Nuclear medicine diagnosis apparatus, nuclear medicine diagnosis method, and storage medium

Abstract

The present application provides a nuclear medicine diagnostic device, a nuclear medicine diagnostic method, and a storage medium. The problem is to reduce the adverse effects on the image due to unexpected structures included in the X-ray CT image. The solution is that the nuclear medicine diagnostic device related to the embodiment has a processing circuit. The processing circuit is configured to obtain an X-ray CT image related to a subject. The processing circuit is configured to obtain a camera image that captures the position and shape of the subject corresponding to the X-ray CT image. The processing circuit is configured to generate an attenuation map based on the camera image and the X-ray CT image. The processing circuit is configured to obtain detection data based on gamma rays radiated from a radiation source injected into the subject. The processing circuit is configured to reconstruct an image based on the attenuation map and the detection data.

Description

[0001] Related applications:

[0002] This application enjoys priority to Japanese Patent Application No. 2022-065734, filed on April 12, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments described herein generally relate to nuclear medicine diagnostic devices, nuclear medicine diagnostic methods, and storage media. Background Technology

[0004] In PET / CT (positron emission tomography / computed tomography) devices, which are used as nuclear medicine diagnostic instruments, attenuation correction is applied to PET images using X-ray CT images obtained through X-ray CT imaging. In X-ray CT imaging, an arc-shaped detector is used by rotation, whereas in PET imaging, a detector positioned on the circumference is used. Consequently, in X-ray CT imaging, when the subject is large, a portion of the subject protrudes from the field of view, creating a deficient area at the detector end; this is not the case in PET imaging. Therefore, PET imaging can reconstruct images covering a larger area in the XY plane. In contrast, in X-ray CT imaging, a sine wave is inferred from the deficient area at the detector end, thereby extending the reconstructable range to a range equal to or greater than that of PET imaging. This technique is known as extended reconstruction.

[0005] This extended reconstruction, due to the inference of the sine wave, sometimes includes unexpected structures such as artifacts in the X-ray CT images reconstructed from the sine wave. In such cases, it may adversely affect the image (nuclear medicine image) reconstructed from the X-ray CT image. For example, in PET / CT devices, the attenuation map generated from the X-ray CT image is used to reconstruct the PET image (nuclear medicine image). Therefore, errors in the attenuation map due to artifacts in the X-ray CT image may occur, reducing the image quality and quantifiability of the PET image.

[0006] Existing technical documents:

[0007] [Patent Document 1] Japanese Patent Publication No. 2015-526708 Summary of the Invention

[0008] The problem that the invention aims to solve:

[0009] One of the problems that the embodiments disclosed in this specification and accompanying drawings aim to solve is to reduce the adverse effects on images caused by unexpected structures included in X-ray CT images.

[0010] However, the problems to be solved by the embodiments disclosed in this specification and accompanying drawings are not limited to the problems described above. Problems corresponding to the effects of the various configurations shown in the embodiments described below can also be identified as other problems.

[0011] The nuclear medicine diagnostic apparatus according to the embodiments includes a processing circuit. The processing circuit is configured to acquire an X-ray CT image associated with a subject. The processing circuit is configured to acquire a camera image that captures the position and shape of the subject corresponding to the X-ray CT image. The processing circuit is configured to generate an attenuation map based on the camera image and the X-ray CT image. The processing circuit is configured to acquire detection data based on gamma rays emitted from a radiation source delivered to the subject. The processing circuit is configured to reconstruct an image based on the attenuation map and the detection data.

[0012] Invention effects:

[0013] The nuclear medicine diagnostic device constructed as described above can reduce the adverse effects on images caused by unexpected structures included in X-ray CT images. Attached Figure Description

[0014] Figure 1 This is a diagram showing the configuration of the nuclear medicine diagnostic device according to the first embodiment.

[0015] Figure 2 This is a schematic diagram showing the configuration of the camera in the nuclear medicine diagnostic apparatus according to the first embodiment.

[0016] Figure 3 This is a flowchart illustrating an example of the operation in the first embodiment.

[0017] Figure 4 This is a flowchart used to explain step ST50 in detail.

[0018] Figure 5 This is a schematic diagram used to illustrate step ST51.

[0019] Figure 6 This is a schematic diagram used to illustrate step ST52.

[0020] Figure 7 This is a schematic diagram illustrating an example of step ST52 in detail.

[0021] Figure 8 This is a schematic diagram used to illustrate step ST53.

[0022] Figure 9 This is a schematic diagram used to illustrate step ST54.

[0023] Figure 10 This is a schematic diagram illustrating step ST53 in a variation of the first embodiment.

[0024] Figure 11 This is a flowchart illustrating an example of the operation in the second embodiment.

[0025] Figure 12 This is a schematic diagram used to illustrate step ST70a.

[0026] Figure 13 This is a flowchart used to explain step ST71a in detail.

[0027] Figure 14 This is a schematic diagram used to illustrate step ST71a1.

[0028] Figure 15 This is a schematic diagram used to illustrate step ST71a2.

[0029] Figure 16 This is a schematic diagram illustrating step ST71a2 in a modified example of the second embodiment.

[0030] Figure 17 This is a flowchart used to explain the operations in other variations of the second embodiment.

[0031] Figure 18 This is a schematic diagram showing the configuration of the camera in a modified embodiment of the nuclear medicine diagnostic apparatus.

[0032] Figure 19 It is used for explanation Figure 18 A schematic diagram of a portion of the XIX-XIX line-directed view section.

[0033] Figure 20 This is a schematic diagram illustrating step ST52 in a variation of the first embodiment.

[0034] Figure 21 This is a schematic diagram illustrating step ST53 in a variation of the first embodiment.

[0035] Figure 22 This is a schematic diagram illustrating step ST54 in a variation of the first embodiment.

[0036] Figure 23 This is a schematic diagram illustrating step ST71a2 in a modified example of the second embodiment.

[0037] Figure 24This is a diagram showing the configuration of the nuclear medicine diagnostic device involved in the variations of each embodiment.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1…Nuclear medicine diagnostic device, 10…PET stand, 11…Detector ring, 13…Signal processing circuit, 15…Simultaneous counting circuit, 17…Gamma ray detector, 30…CT stand, 31…X-ray tube, 32…X-ray detector, 33…Rotating frame, 34…X-ray high voltage device, 35…CT control device, 36…Wedge, 37…Collimator, 50…Examination bed, 51…Base, 52…Support frame, 53…Top plate, 54…Examination bed drive device, 70…Control console, 71…PET data storage, 72…CT data storage, 73…Processing circuit, 74… ...Display, 75...Memory, 76...Input interface, 731...Reconstruction function, 732...Image processing function, 733...Camera control function, 733a...CT image acquisition function, 734...Camera image acquisition function, 735...Attenuation mapping generation function, 736...Display control function, P...Subject, atf...Artifact, g1, g3...Photographic images, g2, g4...Camera images, ct1~ct2...X-ray CT images, bin1~bin4...Binary images, mk1~mk4, mk1a~mk2a...Mask images, att1~att4...Attenuation mapping, w1...Wall. Detailed Implementation

[0040] Hereinafter, each embodiment will be described with reference to the accompanying drawings. Furthermore, in the following description, repetitive descriptions will be omitted by using the same reference numerals for substantially the same parts across different drawings. Additionally, the nuclear medicine diagnostic apparatus according to each embodiment has at least a camera mechanism for performing PET imaging. Examples of such medical imaging diagnostic apparatus include, for example, a PET device with only PET imaging function, and a PET / CT device having both a PET camera mechanism and an X-ray CT imaging mechanism. Furthermore, the medical imaging diagnostic apparatus according to this embodiment may also have at least a camera mechanism for performing SPECT (single photon emission CT) imaging. Examples of such medical imaging diagnostic apparatus include, for example, a SPECT device with only SPECT imaging function, and a SPECT / CT device having both a SPECT camera mechanism and an X-ray CT imaging mechanism. The nuclear medicine diagnostic apparatus according to this embodiment can also be applied to any of the above-mentioned types of apparatus, but for the sake of detailed explanation below, it is specified as a PET / CT device.

[0041] <First Embodiment>

[0042] Figure 1 This is a diagram showing the configuration of the nuclear medicine diagnostic device 1 according to the first embodiment. Figure 2 This is a schematic diagram showing the configuration of the camera 60 in the nuclear medicine diagnostic device 1. (Example) Figure 1 and Figure 2 As shown, the nuclear medicine diagnostic apparatus 1 includes a PET stand 10, a CT stand 30, an examination bed 50, a camera 60, and a control console 70. Furthermore, the PET stand 10 and the CT stand 30 are integrated into a PET / CT stand 40. Typically, the PET / CT stand 40 and the examination bed 50 are located in a common examination room. The camera 60 is mounted on the ceiling of the examination room to photograph the subject P on the examination bed 50. However, it is not limited to the ceiling; the camera 60 may also be mounted on the wall of the examination room or on the PET / CT stand 40. The control console 70 is located in a control room adjacent to the examination room. The PET stand 10 is a camera device for performing PET imaging of the subject P. The CT stand 30 is a camera device for performing X-ray CT imaging of the subject P. The examination bed 50 supports a top plate 53 on which the subject P, the object of imaging, is placed, allowing for free movement. The control console 70 is a computer for controlling the PET stand 10, the CT stand 30, and the examination bed 50.

[0043] like Figure 1 As shown, the PET stand 10 has a detector ring 11, a signal processing circuit 13, and a simultaneous counting circuit 15.

[0044] The detector ring 11 has multiple gamma-ray detectors 17 arranged in a circle around the central axis Z. An image field of view (FOV) is set at the opening of the detector ring 11. The subject P is positioned such that the imaged portion of the subject P is included in the image field of view. A reagent labeled by a positron-emitting nuclide is applied to the subject P. The positrons emitted from the positron-emitting nuclide annihilate with surrounding electrons, producing a pair of annihilated gamma rays. The gamma-ray detectors 17 detect the annihilated gamma rays emitted from within the subject P and generate an electrical signal corresponding to the amount of annihilated gamma rays detected. For example, the gamma-ray detectors 17 have multiple scintillators and multiple photomultiplier tubes. The scintillators receive annihilated gamma rays caused by radioactive isotopes within the subject P and generate light. The photomultiplier tubes generate an electrical signal corresponding to the amount of light. The generated electrical signal is supplied to a signal processing circuit 13.

[0045] The signal processing circuit 13 generates single-event data based on the electrical signal from the gamma ray detector 17. Specifically, the signal processing circuit 13 performs detection timing measurement processing, position calculation processing, and energy calculation processing. The signal processing circuit 13 is implemented using an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), other complex programmable logic devices (CPLDs), or simple programmable logic devices (SPLDs) configured to perform detection timing measurement processing, position calculation processing, and energy calculation processing.

[0046] In the detection time measurement process, the signal processing circuit 13 measures the detection time when the gamma ray is detected by the gamma ray detector 17. Specifically, the signal processing circuit 13 monitors the peak value of the electrical signal from the gamma ray detector 17 and measures the moment when the peak value exceeds a preset threshold as the detection time. In other words, the signal processing circuit 13 detects when the peak value exceeds the threshold, thereby detecting the annihilated gamma ray electrically. In the position calculation process, the signal processing circuit 13 calculates the incident position of the annihilated gamma ray based on the electrical signal from the gamma ray detector 17. The incident position of the annihilated gamma ray corresponds to the position coordinates of the scintillator into which the annihilated gamma ray is incident. In the energy calculation process, the signal processing circuit 13 calculates the energy value of the detected annihilated gamma ray based on the electrical signal from the gamma ray detector 17. The detection time data, position coordinate data, and energy value data associated with a single event are correlated. The combination of the energy value data, position coordinate data, and detection time data associated with a single event is called single event data. Single-event data is generated sequentially each time an annihilation gamma ray is detected. The generated single-event data is supplied to the simultaneous counting circuit 15.

[0047] Simultaneous counting circuit 15 performs simultaneous counting processing on single-event data from signal processing circuit 13. As hardware resources, simultaneous counting circuit 15 is implemented by an ASIC, FPGA, CPLD, or SPLD configured to perform simultaneous counting processing. In simultaneous counting processing, simultaneous counting circuit 15 repeatedly identifies single-event data related to two single events within a predetermined time frame from the repeatedly supplied single-event data. The paired single events are inferred to originate from annihilated gamma rays generated from the same annihilation point. The paired single events are collectively referred to as simultaneous counting events. The line connecting the paired gamma ray detectors 17 (more specifically, scintillators) that detect the annihilated gamma rays is called the LOR (line of response). The event data related to the paired events constituting the LOR is called simultaneous counting event data. Simultaneous counting event data and single-event data are transmitted to console 70. Furthermore, when not specifically distinguishing between simultaneous counting event data and single-event data, they are referred to as PET event data. Simultaneous counting event data is an example of detection data based on gamma rays emitted from a radiation source delivered to the subject P. Furthermore, "gamma rays emitted from a radiation source delivered to the subject P" can also be referred to as "gamma rays emitted from the subject P." Additionally, "radiation source" can also be referred to as "radioactive isotope." The detector ring 11, signal processing circuit 13, and simultaneous counting circuit 15 are an example of a data acquisition unit.

[0048] Furthermore, in the above configuration, the signal processing circuit 13 and the simultaneous counting circuit 15 are included in the PET stand 10, but this embodiment is not limited to this. For example, the simultaneous counting circuit 15, or both the signal processing circuit 13 and the simultaneous counting circuit 15, may be included in a device separate from the PET stand 10. In addition, either a single simultaneous counting circuit 15 can be provided for the multiple signal processing circuits 13 mounted on the PET stand 10, or the multiple signal processing circuits 13 mounted on the PET stand 10 can be divided into multiple groups, and a single simultaneous counting circuit 15 can be provided for each group.

[0049] like Figure 1 As shown, the CT stand 30 includes an X-ray tube 31, an X-ray detector 32, a rotating frame 33, an X-ray high-voltage device 34, a CT control device 35, a wedge 36, a collimator 37, and a DAS 38.

[0050] X-ray tube 31 generates X-rays. Specifically, X-ray tube 31 includes a vacuum tube that holds a cathode that generates thermionic electrons and an anode that receives the thermionic electrons flying from the cathode and generates X-rays. X-ray tube 31 is connected to X-ray high-voltage device 34 via a high-voltage cable. A tube voltage is applied between the cathode and the anode by X-ray high-voltage device 34. By applying tube voltage, thermionic electrons fly from the cathode toward the anode. The flow of tube current is caused by the thermionic electrons flying from the cathode toward the anode. By applying high voltage and supplying filament current from X-ray high-voltage device 34, thermionic electrons fly from the cathode toward the anode, colliding with the anode, thereby generating X-rays.

[0051] X-ray detector 32 detects X-rays generated from X-ray tube 31 that have passed through the subject P, and outputs an electrical signal to DAS 38 corresponding to the dose of the detected X-rays. X-ray detector 32 has a structure in which multiple rows of X-ray detection elements arranged in the channel direction are arranged along the slice direction (row direction). X-ray detector 32 can be, for example, an indirect conversion type detector having a grid, a scintillator array, and a photodetector array. The scintillator array has multiple scintillators. Each scintillator outputs light in an amount corresponding to the incident X-ray dose. The grid is disposed on the X-ray incident surface side of the scintillator array and has an X-ray shielding plate that absorbs and scatters X-rays. The photodetector array converts the light into an electrical signal corresponding to the amount of light from the scintillators. For example, a photodiode or photomultiplier tube can be used as the photodetector. Alternatively, X-ray detector 32 can also be a direct conversion type detector (semiconductor detector) having a semiconductor element that converts incident X-rays into an electrical signal.

[0052] The rotating frame 33 is an annular frame that supports the X-ray tube 31 and the X-ray detector 32, enabling them to rotate about the rotation axis Z. Specifically, the rotating frame 33 supports the X-ray tube 31 and the X-ray detector 32 opposite to each other. The rotating frame 33 is supported by a fixed frame (not shown) to allow it to rotate about the rotation axis Z. The rotating frame 33 rotates about the rotation axis Z via the CT control device 35, thereby causing the X-ray tube 31 and the X-ray detector 32 to rotate about the rotation axis Z. The rotating frame 33 receives power from the drive mechanism of the CT control device 35 and rotates about the rotation axis Z at a certain angular velocity. An image field of view (FOV) is provided at the opening of the rotating frame 33.

[0053] Furthermore, in this embodiment, the rotation axis of the rotating frame 33 in the non-tilted state or the length direction of the top plate 53 of the examination bed 50 is defined as the Z-axis direction, the axis direction that is orthogonal to the Z-axis direction and horizontal relative to the ground is defined as the X-axis direction, and the axis direction that is orthogonal to the Z-axis direction and perpendicular to the ground is defined as the Y-axis direction.

[0054] The X-ray high-voltage device 34 includes electrical circuits such as a transformer and a rectifier, and has a high-voltage generating device for generating the high voltage applied to the X-ray tube 31 and the filament current supplied to the X-ray tube 31, as well as an X-ray control device for controlling the output voltage corresponding to the X-rays irradiated by the X-ray tube 31. The high-voltage generating device can be either a transformer or an inverter. The X-ray high-voltage device 34 can be installed in either a rotating frame 33 within the CT gantry 30 or a fixed frame (not shown) within the CT gantry 30.

[0055] The wedge 36 adjusts the dose of X-rays irradiated onto the subject P. Specifically, the wedge 36 attenuates the X-rays so that the dose of X-rays irradiated onto the subject P from the X-ray tube 31 is a predetermined distribution. For example, the wedge 36 can be a metal plate such as aluminum, such as a wedge filter or a bow-tie filter.

[0056] Collimator 37 limits the irradiation range of the X-rays transmitted through wedge 36. Collimator 37 supports multiple lead plates that shield the X-rays so that they can slide and adjust the shape of the slit formed by the multiple lead plates.

[0057] The DAS38 (Data Acquisition System) reads an electrical signal corresponding to the dose of X-rays detected by the X-ray detector 32, amplifies the read electrical signal with a variable amplification rate, and accumulates the electrical signal during the viewing period, thereby acquiring raw CT data with digital values ​​corresponding to the dose of X-rays during that viewing period. The DAS38 is implemented, for example, by an ASIC equipped with circuit elements capable of generating raw CT data. The raw CT data is transmitted to the control console 70 via a non-contact data transmission device or the like.

[0058] The CT control unit 35 controls the X-ray high-voltage device 34 and DAS 38 for performing X-ray CT imaging via the camera control function 733 of the processing circuit 73 of the console 70. The CT control unit 35 includes a processing circuit with a CPU, and drive mechanisms such as motors and actuators. The processing circuit includes processors such as CPUs and MPUs (Micro-Processing Units) and memories such as ROM and RAM as hardware resources. Alternatively, the CT control unit 35 can also be implemented using an ASIC, FPGA, CPLD, or SPLD.

[0059] Furthermore, the CT gantry 30 is an example of a rotational / rotate-type (3rd generation CT) in which the X-ray tube 31 and the X-ray detector 32 are integrated and rotate around the subject P.

[0060] like Figure 1 As shown, the examination table 50 holds the subject P, which is the object to be scanned, and moves the subject P. The examination table 50 is shared by the PET gantry 10 and the CT gantry 30.

[0061] The examination table 50 includes a base 51, a support frame 52, a top plate 53, and an examination table drive unit 54. The base 51 is disposed on the ground. The base 51 is a housing that supports the support frame 52 and is movable in a direction perpendicular to the ground (Y-axis direction). The support frame 52 is a frame disposed on the upper part of the base 51. The support frame 52 supports the top plate 53 and is slidable along the central axis Z. The top plate 53 is a flexible plate for placing the subject P.

[0062] The examination bed drive unit 54 is housed within the housing of the examination bed 50. The examination bed drive unit 54 is a motor or actuator that generates power to move the support frame 52 and the top plate 53 on which the subject P is placed. The examination bed drive unit 54 operates according to the control of the control console 70, etc.

[0063] The PET stand 10 and CT stand 30 are configured such that the central axis Z of the opening of the PET stand 10 is approximately aligned with the central axis Z of the opening of the CT stand 30. The examination table 50 is configured such that the long axis of the top plate 53 is parallel to the central axis Z of the openings of the PET stand 10 and CT stand 30. The CT stand 30 and PET stand 10 are arranged in order from near to far from the examination table 50.

[0064] like Figure 1 and Figure 2As shown, camera 60 and examination table 50 are mounted opposite each other on the ceiling of the examination room. Specifically, for example, camera 60 is positioned above examination table 50 and rotation axis Z, with the direction perpendicular to rotation axis Z serving as the imaging direction. Furthermore, the position of camera 60 is pre-recorded on console 70. Therefore, by using the position of camera 60 and the distance by which the top plate 53 slides along rotation axis Z, a correspondence can be established between the positions of the camera image and the X-ray CT image on rotation axis Z. However, this is not a limitation; for example, markings can be pre-printed on the support frame 52 of examination table 50, and based on the markings of the support frame 52 reflected in the image and the distance by which the top plate 53 slides, a correspondence can be established between the positions of the image and the X-ray CT image. Additionally, camera 60 photographs the subject P on examination table 50 and sends the resulting image to console 70. This image is stored in memory 75 within console 70. As the camera 60, optical cameras, 3D cameras, infrared cameras, ultrasonic sensors, and terahertz cameras can be appropriately used, for example. Furthermore, when the camera 60 is one optical camera, one infrared camera, or one terahertz camera, the obtained photographic image becomes a 2D image composed of an area showing the position and shape of the subject P and an external area different from that area. Here, when the camera 60 is an infrared camera or a terahertz camera, since it captures an image corresponding to the body temperature of the subject P and the temperature of the external area, the influence of the examination garment on the surface of the subject can be suppressed compared to an optical camera. "Infrared camera and terahertz camera" can also be called "temperature detection camera" or "thermal imaging camera." Additionally, when the camera 60 is a 3D camera or an ultrasonic camera, the obtained photographic image becomes an image including distance information between the camera 60 and each subject P and the examination table 50. Furthermore, not limited to this, multiple cameras 60 can be used. When multiple cameras 60 are arranged in approximately the same position, such as optical cameras and infrared cameras of different types, it is preferable from the viewpoint of improving measurement accuracy through mutual complementarity. Furthermore, when multiple cameras 60 are arranged with mutually orthogonal photographic directions, each camera 60 can be either of the same type or of different types. In this embodiment, a single 3D camera is used as camera 60.

[0065] like Figure 1 As shown, the console 70 includes a PET data memory 71, a CT data memory 72, a processing circuit 73, a display 74, a memory 75, and an input interface 76. For example, data communication between the PET data memory 71, the CT data memory 72, the processing circuit 73, the display 74, the memory 75, and the input interface 76 is performed via a bus.

[0066] The PET data storage device 71 is a storage device that stores single-event data and simultaneously counted event data transmitted from the PET rack 10. The PET data storage device 71 can be a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or an integrated circuit storage device.

[0067] The CT data storage device 72 is a storage device that stores the raw CT data transmitted from the CT gantry 30. The CT data storage device 72 can be a storage device such as an HDD, SSD, or integrated circuit storage device.

[0068] The processing circuit 73 controls the overall operation of the nuclear medicine diagnostic device 1 according to the electrical signals of the input operation output from the input interface 76. For example, the processing circuit 73 has a processor such as a CPU or MPU, a GPU (Graphics Processing Unit), and a memory such as ROM and RAM as hardware resources. The processing circuit 73 implements the reconstruction function 731, image processing function 732, camera control function 733, camera image acquisition function 734, attenuation mapping generation function 735, and display control function 736 by executing various programs read from the memory. Furthermore, the reconstruction function 731, image processing function 732, camera control function 733, camera image acquisition function 734, attenuation mapping generation function 735, and display control function 736 can be mounted on a single substrate of the processing circuit 73 or distributed across multiple substrates of the processing circuit 73. Additionally, as various programs, it may include, for example, a program for enabling the computer to perform the following functions: acquiring X-ray CT images related to the subject P; acquiring camera images capturing the position and shape of the subject P corresponding to the X-ray CT images; generating attenuation maps based on the camera images and X-ray CT images; acquiring detection data based on gamma rays emitted from a radiation source directed to the subject P; and reconstructing images based on the attenuation maps and detection data. Furthermore, this program can also be read from memory 75. The memory within processing circuitry 73 and memory 75 are examples of non-volatile, computer-readable storage media.

[0069] In reconstruction function 731, processing circuit 73 reconstructs an X-ray CT image showing the spatial distribution of CT values ​​related to the subject P based on raw CT data transmitted from CT gantry 30. Existing image reconstruction algorithms such as FBP (filtered back projection) or successive approximation reconstruction can be used as the image reconstruction algorithm. Alternatively, an extended reconstruction technique can be used to expand the reconstructable range by inferring the missing locations of missing sine waves. Furthermore, processing circuit 73 reconstructs a PET image representing the distribution of positron-emitting nuclides projected onto the subject P based on simultaneous count event data transmitted from PET gantry 10 and attenuation maps generated by attenuation map generation function 735. Additionally, processing circuit 73 can also generate localization images related to PET imaging based on PET event data, or localization images related to X-ray CT imaging based on raw CT data. Moreover, CT gantry 30, reconstruction function 731, and processing circuit 73 are examples of a CT image acquisition unit that acquires X-ray CT images related to the subject P. The reconstruction function 731 and processing circuit 73 are examples of a reconstruction unit that reconstructs an image (nuclear medicine image) based on attenuation mapping and detection data. A PET image is an example of an image being reconstructed.

[0070] In image processing function 732, processing circuit 73 applies various image processing techniques to the PET images and X-ray CT images reconstructed by reconstruction function 731. For example, based on an input operation received from the operator via input interface 76, processing circuit 73 uses known methods to convert the X-ray CT image data generated by reconstruction function 731 into tomographic image data of arbitrary cross sections or 3D image data (volume data). Volume data is data with distribution information of CT values ​​in 3D space. Furthermore, the generation of 3D image data can also be performed directly by reconstruction function 731. In addition, for example, processing circuit 73 applies 3D image processing techniques such as volume rendering, surface rendering, pixel value projection processing, MPR (Multi-Planer Reconstruction) processing, and CPR (Curved MPR) processing to PET images and X-ray CT images to generate display images.

[0071] In the camera control function 733, the processing circuit 73 synchronously controls the PET stage 10 and the examination table 50 for PET imaging. The PET imaging according to this embodiment is configured as an intermittent moving scan (stepping scan mode) where the top plate 53 moves intermittently and acquires PET event data according to each acquisition area. Additionally, the processing circuit 73 synchronously controls the CT stage 30 and the examination table 50 for X-ray CT imaging. In the case of continuous PET imaging and X-ray CT imaging, the PET stage 10, CT stage 30, and examination table 50 are synchronously controlled. Furthermore, the processing circuit 73 can perform positioning scans based on the PET stage 10 (hereinafter referred to as PET positioning scans) and positioning scans based on the CT stage 30 (hereinafter referred to as CT positioning scans). For PET positioning scans, the processing circuit 73 synchronously controls the PET stage 10 and the examination table 50. For CT positioning scans, the processing circuit 73 synchronously controls the CT stage 30 and the examination table 50.

[0072] In the camera image acquisition function 734, the processing circuit 73 acquires a camera image capturing the position and shape of the subject P corresponding to the X-ray CT image. The camera image is acquired by cutting out the position (position on the Z-axis) corresponding to the X-ray CT image from the photographic images stored in the memory 75. Such a camera image is acquired by the camera image acquisition function 734 from photographic images captured by the camera 60, which is at least one optical camera, 3D camera, infrared camera, ultrasonic sensor, or terahertz camera. The camera image acquisition function 734 and the processing circuit 73 are examples of a camera image acquisition unit.

[0073] In the attenuation map generation function 735, the processing circuit 73 generates an attenuation map based on the camera image acquired by the camera image acquisition function 734 and the X-ray CT image reconstructed by the reconstruction function 731. For example, the processing circuit 73 may also update the X-ray CT image based on the camera image by removing artifact regions from the X-ray CT image that are different from the region of the subject P, and generate an attenuation map based on the updated X-ray CT image. In this case, the attenuation map generation function 735 may also include the following functions (i) to (iv). Functions (i) and (ii) can be executed in either order.

[0074] (i) The process of binarizing the X-ray CT image to generate a first binary image based on whether it is a region related to the subject P. Alternatively, the first binary image may also be a first attenuation map generated from the X-ray CT image.

[0075] (ii) The process of generating a mask image by binarizing the camera image based on whether it is a region of the subject P. Furthermore, the mask image can also be referred to as subject construction information representing whether a region is a subject P.

[0076] (iii) A process for generating a second binary image based on the mask image, by extracting artifact regions different from the region of the subject P included in the first binary image. (iv) A process for updating the X-ray CT image based on the second binary image, in a manner that removes regions corresponding to the artifact regions of the second binary image from the X-ray CT image. Furthermore, when removing regions corresponding to the artifact regions of the second binary image from the X-ray CT image, the attenuation mapping generation function 735 sets the pixel value of the region removed from the X-ray CT image to -1000 HU as air.

[0077] Furthermore, the "artifact regions" extracted and removed above are regions different from the area of ​​the subject P, corresponding to areas further outward from the field of view of the CT gantry 30. These areas are prone to artifacts due to expanded reconstruction, hence the term "artifact regions." In addition, the "artifact regions" extracted and removed above are not limited to areas where artifacts actually exist in the X-ray CT image. Therefore, the term "artifact region" can also be interpreted as "considered an artifact region," "outer region," or "expanded field of view region," among other terms.

[0078] In display control function 736, processing circuit 73 displays various information on display 74. For example, processing circuit 73 displays PET images and X-ray CT images reconstructed by reconstruction function 731. Alternatively, for example, processing circuit 73 may also display X-ray CT images updated by attenuation mapping generation function 735. Additionally, for example, processing circuit 73 may also display photographic images stored in memory 75, or camera images acquired by camera image acquisition function 734.

[0079] The display 74 is controlled by the processing circuit 73 in the display control function 736 to display various information. The display 74 can be, for example, a CRT (cathode ray tube) display, a liquid crystal display, an organic EL (electro-luminescence) display, an LED (light-emitting diode) display, a plasma display, or any other display known in the art.

[0080] The memory 75 is a storage device such as an HDD, SSD, or integrated circuit storage device that stores various types of information. Alternatively, the memory 75 can also be a drive device for reading and writing various types of information to removable storage media such as CD-ROM (Compact Disk Read Only Memory) drives, DVD (Digital Versatile Disc) drives, and flash memory. For example, the memory 75 stores photographic images transmitted from the camera 60.

[0081] Input interface 76 receives various commands from the user. Specifically, input interface 76 is connected to an input device. Input devices can include keyboards, mice, trackballs, joysticks, touchpads, touchscreens that integrate the display screen and touchpad, contactless input circuits using optical sensors, voice input circuits, and various switches. Input interface 76 supplies output signals from the input device to processing circuit 73 via a bus. Furthermore, in this specification, input interface 76 is not limited to physical operating components such as mice and keyboards. For example, a processing circuit that receives electrical signals corresponding to input operations from an external input device separate from the device and outputs those electrical signals to processing circuit 73 is also included in the example of input interface 76.

[0082] Next, use Figure 3 and Figure 4 Flowchart and Figures 5 to 9 The schematic diagram illustrates the operation of the nuclear medicine diagnostic device 1 constructed as described above. The following description follows the procedure of a PET / CT examination. A PET / CT examination is a medical examination that performs both PET imaging and X-ray CT imaging.

[0083] like Figure 3 As shown, in step ST10, the camera 60, for example in response to the operation of the control panel provided on the PET / CT gantry 40, takes an image of the subject P on the top plate 53 supported by the support frame 52, and sends the image to the control console 70. In the image, the support frame 52 is shown on both sides of the supine subject P. Alternatively, the top plate 53 may be obscured by the subject P and not shown in the image. However, this is not a limitation; the top plate 53 and the support frame 52 may also be shown in the image in the order of their positions on both sides of the subject P.

[0084] Following step ST10, in step ST20, the processing circuit 73 synchronously controls the CT gantry 30 and the examination table 50, performing a CT positioning scan via the CT gantry 30. A CT positioning scan is an X-ray CT imaging technique used to acquire whole-body images of the subject P for purposes such as confirming and setting the imaging range. As a CT positioning scan, either scanography or spiral scanning can be used. With the rotation angles of the X-ray tube 31 and the X-ray detector 32 fixed, X-ray irradiation is performed by the X-ray tube 31 and X-ray detection by the X-ray detector 32, while the top plate 53 slides, thereby performing a scan. The rotation angles of the X-ray tube 31 and the X-ray detector 32 are typically fixed in the frontal or lateral direction of the subject P. With the X-ray tube 31 and the X-ray detector 32 rotating at high speed, X-ray irradiation is performed by the X-ray tube 31 and X-ray detection by the X-ray detector 32, while the top plate 53 slides, thereby performing a spiral scan.

[0085] In addition, the processing circuit 73 generates a CT positioning image based on the raw CT data acquired through positioning scans and displays this CT positioning image on the display 74. This allows the user to more precisely confirm the positional relationship between the acquisition area of ​​the PET image and the subject P, and to fine-tune the acquisition area as needed.

[0086] Then, the processing circuit 73 synchronously controls the CT stand 30 and the examination table 50, and the CT stand 30 performs CT imaging.

[0087] Following step ST20, in step ST30, the processing circuit 73 reconstructs the X-ray CT image based on the raw CT data acquired through X-ray CT imaging. Furthermore, in this reconstruction, an extended reconstruction technique is used to expand the reconstructable range by inferring the missing locations of the missing sine wave. However, with extended reconstruction, the X-ray CT image includes artifact regions around the area of ​​the subject P, which are prone to artifacts. Through these steps ST20 to ST30, the processing circuit 73 obtains an X-ray CT image related to the subject P.

[0088] Following step ST30, in step ST40, processing circuit 73 acquires a camera image capturing the position and shape of the subject P corresponding to the X-ray CT image. For example, processing circuit 73 extracts the position corresponding to the X-ray CT image from the photographic images stored in memory 75 to acquire the camera image.

[0089] Following step ST40, in step ST50, processing circuit 73 updates the X-ray CT image based on the acquired camera image by removing artifact regions from the X-ray CT image that differ from the region of the subject P. For example... Figures 4-9 As shown, step ST50 is executed through steps ST51 to ST54.

[0090] In step ST51, as Figure 4 and Figure 5 As shown, the processing circuit 73 binarizes the X-ray CT image ct1 to generate a first binary image bin1 based on whether the region is related to the subject P. The first binary image bin1 represents regions in the X-ray CT image ct1 related to the subject P as "1", and regions in the X-ray CT image ct1 other than regions related to the subject P as "0". Furthermore, the first binary image bin1 can also be a first attenuation map generated from the X-ray CT image ct1. Figure 5 In the first binary image bin1, there is a region representing the subject P, the artifact atf, and the top plate 53, which is a region related to the subject P. Furthermore, the first binary image bin1 has a roughly elliptical region of the subject P in the approximate center, regions of the artifact atf on the left and right sides of the subject P, and a region of the top plate 53 below the subject P. In addition, the support frame 52 supporting the top plate 53 does not slide within the PET / CT gantry 40 and is therefore not reflected in the X-ray CT image ct1 or the first binary image bin1.

[0091] After step ST51, in step ST52, as follows Figure 4 and Figure 6 As shown, the processing circuit 73 binarizes the camera image g2 obtained from the photographic image g1 based on whether the region is a subject P to generate a mask image mk1 or a mask image mk2. Mask images mk1 and mk2 represent the region of the subject P in the camera image g2 as "1" and represent artifact regions in the camera image g2 that are different from the region of the subject P as "0". Furthermore, mask image mk1 is an example when the photographic image g1 and the camera image g2 are 2D images.

[0092] On the other hand, the mask image mk2 is a binarized image generated based on the camera image g2, assuming that both the photographic image g1 and the camera image g2 are images including distance information. Here, the camera image g2 also captures the examination bed 50 on which the subject P is placed. In this case, for example, the processing circuit 73 detects the boundary between the subject P and the examination bed 50 based on the examination bed 50 within the camera image g2 and pre-set information related to the shape of the examination bed 50, and generates the mask image mk2 by including the side opposite to the subject P relative to this boundary as part of a region different from the subject P. Specifically, for example... Figure 7As shown, the processing circuit 73 generates an image mk21 based on the region of the subject P located at the center of the camera image g2, which includes a curve corresponding to the distance from the camera 60 to the subject P. Additionally, based on the regions of the support frame 52 located at both ends of the camera image g2, the processing circuit 73 aligns the surface shapes of the support frame 52 and the top plate 53 according to the distance from the camera 60 to the support frame 52. Furthermore, the surface shape data of the support frame 52 and the top plate 53 is pre-stored in the memory 75. The surface shape data of the support frame 52 and the top plate 53 is an example of information related to the shape of the examination table 50. Thus, the processing circuit 73 generates a mask image mk22 depicting the surface shapes of the support frame 52 and the top plate 53. Next, the processing circuit 73 overlaps and synthesizes the two mask images mk21 and mk22, removes the surface shape of the support frame 52, and draws a curve Le connecting the end of the surface shape of the top plate 53 to the end of the curve of the subject P to generate a synthesized image mk23. Then, the processing circuit 73 represents the interior of the closed curve of the synthesized image mk23 with "1" in the region of the subject P, and the exterior of the closed curve with "0" in the artifact region, thereby generating a mask image mk2. In step ST52, it is assumed that the mask image mk2 has been generated.

[0093] After step ST52, in step ST53, as follows Figure 4 As shown, the processing circuit 73 obtains the difference between the first binary image bin1 and the mask image mk2, and extracts the artifact region. That is, the processing circuit 73... Figure 8 As shown, based on the mask image mk2, a second binary image bin2 is generated by extracting artifact regions different from those of the subject P from the region related to the subject P included in the first binary image bin1. Figure 8 In the first binary image bin1, the region related to the subject P is represented as a white region "1", and the region different from the region related to the subject P is represented as a black region "0". In the mask image mk2, the region of the subject P is represented as a white region "1", and the artifact region is represented as a black region "0". Thus, the difference operation is performed as four operations (1) to (4).

[0094] (1) The operation of subtracting the black region “0” in the mask image mk2 from the black region “0” in the first binary image bin1 (in the figure, black - black = black(0)).

[0095] (2) The operation of subtracting the black region “0” in the mask image mk2 from the white region “1” in the first binary image bin1 (in the figure, white - black = white (1)).

[0096] (3) The operation of subtracting the white region “1” in the mask image mk2 from the white region “1” in the first binary image bin1 (in the figure, white - white = black (0)).

[0097] (4) The operation of subtracting the white region "1" in the mask image mk2 from the black region "0" in the first binary image bin1 (in the figure, black-white=black(0)). In the case of (4), in order to match the binary "0" and "1" of the second binary image bin2, the subtraction result "0" corresponding to the binary image is used instead of the simple subtraction result "-1" (=0-1). The second binary image bin2 does not include the region of the subject P, but includes the artifact region representing the artifact atf and the top plate 53. The second binary image bin2 represents the artifact region in the region of the first binary image bin1 related to the subject P as "1", and represents the region of the subject P in the region of the first binary image bin1 related to the subject P as "0". In addition, as the second binary image bin2, the region of the first binary image bin1 related to the subject P is represented by "0". Furthermore, since the second binary image bin2 is a binary image, although a portion of the region in the second binary image bin2 that differs from the region related to the subject P in the first binary image bin1 is displayed as "-1", this region is also displayed as "0". Additionally, in Figure 8 In the diagram, the dashed lines x1 and x2 correspond to the x-coordinates of the mask image mk2, the first binary image bin1, and the second binary image bin2.

[0098] Following step ST53, in step ST54, the processing circuit 73... Figure 4 and Figure 9 As shown, based on the second binary image bin2, the X-ray CT image ct1 is updated by removing the region corresponding to the artifact region "1" of the second binary image bin2 from the X-ray CT image ct1. The updated X-ray CT image ct2 includes the region of the subject P, but excludes the regions of the artifact atf and the top plate 53. In addition, the processing circuit 73 saves the updated X-ray CT image ct2 to the memory 75. Thus, step ST50, consisting of steps ST51 to ST54, ends.

[0099] return Figure 3 In step ST60, the processing circuit 73 synchronously controls the PET stage 10 and the examination table 50 according to the acquisition area that was fine-tuned in step ST20, and performs PET imaging in a step-scan mode through the PET stage 10. Through this PET imaging, simultaneous counting event data is acquired.

[0100] Following step ST60, in step ST70, processing circuit 73 generates an attenuation map based on the X-ray CT image updated in step ST50.

[0101] Following step ST70, in step ST80, processing circuit 73 reconstructs the PET image based on attenuation mapping and simultaneous count event data. Then, processing circuit 73 displays the X-ray CT image and the PET image on display 74. Thus, the PET / CT examination is completed.

[0102] As described above, according to the first embodiment, an X-ray CT image related to the subject is acquired, and a camera image capturing the position and shape of the subject corresponding to the X-ray CT image is acquired. An attenuation map is generated based on the camera image and the X-ray CT image. Furthermore, detection data based on gamma rays radiated from a radiation source directed at the subject is acquired, and an image is reconstructed based on the attenuation map and the detection data. By configuring the attenuation map to be generated based on the camera image capturing the position and shape of the subject corresponding to the X-ray CT image and the X-ray CT image, adverse effects on the image caused by unexpected structures included in the X-ray CT image can be reduced.

[0103] Furthermore, for example, in 3D X-ray CT image data (volume data), artifacts (unexpected structures) may occur at the periphery of the subject due to the inference of a sine wave during extended reconstruction, and be observed in all directions outside the subject. Such artifacts are observed in each 2D X-ray CT image obtained by slicing the volume data. For example, in cases where the 2D X-ray CT image includes the location where the artifact occurs, the artifact is observed to extend from the periphery of the subject within the X-ray CT image. Additionally, for example, in cases where the 2D X-ray CT image is separated from the location where the artifact occurs, the artifact is observed at a position slightly separated from the subject within the X-ray CT image. In any case, it is necessary to reduce artifacts in X-ray CT images. According to the first embodiment, based on camera images, both artifacts extending from the periphery of the subject and artifacts slightly separated from the subject can be reduced from X-ray CT images. Therefore, by reconstructing nuclear medicine images based on images with reduced artifacts, the image quality / quantitative value of nuclear medicine diagnostic devices can be improved.

[0104] Furthermore, according to the first embodiment, the X-ray CT image is updated based on the camera image by removing artifact regions from the X-ray CT image that differ from the area of ​​the subject, and an attenuation map is generated based on the updated X-ray CT image. Therefore, by configuring the attenuation map to be generated based on the X-ray CT image after removing artifact regions, the adverse effects of X-ray CT image artifacts on nuclear medicine images can be reduced, similar to the effects described above.

[0105] Furthermore, according to the first embodiment, a first binary image is generated by binarizing the X-ray CT image based on whether it is a region related to the subject, and a mask image is generated by binarizing the camera image based on whether it is a region related to the subject. Additionally, based on the mask image, a second binary image is generated by extracting artifact regions that differ from the subject region from the region related to the subject included in the first binary image. Furthermore, based on the second binary image, the X-ray CT image is updated by removing regions corresponding to the artifact regions of the second binary image. Therefore, in addition to the effects described above, by configuring the processing to use binary images, it is relatively easy to remove regions corresponding to the artifact regions of the second binary image from the X-ray CT image.

[0106] Alternatively, according to the first embodiment, the first binary image can also be a first attenuation map generated from an X-ray CT image. In this case, the same effect as described above can also be obtained.

[0107] Furthermore, according to the first embodiment, the camera image also captures the examination bed on which the subject is placed. Additionally, based on the examination bed within the camera image and pre-defined information related to the shape of the examination bed, the boundary between the subject and the examination bed is detected, and a mask image is generated by treating the side opposite to the subject relative to the boundary as part of a region different from the subject. Therefore, in addition to the effects described above, the mask image is generated using the boundary between the subject and the examination bed that is not reflected in the camera image, thus improving the accuracy of the mask image used for removing artifact regions.

[0108] Furthermore, according to the first embodiment, the camera image is an image acquired by the processing circuit 73 from at least one optical camera, 3D camera, infrared camera, ultrasonic sensor, or terahertz camera. Therefore, in addition to the effects described above, camera images can be acquired from various cameras, etc., thus enabling easy installation.

[0109] Furthermore, according to the first embodiment, the image reconstructed based on attenuation mapping and detection data is a PET image, and thus, similar to the effect described above, the adverse effects of artifacts in X-ray CT images on PET images can be reduced.

[0110] Furthermore, according to the first embodiment, the nuclear medicine diagnostic device is a PET / CT device that integrates a PET device and an X-ray CT device. Therefore, similar to the effects described above, it is possible to reduce the adverse effects of X-ray CT image artifacts on PET images.

[0111] Furthermore, the first embodiment uses a mask image mk2 generated when the photographic image of the camera 60 includes distance information when extracting artifact regions, but is not limited to this. For example... Figure 10 As shown, when extracting artifact regions, a mask image mk1 generated when the photographic image of camera 60 does not include distance information can also be used. Figure 10 In this case, the mask image mk1 represents the area of ​​the subject P as a white region "1" and the artifact region as a black region "0". In step ST53, the processing circuit 73 generates a second binary image bin3 based on the mask image mk1, which is obtained by extracting the artifact region that is different from the area of ​​the subject P from the area related to the subject P included in the first binary image bin1. The difference operation is performed in the same way as above, by subtracting the black region "0" or the white region "1" in the mask image mk1 from the black region "0" or the white region "1" in the first binary image bin1. In addition, in the case of subtracting the white region "1" in the mask image mk1 from the black region "0" in the first binary image bin1 (in the figure, black-white=black(0)), the subtraction result "0" corresponding to the binary image is used instead of the simple subtraction result "-1" (=0-1). The second binary image bin3 does not include the areas of subject P and top plate 53, but includes the artifact areas representing the artifact ATF. The second binary image bin3 displays the artifact areas in the region "1" related to subject P in the first binary image bin1 as "1", and displays the areas of subject P and top plate 53 in the region "1" related to subject P in the first binary image bin1 as "0". Furthermore, in Figure 10 In the diagram, the dashed lines x1 and x2 correspond to the x-coordinates of the mask image mk1, the first binary image bin1, and the second binary image bin3. Furthermore, the mask image mk1 is only one-dimensional along the x-axis; therefore, the second binary image bin3 and... Figure 8 Unlike other examples, the region of the top plate 53 located in the x-coordinate region overlapping with the subject P cannot be extracted. However, the adverse effect of the top plate 53 in the X-ray CT image on the nuclear medicine image is less than that of the artifact atf in the X-ray CT image. Therefore, even if the mask image generated in the image taken by the camera 60 does not include distance information, the same effect can be obtained, although it is slightly worse than the first embodiment.

[0112] <Second Implementation>

[0113] The second embodiment is a variation of the first embodiment, in which the attenuation map generated based on the X-ray CT image is updated instead of the X-ray CT image. Furthermore, in the second embodiment, this update is not performed before PET acquisition, but rather as a preprocessing step for PET reconstruction.

[0114] Along with this, the attenuation map generation function 735 of the processing circuit 73 generates a first attenuation map based on the X-ray CT image, and removes artifact regions that are different from the region of the subject P from the first attenuation map based on the camera image, thereby generating (updating) the attenuation map.

[0115] For example, the attenuation map generation function 735 binarizes the X-ray CT image to generate a first attenuation map based on whether the region is related to the subject P. Additionally, the attenuation map generation function 735 binarizes the camera image to generate a mask image based on whether the region is related to the subject P. Furthermore, based on the mask image, the attenuation map generation function 735 removes artifact regions that differ from the region of the subject P included in the first attenuation map, thereby generating the attenuation map. Furthermore, when removing artifact regions from the first attenuation map, the attenuation map generation function 735, for example, sets the pixel values ​​of the artifact regions of the first attenuation map to 0.

[0116] The other components are the same as in the first embodiment.

[0117] Next, use Figure 11 and Figure 13 Flowchart and Figure 12 , Figure 14 and Figure 15 The diagram illustrates the operation of the nuclear medicine diagnostic device 1 constructed as described above.

[0118] like Figure 11 As shown, steps ST10 to ST30 are performed in the same manner as described above. As a result, the photographic images taken by the camera 60 are stored in the memory 75, and the X-ray CT images obtained by X-ray CT imaging are acquired by the processing circuit 73.

[0119] Following step ST30, unlike the above, step ST60 is executed. In step ST60, the processing circuit 73, as described above, synchronously controls the PET stage 10 and the examination table 50, and performs PET imaging in a step-scan mode via the PET stage 10. Through this PET imaging, simultaneous counting event data is acquired.

[0120] Following step ST60, in step ST40a, processing circuit 73 acquires a camera image capturing the position and shape of the subject P corresponding to the X-ray CT image. For example, processing circuit 73 acquires the camera image by cutting out the position corresponding to the X-ray CT image from the photographic images stored in memory 75.

[0121] Following step ST40a, in step ST70a, the processing circuit 73, as follows: Figure 11 and Figure 12As shown, the processing circuit 73 binarizes the X-ray CT image ct1 to generate a first attenuation map att1 based on whether the region is related to the subject P. The first attenuation map att1 represents regions in the X-ray CT image ct1 related to the subject P as "1" and regions in the X-ray CT image ct1 that are not related to the subject P as "0". Furthermore, the first attenuation map att1 includes regions representing the subject P, the artifact att, and the top plate 53 as regions related to the subject P. In addition, the first attenuation map att1 has a region in the approximate center of the approximately elliptical area of ​​the subject P, regions on the left and right sides of the subject P containing the artifact att, and a region below the subject P containing the top plate 53. Furthermore, the support frame 52 supporting the top plate 53 does not slide within the PET / CT gantry 40 and is therefore not reflected in the X-ray CT image ct1 and the first attenuation map att1.

[0122] Following step ST70a, in step ST71a, processing circuit 73, based on the camera image, removes artifact regions from the first attenuation map att1 that differ from the region of the subject P, thereby generating an attenuation map. This step ST71a is as follows: Figures 13-15 As shown, this is performed through steps ST71a1 to ST71a2.

[0123] In step ST71a1, as Figure 13 and Figure 14 As shown, the processing circuit 73 binarizes the camera image g2 obtained from the photographic image g1 to generate a mask image mk1a or mk2a based on whether the region is a subject P. The mask images mk1a and mk2a represent the region of the subject P in the camera image g2 as "0" and represent artifact regions in the camera image g2 that are different from the region of the subject P as "1". Furthermore, the mask image mk1a is an example when the photographic image g1 and the camera image g2 are 2D images.

[0124] On the other hand, the mask image mk2a is a binarized image generated based on camera image g2, assuming that both the photographic image g1 and camera image g2 are images including distance information. Here, camera image g2 also captures the examination bed 50 on which the subject P is placed. In this case, for example, the processing circuit 73 detects the boundary between the subject P and the examination bed 50 based on the examination bed 50 within camera image g2 and pre-set information related to the shape of the examination bed 50, and generates the mask image mk2a by including the side opposite to the subject P relative to this boundary as part of a region different from the subject P. For example... Figure 7As shown, images mk21, mk22 and a composite image mk23 are generated. The interior of the closed curve in the composite image mk23 is represented by "0" in the region of the subject P, while the exterior of the closed curve is represented by "1" in the artifact region, thereby generating a mask image mk2a. In step ST71a1, it is assumed that the mask image mk2a has been generated.

[0125] After step ST71a1, in step ST71a2, as follows Figure 15 As shown, the processing circuit 73 obtains the difference between the first attenuation map att1 and the mask image mk2a, and removes the artifact region. Furthermore, in Figure 15 In the diagram, the dashed lines x1 and x2 correspond to the x-coordinate values ​​of the mask image mk2a, the first attenuation map att1, and the attenuation map att2. That is, based on the mask image mk2a, the processing circuit 73 removes artifact regions that are different from the region of the subject P included in the first attenuation map att1, thereby generating the attenuation map att2. The difference operation is performed in the same way as above, by subtracting the black region "0" or the white region "1" in the mask image mk2a from the black region "0" or the white region "1" in the first attenuation map att1. In addition, in the case of subtracting the white region "1" in the mask image mk2a from the black region "0" in the first attenuation map att1 (in the figure, black-white=black(0)), the simple subtraction result "-1" (=0-1) is replaced by the subtraction result "0" corresponding to the binary image. Attenuation mapping att2 includes the region of the subject P, but excludes the artifact regions representing the atf and the top plate 53. Attenuation mapping att2 represents the region of the subject P in attenuation mapping att1 as "1" and the artifact regions in attenuation mapping att1 as "0". In addition, processing circuit 73 updates the first attenuation mapping att1 to attenuation mapping att2 and saves the updated attenuation mapping att2 to memory 75. Thus, step ST71a, consisting of steps ST71a1 to ST71a2, ends.

[0126] return Figure 11 Following step ST71a, in step ST80, processing circuit 73 reconstructs the PET image based on the updated attenuation mapping and simultaneous count event data. Then, processing circuit 73 displays the X-ray CT image and the PET image on display 74. Thus, the PET / CT examination ends.

[0127] As described above, according to the second embodiment, a first attenuation map is generated based on the X-ray CT image, and artifact regions that differ from the area of ​​the subject are removed from the first attenuation map based on the camera image, thereby generating the attenuation map. Therefore, in addition to the effects of the first embodiment, it is possible to reduce artifact regions within the attenuation map as a preprocessing step for PET reconstruction without updating the X-ray CT image before PET imaging. Furthermore, by reconstructing nuclear medicine images based on the attenuation map with reduced artifacts, the image quality / quantitative values ​​of the nuclear medicine diagnostic device can be improved.

[0128] Furthermore, according to the second embodiment, the X-ray CT image is binarized to generate a first attenuation map based on whether it is a region related to the subject, and the camera image is binarized to generate a mask image based on whether it is a region related to the subject. Additionally, based on the mask image, artifact regions that differ from the subject region are removed from the subject-related regions included in the first attenuation map, thereby generating the attenuation map. Therefore, by configuring the processing to use the binarized mask image, artifact regions can be removed from the attenuation map more easily.

[0129] Furthermore, the second embodiment uses a mask image mk2a generated when the photographic image of the camera 60 includes distance information when extracting artifact regions, but is not limited to this. For example... Figure 16 As shown, a mask image mk1a generated when the photographic image of camera 60 does not include distance information can also be used when extracting artifact regions. Figure 16In the image, the mask image mk1a represents the area of ​​the subject P as a black region "0", and the artifact area as a white region "1". In this case, the processing circuit 73 generates an attenuation map att3 based on the mask image mk1a, which is obtained by removing a portion of the artifact area that is different from the area of ​​the subject P from the area included in the first attenuation image att1. The difference operation is performed in the same way as above, by subtracting the black region "0" or the white region "1" in the mask image mk1a from the black region "0" or the white region "1" in the first attenuation map att1. In addition, in the case of subtracting the white region "1" in the mask image mk1a from the black region "0" in the first attenuation map att1 (in the figure, black-white=black(0)), the subtraction result "0" corresponding to the binary image is used instead of the simple subtraction result "-1" (=0-1). Attenuation map att3 includes the region of subject P but excludes the region of artifact atf within the artifact region, while including the region of top plate 53. Attenuation map att3 represents the artifact region within region "1" of the first attenuation map att1 related to subject P as "0", and represents the regions of subject P and top plate 53 within region "1" of the first attenuation map att1 related to subject P as "1". Furthermore, in Figure 16 In the diagram, the dashed lines x1 and x2 correspond to the x-coordinates of the mask image mk1, the first attenuation map att1, and the attenuation map att3. Furthermore, the mask image mk1a is only one-dimensional along the x-axis; therefore, the attenuation map att3 and... Figure 15 Unlike other examples, the region of the top plate 53 located in the x-coordinate region overlapping with the subject P cannot be removed. However, the adverse effect of the top plate 53 in X-ray CT images on nuclear medicine images is less than that of the artifact atf in X-ray CT images. Therefore, even if the mask image generated in the image taken by the camera 60 does not include distance information, the same effect can be obtained, although it is slightly worse than the second embodiment.

[0130] Furthermore, the second embodiment removes artifact regions from the attenuation map after acquiring simultaneous counting event data via PET imaging, but is not limited to this. For example... Figure 17 As shown, after acquiring simultaneous counting event data via PET imaging, processing to obtain a camera image corresponding to the X-ray CT image (step ST40a) and processing to update the X-ray CT image based on the camera image (step ST50a) can also be performed. Steps ST40a and ST50a are the same processes as steps ST40 and ST50 in the first embodiment. As such a variation, in addition to the effects of the first embodiment, it is also possible to avoid updating the X-ray CT image before PET imaging, and to reduce artifact regions within the attenuation map as a preprocessing step for PET reconstruction.

[0131] Furthermore, both the first and second embodiments utilize only a camera 60 mounted on the ceiling above the examination table 50 to photograph the subject P, but are not limited to this. For example... Figure 18 As shown, the patient P can also be imaged from above and from the side using two cameras: one mounted on the ceiling and the other mounted on the wall w1 on the side of the examination bed 50. Specifically, the additional camera 60 is located, for example, on the side of the examination bed 50 and the rotation axis Z, and is mounted on the wall w1 with the direction perpendicular to the rotation axis Z as the imaging direction. Furthermore, on the side of the support frame 52 in the examination bed 50, such as... Figure 18 and Figure 19 As shown, a straight section Lb representing the height of the bottom 53b of the top plate 53 can be formed, or the upper and lower sides can have different colors with the straight section Lb as the boundary. However, it is not limited to this. The height of the bottom 53b of the top plate 53 can be calculated based on the photographic image obtained by taking a picture of the side of the support frame 52, based on the height difference between the top of the support frame 52 and the bottom 53b of the top plate 53, which is set in advance. In addition, the positions of each camera 60 are set in advance on the control console 70. In this case, as two cameras, for example, an optical camera, an infrared camera, and a terahertz camera that do not have distance information can be used appropriately. However, it is not limited to this. Two cameras with distance information can also be set to improve the accuracy of the mask image. In addition, in the case of an optical camera, an infrared camera, and a terahertz camera, the obtained photographic image becomes a 2D image composed of an area representing the position and shape of the subject P and an external area different from that area. In addition, the camera image cut out from the photographic image also becomes a 2D image.

[0132] Therefore, in step ST52 of the first embodiment, the processing circuit 73 is as follows: Figure 6 As shown, depending on whether it is a region of the subject P, the camera image g2 obtained from the photographic image g1 taken by the camera 60 positioned on the ceiling is binarized to generate a mask image mk1. In addition, in step ST52, the processing circuit 73... Figure 20 As shown, depending on whether the region is the subject P, the camera image g4 obtained from the photographic image g3 taken by the camera 60 positioned on the wall w1 is binarized to generate a mask image mk3. Furthermore, in the mask image mk3, the lower region among the regions above and below the region that is not the subject P is the region lower than the aforementioned straight section Lb. The mask image mk3 represents the region of the subject P in the camera image g4 as "1", and represents artifact regions in the camera image g4 that are different from the region of the subject P as "0".

[0133] Additionally, in step ST53, the processing circuit 73, as follows: Figure 10 As shown, based on the mask image mk1, a second binary image bin3 is generated by extracting the artifact region "1" that is different from the region of the subject P from the region "1" related to the subject P included in the first binary image bin1. In addition, in step ST53, the processing circuit 73 as follows... Figure 21 As shown, based on the mask image mk3, a second binary image bin4 is generated by extracting an artifact region "1" that is different from the region of subject P from the region "1" related to subject P included in the first binary image bin1. The second binary image bin4 represents subject P, artifact aft, and the region above the bottom of top plate 53 in the region "1" related to subject P in the first binary image bin1 as a black region "0", and represents the region below the bottom of top plate 53 in the region "1" related to subject P in the first binary image bin1 as a white region "1". This white region "1" below the bottom of top plate 53 is the artifact region "1" of the second binary image bin4. The bottom of top plate 53 can also be referred to as the bottom of subject P.

[0134] Then, in step ST54, as Figure 22 As shown, based on the two second binary images bin3 and bin4, the X-ray CT image ct1 is updated by removing the region corresponding to the artifact region "1" of the second binary images bin3 and bin4. The updated X-ray CT image ct3 includes the region of the subject P, but excludes the artifact atf and the region below the bottom 53b of the top plate 53. Furthermore, the processing circuit 73 saves the updated X-ray CT image ct3 to the memory 75. Hereinafter, the processing is performed in the same manner as in the first embodiment. Therefore, as... Figure 22 As shown, the amount of artifact region "1" that can be removed from the second binary image bin4 is greater than that of the second binary image bin4. Figure 10 Examples show slightly larger areas of artifacts.

[0135] On the other hand, in the case applicable to the second embodiment, in step ST71a1, the processing circuit 73 is as follows: Figure 14 As shown, depending on whether it is a region of the subject P, the camera image g2 obtained from the photographic image g1 taken by the camera 60 positioned on the ceiling is binarized to generate a mask image mk1a. In addition, in step ST71a1, the processing circuit 73, as shown... Figure 20As shown, depending on whether the region is the subject P, the camera image g4 obtained from the photographic image g3 taken by the camera 60 positioned on the wall w1 is binarized to generate a mask image mk3a. Furthermore, in the mask image mk3a, the lower region among the regions above and below the region that is not the subject P is the region lower than the aforementioned straight section Lb. The mask image mk3a represents the region of the subject P in the camera image g4 as "0", and represents artifact regions in the camera image g4 that are different from the region of the subject P as "1".

[0136] Additionally, in step ST71a2, as Figure 16 As shown, processing circuit 73, based on mask image mk1a, removes artifact regions different from the region of subject P within the first attenuation map att1, generating attenuation map att3. Additionally, in step ST71a2, as... Figure 23 As shown, processing circuit 73, based on mask image mk3a, removes artifact regions different from the region of subject P from the region associated with attenuation map att3, generating attenuation map att4. The generated attenuation map att4 includes the region of subject P, but excludes the artifact atf and the region below the bottom 53b of top plate 53. Attenuation map att4 represents subject P, artifact atf, and the region above the bottom of top plate 53 within the region "1" associated with subject P in attenuation map att3 as white region "1", and represents the region below the bottom of top plate 53 within the region "1" associated with subject P in attenuation map att3 as black region "0". Therefore, as... Figure 23 As shown, it is possible to remove the area below the bottom 53b of the top plate 53 without excluding the area below the bottom 53b of the top plate 53. Figure 16 Examples show a larger range of artifact regions.

[0137] Furthermore, the first and second embodiments and their variations have been described using the case where the nuclear medicine diagnostic device is a PET / CT device and the nuclear medicine image is a PET image as an example, but as mentioned above, they are not limited to this. For example, when the nuclear medicine diagnostic device is a SPECT / CT device that integrates a SPECT device and an X-ray CT device, and the nuclear medicine image is a SPECT image, the same effects as those in the first and second embodiments can be obtained.

[0138] Furthermore, the first and second embodiments and their variations have been described using the case where the nuclear medicine diagnostic device is a PET / CT device as an example, but as mentioned above, they are not limited to this. For example, the nuclear medicine diagnostic device may also be implemented by any of the following: a PET device, a SPECT device, and a SPECT / CT device that integrates a SPECT device and an X-ray CT device. For example, Figure 24 This indicates the configuration when the nuclear medicine diagnostic device 1 is a PET device. Figure 24 In the middle, nuclear medicine diagnostic device 1 and Figure 1 Compared to the configuration of the PET / CT apparatus shown, the CT gantry 30 and CT data storage 72, which are related to the CT apparatus, are omitted, and a CT image acquisition function 733a is added to the processing circuit 73. This CT image acquisition function 733a acquires X-ray CT images related to the subject P obtained by X-ray CT imaging performed by a CT apparatus (not shown) separate from the nuclear medicine diagnostic apparatus 1, and saves these X-ray CT images to the storage 75. Specifically, for example, in the CT image acquisition function 733a, the processing circuit 73 acquires X-ray CT images related to the subject P from an external CT apparatus or server apparatus via a network (not shown). The CT image acquisition function 733a and the processing circuit 73 are another example of the CT image acquisition unit. Other configurations are the same as in the first and second embodiments. In this way, even if the nuclear medicine diagnostic apparatus 1 is a PET apparatus that acquires X-ray CT images from an external source, the same effect as in the first and second embodiments can be obtained. This is also true when the nuclear medicine diagnostic apparatus 1 is a SPECT apparatus and the reconstructed image (nuclear medicine image) is a SPECT image.

[0139] According to at least one embodiment described above, it is possible to reduce the adverse effects on images caused by unexpected structures included in X-ray CT images.

[0140] The term "processor" used in the above description can refer to circuits such as CPU (Central Processing Unit), GPU (Graphics Processing Unit), Application Specific Integrated Circuit (ASIC), or programmable logic device (e.g., Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). When the processor is, for example, a CPU, the processor implements its function by reading and executing a program stored in a memory circuit. On the other hand, when the processor is, for example, an ASIC, the program is not stored in a memory circuit, but rather the function is directly assembled into the processor's circuitry as logic circuitry. Furthermore, the processors in this embodiment are not limited to being configured as a single circuit; multiple independent circuits can be combined to form a single processor and implement its function. Furthermore, it is also possible to... Figure 1 or Figure 24 Multiple components are integrated into a single processor to achieve their functions.

[0141] The foregoing has described several embodiments of the present invention, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope or spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

[0142] Regarding the above-described embodiments, the following notes are disclosed as one aspect and optional feature of the invention.

[0143] (Postscript 1)

[0144] A nuclear medicine diagnostic device, comprising:

[0145] The CT image acquisition unit acquires X-ray CT images related to the subject.

[0146] The camera image acquisition unit acquires a camera image, which captures the position and shape of the subject corresponding to the X-ray CT image;

[0147] The attenuation mapping generation unit generates an attenuation mapping based on the camera image and the X-ray CT image;

[0148] The acquisition unit acquires detection data based on gamma rays emitted from a radiation source directed at the subject; and

[0149] The reconstruction unit reconstructs the image based on the attenuation map and the detection data.

[0150] (Postscript 2)

[0151] Alternatively, the attenuation mapping generation unit,

[0152] Based on the camera images, the X-ray CT images are updated by removing artifact regions from the X-ray CT images that differ from the region of the examined object.

[0153] The attenuation map is generated based on the updated X-ray CT images.

[0154] (Note 3)

[0155] Alternatively, the attenuation mapping generation unit,

[0156] The X-ray CT image is binarized to generate a first binary image based on whether it is a region related to the subject.

[0157] Based on whether the region corresponds to the subject being examined, the camera image is binarized to generate a mask image.

[0158] Based on the mask image, a second binary image is generated by extracting artifact regions that are different from the region of the subject from the region related to the subject included in the first binary image.

[0159] Based on the second binary image, the X-ray CT image is updated by removing regions from the X-ray CT image that correspond to artifact regions of the second binary image.

[0160] (Note 4)

[0161] Alternatively, the camera image may also capture the examination bed on which the subject is placed.

[0162] Alternatively, the attenuation mapping generation unit can detect the boundary between the subject and the examination bed based on the examination bed in the camera image and pre-set information related to the shape of the examination bed, and generate the mask image by taking the side opposite to the subject relative to the boundary as part of a region different from the subject.

[0163] (Note 5)

[0164] Alternatively, the first binary image may be a first attenuation map generated from the X-ray CT image.

[0165] (Note 6)

[0166] Alternatively, the attenuation mapping generation unit,

[0167] The first attenuation map is generated based on the X-ray CT image.

[0168] Based on the camera image, artifact regions that differ from the region of the subject are removed from the first attenuation map, thereby generating the attenuation map.

[0169] (Note 7)

[0170] Alternatively, the attenuation mapping generation unit,

[0171] The X-ray CT image is binarized to generate the first attenuation map based on whether it is a region related to the subject.

[0172] Based on whether the region corresponds to the subject being examined, the camera image is binarized to generate a mask image.

[0173] Based on the mask image, artifact regions that are different from the region of the subject are removed from the region associated with the subject included in the first attenuation map, thereby generating the attenuation map.

[0174] (Note 8)

[0175] Alternatively, the camera image may be an image acquired by the camera image acquisition unit from at least one optical camera, 3D camera, infrared camera, ultrasonic sensor, or terahertz camera.

[0176] (Note 9)

[0177] Alternatively, the reconstructed image may be a PET image or a SPECT image.

[0178] (Postscript 10)

[0179] Alternatively, the nuclear medicine diagnostic device may be any one of a PET device, a SPECT device, a PET / CT device that integrates a PET device and an X-ray CT device, or a SPECT / CT device that integrates a SPECT device and an X-ray CT device.

[0180] (Postscript 11)

[0181] A nuclear medicine diagnostic method, comprising:

[0182] Obtain X-ray CT images related to the subject;

[0183] Acquire camera images, which capture the position and shape of the subject corresponding to the X-ray CT image;

[0184] Based on the camera image and the X-ray CT image, an attenuation map is generated;

[0185] Acquire detection data based on gamma rays emitted from a radiation source applied to the subject; and

[0186] The image is reconstructed based on the attenuation map and the detection data.

[0187] (Postscript 12)

[0188] A program for enabling a computer to perform the following functions:

[0189] The ability to acquire X-ray CT images related to the subject;

[0190] The camera image is used to capture the position and shape of the subject corresponding to the X-ray CT image.

[0191] The function of generating attenuation maps based on the camera images and the X-ray CT images;

[0192] The function of acquiring detection data based on gamma rays emitted from a radiation source applied to the subject; and

[0193] The function of reconstructing the image based on the attenuation mapping and the detection data.

Claims

1. A nuclear medicine diagnostic device, wherein, It includes a processing circuit, which is configured as follows: Obtain X-ray CT images relevant to the subject. A camera image is acquired, which captures the position and shape of the subject corresponding to the X-ray CT image. Based on the camera image and the X-ray CT image, an attenuation map is generated. Obtain detection data based on gamma rays emitted from a radiation source applied to the subject. The image is reconstructed based on the attenuation map and the detection data. The processing circuit is further configured as follows: The X-ray CT image is binarized to generate a first binary image based on whether it is a region related to the subject. Based on whether the region is the subject of the inspection, the camera image is binarized to generate a mask image; Based on the mask image, a second binary image is generated by extracting artifact regions that are different from the regions of the subject from the regions included in the first binary image that are related to the subject. Based on the second binary image, the X-ray CT image is updated by removing the regions corresponding to the artifact regions of the second binary image from the X-ray CT image; as well as The attenuation map is generated based on the updated X-ray CT images.

2. The nuclear medicine diagnostic device as described in claim 1, wherein, The camera images also captured the examination bed on which the subject was placed. The processing circuit is further configured as follows: Based on the examination bed within the camera image and pre-defined information related to the shape of the examination bed, the boundary between the subject and the examination bed is detected, and the mask image is generated by taking the side opposite to the subject relative to the boundary as part of a region different from the subject.

3. The nuclear medicine diagnostic device as described in claim 1, wherein, The first binary image is a first attenuation map generated based on the X-ray CT image.

4. A nuclear medicine diagnostic device, wherein, It includes a processing circuit, which is configured as follows: Obtain X-ray CT images related to the subject; Acquire camera images, which capture the position and shape of the subject corresponding to the X-ray CT image; Based on the camera image and the X-ray CT image, an attenuation map is generated; Acquire detection data based on gamma rays emitted from a radiation source applied to the subject; and The image is reconstructed based on the attenuation map and the detection data. The processing circuit is further configured as follows: The X-ray CT image is binarized to generate a first attenuation map based on whether it is a region related to the subject. Based on whether the region is the subject of the inspection, the camera image is binarized to generate a mask image; as well as Based on the mask image, artifact regions that are different from the region of the subject are removed from the region associated with the subject included in the first attenuation map, thereby generating the attenuation map.

5. The nuclear medicine diagnostic device as described in claim 1 or 4, wherein, The camera image is an image obtained by the processing circuit from at least one optical camera, ultrasonic sensor, or terahertz camera.

6. The nuclear medicine diagnostic device as described in claim 1 or 4, wherein, The reconstructed image is a PET image or a SPECT image.

7. The nuclear medicine diagnostic device as described in claim 1 or 4, wherein, The nuclear medicine diagnostic device is any one of a PET device, a SPECT device, a PET / CT device that integrates a PET device and an X-ray CT device, and a SPECT / CT device that integrates a SPECT device and an X-ray CT device.

8. A nuclear medicine diagnostic method, wherein, include: Obtain X-ray CT images related to the subject; Acquire camera images, which capture the position and shape of the subject corresponding to the X-ray CT image; Based on the camera image and the X-ray CT image, an attenuation map is generated; Obtain detection data based on gamma rays emitted from a radiation source delivered to the subject; as well as The image is reconstructed based on the attenuation map and the detection data. The nuclear medicine diagnostic methods also include: The X-ray CT image is binarized to generate a first binary image based on whether it is a region related to the subject. Based on whether the region is the subject of the inspection, the camera image is binarized to generate a mask image; Based on the mask image, a second binary image is generated by extracting artifact regions that are different from the regions of the subject from the regions included in the first binary image that are related to the subject. Based on the second binary image, the X-ray CT image is updated by removing regions corresponding to artifact regions in the second binary image; and The attenuation map is generated based on the updated X-ray CT images.

9. A computer-readable storage medium storing a computer program that, when executed by a processor, causes the computer to perform the following: Obtain X-ray CT images related to the subject; Acquire camera images, which capture the position and shape of the subject corresponding to the X-ray CT image; Based on the camera image and the X-ray CT image, an attenuation map is generated; Acquire detection data based on gamma rays emitted from a radiation source applied to the subject; and The image is reconstructed based on the attenuation map and the detection data. Furthermore, it causes the computer to perform the following: The X-ray CT image is binarized to generate a first binary image based on whether it is a region related to the subject. Based on whether the region is the subject of the inspection, the camera image is binarized to generate a mask image; Based on the mask image, a second binary image is generated by extracting artifact regions that are different from the regions of the subject from the regions included in the first binary image that are related to the subject. Based on the second binary image, the X-ray CT image is updated by removing the regions corresponding to the artifact regions of the second binary image from the X-ray CT image; as well as The attenuation map is generated based on the updated X-ray CT images.

Images