JP2024162394A - Medical image processing device, medical image processing method, and program - Google Patents

Abstract

To accurately grasp the cauterization status.
[Solution] A medical image processing device according to an embodiment has an acquisition unit, a generation unit, and a registration unit. The acquisition unit acquires a pre-ablation image before ablation of a subject and a post-ablation image after ablation of the subject. The generation unit generates a virtual pre-ablation image that is an image of the pre-ablation image based on the acquired post-ablation image. The registration unit aligns the pre-ablation image with the virtual pre-ablation image, and transforms the post-ablation image using registration information obtained at the time of alignment to generate an aligned post-ablation image.
[Selected Figure] Figure 1

Description

The embodiments disclosed in this specification and the drawings relate to a medical image processing device, a medical image processing method, and a program.

For example, a treatment for a tumor region may involve cauterizing the target (hereinafter referred to as ablation treatment). Ablation treatment is a treatment that uses radio waves or the like to heat the tumor region, such as cancer cells, that is the target of ablation, to a high temperature, thereby killing the tumor cells. In ablation treatment, for example, the tumor region is heated to a sufficient temperature, and it is monitored to ensure that normal tissue is not heated more than necessary.

Monitoring is preferably performed non-invasively, and an example of a non-invasive monitoring technique is a technique that uses thermo-CT. The CT value in thermo-CT is temperature dependent, and the higher the temperature, the lower the CT value becomes. Thermo-CT can calculate the temperature change value of the tumor area by calculating the difference in CT values before and immediately after ablation, and multiplying it by a conversion coefficient.

Conventional ablation treatments, for example, involve simulating the effects on abnormal tissue to confirm whether ablation has been performed sufficiently. Ablation treatments usually take about five minutes. Although patients undergoing treatment are usually breathing, they must stop breathing when taking CT images before, during, and immediately after ablation. Therefore, the positions of organs and tumor tissues in each CT image move and change shape, making nonlinear alignment necessary.

Patent No. 6042718

Conventional nonlinear registration techniques use differences in CT values to register tissue shapes, such as organ contours and structures such as blood vessels. For example, ablation of a tumor in the liver region has a relatively uniform organ and uniform CT values. However, if the CT value of the region where ablation is being performed changes, it is difficult to accurately capture the deformation of the tumor shape, making it difficult to grasp the ablation status.

The problem that the embodiments disclosed in this specification and the drawings aim to solve is to be able to grasp the cauterization situation with precision. However, the problems that the embodiments disclosed in this specification and the drawings aim to solve are not limited to the above problem. Problems that correspond to the effects of each configuration shown in the embodiments described below can also be positioned as other problems.

The medical image processing device of the embodiment has an acquisition unit, a generation unit, and an alignment unit. The acquisition unit acquires a pre-ablation image before the subject is ablated and a post-ablation image after the subject is ablated. The generation unit generates a virtual pre-ablation image that is an image of the pre-ablation image based on the acquired post-ablation image. The alignment unit aligns the pre-ablation image and the virtual pre-ablation image, and transforms the post-ablation image using alignment information obtained at the time of alignment to generate an aligned post-ablation image.

1 is a configuration diagram of an X-ray CT apparatus 1 according to an embodiment. 4 is a flowchart showing an example of processing of the X-ray CT apparatus 1. 13A to 13C are diagrams for explaining the images of each CT image from the time of acquiring the pre-ablation image and the post-ablation image until the time of generating a confirmation image. 13A to 13C are diagrams for explaining the images of each CT image from the time of acquiring the pre-ablation image and the post-ablation image until the time of generating a confirmation image. 11A and 11B are diagrams for explaining the images of each CT image from the time of acquiring a pre-drug administration CT image and a post-drug administration CT image until a confirmation image is generated.

The following describes the medical image processing device, medical image processing method, and program of the embodiment with reference to the drawings.

Figure 1 is a configuration diagram of an X-ray CT device 1 according to an embodiment. The X-ray CT device 1 includes, for example, a gantry device 10, a bed device 30, and a console device 40. For convenience of explanation, FIG. 1 shows both a view of the gantry device 10 from the Z-axis direction and a view from the X-axis direction, but in reality, there is only one gantry device 10. In the embodiment, the rotation axis of the rotating frame 17 in a non-tilted state or the longitudinal direction of the top plate 33 of the bed device 30 is defined as the Z-axis direction, an axis perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the X-axis direction, and a direction perpendicular to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. The X-ray CT device 1 is an example of a medical image processing device.

The X-ray CT device 1 of the embodiment is used, for example, in radio ablation treatment under CT guidance, which is performed as a cancer treatment. Ablation is performed, for example, by inserting an ablation needle into cancer cells and applying high frequency waves to cause necrosis of the cancer cells with radio waves. To cause necrosis of cancer cells by ablation, it is required that the time it takes for the cancer cells to reach a target temperature, for example 70°C, is a predetermined time, for example 5 minutes or more. The X-ray CT device 1 captures a CT image of a subject including a subject to be ablated, and detects the temperature of the subject to be ablated based on the CT value obtained from the CT image. A doctor ablate the subject while checking the temperature of the subject detected by the X-ray CT device 1.

The gantry device 10 includes, for example, an X-ray tube 11, a wedge 12, a collimator 13, an X-ray high voltage device 14, an X-ray detector 15, a data acquisition system (hereinafter, DAS: Data Acquisition System) 16, a rotating frame 17, and a control device 18.

The X-ray tube 11 generates X-rays by irradiating thermoelectrons from a cathode (filament) to an anode (target) when a high voltage is applied from the X-ray high voltage device 14. The X-ray tube 11 includes a vacuum tube. For example, the X-ray tube 11 is a rotating anode type X-ray tube that generates X-rays by irradiating thermoelectrons to a rotating anode.

The wedge 12 is a filter for adjusting the amount of X-rays irradiated from the X-ray tube 11 to the subject P who is the subject of image diagnosis. The wedge 12 attenuates the X-rays that pass through it so that the distribution of the amount of X-rays irradiated from the X-ray tube 11 to the subject P becomes a predetermined distribution. The wedge 12 is also called a wedge filter or a bow-tie filter. The wedge 12 is, for example, made of processed aluminum so that it has a predetermined target angle and a predetermined thickness.

The collimator 13 is a mechanism for narrowing the irradiation range of the X-rays that have passed through the wedge 12. The collimator 13 narrows the irradiation range of the X-rays, for example, by forming a slit by combining multiple lead plates. The collimator 13 is sometimes called an X-ray aperture. The narrowing range of the collimator 13 may be mechanically operable.

The X-ray high voltage device 14 has, for example, a high voltage generator and an X-ray control device. The high voltage generator has an electric circuit including a transformer and a rectifier, and generates a high voltage to be applied to the X-ray tube 11. The X-ray control device controls the output voltage of the high voltage generator according to the amount of X-rays to be generated by the X-ray tube 11. The high voltage generator may be one that boosts the voltage using the above-mentioned transformer, or one that boosts the voltage using an inverter. The X-ray high voltage device 14 may be provided on the rotating frame 17, or on the side of the fixed frame (not shown) of the gantry device 10.

The X-ray detector 15 detects the intensity of the X-rays generated by the X-ray tube 11 and passing through the subject P. The X-ray detector 15 outputs an electrical signal (which may be an optical signal, etc.) corresponding to the intensity of the detected X-rays to the DAS 16. The X-ray detector 15 has, for example, multiple rows of X-ray detection elements. Each of the multiple rows of X-ray detection elements has multiple X-ray detection elements arranged in the channel direction along an arc centered on the focal point of the X-ray tube 11. The multiple rows of X-ray detection elements are arranged in the slice direction (row direction).

The X-ray detector 15 is an indirect detector having, for example, a grid, a scintillator array, and an optical sensor array. The scintillator array has a plurality of scintillators. Each scintillator has a scintillator crystal. The scintillator crystal emits an amount of light according to the intensity of the incident X-rays. The grid is arranged on the surface of the scintillator array on which the X-rays are incident, and has an X-ray shielding plate that has the function of absorbing scattered X-rays. The grid is sometimes called a collimator (one-dimensional collimator or two-dimensional collimator). The optical sensor array has, for example, an optical sensor such as a photomultiplier tube (PMT). The optical sensor array outputs an electrical signal according to the amount of light emitted by the scintillator. The X-ray detector 15 may be a direct conversion type detector having a semiconductor element that converts the incident X-rays into an electrical signal.

DAS16 includes, for example, an amplifier, an integrator, and an A/D converter. The amplifier performs an amplification process on the electrical signal output by each X-ray detection element of the X-ray detector 15. The integrator integrates the amplified electrical signal over a view period. The A/D converter converts the electrical signal indicating the integration result into a digital signal. DAS16 outputs detection data based on the digital signal to the console device 40.

The rotating frame 17 is an annular member that supports the X-ray tube 11, wedge 12, and collimator 13 in opposing relation to the X-ray detector 15. The rotating frame 17 is an annular member that has two circular side surfaces with a circular opening in the center, an inner side surface that connects the inner circles on both sides, and an outer side surface that connects the outer circles on both sides. Both side surfaces of the rotating frame 17 are flat, and the inner and outer sides are curved.

The rotating frame 17 is supported by a fixed frame (not shown) so as to be freely rotatable around the subject P introduced inside. The rotating frame 17 further supports the DAS 16. The detection data output by the DAS 16 is transmitted by optical communication from a transmitter having a light-emitting diode (LED) provided on the rotating frame 17 to a receiver having a photodiode provided on a non-rotating part (e.g., the fixed frame) of the gantry device 10, and is then transferred to the console device 40 by the receiver. Note that the method of transmitting the detection data from the rotating frame 17 to the non-rotating part is not limited to the above-mentioned method using optical communication, and any non-contact transmission method may be adopted. The rotating frame 17 is not limited to a ring-shaped member, and may be an arm-like member as long as it can support and rotate the X-ray tube 11, etc.

The X-ray CT device 1 is, for example, a Rotate/Rotate-type X-ray CT device (third generation CT) in which both the X-ray tube 11 and the X-ray detector 15 are supported by a rotating frame 17 and rotate around the subject P, but is not limited to this and may also be a Stationary/Rotate-type X-ray CT device (fourth generation CT) in which multiple X-ray detection elements arranged in a circular ring are fixed to a fixed frame and the X-ray tube 11 rotates around the subject P.

The control device 18 has, for example, a processing circuit having a processor such as a CPU (Central Processing Unit) and a drive mechanism including a motor, actuator, etc. The processing circuit realizes these functions by, for example, a hardware processor executing a program stored in a storage device (storage circuit).

The hardware processor refers to a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD) or a Complex Programmable Logic Device (CPLD), or a Field Programmable Gate Array (FPGA). Instead of storing a program in a storage device, the program may be directly built into the circuit of the hardware processor. In this case, the hardware processor realizes a function by reading and executing the program built into the circuit. The hardware processor is not limited to being configured as a single circuit, but may be configured as a single hardware processor by combining multiple independent circuits to realize each function. The storage device may be a non-transitory (hardware) storage medium. Also, multiple components may be integrated into a single hardware processor to realize each function.

The control device 18, for example, rotates the rotating frame 17, tilts the gantry of the gantry device 10, moves the top plate 33 of the bed device 30 by vertical movement, and radiates (exposes) X-rays from the X-ray tube 11. The control device 18 may be provided in the gantry device 10 or in the console device 40.

The bed device 30 is a device on which the subject P to be scanned is placed, moved, and introduced into the rotating frame 17 of the gantry device 10. The bed device 30 includes, for example, a base 31, a bed vertical movement device 32, a top plate 33, and a support frame 34. The base 31 includes a housing that supports the support frame 34 so that it can move in the vertical direction (Y-axis direction).

The console device 40 has, for example, a memory 41, a display 42, an input interface 43, and a processing circuit 50. In the embodiment, the console device 40 is described as being separate from the gantry device 10, but the gantry device 10 may include some or all of the components of the console device 40.

The memory 41 is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory), a flash memory, a hard disk, an optical disk, etc. The memory 41 stores, for example, detection data, projection data, reconstructed image data, CT image data, etc. These data may be stored in an external memory with which the X-ray CT device 1 can communicate, instead of the memory 41 (or in addition to the memory 41). The external memory is controlled by, for example, a cloud server that manages the external memory, by the cloud server accepting a read/write request.

The display 42 displays various types of information. For example, the display 42 displays medical images (CT images) generated by the processing circuit 50, GUI (Graphical User Interface) images that accept various operations by operators such as doctors and engineers, and the like. The display 42 is, for example, a liquid crystal display, a CRT (Cathode Ray Tube), an organic EL (Electroluminescence) display, or the like. The display 42 may be provided on the pedestal device 10. The display 42 may be a desktop type, or may be a display device (e.g., a tablet terminal) that can wirelessly communicate with the main body of the console device 40.

The input interface 43 accepts various input operations by the operator and outputs an electrical signal indicating the content of the accepted input operation to the processing circuit 50. For example, the input interface 43 accepts input operations such as collection conditions when collecting detection data or projection data, reconstruction conditions when reconstructing a CT image, and image processing conditions when generating a post-processed image from a CT image.

The input interface 43 is realized, for example, by a mouse, a keyboard, a touch panel, a drag ball, a switch, a button, a joystick, a dial, a camera, an infrared sensor, a microphone, etc. The input interface 43 may also be realized by a display device (e.g., a tablet terminal) capable of wireless communication with the main body of the console device 40.

The input interface 43 further accepts input operations of subject P, such as the subject P's name and weight (body weight), when capturing a contrast CT image of the subject P. The input interface 43 accepts input operations of input information for adjusting the window level and window width when setting the window level and window width. In the following description, the adjustment of the window level and window width may be referred to as brightness adjustment. The input operations for brightness adjustment will be described further below.

In this specification, the input interface is not limited to an interface equipped with physical operating parts such as a mouse and a keyboard. For example, an example of an input interface also includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs this electrical signal to a control circuit.

The processing circuitry 50 controls the overall operation of the X-ray CT device 1. The processing circuitry 50 includes, for example, a control function 51, a pre-processing function 52, a reconstruction processing function 53, an image processing function 54, an acquisition function 55, a generation function 56, an alignment function 57, and a display control function 58. The processing circuitry 50 realizes these functions, for example, by a hardware processor executing a program stored in a storage device (storage circuit).

The hardware processor refers to a circuit such as a CPU, GPU, application specific integrated circuit, programmable logic device or composite programmable logic device, or field programmable gate array. Instead of storing the program in a memory device, the program may be directly embedded in the circuit of the hardware processor. The hardware processor is not limited to being configured as a single circuit, but may be configured as a single hardware processor by combining multiple independent circuits to realize each function. The memory device may be a non-transitory (hardware) storage medium. In addition, multiple components may be integrated into a single hardware processor to realize each function.

Each component of the console device 40 or the processing circuit 50 may be distributed and realized by multiple pieces of hardware. The processing circuit 50 may be realized by a processing device capable of communicating with the console device 40, rather than being a component of the console device 40. The processing device is, for example, a workstation connected to one X-ray CT device, or a device (e.g., a cloud server) connected to multiple X-ray CT devices and collectively executing processing equivalent to that of the processing circuit 50 described below. Each function included in the processing circuit 50 may be distributed to multiple circuits, or may be made available by starting application software stored in the memory 41.

The control function 51 controls various functions of the processing circuit 50 based on the input operations received by the input interface 43. For example, the control function 51 controls the X-ray high voltage device 14, the DAS 16, the control device 18, and the bed vertical movement device 32 to perform the collection process of the detection data in the gantry device 10, etc.

The pre-processing function 52 performs pre-processing such as logarithmic conversion, offset correction, inter-channel sensitivity correction, and beam hardening correction on the detection data output by the DAS 16, generates projection data, and stores the generated projection data in the memory 41.

The reconstruction processing function 53 performs reconstruction processing using a filtered back projection method, an iterative reconstruction method, or the like on the projection data generated by the preprocessing function 52 to generate a CT image (CT image data). The reconstruction processing function 53 stores the generated CT image in the memory 41. The CT image is an image based on the detection result of the X-ray detector 15. The CT image captured before the subject is ablated is a pre-ablation image, and the CT image captured after the subject is ablated is a post-ablation image.

The image processing function 54 converts the CT image data into three-dimensional image data or cross-sectional image data of an arbitrary cross section by a known method based on the input operation received by the input interface 43. The conversion into three-dimensional image data may be performed by the pre-processing function 52. The image processing function 54 generates, for example, multiple cross-sectional images corresponding to multiple cross sections in the CT image generated by the reconstruction processing function 53.

The acquisition function 55 acquires a pre-ablation image before the ablation target is ablated and a post-ablation image after the ablation target is ablated, which are generated by the reconstruction processing function 53 or stored in the memory 41. As the pre-ablation image and the post-ablation image, a CT image generated by the reconstruction processing function 53 or the image processing function 54 may be used. The acquisition function 55 is an example of an acquisition unit.

The generation function 56 generates a virtual pre-ablation image that is an image of the pre-ablation image based on the post-ablation image acquired by the acquisition function 55. The generation function 56 generates the virtual pre-ablation image, for example, by a thermal equation simulation using the post-ablation thermal image. The generation function 56 may generate the virtual pre-ablation thermal image by other methods. The generation function 56 is an example of an acquisition unit.

The alignment function 57 aligns the pre-ablation image acquired by the acquisition function 55 with the virtual pre-ablation image generated by the generation function 56. The virtual pre-ablation image generated by the generation function 56 is generated from the post-ablation image, and therefore often differs in shape and size from the pre-ablation image. The alignment function 57 aligns the pre-ablation image and the virtual pre-ablation image by adjusting the shape and size of the virtual pre-ablation image so that the shape and size of the virtual pre-ablation image are similar to those of the pre-ablation image. The alignment function 57 is an example of an alignment unit.

The alignment function 57 acquires information (hereinafter, alignment information) obtained when the virtual pre-ablation image is adjusted when aligning the pre-ablation image and the virtual pre-ablation image. The alignment function 57 uses the acquired alignment information to deform the post-ablation image and generate an aligned post-ablation image.

The alignment function 57 performs a thermo-CT calculation using the pre-ablation image acquired by the acquisition function 55 and the generated aligned post-ablation image. In the thermo-CT calculation, the temperature of each part of the subject is calculated based on the CT value in the CT image. The alignment function 57 acquires information regarding the temperature of the ablation target and the temperature of parts other than the ablation target based on the results of the thermo-CT calculation.

The display control function 58 causes the display 42 to display the three-dimensional image data, cross-sectional image data, etc., converted by the image processing function 54. The cross-sectional image displayed on the display 42 is an image with an adjusted window level and window width, and is, for example, an image used for diagnosis by a doctor or the like (hereinafter, a diagnostic image). The cross-sectional image is a two-dimensional cross-sectional image reconstructed from CT scan data by the reconstruction processing function 53.

The display control function 58 further generates a confirmation image showing the temperature distribution of each part of the subject based on the information regarding the temperature of the ablation target and the temperature of parts other than the ablation target obtained by the positioning function 57. The display control function 58 displays the generated confirmation image on the display 42.

Next, the operation of the X-ray CT device 1 of the embodiment will be described. Here, the processing of the X-ray CT device 1 when used for ablation treatment will be described. When performing ablation treatment, a pre-ablation image is captured before ablation of the ablation target, and a post-ablation image is captured after ablation of the ablation target is completed. The captured pre-ablation image and post-ablation image are stored in the memory 41. The processing of the X-ray CT device 1 following this state will be described.

Figure 2 is a flowchart showing an example of processing by the X-ray CT device 1. First, the X-ray CT device 1 acquires a pre-ablation image by the acquisition function 55 (step S101). Here, the acquisition function 55 acquires the pre-ablation image that is captured (reconstructed) immediately before the start of the ablation treatment and stored in the memory 41.

Then, the acquisition function 55 acquires a post-ablation image (step S103). Here, the acquisition function 55 acquires a post-ablation image acquired during the ablation treatment, immediately before it is determined whether the ablation of the ablation target has been sufficiently performed after the ablation target has been ablated. The post-ablation image may be a CT image reconstructed by the reconstruction processing function 53, or a CT image reconstructed by the reconstruction processing function 53 or generated by the image processing function 54 and stored in the memory 41.

Then, the generation function 56 generates a virtual pre-ablation image based on the post-ablation image acquired by the acquisition function 55 (step S105). FIG. 3 is a diagram explaining the image of each CT image from the acquisition of the pre-ablation image and the post-ablation image until the generation of the confirmation image. For example, in the pre-ablation image shown in the first image IM11 of FIG. 3, a tumor region (region occupied by the tumor to be ablated) K exists in the organ Z, and in the post-ablation image shown in the second image IM12, a first heated region H around the tumor region K is displayed.

When generating the virtual pre-ablation image, the generation function 56 uses, for example, a heat equation simulation. When executing a heat equation simulation, the generation function 56 first identifies the position of the probe and the shape and size of the organ Z and the tumor region K based on the post-ablation image. Furthermore, the generation function 56 identifies the position of the ablation probe when the tumor region K is ablated and the electrical profile when power is applied by the ablation probe. The electrical profile includes, for example, power and time.

Then, the generation function 56 predicts how the heat radiated from the cauterization probe will diffuse by simulating it. At this time, the generation function 56 may acquire the state of blood flow through blood vessels in the organ Z or the tumor region K, and perform a heat equation simulation taking into account the so-called radiator effect, in which the state of blood flow through blood vessels reduces temperature changes. By performing such a heat equation simulation, the generation function 56 generates a virtual pre-cauterization image, for example, as shown in the third image IM13 in FIG. 3.

The generation function 56 may generate a virtual pre-ablation image by heat equation simulation based only on the post-ablation image, or may use a heat equation simulation using an image during ablation captured between the time when the post-ablation image was captured and the time when the pre-ablation image was captured. The heat equation simulation may be performed using a model function assumed in advance, or may be performed using deep learning. The pre-ablation image and the post-ablation image do not have to be CT images; for example, an image showing a figure showing the tumor region boundary line created based on a CT image may be used.

Next, the alignment function 57 aligns the pre-ablation image acquired by the acquisition function 55 with the virtual pre-ablation image generated by the generation function 56, and generates an aligned image shown in the fourth image IM14 in FIG. 3. The image shown in the fourth image IM14 shows an image for generating a virtual pre-ablation image, so the virtual pre-ablation image itself does not need to be generated. Since it takes a certain amount of time to ablate a tumor, the shape and size of the organ Z including the tumor region K change over time due to pulsation, etc.

For this reason, the shape and size of organ Z in the pre-ablation image in the first image IM11 often differs from that of organ Z in the post-ablation image in the second image IM12. In such cases, it becomes difficult to compare the pre-ablation image with the post-ablation image. Therefore, the alignment function 57 aligns the pre-ablation image and the virtual pre-ablation image, which have different shapes and sizes. For example, nonlinear alignment is performed as the alignment here.

The alignment function 57 performs nonlinear alignment processing of the virtual pre-ablation image with respect to the pre-ablation image, and obtains information on the amount of movement in the X, Y, and Z directions obtained during the process as alignment information (step S107). Any method may be used for nonlinear alignment. For example, the alignment function 57 may use a method of tracking areas of similar density regions in the CT images (pre-ablation image and virtual pre-ablation image) as shown in the fourth image IM14 in FIG. 3, or may use a method of tracking the boundaries of tissues (such as tumors and organs) in the images.

Furthermore, the pre-ablation image may be captured before the ablation probe is inserted into the subject, and the post-ablation image may be captured after the ablation probe is inserted into the subject. In this case, a virtual probe position may be set in the pre-ablation image based on the positional relationship between the ablation probe and the overall shape of the organ during ablation, and used in nonlinear registration processing to improve the accuracy of registration.

Next, the alignment function 57 uses the acquired alignment information to adjust the shape and size of the post-ablation image (step S109) and deforms the post-ablation image so as to inversely transform it. The fifth image IM15 shown in FIG. 3 shows an aligned post-ablation image in which the post-ablation image has been adjusted based on the alignment information.

In the fifth image IM15, the first heated region H and the second heated region M are displayed as superimposed images on the images of the organ Z and the tumor region K. The first heated region H is a region that has been heated to a temperature of 70 degrees or higher for a predetermined period of time or more, and the second heated region M is a region that has been heated to a temperature of 70 degrees or higher for less than the predetermined period of time.

The registration function 57 adjusts the shape and size of the post-ablation image to generate a registered post-ablation image that matches the shape and size of the organ Z and tumor region K in the pre-ablation image and post-ablation image. When an in-progress image of an in-progress ablation stage is generated, registration information may be obtained based on this in-progress image to adjust the post-ablation image.

Then, the alignment function 57 performs a thermo-CT calculation between the pre-ablation image and the aligned post-ablation image (step S111). In the thermo-CT calculation, the difference between the pre-ablation image and the aligned post-ablation image is calculated, and the temperature of the organ Z and the tumor region K is calculated by multiplying the difference by a predetermined conversion coefficient.

Next, the display control function 58 superimposes information corresponding to the results of the thermo-CT calculation (hereinafter, superimposed display information) on the pre-ablation image or the post-ablation image (step S113). The sixth image IM16 shown in FIG. 3 shows a confirmation image including superimposed display information. In the confirmation image, the first heating region H and the second heating region M are superimposed on the organ Z and the tumor region K. The first heating region H and the second heating region M are the superimposed display information. By including the tumor region K in the first heating region H, it is recognized that the tumor region K has been sufficiently heated.

The display control function 58 may, for example, calculate the results (temperature) of the thermo-CT calculation for each pixel, and display the calculated temperature as superimposed display information by changing the color of each pixel, displaying it as a numerical value, or may generate and display temperature contour lines. The superimposed display information may, for example, display an area indicating a sufficiently cauterized range, for example, an area where a temperature of 70 degrees or more has been applied for a predetermined period of time or more. In this way, the X-ray CT device 1 ends the processing shown in FIG. 2.

The medical image processing device of the embodiment generates a virtual pre-ablation image based on a post-ablation image, aligns the generated virtual pre-ablation image with the pre-ablation image to obtain alignment information, and adjusts the post-ablation image based on the alignment information, thereby making it possible to accurately obtain the effect of ablation (temperature distribution) on the ablation target. Therefore, the ablation state of the ablation target can be confirmed with high accuracy. As a result, the ablation target can be heated to the required amount while preventing excess heating of areas other than the ablation target.

(Variation 1)
Next, a first modified example of the embodiment will be described. In the above embodiment, a virtual pre-ablation image is generated based on a post-ablation image, and the post-ablation image is adjusted based on registration information obtained by aligning the virtual pre-ablation image and the pre-ablation image. In contrast, in the first modified example, a virtual post-ablation image is generated based on a pre-ablation image.

Figure 4 is a diagram illustrating the image of each CT image after the pre-ablation image and the post-ablation image are acquired and before the confirmation image is generated. For example, the acquisition function 55 acquires the pre-ablation image shown in the first image IM21 and the post-ablation image shown in the second image IM22. The acquisition of the pre-ablation image and the post-ablation image is similar to the above embodiment.

Then, the generation function 56 generates a virtual post-ablation image shown in the third image IM23 based on the pre-ablation image. Here, the generation function 56 generates a virtual post-ablation thermal image from the pre-ablation thermal image by heat equation simulation in a manner similar to the procedure in the above embodiment in which the virtual pre-ablation image was generated from the post-ablation image by heat equation simulation.

Then, the alignment function 57 nonlinearly aligns the virtual post-ablation image generated by the generation function 56 with the post-ablation image acquired by the acquisition function 55 to acquire an aligned post-ablation image shown in the fourth image IM24. The first heating region H and the second heating region M displayed in the aligned post-ablation image are based on the virtual post-ablation image. In the first modification example, the post-ablation image includes the first heating region H and the second heating region M, but the post-ablation image does not necessarily need to include the first heating region H and the second heating region M.

Then, the alignment function 57 performs a thermo-CT calculation using the post-ablation image acquired by the acquisition function 55 and the aligned post-ablation image generated by the generation function 56, in the same manner as in the above embodiment. The subsequent processing is the same as in the above embodiment, and finally generates a confirmation image shown in the fifth image IM25.

The medical image processing device of the first modification has the same effect as the medical image processing device of the above embodiment. In the medical image processing device of the first modification, a virtual post-ablation image is generated based on a pre-ablation image, and an aligned post-ablation image is generated based on the virtual post-ablation image. In this way, a virtual post-ablation image can also be generated using a pre-ablation image.

(Variation 2)
Next, a description will be given of Modification 2. In the above embodiment, CT images are used as both the pre-ablation image and the post-ablation image. In contrast, in Modification 2, an image other than a CT image, for example, a PET (Positron Emission Tomography) image, is used as the pre-ablation image or the post-ablation image, for example, the post-ablation image. The PET image is an image captured by PET-CT.

Figure 5 is a diagram explaining the image of each CT image from the acquisition of the pre-drug administration CT image and the post-drug administration CT image until the generation of the confirmation image. For example, the acquisition function 55 acquires the pre-drug administration CT image shown in the first image IM31 and the PET image shown in the second image IM32. The PET image is, for example, an image captured by a PET-CT (not shown). The PET image includes the organ Z and the tumor region K as well as the drug region Y. The drug region Y is the region where the drug for treatment has spread.

Furthermore, the acquisition function 55 acquires a CT image for generating a post-drug administration image captured by the X-ray CT device 1 after capturing the pre-drug administration CT image. The CT image for generating a post-drug administration image acquired by the acquisition function 55 is a CT image captured to generate a post-drug administration CT image. The X-ray CT device 1 is an example of a first imaging device. The pre-drug administration CT image is an example of a first image.

Then, after the drug is administered to the subject, the generation function 56 extracts an image of the distribution of the drug administered to the subject when the PET image was captured and included in the PET image, based on the PET image captured by the PET-CT and acquired by the acquisition function 55. The generation function 56 generates a post-drug administration CT image shown in the third image IM33 by superimposing the extracted drug region Y on the CT image for generating the post-drug administration image acquired by the acquisition function 55. The PET-CT is an example of a second imaging device. The PET image is an example of a second image. The CT image for generating the post-drug administration image is the same type of image as the pre-drug administration CT image, and is an example of a third image.

Furthermore, the generation function 56 generates a virtual post-drug administration CT image shown in the fourth image IM34 based on the pre-drug administration CT image acquired by the acquisition function 55. Here, the generation function 56 generates a virtual post-drug administration CT image from the pre-drug administration CT image by a drug administration simulation similar to the heat equation simulation in the above embodiment. The virtual post-drug administration CT image is an image that simulates the pre-drug administration CT image, and is an example of a virtual third image.

Then, the alignment function 57 nonlinearly aligns the virtual post-drug administration CT image generated by the generation function 56 with the post-drug administration CT image to obtain an aligned post-drug administration CT image. The same processing as in the above embodiment is performed by replacing the post-ablation image with the post-drug administration CT image and the aligned post-ablation image with the aligned post-drug administration CT image.

The medical image processing of the second modification provides the same effect as the medical image processing of the above embodiment. In the medical image processing of the second modification, a virtual post-drug administration CT image is generated based on a pre-drug administration CT image. Therefore, when images captured by multiple types of imaging devices are used, the situation of the drug distribution, etc. can be known.

The process of checking the status of drug administration may be performed, for example, by the same device as the process of checking the status of cauterization. In short, the process from administering the drug to performing the cauterization may be performed by a single device. Similar processes other than drug administration and cauterization may also be performed by a single device.

In the above embodiment, the pre-ablation image and the post-ablation image are CT images, but the pre-ablation image and the post-ablation image may be other images. The pre-ablation image and the post-ablation image may be, for example, an MRI image, an ultrasound image, or a PET image. In the above embodiment, the pre-ablation image and the post-ablation image are the same type of image, but the pre-ablation image and the post-ablation image may be different types of images. For example, the pre-ablation image may be a CT image and the post-ablation image may be an MRI image.

In the above embodiment, the ablation status is confirmed based on the temperature change of the subject, but the ablation status may be confirmed based on information other than the temperature change of the subject. For example, the ablation status may be confirmed based on the density change of the CT value based on the shade of the contrast agent administered to the subject. Furthermore, in the above embodiment, the image is generated based on a heat equation simulation, but the image may be generated based on a method other than a heat equation simulation. For example, when observing the change in the contrast agent, the image may be generated using a perfusion model (e.g., a compartment model.

According to at least one of the embodiments described above, the state of ablation can be grasped with high accuracy by having an acquisition unit that acquires a pre-ablation image before ablation of the subject and a post-ablation image after ablation of the subject, a generation unit that generates a virtual pre-ablation image based on the acquired post-ablation image and that simulates the pre-ablation image, and an alignment unit that aligns the pre-ablation image with the virtual pre-ablation image, transforms the post-ablation image using the alignment information obtained during the alignment, and generates an aligned post-ablation image.

Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and spirit of the invention.

1... X-ray CT device 10... gantry device 11... X-ray tube 12... wedge 13... collimator 14... X-ray high voltage device 15... X-ray detector 16... DAS
17...Rotating frame 18...Control device 30...Bed device 31...Base 32...Bed up and down movement device 33...Tabletop 34...Support frame 40...Console device 41...Memory 42...Display 43...Input interface 50...Processing circuit 51...Control function 52...Pre-processing function 53...Reconstruction processing function 54...Image processing function 55...Acquisition function 56...Generation function 57...Alignment function 58...Display control function H...First heating region K...Tumor region M...Second heating region P...Subject Y...Drug region

Claims (9)

An acquisition unit that acquires a pre-ablation image before ablation of the subject and a post-ablation image after ablation of the subject;
A generating unit that generates a virtual pre-ablation image assuming the pre-ablation image based on the acquired post-ablation image;
A registration unit that aligns the pre-ablation image and the virtual pre-ablation image, and transforms the post-ablation image using registration information obtained when the images are aligned to generate an aligned post-ablation image.
Medical imaging equipment. The generation unit generates the virtual pre-ablation image by a heat equation simulation using the post-ablation image.
The medical image processing device according to claim 1 . The acquisition unit further acquires an in-process image of the ablation process,
generating the virtual pre-ablation image based on the in-between-ablation image and the post-ablation image;
The medical image processing device according to claim 1 . The generating unit identifies a position of a probe used for the ablation based on the post-ablation image, and generates the virtual pre-ablation image based on an electrical profile set in the probe.
The medical image processing device according to claim 1 . The pre-ablation image and the post-ablation image include a CT image captured by an X-ray CT device.
The medical image processing device according to claim 1 . The alignment unit performs the alignment by tracing a boundary line of the tissue to be cauterized.
The medical image processing device according to claim 1 . an acquisition unit that acquires a first image captured by a first imaging device before administering a drug to the subject and a second image captured by a second imaging device after administering the drug to the subject;
a generating unit that generates a third image of the same type as the first image based on the second image, and generates a virtual third image that is an image of the second image based on the first image;
and a registration unit that performs registration between the first image and the virtual third image.
Medical imaging equipment. The computer
Obtaining a pre-ablation image before ablatating the subject and a post-ablation image after ablatating the subject;
A virtual pre-ablation image is generated based on the acquired post-ablation image, the virtual pre-ablation image being assumed to be the pre-ablation image;
The pre-ablation image and the virtual pre-ablation image are aligned, and a post-ablation image is deformed using alignment information obtained by the alignment to generate an aligned post-ablation image.
Medical image processing method. On the computer,
Obtaining a pre-ablation image before ablatating the subject and a post-ablation image after ablatating the subject;
A virtual pre-ablation image is generated based on the acquired post-ablation image, the virtual pre-ablation image being assumed to be the pre-ablation image;
The pre-ablation image and the virtual pre-ablation image are aligned, and the post-ablation image is deformed using alignment information obtained when the alignment is performed, thereby generating an aligned post-ablation image.
program.

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