733 counts and stores the number of photons based on the third electrical signal S13.

In the first storage unit 730, the energy band of the photons to be counted is determined according to the first reference value ref1 and the second reference value ref2. Photons counted by the first counter 733 are included in the first energy band and subsequently used to recover the image of the first energy band. Hereinafter, an image reconstructed using photons included in the first energy band is referred to as a 'first image'.

The first comparator 741 of the second storage unit 740 compares the first electrical signal S1 with the first reference value ref3 when the first electrical signal S1 is equal to or greater than the first reference value ref3, And outputs the second electrical signal S22 corresponding to the difference value of the second electric signal S22.

The second comparator 742 compares the second electrical signal S22 with the second reference value ref4 and outputs the third electrical signal S23.

The first counter 743 counts and stores the number of photons based on the third electrical signal S23.

In the second storage unit 740, the energy band of the photons to be counted is determined according to the first reference value ref3 and the second reference value ref4. The photon counted in the first counter 743 is included in the second energy band and subsequently used to recover the image of the second energy band. Hereinafter, an image reconstructed using photons included in the second energy band is referred to as a 'second image'.

In the third storage unit 750, the first comparator 751 compares the first electrical signal S1 with the first reference value ref5 when the first electrical signal S1 is equal to or greater than the first reference value ref5, And outputs the second electric signal S32 corresponding to the difference value of the second electric signal S32.

The second comparator 752 compares the second electrical signal S32 with the second reference value ref6 and outputs a third electrical signal S33.

The first counter 753 counts and stores the number of photons based on the third electrical signal S33.

In the third storage unit 750, the energy band of the photons to be counted is determined according to the first reference value ref5 and the second reference value ref6. The photon counted in the first counter 753 is included in the third energy band and is subsequently used to recover the image of the third energy band. Hereinafter, an image reconstructed using photons included in the third energy band is referred to as a 'third image'.

Since the operations of the first storage unit 730, the second storage unit 740 and the third storage unit 750 are all the same, the first and second storage units 730 and 730 will be described in detail below. do.

Specifically, the first reference value ref1 may be a voltage signal, and the second reference value ref2 may be a current signal. The first reference value ref1 and the second reference value ref2 are values that vary according to the energy band of the photon used in the multi-energy CT image.

The first comparator 731 compares the electrical signal S1 representing the energy intensity of the photon with the first reference value ref1 and if the electrical signal S1 is greater than the first reference value ref1, A predetermined current corresponding to the difference value of the first reference value ref1 can be generated as the second electric signal S12.

The second comparator 732 may compare the second electrical signal S12 with a second reference value ref2 which is a current signal and output a third electrical signal S13 for determining whether to count the photons .

For example, if the first reference value ref1 is set to 25 keV, the first comparator 731 classifies photons whose photon energy is 25 keV or more. For example, assume that the first electrical signal S1 corresponding to the photon is 40 keV, and the second reference value ref2 is a current value corresponding to 5 keV. In this case, the first comparator 731 compares 40 keV, which is the first electrical signal S1, with 25 keV, which is the first reference value ref1. If the first electrical signal S1 is larger than the first reference value ref1, 1 electric signal S1 and the first reference value ref1 as a second electric signal S12. The second comparator 732 compares the current corresponding to 15 keV, which is the second electric signal S12, with the current value corresponding to 5 keV which is the second reference value ref2. Since the second electrical signal S12 is larger than the second reference value ref2, the second comparator 732 outputs a third electrical signal S13 which causes the number of photons to be +1 and counted. Then, the counter 733 increments the number of photons by +1 based on the third electrical signal S13. Accordingly, in the first storage unit 730, photons having an energy value larger than the sum of the voltage of the first reference value ref1 and the voltage value corresponding to the second reference value ref2 can be sorted and counted .

When a photon having an energy value smaller than the sum of the voltage value of the first reference value ref1 and the voltage value corresponding to the second reference value ref2 is absorbed by the radiation absorbing layer 710, the second comparator 732 ) Outputs a third electrical signal S13 that prevents the number of photons from being counted, and accordingly, the counter 733 does not count the number of photons.

In the example described above, the first counter 733 can classify and count photons having an energy greater than 30 keV, which is a sum of the voltage value of the first reference value ref1 and the voltage value corresponding to the second reference value ref2 have.

In the example described above, the first counter 733 can classify and count photons having an energy greater than 30 keV, which is a sum of the voltage value of the first reference value ref1 and the voltage value corresponding to the second reference value ref2 have.

까지 32 단계의 전류 값들 중 어느 하나의 값으로 설정될 수 있다. 작은 간격 값들을 갖는 복수개의 전류 값들을 이용하여, 제2 기준값(ref2)을 세밀하게 조절할 수 있다. 구체적으로, 제1 기준값(ref1)은 비교적 큰 전압 값으로 설정하여, 광자를 1차적으로 대략적으로 분류하고, 제2 기준값(ref2)을 이용하여, 광자를 2차적으로 세밀하게 분류할 수 있다. Specifically, the second reference value ref2 is 0

May be set to any one of the current values of the 32 stages. The second reference value ref2 can be finely adjusted by using a plurality of current values having small interval values. Specifically, the first reference value ref1 can be set to a relatively large voltage value, and the photons can be roughly classified first, and the photon can be secondarily classified finely using the second reference value ref2.

 Therefore, in each of the storage units 730, 740, and 750, a first reference value and a second reference value can be set according to the energy band image to be restored.

When the first reference values ref1, ref3 and ref5 are set as the voltage values and the second reference values ref2, ref4 and ref6 are set as the current values, the number of the voltage sources is set to the number of the counters 733, 743, and 753, the energy band of the photon to be classified can be set to be changed stepwise.

For example, the second reference values ref2, ref4, and ref6, which are current values, can be generated by applying at least one of the first reference values ref1, ref3, ref5 to the analog-to-digital converter ADC. Therefore, it is possible to generate the second reference values ref2, ref4, ref6 without providing a separate power source other than the first reference values ref1, ref3, ref5.

The plurality of first reference values ref1, ref3 and ref5 and the second reference values ref2, ref4 and ref6 are reference values for classifying the photons according to their energy magnitudes. The reference values include the type of the incident radiation, , The setting of the user, and the like. For example, when the X-ray photon is incident on the radiation absorbing layer 710, the first counter 733 calculates the photon having an energy of 30 keV or more in consideration of the energy amount that the X-ray photon can have, Ref3 and ref5 and the second reference values ref2 and ref3 so that photons having an energy of 60 keV or more are counted in the third counter 753 and photons having an energy of 90 keV or more are counted in the third counter 753, ref4, ref6) can be set.

7B is a view showing a radiation detector according to another embodiment of the present invention. 7B shows the unit detector 760. In Fig. 7B, the same components as those in Fig. 7A are denoted by the same reference numerals, and a description overlapping with that in Fig. 7A is omitted.

Referring to FIG. 7B, the counters 733, 743, and 753 included in the unit detector 720 shown in FIG. 7A may be formed of counting memories 761, 762, and 763. The coefficient memories 761, 762, and 763 store the number of photons counted while accumulating the number of photons. For example, the coefficient memory may be a storage device capable of storing cumulative coefficients such as registers and the counted number.

Here, the storage capacity of the coefficient memory (e.g., 761) may be set according to the number of photons that one coefficient pixel should count for a predetermined time. For example, when one pixel containing m coefficient pixels absorbs approximately n photons for a predetermined time, the coefficient memory 761 has a storage capacity of n / m value. For example, if a pixel counts by absorbing at least about 200 M photons per second, and one pixel includes 25 coefficient pixels, then the coefficient memory 761 may include approximately 200/25 M = 8 M or more photons It is possible to store the number of bits corresponding to approximately 8M so that the number can be stored.

7B illustrates the case where the coefficient memory 761 is included in the photon processing unit 720. However, the coefficient memory 761 may be provided separately from the photon processing unit 720. [ More specifically, the storage unit 730 included in the photon processing unit 720 includes a comparator 731 and a comparator 732 for performing a photon selection operation for photon counting, and a coefficient memory 730 connected to a subsequent stage of the photon processing unit 720, The number of selected photons may be counted and stored.

7C is a view showing a radiation detector according to another embodiment of the present invention. Figure 7c shows the unit detector 780. In Fig. 7C, the same components as those in Fig. 7A are denoted by the same reference numerals, and a description overlapping with that in Fig. 7A is omitted.

7C, the counters 733, 743 and 753 included in the unit detector 720 shown in FIG. 7A include counting devices 781, 784 and 787 and memories 782, 785 and 788, . ≪ / RTI > For example, the first storage unit 730 may include a coefficient device 781 and a memory 782 instead of the coefficient memory 761 shown in FIG. 7B.

Referring to the first storage unit 730, the counting unit 781 counts the number of photons in accordance with the output signal of the second comparator 732. Then, the memory 782 stores the number of photons counted. That is, the coefficient memory 761 of FIG. 7B performs the operation of storing the photon count and the photon number at one time, while in FIG. 7C, each of the counting device 781 and the memory 782 performs the counting and storing operation of the photon number can do.

8 is a view for explaining a radiation detector according to an embodiment of the present invention. In each of the graphs shown in FIG. 8, the x axis represents the energy magnitude of the photon, and the y axis represents the number of photons incident on the radiation detector at a predetermined area.

At least one of the first reference value and the second reference value of the unit detector 700 may be set to a value different from at least one of the first reference value and the second reference value of the adjacent unit detector.

In the case of using the unit detector 700 according to an embodiment of the present invention, even if the unit detector 700 includes three counters, photons can be classified and counted in a larger energy band. For example, when the unit detector 700 includes three counters, the energy band for classifying the photons is an energy band of Th1 or more, an energy band of Th2 or more, an energy band of Th3 or more, an energy band of Th4 or more, And may be five energy bands including the energy bands.

Th1 = 30 keV, Th2 = 60 keV, Th3 = 75 keV, Th4 = 90 keV, and Th5 = 105 keV. In each of the storage units, the first reference value and the second reference value may be set to have a predetermined value according to the energy band value of the photon to be classified.

Further, the number of photons having an energy of Th1 or more is used for restoring the first image in the multi-energy CT image. The number of photons having an energy of Th2 or more is used for restoring the second image in the multi-energy CT image. The number of photons having an energy of Th3 or more is used to restore the third image in the multi-energy CT image, and the number of photons having the energy of Th4 or more is used in the multi-energy CT image to restore the fourth image do. Further, the number of photons having an energy of Th5 or more is used for restoring the fifth image in the multi-energy CT image.

9 is another view for explaining a radiation detector according to an embodiment of the present invention.

9, there is shown a radiation detector 910, 950 that includes a plurality of pixels.

Referring to FIG. 9A, when the radiation detector 910 includes a plurality of pixels 901 and 902, the first pixel 901 and the second pixel 902, which are disposed adjacent to each other, The energy band of the desired photon can be set differently. That is, at least one of the first reference value and the second reference value may be set to different values in the first pixel 901 and the second pixel 902 disposed adjacent to each other.

Specifically, the second reference values ref2, ref4, and ref6 used in at least one of the plurality of storage units 730, 740, and 750 may include a first pixel 901 and a second pixel 902, 901, < / RTI >

For example, in the first pixel 901, the first storage unit 730 sets the first reference value ref1 to 30 keV so that photons having an energy of Th1 = 30 keV or more are categorized and counted as in the 811 graph, The second reference value ref2 can be set to a current value corresponding to 0 keV.

In the first pixel 901, the second reference value ref3 is set to 60 keV so that the photon having the energy of Th2 = 60 keV or more is categorized and counted as in the 821 graph in the second storage unit 740, The second reference value ref4 can be set to a current value corresponding to 0 keV.

In the first pixel 901, the third threshold value ref5 is set to 90 keV so that the third storage unit 750 classifies and counts photons having an energy of Th4 = 90 keV or more as in the graph 841, The second reference value ref6 can be set to a current value corresponding to 0 keV.

In the second pixel 902, the first storage unit 730 sets the first reference value ref1 to 30 keV so as to classify and count the photons having an energy of Th = 30 keV or more as in the 811 graph, The reference value ref2 can be set to a current value corresponding to 0 keV.

In the second pixel 902, the second reference value ref3 is set to 60 keV so that the photon having the energy of Th3 = 75 keV or more is categorized and counted in the second storage unit 740 as in the 831 graph, The second reference value ref4 can be set to a current value corresponding to 15 keV. That is, the second reference value ref4 in the first pixel 901 is set to a current value corresponding to 0 keV, while the second reference value ref4 in the second pixel 902 is set to a current value corresponding to 15 keV . Accordingly, the second counter 743 included in the first pixel 901 and the second counter 743 included in the second pixel 902 can classify and count photons having different energy bands.

In the second pixel 902, the third threshold value ref5 is set to 90 keV so that the third storage unit 750 classifies and counts photons having energy of Th5 = 105 keV or more as in the 851 graph, The second reference value ref6 can be set to a current value corresponding to 15 keV.

In the above-described example, the second reference value is set differently by using three voltage values of 30 keV, 60 keV, and 90 keV as the voltage source, so that the energy band that the first pixel 901 can classify is an energy band , An energy band of 60 keV or more, and an energy band of 90 keV or more. The energy band that the second pixel 902 can classify can be set to an energy band of 30 keV or more, an energy band of 75 keV or more, and an energy band of 105 keV or more.

The second reference values ref2, ref4 and ref6 applied to the first pixel 901 may be set to values larger or smaller than the second reference values ref2, ref4 and ref6 applied to the second pixel 902. [ Accordingly, at least one of the energy bands of the photons classified by the first pixel 901 and the energy bands of the photons classified by the second pixel 902 may be different from each other .

The first reference value ref1, ref1, ref1 used in at least one storage unit of the plurality of storage units 730, 740 and 750 may include a first pixel 901 and a first pixel 901 The second pixel 902 adjacent to the second pixel 902 may be set to a different value.

Also, at least one of the first reference value and the second reference value may be set differently for each pixel in the pixel group including a plurality of adjacent pixels.

As described above, the number of photons having an energy of Th1 or more is used for restoring the first image in the multi-energy CT image. The number of photons having an energy of Th2 or more is used for restoring the second image in the multi-energy CT image. The number of photons having an energy of Th3 or more is used to restore the third image in the multi-energy CT image, and the number of photons having the energy of Th4 or more is used in the multi-energy CT image to restore the fourth image do. Further, the number of photons having an energy of Th5 or more is used for restoring the fifth image in the multi-energy CT image.

Accordingly, the radiation detector 400 according to an embodiment of the present invention can vary the energy band that can be obtained by adjusting at least one of the first reference value and the second reference value of the unit detector 700 .

Further, the first reference value can be set roughly and the second reference value can be set precisely. Specifically, the photons classified according to the first reference value can be precisely classified again using the second reference value, thereby correcting errors that may occur when classification is performed using only the voltage value during photon classification.

Referring to FIG. 9B, when the radiation detector 950 includes a plurality of pixels 951, 952, and 953, adjacent pixels are grouped so that a predetermined number of pixels are included, The energy band of the photon to be classified can be set differently in each of the pixels 951, 952, and 953 included in the photodetector. That is, at least one of the first reference value and the second reference value may be set to different values in the first pixel 951, the second pixel 952, and the third pixel 953 included in the pixel group 960 .

For example, in the first pixel 951, the first reference value and the second reference value can be set so as to classify and count photons having energy of Th1 = 30 keV, Th2 = 60 keV, and Th4 = 90 keV. In the second pixel 952, the first reference value and the second reference value can be set so as to classify and count photons having energy of Th1 = 30 keV, Th3 = 75 keV, and Th5 = 105 keV. In the third pixel 953, the first reference value and the second reference value can be set so as to classify and count photons having energy of Th1 = 30 keV, Th6 = 80 keV, and Th7 = 110 keV.

10 is another view for explaining a radiation detector according to an embodiment of the present invention.

Referring to the radiation detector 1000 of FIG. 10, a case where the radiation detector 1000 includes a plurality of sub-pixels 1010, 1020, 1030 is shown by way of example.

The energy bands of the photons to be classified and counted in the first subpixel 1010 and the second subpixel 1020 arranged adjacent to each other can be set differently. That is, at least one of the first reference value and the second reference value may be set to different values in the first subpixel 1010 and the second subpixel 1020 disposed adjacent to each other.

In addition, adjacent subpixels are grouped so that a predetermined number of subpixels are included, so that energy bands of photons to be classified can be set differently in each of the subpixels included in the subpixel group 1040. That is, when the subpixel group 1040 includes three adjacent subpixels, the first subpixel 1010, the second subpixel 1020, and the third subpixel 1030 included in the subpixel group 1040 , At least one of the first reference value and the second reference value may be set to a different value.

For example, in the first subpixel 1010, the first reference value and the second reference value can be set so as to classify and count photons having energy of Th1 = 30 keV, Th2 = 60 keV, and Th4 = 90 keV. In addition, in the second subpixel 1020, the first reference value and the second reference value can be set so as to classify and count photons having energy of Th1 = 30 keV, Th3 = 75 keV, and Th5 = 105 keV. In addition, in the third sub-pixel 1030, the first reference value and the second reference value can be set so as to classify and count photons having energy of Th1 = 30 keV, Th6 = 80 keV, and Th7 = 110 keV.

11 is another view for explaining a radiation detector according to an embodiment of the present invention.

Also, in the unit detector 700, the plurality of counters 733, 743, and 753 counts the number of photons classified according to the energy magnitude. The counter may be a counter for accumulating and storing the number of photons, or a counting memory, as described in FIG. 7B.

The plurality of counters 1110, 1120, and 1130 shown in FIG. 11 correspond to the plurality of counters 733, 743, and 753 of the unit detector 700, respectively.

Specifically, the plurality of counters 733, 743, and 753 counts and stores the number of photons classified into each of the plurality of energy bands, and has a size corresponding to the reference values applied for photon classification.

When the energy bands to be classified are set to energy bands Th1 = 30 keV or more, Th2 = 60 keV or more, and Th3 = 90 keV or more, as in the above example, the first counter 733 is a photon having energy of 30 keV or more And stores the number of photons counted. The second counter 743 counts the number of photons having an energy of 60 keV or more, and the third counter 753 counts the number of photons having an energy of 90 keV or more.

Referring to FIG. 11, the number of photons having an energy of Th1 = 30 keV or more is proportional to the area 1116 of the 1115 graph, and the number of photons having an energy of Th2 = 60 keV or more is proportional to the area 1126 of the 1125 graph. The number of photons having an energy of Th4 = 90 keV or more is proportional to the area 1135 of the 1135 graph.

Thus, the first counter 1110 may have a size corresponding to the area 1116. Also, the second counter 1120 may have a size corresponding to the area 1126, and the third counter 1130 may have a size corresponding to the area 1136.

As described above, the sizes of the first counter 1110, the second counter 1120, and the third counter 1130 may be determined differently, corresponding to the energy values of the classified photons, as described above.

Since the energy band of the photons to be classified depends on at least one of the first reference value and the second reference value, the size of the counter can be determined based on at least one of the first reference value and the second reference value.

Specifically, the counter may have a first bit depth if the energy band of the classified photon is a low energy band, and a second bit depth that is smaller than the first bit depth if the energy band of the classified photon is a high energy band.

Referring to FIG. 11, the first counter 1110 has a low energy as compared to the photons that the photons counted by the second and third counters 1120 and 1130 count. Accordingly, when the bit depth of the first counter 1110 is 13 bits, the bit depth of the second counter 1120 becomes 12 bits smaller than the bit depth of the first counter 1110 And the bit depth of the third counter 1130 may be 11 bits less than the bit depth of the second counter 1120. [

Also, the size of each of the plurality of counters 1110, 1120, and 1130 may vary depending on the minimum energy value of the classified photon. In addition, the minimum energy value of the photon counted by the counter can correspond to the minimum value Th1, Th2, Th4 of the energy band.

Specifically, the size of the counter may be inversely proportional to the energy value of the classified photons.

12 is a view for explaining a general radiation detector.

11, the bit depth of the first counter 1110 is 13 bits, the bit depth of the second counter 1120 is 12 bits, and the bit depth of the third counter 1130 bit depth is 11 bits, the total size of the counters 1110, 1120, and 1130 included in the unit detector 700 corresponds to 36 bits.

In the case of a typical radiation detector, when multiple counters are included in one pixel for multiple energy measurements, the multiple counters have the same size.

Referring to FIG. 12, in a general radiation detector, a plurality of counters may have the same size. When the total size of the counters included in one pixel is 36 bits as shown in FIG. 9, the plurality of counters 1210, 1220 and 1230 all have a 12-bit depth.

For example, if the number of photons having an energy value of Th1 = 30 keV or more that can be counted by the first counter 1210 corresponds to 13 bits 1211, the number of photons having an energy value of Th2 = 60 keV or more corresponds to 11 bits (1221), and the number of photons having an energy value of Th4 = 90 keV or more corresponds to 10 bits (1231).

In the case of a general radiation detector, since the size of the first counter 1210 is 12 bits, the first counter 1210 is saturated without counting the number of photons having an energy value of Th1 = 30 keV or more.

When the first counter 1210 is saturated, the second counter 1220 and the third counter 1230 can no longer perform the counting operation. Accordingly, the second counter 1220 stores only the number of photons less than the number of bits 1222, although the number of photons having an energy value of Th2 = 60 keV or more corresponds to 11 bits (1221). The third counter 1230 can store only the number of photons less than the number of bits 1232, although the number of photons having an energy value of Th4 = 90 keV or more corresponds to 10 bits 1231. [

In contrast, in the radiation detector according to the embodiment of the present invention, the size of the plurality of counters is designed differently according to the energy value of the photons to be counted, so that the number of photons corresponding to each energy band can be sufficiently . Accordingly, the number of measurable photons can be increased, and the detection performance of photons can be enhanced for each energy band.

11, since the number of photons counted by the first counter 1110 is smaller than the capacity of the first counter 1110, the photons having Th1 = 30 keV or more are all counted The first counter 1110 is not saturated. Therefore, the photon can be sufficiently counted in the second counter 1120 and the third counter 1130 as well.

Also, the number of bits that can not be used as in the second and third counters 1220 and 1230 of FIG. 12 can be eliminated, so that the size of the counter can be minimized.

13 is a view showing a radiation detector according to another embodiment of the present invention. The radiation detector according to another embodiment of the present invention includes a plurality of unit detectors 1300. Here, the unit detector 1300 may correspond to the pixel 401 or the subpixel 560 described with reference to Figs. 4 to 5A.

13, the radiation absorbing layer 1310 and the photon processing portion 1320 correspond to the radiation absorbing layer 710 and the photon processing portion 720 in Fig. 7A, respectively. Therefore, a description overlapping with that in Fig. 7A is omitted. The unit detector 1300 may further include a plurality of counters 1334, 1344, and 1354 as compared with the unit detector 700. [ Hereinafter, the first storage unit 1330 will be described as an example. Hereinafter, for convenience of explanation, the counter 1334 connected to the output terminal of the second comparator (for example, 1332) is referred to as a first counter 1334 and the counter 1334 connected to the output terminal of the first comparator (for example, 1331) (1333) is referred to as a second counter 1333.

The first storage unit 330 compares the first electrical signal S1 with the first reference value ref1 and counts the number of photons based on the second electrical signal S12. Then, the number of photons is counted based on the third electrical signal S13 which is a result of comparing the second electrical signal S12 with the second reference value ref2.

Specifically, the first storage unit 330 stores the number of photons counted based on the second electrical signal S12 in the second counter 1333, and the photon counted based on the third electrical signal S13 In the first counter 1334.

Specifically, the storage unit 1330 may further include a second counter 1333 connected to the first comparator 1331 as compared to the storage unit 730.

For example, when the first reference value ref1 is set to 25 keV, the first comparator 1331 classifies photons whose photon energy is 25 keV or more. For example, assume that the first electrical signal S1 corresponding to the photon is 40 keV, and the second reference value ref2 is a current value corresponding to 5 keV. In this case, the first comparator 1331 compares 40 keV, which is the first electric signal S1, with 25 keV, which is the first reference value ref1, and if it is larger than the first electric signal S1 and the first reference value ref1, 1 electric signal S1 and the first reference value ref1 as a second electric signal S12. Then, the second counter 1333 counts the number of photons by +1 based on the second electrical signal S12. The second comparator 1332 compares the current corresponding to the second electric signal S12 of 15 keV and the current value corresponding to the second reference value ref2 of 5 keV. Since the second electrical signal S12 is larger than the second reference value ref2, the second comparator 1332 outputs a third electrical signal S13 that causes the number of photons to be +1 and counted. Then, the first counter 1333 increments the number of photons by +1 based on the third electrical signal S13. Accordingly, the second counter 1333 can classify and count photons having an energy larger than the voltage value of the first reference value ref1. The first counter 1334 can classify and count photons having an energy value greater than a sum of the voltage of the first reference value ref1 and the voltage value corresponding to the second reference value ref2.

The operation and configuration of the second storage unit 1340 and the third storage unit 1350 are the same as those of the first storage unit 1330 described above, and a duplicate description will be omitted.

As described above, by including the first counter 1334 and the second counter 1333 in each storage unit (for example, 1330) of the unit detector 1300, the photodetector 1300 can count It is possible to increase the number of energy bands. Accordingly, by using the unit detector 1300, it is possible to increase the number of obtainable images per energy band.

14 is another view showing a radiation detector according to another embodiment of the present invention. Specifically, the radiation detector 1410 includes a plurality of unit detectors 1421 and 1422. The unit detector (for example, 1421) may correspond to the pixel 401 or the subpixel 560 described with reference to Figs. 4 to 5A.

The radiation detector 1410 according to an embodiment of the present invention includes a first unit detector 1421 for detecting radiation and a second unit detector 1422 adjacent to the first unit detector 1421.

Specifically, the plurality of unit detectors 1421 and 1422 included in the radiation detector 1410 include the same configuration, and the reference value input to the comparator may be different for each unit detector.

The first unit detector 1421 compares the radiation absorption layer 1430 and the first electrical signal S1 for converting the incident photons into a first electrical signal S1 with a first reference value (e.g., ref11) And a photon processing unit 1440 including a plurality of storage units (for example, 1450) for storing and storing the number of photons based on the second electrical signal S2 as a comparison result.

Although the first unit detector 1421 includes the first, second, and third storage units 1450, 1460, and 1470 in FIG. 14 as an example, the first unit detector 1421 may include two or four or more storage units have.

The second unit detector 1422 includes the same configuration as the first unit detector 1421, and thus a detailed description thereof will be omitted.

At least one of the first reference values ref11, ref12, and ref13 used in at least one of the plurality of storage units 1450, 1460, and 1470 included in the first unit detector 1421 is (At least one of ref21, ref22, and ref23) used in at least one of the plurality of storage units 1480, 1485, 1490 included in the second unit detector 1422, Respectively.

For example, when ref11 = 30 keV, ref12 = 60 keV, and ref13 = 90 keV in the first unit detector 1421, ref21 = 30 keV, ref22 = 75 keV and ref23 = 1105 keV in the second unit detector 1422 Can be set.

Specifically, the radiation absorbing layer 1430 converts the incident radiation photons into an electrical signal S1. Specifically, the radiation absorbing layer 1430 converts an incident X-ray photon into an electrical signal. Specifically, the radiation absorbing layer 1430 can convert the photons into hole-electron pairs and generate an electrical signal S1 corresponding to the energy of the incident photons. Further, the electric signal S1 may be a voltage signal or a current signal. Hereinafter, the case where the electric signal S1 is a voltage signal will be described as an example.

The radiation absorbing layer 1430 transmits the converted electric signal S1 to a plurality of storage units 1450, 1460, and 1470 connected to a subsequent stage, respectively. Since the radiation absorbing layer 1430 corresponds to the radiation absorbing layer 710 described in the seventh further description, a description overlapping with that in Fig. 7A is omitted.

The photon processing section 1440 includes a plurality of storage sections for counting and storing the number of photons based on the first electrical signal S1. In detail, the photon processing unit 1440 includes a plurality of storage units 1450, 1460, and 1470 according to the number of energy bands to be distinguished.

Each storage unit (e.g., 1450) compares the first electrical signal S1 with the first reference value ref1 and counts the number of photons based on the second electrical signal S2 as the comparison result .

Each storage (e.g., 1450) may include a comparator 1451 and a counter 1452.

Specifically, the first comparator 1451 compares the electric signal S1 with the first reference value ref11. When the electric signal S1 is larger than the first reference value ref11, the first counter 1451 accumulates And outputs a signal to be counted to the counter 1452.

The second comparator 1461 compares the electric signal S1 with the second reference value ref12 so that when the electric signal S1 is larger than the second reference value ref12, To the second counter 1462. The second counter 1462 outputs a signal to the second counter 1462. [

The third comparator 1471 compares the electric signal S1 with the third reference value ref13 so that when the electric signal S1 is larger than the third reference value ref13, Can be output to the third counter 1472.

For example, when the first comparator 1451 is biased to the + Vh and -Vh voltages, the + Vh voltage is outputted as a logic high level signal and the -Vh voltage is outputted as a logic low level signal Can be output. The first comparator 1451 outputs a + Vh voltage value corresponding to a logic high value when the magnitude of the electrical signal corresponding to the photon is greater than the first reference value ref11, and the first counter 1452 outputs a + Vh voltage value When input, the number of photons can be counted by +1 accumulation. The first comparator 1451 outputs a -Vh voltage value when the magnitude of the electric signal corresponding to the photon is smaller than the first reference value ref11 and the first counter 1452 outputs the voltage value when the voltage value of -Vh is input. Are not cumulatively counted.

Each of the plurality of storage units 1450, 1460, and 170 may distinguish the photons in a plurality of energy bands according to the first reference values ref11, ref12, and ref13.

In the radiation detector 1410 according to another embodiment of the present invention, the first reference value used for comparing the photon energy magnitudes in the adjacent first unit detector 1421 and the second unit detector 1422 are set differently from each other , The number of measurable energy bands can be expanded.

15 is a view showing a computer tomography apparatus according to an embodiment of the present invention.

Referring to FIG. 15, the computer tomography apparatus 1500 includes a radiation detector 1510 including a plurality of unit detectors 1570 and 1580. The configuration of the radiation detector 1510 including the plurality of unit detectors 1570 and 1580 corresponds to the configuration of the radiation detector 1410 including the plurality of unit detectors 1421 and 1422 described in FIG. And the description overlapping with those in FIG. In addition, the configuration of the unit detector included in the radiation detector 1510 may correspond to the unit detectors 700, 760, and 780 shown in FIGS. 7A, 7B, or 7C.

Referring to FIG. 15, the radiation detector 1510 includes a plurality of unit detectors 1570 and 1580. Each of the plurality of unit detectors 1570 and 1580 includes the same configuration, and the reference value input to the comparator may be different for each unit detector. Hereinafter, a unit detector included in the radiation detector 1510 will be described as an example of the unit detector 1570. Hereinafter, any one unit detector among a plurality of unit detectors included in the radiation detector 1510 will be referred to as a first unit detector 1570, and the other unit detector will be referred to as a second unit detector 1580. The first unit detector 1570 may be disposed adjacent to the second unit detector 1580.

이하의 크기를 가질 수 있다. 따라서, 단위 디텍터(1570)가 픽셀에 동일 대응되는 경우, 단위 디텍터(1570)의 전면 크기는 1 제곱 미리미터 이하가 될 수 있다. In addition, the unit detector 1570 may be a pixel or a subpixel. In addition, the pixel size may have a size of less than one square millimeter so that the area of the front surface of the unit detector 1570 is 1

Or less. Accordingly, when the unit detector 1570 corresponds to a pixel, the front size of the unit detector 1570 may be less than one square millimeter.

The unit detector 1570 includes a radiation absorbing layer 1430 and a photon processing unit 1440. The photon processing unit 1440 includes a plurality of comparators 1451, 1461, and 1471 and a plurality of counters 1452, 1462, and 1472.

The radiation absorbing layer 1430 converts the incident photons into a first electrical signal S1.

The plurality of comparators 1451, 1461 and 1471 compares the first electrical signal S1 with a plurality of reference values ref11, ref12 and ref13 to classify the photons into a plurality of energy bands.

Hereinafter, in each unit detector (for example, 1570), a reference value input to the first comparator 1451 is referred to as a first reference value ref11, a reference value input to the second comparator 1461 is referred to as a second reference value (ref12). The reference value input to the third comparator 1471 is referred to as a third reference value ref13. Specifically, the first comparator 1451 compares the first electrical signal S1 with the first reference value ref11. The second comparator 1461 compares the first electrical signal S1 with the second reference value ref12. The third comparator 1471 compares the first electrical signal S1 with the third reference value ref13.

The plurality of counters 1452, 1462, and 1472 counts and stores the number of photons classified into each of the plurality of energy bands.

Each of the plurality of counters 1452, 1462, 1472 may have a size corresponding to the reference values applied for photon classification. Specifically, when the first reference value ref11, the second reference value ref12, and the third reference value ref13 are set to 30 keV, 60 keV, and 90 keV, respectively, as described with reference to Fig. 11, ) Counts the number of photons having an energy of 30 keV or more, and stores the number of photons counted. The second counter 1462 counts the number of photons having an energy of 60 keV or more, and the third counter 1472 counts the number of photons having an energy of 90 keV or more.

Referring to FIG. 11, the number of photons having an energy of 30 keV or more is proportional to the area 1116 of the 1115 graph, and the number of photons having an energy of 60 keV or more is proportional to the area 1126 of the 1125 graph. The number of photons with an energy of 90 keV or more is proportional to the area 1135 of the 1135 graph.

Thus, the first counter 1452 may have a size corresponding to the area 1116. Also, the second counter 1462 may have a size corresponding to the area 1126, and the third counter 1472 may have a size corresponding to the area 1136.

Also, at least one of the plurality of reference values ref11, ref12, ref13 used in the first unit detector 1570 among the plurality of unit detectors is a plurality of reference values ref11, ref12, ref13 used in the second unit detector 1580 And has a different value from at least one of the reference values ref21, ref22, ref23. For example, two reference values ref12 and ref13 input to two comparators (for example, 1461 and 1471) included in the first unit detector 1570 are included in the second unit detector 1580, And has a different value from the two reference values ref22 and ref23 input to the two comparators 1486 and 1491.

At least one of the plurality of reference values ref11, ref12 and ref13 used in the first unit detector 1570 is at least one of a plurality of reference values ref21, ref22 and ref23 used in the second unit detector 1580 It can have the same value as one.

Specifically, the reference value for classifying the lowest energy band can be set to the same value in the first unit detector 1570 and the second unit detector 1580. In generating multi-energy CT images, information on the low energy band is most important. Therefore, it is possible to set the reference value for the low energy band to be the same, and to perform photon classing in the same low energy band in all unit detectors included in the radiation detector 1510.

That is, the reference value ref11 used to classify the low energy band among the plurality of reference values used in the first unit detector 1570 is classified into the low energy band among the plurality of reference values used in the second unit detector 1580 And may have the same value as the reference value ref21.

At least one of the first to third reference values ref11, ref12 and ref13 used in the first unit detector 1570 may correspond to the first to third reference values ref21, ref22, ref23) by a predetermined offset.

For example, it has the same value as the first reference value ref11 and the first reference value ref21 and has a value of 30 keV. The remaining reference values have different values in the first unit detector 1570 and the second unit detector 1580. Specifically, the second reference value ref12 has a value of 60 keV, and the second reference value ref22 has a value of 75 keV. The third reference value ref13 has a value of 90 keV, and the third reference value ref23 has a value of 105 keV. That is, the first reference values ref11 and ref21 are the same value in the first unit detector 1570 and the second unit detector 1580, and the second reference values ref12 and ref22 and the third reference values ref13 and ref23 are The first unit detector 1570 and the second unit detector 1580 may be set to have a predetermined offset = 15 keV.

In the example described above, the first unit detector 1570 can count the number of photons at 30 keV, 60 keV, and 90 keV, respectively. The second unit detector 1580 can count the number of photons at 30 keV, 75 keV, and 105 keV, respectively.

Further, the computer tomography apparatus 1500 may further include an input / output unit 1530. The input / output unit 1530 outputs a user interface screen for setting a plurality of reference values. Embodiments of the user interface screen output by the input / output unit 1530 will be described in detail with reference to FIG. 16 and FIG.

Specifically, the input / output unit 1530 may include a display unit 1531 and an input unit 1532. Here, the display unit 1531 and the input unit 1532 correspond to the display unit 130 and the input unit 128 shown in FIG. 2, respectively.

The display unit 1530 displays a screen on a display panel. Specifically, the medical image generated using the radiation sensed by the radiation detector 1510 can be displayed. Also, a user interface screen can be displayed.

The input unit 1532 receives a predetermined request, command, or other data from the user.

For example, the input unit 1532 may include a touch pad, a mouse, a keyboard, or an input device including hard keys for inputting predetermined data. For example, the user can input a predetermined command by operating at least one of a touch pad, a mouse, a keyboard, and other input devices included in the input unit 1532.

The input / output unit 1530 may be formed as a touch screen. More specifically, the input unit 1532 includes a touch pad (not shown) coupled with a display panel (not shown) included in the display unit 1531 to display a user interface screen Output. When a predetermined command is input through the touch screen, the touch pad can detect the command.

Specifically, when the input / output unit 1530 is formed as a touch screen, the input unit 1531 may output a user interface screen on the display panel coupled with the touch pad. When the user touches a predetermined point on the user interface screen, the input unit 1532 detects the touched point. Then, it recognizes the user's request or command corresponding to the menu displayed at the detected point, and can execute the recognized request or command.

Further, the computer tomography apparatus 1500 may further include a power source unit 1550. The power supply unit 1550 supplies the predetermined power to the radiation detector 1510.

Specifically, the power supply unit 1550 generates voltages corresponding to the reference values and supplies the voltages to the comparators 1451, 1461, and 1471 of the unit detector 1570.

For example, when the reference values are voltage signals, the power supply unit 1550 may include a voltage divider (not shown), and may supply a plurality of voltages generated using a voltage divider (not shown) do. For example, a voltage divider (not shown) may generate the remaining reference values (e.g., 30 keV, 60 keV, 75 keV, 90 keV) using a voltage corresponding to the largest reference value (e.g., .

In another example, when the reference values are ac signal values, the power supply 1550 may include a digital to analog converter (DAC) 1551 and may use a digital to analog converter 1551 to generate a plurality It is possible to supply the current signals corresponding to the reference values to the comparators of the unit detectors.

16 is a view showing a user interface screen output from a tomography apparatus or an X-ray imaging apparatus according to an embodiment of the present invention.

Referring to FIG. 16, the input / output unit 1530 may display a user interface screen 1600 and receive reference values through the displayed user interface screen 1600.

Referring to FIG. 16, the user interface screen 1600 may include a menu screen 1610 indicating unit detectors for setting a reference value, and menu screens 1630 and 1640 for setting a reference value per unit detector.

Accordingly, the user can set the reference value of the unit detectors included in the radiation detector through the user interface screen 1600. For example, as described with reference to FIG. 9A, reference values can be set for the first unit detector 1611 which is darkly displayed and the second unit detector 1612 which is brightly displayed. Since the first unit detector 1611 and the second unit detector 1612 correspond to the first unit detector 1570 and the second unit detector 1580 described in FIG. 15, respectively, Is omitted.

That is, the reference values ref11, ref12, and ref13 used in the first unit detector 1611 can be set using the menu window 1630 for setting the reference value of the first unit detector 1611. [ It is also possible to set the reference values ref21, ref22 and ref23 used in the second unit detector 1612 by using the menu window 1640 for setting the reference value of the second unit detector 1612. [ 16, a reference value is set using a menu window 1631 for selecting a reference value. However, a reference value may be set using a menu window (not shown) in which a reference value can be directly input .

Also, in the radiation detector, a plurality of unit detectors may be grouped, and reference values may be set for each grouped unit detector.

FIG. 17 is another diagram showing a user interface screen output from a computer tomography apparatus according to an embodiment of the present invention. FIG.

Referring to FIG. 17, the input / output unit 1530 may display the user interface screen 1700 and receive reference values through the displayed user interface screen 1700.

Referring to FIG. 17, the user interface screen 1700 may include a menu screen 1710 indicating unit detectors for setting a reference value, and menu screens 1730 and 1740 for setting a reference value for each unit detector.

The menu screen 1710 representing the unit detector is the same as the menu screen 1610 shown in FIG. 16, and a detailed description thereof will be omitted.

Referring to FIG. 17, the user interface screen 1700 may display an energy spectrum 1720 representing the energy distribution of the photons incident on the radiation detector. The user can view the energy spectrum 1720 and easily grasp the energy band that the photon can have.

For example, the cursor 1721 may be displayed on the energy spectrum 1720 to display the energy value of the point at which the cursor 1721 is located in the menu window 1722. Also, by selecting the point where the cursor 1721 is located, a predetermined reference value can be set immediately. For example, in setting the first reference value ref11 of the first unit detector 1711, when the cursor 1721 is positioned at a predetermined position and the mouse is double-clicked, the energy value at the predetermined position is set to the first reference value ref11).

At least one of the first to third reference values ref11, ref12 and ref13 used in the first unit detector 1570 may correspond to the first to third reference values ref21, ref22, ref23), the user interface screen output from the input / output unit 1530 includes first through third reference values ref11 used in the first unit detector 1711, second reference values ref11 used in the first unit detector 1711, A user interface screen for setting at least one of the first to third reference values ref21, ref22, ref23 used in the unit detector 1712 and a predetermined offset may be output.

For example, when the first to third reference values ref11, ref12, ref13 and the first to third reference values ref21, ref22, ref23 are set to be different by a predetermined offset, A third reference value ref11 and a menu screen for setting a predetermined offset. In this case, when the user sets the first to third reference values ref11, ref12 and ref13 to 30 keV, 60 keV and 90 keV respectively and sets the predetermined offset to +15 keV, the first to third reference values ref21 and ref22 , ref23) can be automatically set to 45 keV, 75 keV, and 105 keV, respectively.

Further, the power supply unit 1550 may generate a power supply corresponding to the reference values input through the user interface screen, and may supply the generated power to the plurality of comparators. For example, when the power supply unit 1550 includes a digital-to-analog converter (DAC) 1551, the digital-to-analog converter 1551 outputs a plurality of reference values The current signal can be supplied to the comparators of the unit detectors.

18 is a view showing a computer tomography apparatus according to another embodiment of the present invention.

Referring to FIG. 18, a computer tomography apparatus 1800 according to an embodiment of the present invention includes a radiation detector 1810 and an image processing unit 1850.

The radiation detector 1810 includes unit detectors for sensing radiation. The unit detectors correspond to the unit detectors described in Figs. 7A, 7B, 7C, 13, or 14 in the same manner. Further, the radiation detector 1810 corresponds to the radiation detector according to one or another embodiment of the present invention described with reference to Figs. 1A to 17B. Therefore, the description overlapping with FIGS. 1A to 17 is omitted.

The image processor 1850 acquires a medical image based on the photon amount detected by the radiation detector 1810. For example, the image processing unit 1850 can reconstruct a tomographic image, for example, a CT image, based on the x-ray photon quantity detected by the radiation detector 1810. Also, the image processor 1850 can reconstruct the X-ray image based on the amount of the X-ray photons detected by the radiation detector 1810. For example, the image processor 1850 may generate an OCT image, a PET-CT image, a dual energy CT image, a dual energy X-ray image, or the like based on the photon amount detected by the radiation detector 1810 . Hereinafter, the case where the image processor 1850 restores the CT image will be described as an example.

Specifically, the image processing unit 1850 may be included in the CT system 100. For example, it may be a device configuration corresponding to the image processing unit 126 described above with reference to FIG. Alternatively, it may be a device configuration corresponding to the medical device 136 connected to the CT system 100 through the wired / wireless network 301.

Specifically, when each of the plurality of pixels includes the unit detector 700 and performs the radiation counting operation on a pixel-by-pixel basis, the number of photons counted in the at least one pixel included in the radiation detector 1810 is used as the CT It is possible to generate one image pixel value of the image. For example, one image pixel value of the CT image can be generated using the number of photons counted in one pixel included in the radiation detector 1810.

Further, in the radiation detector 1810, when one pixel includes a plurality of subpixels, and the subpixel includes a unit detector to perform a radiation count operation on a subpixel unit basis, A pixel value of one image of the CT image can be generated.

For example, one image pixel value of a CT image can be generated using the number of photons counted in one subpixel. 7A, an image pixel value of a first image corresponding to an energy band of 30 keV or more can be generated using the number of photons counted by the first counter 733. Then, by using the number of photons counted by the second counter 743, one image pixel value of the second image corresponding to an energy band of 60 keV or more can be generated. The number of photons counted by the third counter 753 can be used to generate one image pixel value of the third image corresponding to an energy band of 90 keV or more.

As another example, the number of photons counted in a plurality of subpixels may correspond to one image pixel value of the reconstructed image. Specifically, a plurality of sub-pixels may be grouped to generate one image pixel value of the CT image using the number of photons counted in one group including a plurality of sub-pixels.

19 is a view for explaining generation of an image pixel value of a CT image.

FIG. 19A illustrates an example in which one pixel 1910 includes 6 * 4 = 24 subpixels. In FIG. 19 (b), one pixel 1950 includes 6 * 6 = 36 subpixels as an example.

Referring to FIG. 19A, in each subpixel group 1921, 1922, 1923, 1924, 1925, and 1926 including a plurality of subpixels that are included in one pixel 1910 and are disposed adjacent to each other, The number of total photons counted may correspond to one image pixel value of the reconstructed image. Specifically, the number of total photons counted in one subpixel group (for example, 1921) corresponds to one image pixel value of the reconstructed CT image. Further, one 'subpixel group' (for example, 1921) may be referred to as a 'coefficient pixel group'.

Specifically, one image pixel value of the restored image for each energy band can be generated by using the number of photons per energy band counted in the subpixel group (for example, 1921).

Specifically, referring to FIG. 19A, one pixel 1910 includes six coefficient pixel groups 1921, 1922, 1923, 1924, 1925, and 1926. Here, since the coefficient pixel groups 1921, 1922, 1923, 1924, 1925, and 1926 may be image pixels forming one pixel value, one pixel 1910 may include six image pixels . Therefore, the number of coefficient pixel groups included in the radiation detector may be equal to or greater than the number of pixels included in the radiation detector. Also, the size of the coefficient pixel group (e.g., 1921) may be less than or equal to the size of the pixel 1910.

In FIG. 19 (a), one subpixel group corresponding to one image pixel value includes four subpixels as an example. In this case, when one pixel includes 6 * 4 = 24 subpixels, one pixel is divided into 3 * 2 = 6 groups so that one pixel generates six image pixel values from the reconstructed image can do.

As another example, the 24 subpixels contained in one pixel may be divided into four subpixel groups so that one pixel is reconstructed to produce four image pixel values.

Referring to Figure 19 (b), two adjacent pixels 1950, 1970 are shown.

In the radiation detector 1910, a plurality of subpixels included in a plurality of pixels are divided into a plurality of groups, and the number of photons counted in one divided group is divided into one image pixel value of the reconstructed image .

Referring to FIG. 19 (b), 72 subpixels included in two adjacent pixels 1950 and 1970 are divided into six groups (1981, 1982, 1983, 1984, 1985, 1986) Can be divided. Specifically, one image pixel value of the reconstructed image can be determined according to the number of total photons counted in 16 subpixels included in one group (e.g., 1981).

The image processor 1850 can adjust the number of subpixels used to generate one image pixel value in the CT image according to the resolution of the reconstructed CT image. For example, when an ultrahigh-resolution CT image is to be generated, the image processor 1850 can generate one image pixel value from the reconstructed CT image using the number of photons counted in one subpixel.

As described above, the radiation detector, the tomography apparatus, and the X-ray imaging apparatus according to the embodiment of the present invention can increase the number of distinct energy bands while minimizing the size of the pixels.

A radiation detector, a tomography apparatus, and an X-ray imaging apparatus according to an embodiment of the present invention are characterized in that each of a plurality of pixels included in a radiation detector has a plurality of coefficient pixels, And the operation of storing the number of photographed counts are performed separately. That is, since the photon counting operation is performed for each coefficient pixel, when approximately n photons are incident on one pixel and include m coefficient pixels of one pixel, the number of photons to be processed per coefficient pixel is n / m . Therefore, it is possible to secure a sampling time of 1 / (n / m) seconds per one photon. That is, while the sampling time per photon is 1 / n second in a conventional photodetector for performing the number of photons and the storing logic for each pixel, the present invention is characterized in that 1 / (n / m ) Seconds can be ensured. Therefore, the accuracy of photon counting can be increased, and the photons absorbed in the radiation absorbing layer can be sufficiently counted. Also, since the number of photons to be processed in one storage unit is reduced to n / m, the problem that the conventional photons can not be counted at the same time can be reduced.

The above-described embodiments of the present invention can be embodied in a general-purpose digital computer that can be embodied as a program that can be executed by a computer and operates the program using a computer-readable recording medium.

The computer readable recording medium may be a magnetic storage medium such as a ROM, a floppy disk, a hard disk, etc., an optical reading medium such as a CD-ROM or a DVD and a carrier wave such as the Internet Lt; / RTI > transmission).

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: System
102: Gantry
104: Rotating frame
105: Table
106: X-ray generator
108: X-ray detector
110:
112: collimator
114: Spawning prevention grid
118:
120: Data transmission unit
124:
126:
128:
130:
132:
134: Server
136: Medical devices
301: Network
400: Radiation detector
710: radiation absorbing layer
730, 740, and 750:
1600: Computer tomography apparatus
1610: Radiation detector
1650:

Claims (43)

1. A detector comprising a plurality of pixels for sensing radiation,
Each of the plurality of pixels
A radiation absorbing layer for converting the incident photons into a first electrical signal; And
And a photon processing unit including a plurality of storage units for counting and storing the number of photons based on the first electrical signal,
Wherein at least one of the plurality of storage units
Counts and stores the number of photons based on a third electrical signal obtained by comparing the first electrical signal with a first reference value and comparing the second electrical signal with the second reference value,
Wherein the first reference value has a voltage greater than the second reference value. The method of claim 1, wherein at least one of the first and second reference values is
Wherein at least one of the plurality of pixels is set to a first value and at least one of the plurality of pixels is set to a second value different from the first value. 2. The apparatus of claim 1, wherein the at least one storage unit
A first comparator that outputs the second electrical signal corresponding to the difference between the first electrical signal and the first reference value when the first electrical signal is equal to or greater than the first reference value;
A second comparator for comparing the second electrical signal with the second reference value and outputting the third electrical signal; And
And a first counter for counting and storing the number of photons based on the third electrical signal. The method of claim 3,
The first electrical signal
A voltage signal corresponding to the energy of the incident photon,
Wherein the first reference value has a voltage value,
Wherein the second reference value has a current value. 4. The apparatus of claim 3, wherein the at least one storage unit
And a second counter for counting and storing the number of photons when the first electrical signal is greater than or equal to the first reference value based on the second comparison signal. The method of claim 1, wherein at least one of the first reference value and the second reference value is
Wherein the pixel is set to a different value for each pixel in a group of pixels including a plurality of adjacent pixels. The method of claim 1, wherein the second reference value used in the at least one storage unit
Wherein a different value is set for a first pixel of the plurality of pixels and a second pixel adjacent to the first pixel. 8. The method of claim 7, wherein the second reference value applied to the first pixel is
Wherein the second detector has a value greater than or less than the second reference value applied to the second pixel. 2. The apparatus of claim 1, wherein the first reference value used in the at least one storage unit
Wherein a different value is set for a first pixel of the plurality of pixels and a second pixel adjacent to the first pixel. 2. The apparatus of claim 1, wherein the at least one storage unit
Wherein the size of the radiation detector is determined based on at least one of the first reference value and the second reference value. 2. The apparatus of claim 1, wherein the at least one storage unit
And a second bit depth having a first bit depth if the energy band of the photons to be counted is a low energy band and a second bit depth if the energy band of the photons to be counted is a high energy band higher than the low energy band. Radiation detector. The apparatus of claim 1, wherein the radiation detector
Wherein the radiation detector is a direct radiation detector for generating a CT image based on the photons counted. The method according to claim 1,
The radiation absorbing layer
A radiation detector disposed on a front surface of the radiation detector,
The photon processing unit
Wherein the radiation detector is disposed at a rear portion of the radiation detector. The method of claim 1, wherein the radiation absorbing layer
Cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe). 1. A detector comprising a plurality of pixels for sensing radiation,
Each of the plurality of pixels including a plurality of sub-pixels,
Each of the plurality of sub-
A radiation absorbing layer for converting the incident photons into a first electrical signal; And
And a photon processing unit including a plurality of storage units for counting and storing the number of photons based on the first electrical signal,
Wherein at least one of the plurality of storage units
Counts and stores the number of photons based on a third electrical signal obtained by comparing the first electrical signal with a first reference value and comparing the second electrical signal with the second reference value,
Wherein the first reference value has a voltage value greater than the second reference value. 16. The method of claim 15, wherein at least one of the first and second reference values is
Wherein at least one of the plurality of subpixels is set to a first value and at least one of the plurality of pixels is set to a second value different from the first value. 16. The apparatus of claim 15, wherein the at least one storage unit
A first comparator that outputs the second electrical signal corresponding to a difference between the first electrical signal and the first reference value when the first electrical signal is equal to or greater than the first reference value;
A second comparator for comparing the second electrical signal with the second reference value and outputting the third electrical signal; And
And a first counter for counting and storing the number of photons based on the third electrical signal. 18. The method of claim 17,
The first electrical signal
A voltage signal corresponding to the energy of the incident photon,
Wherein the first reference value has a first voltage value,
Wherein the second reference value has a first current value. 18. The apparatus of claim 17, wherein the at least one storage unit
And a second counter for counting and storing the number of photons when the first electrical signal is greater than or equal to the first reference value based on the second comparison signal. 16. The method of claim 15, wherein at least one of the first reference value and the second reference value is
Wherein the sub-pixel group is set to a different value for each sub-pixel in a sub-pixel group including a plurality of adjacent sub-pixels. 16. The apparatus of claim 15, wherein the second reference value used in the at least one storage unit
Pixels are set to different values in a first sub-pixel of the plurality of sub-pixels and a second sub-pixel adjacent to the first sub-pixel. 22. The method of claim 21, wherein the second reference value applied to the first subpixel is
Wherein the first reference value is greater than the second reference value applied to the second subpixel. 16. The apparatus of claim 15, wherein the first reference value used in the at least one storage unit
Pixels are set to different values in a first sub-pixel of the plurality of sub-pixels and a second sub-pixel adjacent to the first sub-pixel. 16. The apparatus of claim 15, wherein the at least one storage unit
Wherein the size of the radiation detector is determined based on at least one of the first reference value and the second reference value. 16. The apparatus of claim 15, wherein the at least one storage unit
And a second bit depth having a first bit depth if the energy band of the photons to be counted is a low energy band and a second bit depth if the energy band of the photons to be counted is a high energy band higher than the low energy band. Radiation detector. 16. The apparatus of claim 15, wherein the radiation detector
Wherein the radiation detector is attached to the gantry and is emitted from a rotating X-ray source to sense the radiation passing through the object. 16. The apparatus of claim 15, wherein the radiation detector
Wherein the radiation detector is a direct-type radiation detector for generating a multi-energy CT image based on the photons to be counted. The apparatus of claim 1, wherein the radiation detector
Wherein the radiation detector is attached to the mobile device and is emitted from a position adjustable X-ray source to sense the radiation passing through the object. 16. The method of claim 15,
Wherein the radiation detector is a radiation detector used for generating a multi-energy X-ray image. delete delete delete delete delete delete delete delete delete delete delete delete A radiation detector including a plurality of pixels for sensing radiation; And
And an image processor for reconstructing the CT image based on the photon amount detected by the radiation detector,
Each of the plurality of pixels
A radiation absorbing layer for converting the incident photons into a first electrical signal; And
And a photon processing unit including a plurality of storage units for counting and storing the number of photons based on the first electrical signal,
Wherein at least one of the plurality of storage units
Counts and stores the number of photons based on a third electrical signal obtained by comparing the first electrical signal with a first reference value and comparing the second electrical signal with the second reference value,
Wherein the first reference value has a voltage value greater than the second reference value. delete

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