Nuclear medicine diagnosis device, region-of-interest movement state detection method, and program

Abstract

To enable quantitatively performing detection of a movement state of a region of interest in an examination which is performed by imaging a medical image of an analyte.SOLUTION: A nuclear medicine diagnosis device according to an embodiment comprises: a collector, a divider, and a detector. The collector collects radiation data in which radiation based on a radioactive medicine administered on an analyte is detected. The divider divides the radiation data into a plurality of pieces of divided radiation data for each predetermined time width. The detector detects a movement state of a region of interest in a body of the analyte on the basis of each divided radiation data.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a nuclear medicine diagnostic apparatus, a method for detecting the movement state of an area of interest, and a program.

Background Art

[0002] Conventionally, technologies related to systems and apparatuses for performing a PET (Positron Emission Tomography) examination have been disclosed. In a PET examination, a radioactive drug is administered to a subject (patient), and a medical image (PET image) is generated by collecting radiation emitted by the administered radioactive drug for a predetermined period of time.

[0003] By the way, the site in the patient's body where the radioactive drug accumulates (accumulation site) is not limited to the site where a tumor exists. In a diagnosis using a PET image, the state of movement of the accumulation site due to breathing or the like may be additional information useful for diagnosis. For example, when the accumulation site is a tumor, if adhesion occurs between this tumor and the surrounding tissue, periodic movement such as respiratory fluctuation often does not occur. If adhesion does not occur between the tumor and the surrounding tissue, the amount of movement may increase. From this, by confirming the movement state of the tumor or the tissue around the tumor, it may be useful information for determining a surgical method according to the adhesion state between the tumor and the surrounding tissue and for determining the prognosis after surgery in a surgical operation. For example, when the accumulation site is moving over time, the accumulation site may be intestinal contents such as food residues in the intestinal tract. Therefore, by confirming the movement state of the accumulation site, it may be useful information for determining whether the accumulation site is specific (positive) or non-specific (false positive).

[0004] Therefore, in conventional PET examinations, for example, devices such as a respiratory synchronization device that outputs information representing the state of respiration are attached to the patient, or a mark (marker) is attached to the patient and the mark is tracked by imaging with an imaging device such as a camera, and while monitoring the patient's respiratory state, radiation from the radiopharmaceutical administered is collected, and a moving image, so-called cine image, for visually confirming the movement state of the accumulation site is generated and used for judgment. When a device such as a respiratory synchronization device is not attached to the patient, for example, after imaging the patient's whole body, additional imaging of the accumulation site is also performed.

[0005] However, attaching a device such as a respiratory synchronization device to the patient to generate a cine image in a conventional PET examination may cause a physical burden on the patient. In a conventional PET examination, it is possible to perform imaging without attaching a device such as a respiratory synchronization device to the patient to generate a cine image, but in this case, for example, doctors, technicians, etc. need to perform complicated processes different from normal processes after imaging. Moreover, the visual confirmation of the movement state of the accumulation site by the cine image is a qualitative confirmation method. On the other hand, when additional imaging is performed after whole-body imaging in a conventional PET examination, if a radiopharmaceutical for the additional imaging is administered to the patient, the patient's radiation exposure will increase. Furthermore, for example, when additional imaging that doctors, technicians, etc. did not plan is performed, it may become a factor that affects the PET examination plan and schedule.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem to be solved by the present invention is to enable quantitative detection of the movement state of a region of interest in an examination performed by taking a medical image of a subject. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problems. The problems corresponding to the respective effects of the respective configurations shown in the embodiments described later can also be positioned as other problems.

Means for Solving the Problems

[0008] The nuclear medicine diagnostic apparatus according to the embodiment has a collection unit, a division unit, and a detection unit. The collection unit collects radiation data obtained by detecting radiation based on a radioactive drug administered to a subject. The division unit divides the radiation data into a plurality of divided radiation data for each predetermined time width. The detection unit detects the movement state of a region of interest in the body of the subject based on each of the divided radiation data.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] Hereinafter, the nuclear medicine diagnostic apparatus, the method for detecting the movement state of the region of interest, and the program according to the embodiment will be described with reference to the drawings. The nuclear medicine diagnostic apparatus is, for example, a medical diagnostic apparatus that acquires a medical image of a subject placed on a hospital bed device, such as a PET (Positron Emission Tomography) device or a PET-CT (Computed Tomography) device, and performs a diagnosis. In the following description, the case where the nuclear medicine diagnostic apparatus is a PET device will be described as an example.

[0011] FIG. 1 is a configuration diagram of a nuclear medicine diagnostic apparatus (PET apparatus) according to an embodiment. The PET apparatus 1 is a medical diagnostic apparatus that detects radiation emitted by a radioactive substance contained in a radioactive drug administered to a subject P who is a patient, and determines a tendency in which the radioactive drug accumulates from the detected radiation dose. In the PET apparatus 1, an image corresponding to the detected radiation dose is generated and displayed. Thereby, an operator (such as a doctor or a technician) who performs a PET examination can visually confirm whether there is a lesion in the subject or not.

[0012] The PET apparatus 1 includes, for example, a gantry apparatus 10, a couch apparatus 30, and a console apparatus 40. In FIG. 1, for convenience of explanation, both a view of the gantry apparatus 10 as seen from the Z-axis direction and a view as seen from the X-axis direction are shown, but actually, there is one gantry apparatus 10 included in the PET apparatus 1. In the present embodiment, the central axis of the frame 13 or the longitudinal direction of the top plate 33 of the couch apparatus 30 in a non-tilted state is defined as the Z-axis direction, an axis that is orthogonal to the Z-axis direction and horizontal with respect to the floor surface is defined as the X-axis direction, and a direction that is orthogonal to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction.

[0013] The PET apparatus 1 is an example of a "nuclear medicine diagnostic apparatus".

[0014] The gantry apparatus 10 includes, for example, a radiation detector 11, a count information collection unit 12, a frame 13, and a control device 14.

[0015] The radiation detector 11 detects radiation such as gamma rays emitted from the subject P (more specifically, the radioactive drug administered to the subject P). The radiation detector 11 outputs an electrical signal (which may be an optical signal or the like) corresponding to the amount of detected radiation (radiation dose) to the count information collection unit 12. The radiation detector 11 is formed in a cylindrical shape and is arranged so as to surround the imaging port formed in the gantry device 10. In the radiation detector 11, for example, a plurality of PET detector elements 11a are arranged in the circumferential direction and the central axis direction. Each PET detector element 11a detects the radiation emitted from the subject P located in the imaging port to the surroundings. The PET detector element 11a is, for example, a detector having a scintillator array and a photosensor array. The scintillator array has a plurality of scintillators. Each scintillator causes scintillation in response to the incident gamma rays and emits light with an amount of light corresponding to the intensity of the gamma rays. The photosensor array has photosensors such as silicon photomultipliers (SiPMs) and photomultipliers (PMTs). The photosensor array outputs an electrical signal (pulse) having a pulse height corresponding to the amount of light of the light emitted by the scintillator. Thus, in the radiation detector 11, a pulse signal corresponding to the radiation dose detected by each PET detector element 11a is output to the count information collection unit 12.

[0016] The counting information collection unit 12 collects the pulse signals output by each PET detection element 11a provided in the radiation detector 11, and for each radiation incident event (hereinafter simply referred to as "event") detected by each PET detection element 11a, by attaching information on position (Position: P), energy (Energy: E), and time (Timing: T), it generates counting information corresponding to the collected pulse signals. The counting information collection unit 12 has, for example, a processing circuit having a processor such as a CPU (Central Processing Unit), and executes each of the functions of a position information identification function, an energy identification function, and a timing identification function. The position information identification function is a function for identifying the light emission position (scintillation position) of gamma rays in the scintillator. When the pixels of the scintillator and the silicon photomultiplier tubes are coupled one-to-one, in the position information identification function, the position of the pixel of the scintillator corresponding to the silicon photomultiplier tube that output the pulse signal is specified. When a small number of photomultiplier tubes are associated with a large number of pixels of the scintillator, in the position information identification function, the light emission position in the scintillator is estimated by performing a centroid calculation on the pulse signals output by a plurality of silicon photomultiplier tubes. The energy identification function is a function for estimating the energy of the pulse signal output by the optical sensor. In the energy identification function, for example, when the energy is high, such as 511 keV gamma rays, a high energy is estimated, and when the energy is low, such as in the case of scattered events, a low energy is estimated. As a method for estimating energy in the energy identification function, for example, there are an energy integration method in which the range where the pulse signal exceeds a predetermined threshold is integrated for energy and converted into energy, and a ToT (Time-over-Threshold) method in which the time range where the pulse signal exceeds a predetermined threshold is converted into energy. In the estimation of energy by the ToT method, correction of the non-linearity of the estimation result is also performed. The timing identification function is a function for specifying, as timing information, the timing when the pulse signal output by the optical sensor exceeds a predetermined threshold. The counting information collection unit 12 outputs the data of the counting information (hereinafter referred to as "single list mode data") generated by executing these functions to the console device 40.

[0017] Frame 13 is an annular member that supports the radiation detector 11 and the count information collection unit 12. The frame 13 is not limited to an annular member as long as it can support the radiation detector 11 and the count information collection unit 12, and may be a member such as an arm.

[0018] When the nuclear medicine diagnostic apparatus of this embodiment is, for example, a PET-CT apparatus, in addition to the radiation detector 11 and the count information collection unit 12, the frame 13 may be a rotating frame that fixes an X-ray tube that generates X-rays to irradiate the subject P and an X-ray detector that detects the intensity of the X-rays that have passed through the subject P and are incident thereon at opposing positions, and rotatably supports the introduced subject P as the center.

[0019] The control device 14 receives an input signal from an input interface (not shown) such as an operation switch attached to the gantry device 10 or an input interface 43 attached to the console device 40, and controls the operations of the gantry device 10 and the bed device 30. The control device 14 has, for example, a processing circuit having a processor such as a CPU, and a drive mechanism including, for example, a motor or an actuator that moves the gantry device 10 and the top plate 33 of the bed device 30. In the embodiment, the case where the control device 14 is provided in the gantry device 10 is shown, but the control device 14 may be provided in the console device 40. In this specification, the input interface is not limited to those having physical operation components such as a mouse and a keyboard. For example, an electric signal processing circuit that receives an electric signal corresponding to an input operation from an external input device provided separately from the device and outputs this electric signal to the control circuit is also included in the examples of the input interface.

[0020] The control device 14 tilts the gantry device 10, for example, horizontally moves the housing of the gantry device 10 (hereinafter also simply referred to as the "gantry device 10") in the longitudinal direction (Z-axis direction) of the top plate 33 of the bed device 30, or moves the top plate 33 of the bed device 30 up and down in the Y-axis direction (which may include lateral movement in the X-axis direction and rotational movement around the Z-axis). When tilting the gantry device 10, the control device 14 tilts the frame 13 around an axis parallel to the Z-axis direction based on the tilt angle (tilt angle) input to an input interface (not shown) or the input interface 43. The control device 14 grasps the tilt angle of the frame 13 by, for example, the output of a sensor (not shown). The control device 14 provides the tilt angle of the frame 13 to the processing circuit 50 at any time.

[0021] When the nuclear medicine diagnostic apparatus of the present embodiment is, for example, a PET-CT apparatus, the control device 14 may include a drive mechanism including, for example, a motor or an actuator that rotates the rotating frame provided in the frame 13.

[0022] The bed device 30 is a device that places and moves the subject P to be scanned and introduces it into the inside of the frame 13 of the gantry device 10. The bed device 30 includes, for example, a base 31, a bed driving device 32, a top plate 33, and a support frame 34. The base 31 includes a housing that supports the support frame 34 so as to be movable in the vertical direction (up and down direction, Y-axis direction). The bed driving device 32 includes a motor and an actuator. The bed driving device 32 moves the top plate 33 on which the subject P is placed along the support frame 34 in the longitudinal direction (Z-axis direction) of the top plate 33. The amount of movement of the bed driving device 32 for moving the top plate 33 in the longitudinal direction may be an amount of movement that compensates for the horizontal movement amount of the gantry device 10, that is, an amount of movement that allows a part of the subject P that has not been introduced into the inside of the frame 13 even when the control device 14 moves the gantry device 10 horizontally to the maximum to be introduced into the inside of the frame 13. The bed driving device 32 may move the top plate 33 on which the subject P is placed laterally in the horizontal direction (X-axis direction) or rotationally around the Z-axis. The bed driving device 32 may be configured to move both the gantry device 10 and the top plate 33. The bed driving device 32 may move not only the top plate 33 but also the support frame 34 in the longitudinal direction of the top plate 33. The top plate 33 is a plate-shaped member on which the subject P is placed.

[0023] The console device 40 includes, for example, a memory 41, a display 42, an input interface 43, a network connection circuit 44, and a processing circuit 50. In the present embodiment, the console device 40 will be described as being separate from the gantry device 10, but a part or all of the components of the console device 40 may be included in the gantry device 10.

[0024] The memory 41 is implemented by, for example, semiconductor memory elements such as ROM (Read Only Memory), RAM (Random Access Memory), and flash memory, a hard disk drive (HDD), an optical disk, etc. The memory 41 stores data at each processing stage in the PET device 1. The memory 41 stores, for example, single list mode data output by the counting information collection unit 12, a PET image created based on the single list mode data, split list mode data and reconstructed images, etc. created based on the single list mode data, which will be described later. These data may be stored in an external memory that the PET device 1 can communicate with (or in addition to the memory 41). The external memory is controlled by, for example, a cloud server that manages the external memory and accepts read / write requests. The external memory may be implemented by, for example, a system called PACS (Picture Archiving and Communication Systems). PACS is a medical image management system that systematically stores images taken by various imaging diagnostic devices, etc.

[0025] The display 42 displays various types of information. For example, the display 42 displays images such as PET images generated by the processing circuit 50, and GUI (Graphical User Interface) images that accept various operations by the operator of the PET examination. The display 42 is, for example, a liquid crystal display (LCD), a CRT (Cathode Ray Tube) display, an organic EL (Electroluminescence) display, etc. The display 42 may be provided on the gantry device 10. The display 42 may be a desktop type or a display device (for example, a tablet terminal) that can communicate wirelessly with the main body of the console device 40.

[0026] The input interface 43 receives various input operations by the operator of the PET examination and outputs an electrical signal indicating the content of the received input operation to the processing circuit 50. For example, the input interface 43 receives input operations such as collection conditions when collecting single list mode data and reconstruction conditions when reconstructing a PET image. The input interface 43 is realized by, for example, a mouse, a keyboard, a touch panel, a trackball, a switch, a button, a joystick, a camera, an infrared sensor, a microphone, etc. The input interface 43 may be provided in the gantry device 10 as an operation switch or the like with a function of receiving some input operations (particularly, a function of horizontally moving the housing of the gantry device 10). The input interface 43 may be realized by a display device (for example, a tablet terminal) capable of wireless communication with the main body of the console device 40. In this specification, the input interface 43 is not limited to only those having physical operation components such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs this electrical signal to the control circuit is also included in the example of the input interface.

[0027] The network connection circuit 44 includes, for example, a network card having a printed circuit board or a wireless communication module. The network connection circuit 44 implements an information communication protocol according to the form of the network to be connected. The network includes, for example, a LAN (Local Area Network), a WAN (Wide Area Network), the Internet, a cellular network, a dedicated line, etc. The network connection circuit 44 realizes the connection between the external memory realized by, for example, the above-described PACS and the console device 40.

[0028] The processing circuit 50 controls the overall operation of the PET device 1. The processing circuit 50 executes, for example, a system control function 51, a coincidence counting identification function 52, an image reconstruction function 53, a movement state detection function 54, a display control function 55, and the like. The processing circuit 50 realizes these functions, for example, by a hardware processor executing a program (software) stored in the memory 41.

[0029] A hardware processor refers to circuitry such as, for example, a CPU, a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD) or a complex programmable logic device (CPLD), a field programmable gate array (FPGA)). Instead of storing a program in the memory 41, it may be configured to directly incorporate the program into the circuitry of the hardware processor. In this case, the hardware processor realizes its functions by reading and executing the program incorporated in the circuitry. The hardware processor is not limited to being configured as a single circuit, and may be configured as one hardware processor by combining a plurality of independent circuits so as to realize each function. A plurality of components may be integrated into one hardware processor to realize each function. A plurality of components may be incorporated into one dedicated LSI to realize each function. Here, the program (software) may be stored in advance in a semiconductor memory element such as a ROM, a RAM, a flash memory, or a storage device constituting a storage device such as a hard disk drive (a storage device having a non-transitory storage medium), or may be stored in a removable storage medium (a non-transitory storage medium) such as a DVD or a CD-ROM, and may be installed in the storage device provided in the console device 40 by mounting the storage medium on the drive device provided in the console device 40. The program (software) installed in the storage device provided in the console device 40 may be transferred to the processing circuit provided in the control device 14 and executed.

[0030] Each component included in the console device 40 or the processing circuit 50 may be decentralized and realized by a plurality of hardware. The processing circuit 50 may be realized not by a configuration included in the console device 40 but by a processing device communicable with the console device 40. The processing device is, for example, a workstation connected to one PET device or a device (e.g., a cloud server) connected to a plurality of PET devices and executing the same processing as the processing circuit 50 described below collectively. That is, the configuration of the present embodiment can also be realized as a PET inspection system (nuclear medicine diagnosis system) in which a PET device and another processing device are connected via a network.

[0031] The system control function 51 controls various functions of the processing circuit 50 based on, for example, an input operation received by the input interface 43. For example, the system control function 51 controls the count information collection unit 12, the control device 14, and the bed driving device 32 to control the collection process of single list mode data in the gantry device 10.

[0032] The coincidence identification function 52 performs coincidence counting (coincidence) on each event included in the single list mode data output by the count information collection unit 12 to generate list mode data. When generating the list mode data, the coincidence identification function 52 pairs each event detected within a time window of a predetermined time width (e.g., a time width in units of [p seconds]) in order to identify two events detected almost simultaneously. The function of the coincidence identification function 52 may be performed by the count information collection unit 12. The coincidence identification function 52 outputs the generated list mode data to the image reconstruction function 53. The coincidence identification function 52 may store the generated list mode data in the memory 41 and output a notification indicating this to the image reconstruction function 53. The coincidence identification function 52 may output the generated list mode data to the movement state detection function 54.

[0033] The image reconstruction function 53 performs a predetermined reconstruction process on the list mode data output by the coincidence identification function 52 to generate a PET image, which is a medical image of the subject P. As a method for reconstructing the PET image in the image reconstruction function 53, for example, there are the ML-EM (Maximum Likelihood-Expectation Maximization) method and the OS-EM (Ordered Subsets-Expectation Maximization) method that speeds up the ML-EM method.

[0034] The movement state detection function 54 detects the movement state of the region of interest (ROI) in the PET examination based on the single list mode data output by the count information collection unit 12. That is, the movement state detection function 54 detects the movement state of the part (accumulation site) in the body where the radioactive drug administered to the subject P accumulates and that moves due to, for example, the breathing of the subject P. The region of interest is, for example, the accumulation site of the examination target in the body of the subject P that is specified by the operator of the PET examination (such as a doctor or a technician) by performing various input operations and received by the input interface 43. The region of interest may be, for example, the accumulation site (emission position) in the PET image generated by the image reconstruction function 53 and displayed on the display 42, which is specified by the operator of the PET examination. Thereby, the operator of the PET examination can confirm the adhesion state between the region of interest and the surrounding tissues and the movement of the region of interest over time by checking the movement state of the region of interest. The configuration of the movement state detection function 54 and the operation of detecting the movement state of the region of interest will be described later.

[0035] The display control function 55 controls the display mode of the display 42. For example, the display control function 55 controls the display 42 to display a PET image generated by the processing circuit 50 (more specifically, the image reconstruction function 53), a GUI image that receives various operations by the operator (such as a doctor or a technician) of the PET apparatus 1, and the like. The display control function 55 also causes the display 42 to display an information image or the like for presenting the movement state of the region of interest detected by the movement state detection function 54 to the operator of the PET examination.

[0036] Next, the configuration and operation for realizing the moving state detection function 54 will be described. FIG. 2 is a diagram showing an example of the functional configuration of the moving state detection function 54 provided in the nuclear medicine diagnostic apparatus (PET apparatus 1) according to the embodiment. FIG. 2 shows, together with the counting information collection unit 12 related to detecting the moving state of the region of interest in the moving state detection function 54, the display control function 55, and further the display 42. The moving state detection function 54 includes, for example, a collection function 542, a division function 544, and a detection function 546. The detection function 546 includes, for example, a reconstruction image generation function 5461, an arrangement function 5462, and a comparison function 5463.

[0037] The collection function 542 collects a series of single list mode data output by the counting information collection unit 12. The collection function 542 may collect the single list mode data stored in the memory 41. Here, as described above, each single list mode data is provided with information on the position (P), energy (E), and time (T) of the event. The collection function 542 outputs each collected single list mode data to the division function 544. The collection function 542 may store the collected series of single list mode data in the memory 41 and output a notification indicating this to the division function 544. The list mode data output by the coincidence counting identification function 52 may be acquired.

[0038] The collection function 542 is an example of the "collection unit". The single list mode data (which may be list mode data) collected by the collection function 542 is an example of the "radiation data".

[0039] The splitting function 544 splits (time-division) a series of single list mode data output by the collection function 542 into a predetermined time width. More specifically, the splitting function 544 classifies each single list mode data into groups for each predetermined time width based on the time (T) information of the events assigned to the respective single list mode data. The splitting function 544 splits (time-division) a series of single list mode data output by the collection function 542 into at least two or more time widths. The predetermined time width for which the splitting function 544 classifies a series of single list mode data is, for example, 1 [second]. However, the splitting function 544 classifies such that the respective time widths overlap. The overlapping time is, for example, 0.5 [second]. Thereby, a series of single list mode data output by the collection function 542 is split by the splitting function 544 into, for example, a single list mode data group belonging to the time width of 0 to 1 [second] and a single list mode data group belonging to the time width of 0.5 to 1.5 [second]. The splitting function 544 outputs each single list mode data group split into a predetermined time width to the detection function 546. The collection function 542 may store each single list mode data group in the memory 41 and output a notification indicating this to the detection function 546. In the following description, the single list mode data groups split by the splitting function 544 into respective time widths are referred to as "split list mode data".

[0040] The splitting function 544 is an example of a "splitting section". The split list mode data (single list mode data group) split by the splitting function 544 is an example of "split radiation data".

[0041] Based on each split list mode data output by the splitting function 544, the detection function 546 calculates the amount of movement of the region of interest (accumulation site) in the PET examination, thereby detecting the movement state of the region of interest.

[0042] The reconstructed image generation function 5461 generates a reconstructed image corresponding to the divided list mode data output by the division function 544. The reconstructed image generation function 5461 generates at least a reconstructed image representing the position of the region of interest. As a method for generating the reconstructed image in the reconstructed image generation function 5461, for example, a technique for more accurately estimating the distance to an object (here, the emission position of gamma rays including the region of interest) such as Time of Flight (TOF) can be used. In this case, the reconstructed image generation function 5461 identifies the position of the region of interest, for example, by measuring the time difference when the radiation emitted in two directions from the part of the region of interest is detected by two corresponding PET detector elements 11a provided in the radiation detector 11. Here, the number of single list mode data used by the reconstructed image generation function 5461 to identify the position of the region of interest is less than the number of single list mode data used by the coincidence identification function 52 to generate the list mode data used by the image reconstruction function 53 to generate a PET image. However, the reconstructed image generation function 5461 may perform the same processing as that performed by the coincidence identification function 52 and the image reconstruction function 53 to generate a reconstructed image. The reconstructed image generation function 5461 outputs the generated reconstructed image to the rearrangement function 5462. The reconstructed image generation function 5461 may store the generated reconstructed image in the memory 41 and output a notification indicating this to the rearrangement function 5462.

[0043] The reconstructed image generation function 5461 is an example of a "reconstructed image generation unit".

[0044] The rearrangement function 5462 rearranges the reconstructed images output by the reconstructed image generation function 5461 in chronological order in the respiration of the subject P. The rearrangement function 5462 extracts, for example, a feature amount including at least a component (moving component) representing a state in which a region of interest shown in each reconstructed image is moving, using, for example, the function of a learning network by AI (Artificial Intelligence). The learning network sequentially extracts, from the input reconstructed images, feature amounts related to the respiration of the subject P using neural network technologies such as CNN (Convolutional Neural Network) and DNN (Deep Neural Network). The feature amount may include, for example, information indicating which respiratory state in one cycle of the respiration of the subject P or information indicating which time in one cycle of the respiration of the subject P. The rearrangement function 5462 arranges the reconstructed images at any time between the maximum exhalation state and the maximum inhalation state within one cycle of the respiration of the subject P based on the similarity of the feature amounts extracted from each reconstructed image, thereby rearranging each reconstructed image in chronological order. The maximum exhalation state is the most stable exhalation phase defined by the operator performing the PET examination. The maximum exhalation state may be defined, for example, by the operator performing various input operations during the PET examination.

[0045] The sorting function 5462 may sort the reconstructed images in the time order of the respiration of the subject P based on, for example, the information on the time (T) of the events assigned to each single list mode data belonging to the divided list mode data used for generating the reconstructed image. In this case, for example, the dividing function 544 outputs the divided list mode data with the time information representing each single list mode data belonging to the divided list mode data to the detection function 546, and the reconstructed image generation function 5461 may assign the time information to the generated reconstructed image. The time information is, for example, information representing the first, center, or last time width in the time width of the divided list mode data (single list mode data group). The time information may be, for example, the information on the time (T) of the event assigned to the single list mode data representing the divided list mode data. Thereby, the sorting function 5462 can sort each reconstructed image in the time order based on the time information assigned to the reconstructed image.

[0046] In the PET examination, for example, when a device such as a respiration synchronization device that outputs information representing the respiration state is attached to the subject P, or a mark (marker) is attached to the subject P and the mark is tracked by photographing with an imaging device such as a camera to monitor the respiration state of the subject P, the sorting function 5462 may also refer to the information representing the respiration state of the subject P output from the respiration synchronization device or the like and sort the reconstructed images in the time order of the respiration of the subject P.

[0047] The sorting function 5462 assigns information representing the sorted order to each of the reconstructed images output by the reconstructed image generation function 5461 and outputs the result to the comparison function 5463. The sorting function 5462 may assign information representing the sorted order to the reconstructed images stored in the memory 41 and output a notification indicating that the information representing the order has been assigned to the comparison function 5463. The sorting function 5462 may store each of the reconstructed images with the information representing the sorted order again in the memory 41 and output a notification indicating this to the sorting function 5462. In the following description, when distinguishing between the reconstructed images generated by the reconstructed image generation function 5461 and the reconstructed images sorted by the sorting function 5462, the reconstructed images sorted by the sorting function 5462 are referred to as "sorted reconstructed images".

[0048] The sorting function 5462 is an example of a "sorting unit".

[0049] The comparison function 5463 compares the reconstructed image representing the maximum exhalation state of the subject P's respiration and the reconstructed image representing the maximum inhalation state among the sorted reconstructed images output by the sorting function 5462. More specifically, the comparison function 5463 compares the position of the region of interest depicted in the reconstructed image representing the maximum exhalation state of the subject P's respiration with the position of the region of interest depicted in the reconstructed image representing the maximum inhalation state. The comparison function 5463 performs a quantitative comparison of the positions of the regions of interest, for example, by obtaining the difference between the reconstructed image for the time width corresponding to the maximum exhalation state (hereinafter referred to as the "exhalation image") and the reconstructed image for the time width corresponding to the maximum inhalation state (hereinafter referred to as the "inhalation image"). The comparison function 5463 compares the first exhalation image and the inhalation image, and then compares the inhalation image and the next exhalation image to perform a comparison for one cycle of the subject P's respiration. The comparison function 5463 outputs, as a comparison result, information representing the difference in the positions of the regions of interest obtained by comparing the exhalation image and the inhalation image. At this time, the comparison function 5463 includes, in the comparison result, information representing the direction in which the position of the region of interest has changed, that is, the moving direction of the region of interest. More specifically, when the comparison function 5463 sets the moving direction of the region of interest as the positive direction when the position of the region of interest changes from the position depicted in the first exhalation image to the position depicted in the inhalation image, the comparison function 5463 includes, in the comparison result, information indicating whether the moving direction when the position changes from the position depicted in the inhalation image to the position depicted in the next exhalation image is the positive direction or the negative direction opposite to the positive direction.

[0050] The comparison function 5463 is an example of a "comparison unit". The exhalation image is an example of a "first reconstructed image", and the region of interest depicted in the reconstructed image representing the maximum exhalation state of the subject P's respiration is an example of a "first region of interest". The inhalation image is an example of a "second reconstructed image", and the region of interest depicted in the reconstructed image representing the maximum inhalation state of the subject P's respiration is an example of a "second region of interest".

[0051] The detection function 546 detects the movement state of the region of interest based on the information representing the difference in the position of the region of interest included in the comparison result output by the comparison function 5463 and the information representing the movement direction of the region of interest. In other words, the detection function 546 detects a quantitative movement state including the movement direction indicating whether the position of the region of interest changes reciprocally in synchronization with the respiratory cycle of the subject P or changes over time in the same direction regardless of the respiratory cycle of the subject P, and the amount of movement. The detection function 546 outputs the information representing the detected movement state of the region of interest to the display control function 55 as the movement state of the region of interest detected by the movement state detection function 54. Thereby, the display control function 55 generates an information image representing the movement state of the region of interest output by the detection function 546, outputs it to the display 42, and displays it to present it to the operator performing the PET examination.

[0052] The detection function 546 may generate a moving image that enables confirmation of the state of movement of the region of interest according to the respiratory state of the subject P by connecting the rearranged reconstructed images output by the rearrangement function 5462 in the time order of the respiration of the subject P and further repeating them at the respiratory cycle of the subject P. That is, the detection function 546 may generate a moving image similar to a so-called cine image. The detection function 546 outputs the generated moving image to the display control function 55. The detection function 546 may output the rearranged reconstructed image output by the rearrangement function 5462 to the display control function 55 so that the display control function 55 generates a moving image similar to a cine image. The display control function 55 outputs the moving image output by the detection function 546 or the moving image generated by itself to the display 42 for display. Thereby, the operator performing the PET examination can confirm the state of movement of the region of interest according to the respiratory state of the subject P.

[0053] The detection function 546 is an example of a "detection unit".

[0054] FIG. 3 is a flowchart showing an example of a series of processes performed in the movement state detection function 54 included in the nuclear medicine diagnostic apparatus (PET apparatus 1) according to the embodiment. When an operator of the PET apparatus 1 operates the input interface 43 to start imaging by the PET apparatus 1, the movement state detection function 54 starts a process of detecting the movement state of the region of interest in parallel with the processes performed by the coincidence identification function 52 and the image reconstruction function 53. In the following description, it is assumed that the region of interest is designated by the person performing the PET examination and the maximum exhalation state is defined.

[0055] When the process of detecting the movement state of the region of interest is started in the movement state detection function 54, the collection function 542 collects the single list mode data output by the count information collection unit 12 (step S100). The collection function 542 outputs each of the collected single list mode data to the splitting function 544.

[0056] The splitting function 544 splits (time-divides) each of the single list mode data output by the collection function 542 (step S110). The splitting function 544 outputs each of the split list mode data to the detection function 546.

[0057] The reconstruction image generation function 5461 included in the detection function 546 generates a reconstruction image corresponding to the split list mode data output by the splitting function 544 (step S120). The reconstruction image generation function 5461 outputs the generated reconstruction image to the sorting function 5462.

[0058] The rearrangement function 5462 included in the detection function 546 rearranges the reconstructed images output by the reconstructed image generation function 5461 (step S130). More specifically, the rearrangement function 5462 sequentially extracts, for example, the feature amounts related to the respiration of the subject P by the function of the learning network by AI, and rearranges each reconstructed image in the time order in the respiration of the subject P based on the similarity of the extracted feature amounts. The rearrangement function 5462 outputs the rearranged reconstructed images (the reconstructed images to which the information indicating the rearranged order is attached) to the comparison function 5463.

[0059] The comparison function 5463 included in the detection function 546 compares the exhalation image and the inhalation image among the rearranged reconstructed images output by the rearrangement function 5462 (step S140). More specifically, the comparison function 5463 quantitatively compares the positions of the regions of interest for one cycle of the respiration of the subject P by obtaining the difference between the exhalation image and the inhalation image. The comparison function 5463 outputs the information of the comparison result (the difference in the position of the region of interest and the moving direction of the region of interest) obtained by comparing the exhalation image and the inhalation image.

[0060] Based on the comparison result output by the comparison function 5463, the detection function 546 detects the moving state of the region of interest (step S150). The detection function 546 outputs the information indicating the detected moving state of the region of interest to the display control function 55. Thereby, the display control function 55 causes the display 42 to display the information image indicating the moving state of the region of interest output by the moving state detection function 54 (more specifically, the detection function 546), and presents it to the operator who performs the PET examination (step S160).

[0061] With such a configuration and process, in the PET apparatus 1, the movement state detection function 54 collects single list mode data and detects the movement state of the region of interest in the PET examination. More specifically, in the PET apparatus 1, the collection function 542 collects single list mode data, the division function 544 divides (time-division) the single list mode data into a predetermined time width, and the detection function 546 calculates the movement amount of the region of interest based on each single list mode data group (divided list mode data), thereby detecting the movement state of the region of interest. At this time, in the detection function 546, the reconstruction image generation function 5461 generates a reconstruction image corresponding to the divided list mode data, the rearrangement function 5462 rearranges the generated reconstruction images in the time order of the respiration of the subject P, and the comparison function 5463 obtains the difference between the reconstruction image (expiration image) representing the maximum expiration state and the reconstruction image (inspiration image) representing the maximum inspiration state, thereby detecting the quantitative movement state of the region of interest. Then, in the PET apparatus 1, the display control function 55 presents the information on the movement state of the region of interest detected by the movement state detection function 54 to the operator of the PET examination. As a result, the operator of the PET examination can confirm the movement state of the region of interest detected by the movement state detection function 54, and can determine the adhesion state between the region of interest and the surrounding tissues, and whether the region of interest is specific (positive) or non-specific (false positive).

[0062] Moreover, in the PET apparatus 1, by using the single list mode data collected by the count information collection unit 12 during the PET examination, for example, a respiration synchronization device that outputs information representing the respiration state (which may obtain the respiration state by attaching a mark (marker) to the subject P and tracking the mark with an imaging device such as a camera) or the like can be detected without attaching the device to the subject P. the movement state of the region of interest. Therefore, in the PET apparatus 1, the movement state of the region of interest can be detected without imposing a physical burden on the subject P and without performing additional imaging.

[0063] As described above, in the PET device 1 which is a nuclear medicine diagnostic device according to the embodiment, the movement state detection function 54 collects single list mode data and generates a reconstructed image corresponding to each single list mode data group (divided list mode data) divided (time-division) into a predetermined time width. Then, in the PET device 1 according to the embodiment, the movement state detection function 54 rearranges the generated reconstructed images in the chronological order of the respiration of the subject P, and obtains the difference between the reconstructed image (expiration image) representing the maximum expiration state and the reconstructed image (inspiration image) representing the maximum inspiration state, thereby detecting the quantitative movement state of the region of interest. Thereby, in the PET device 1 according to the embodiment, the information on the movement state of the region of interest can be presented to the operator of the PET examination. In other words, in the PET device 1 according to the embodiment, additional information useful for the diagnosis by the PET examination, which represents the state in which the region of interest moves according to the respiration of the subject P or the like, can be presented to the operator of the PET examination. Thus, the operator who performs the PET examination using the PET device 1 according to the embodiment can confirm the movement state of the region of interest and determine the adhesion state between the region of interest and the surrounding tissues, and whether the region of interest is specific (positive) or non-specific (false positive).

[0064] Moreover, in the PET device 1 according to the embodiment, in addition to collecting single list mode data in the PET examination, for example, even if information representing the respiration state of the subject P is not obtained by a device such as a respiration synchronization device or a camera, the movement state of the region of interest can be detected. That is, in the PET device 1 according to the embodiment, the movement state of the region of interest can be detected without imposing a physical burden on the subject P as in the PET examination performed using a conventional PET device. Further, in the PET device 1 according to the embodiment, the movement state of the region of interest can be detected without performing additional imaging as in the PET examination performed using a conventional PET device, and the PET examination can be performed according to the prior plan and schedule.

[0065] Furthermore, in the PET apparatus 1 of the embodiment, by stitching together reconstructed images based on the divided list mode data arranged in the time sequence of the respiration of the subject P, a moving image similar to the cine image generated using a conventional PET apparatus can be generated. That is, in the PET apparatus 1 of the embodiment, unlike the case of generating a cine image in a conventional PET apparatus, a moving image similar to the cine image can be generated by a simpler method without causing the operator of the PET examination to perform complicated processes different from normal processes after imaging. Thereby, in the PET apparatus 1 of the embodiment, the generated moving image can be presented to the operator of the PET examination. As a result, an operator performing a PET examination using the PET apparatus 1 of the embodiment can visually confirm the state in which the region of interest moves according to the respiration state of the subject P.

[0066] In the above-described embodiment, the configuration in which the function of the movement state detection function 54 is executed by the processing circuit 50 provided in the PET apparatus 1 has been described as an example. However, this is merely an example, and the apparatus that executes the function of the movement state detection function 54 is not limited to the components provided in the PET apparatus 1. For example, the function of the movement state detection function 54 may be executed by a computer device such as a personal computer (PC) installed in an examination room of a hospital where the PET apparatus 1 is installed, or an examination room in a hospital. In this case, a display device such as a display for presenting information to the operator of the PET examination, and an input interface for the operator of the PET examination to input operations and information to the computer device are connected to the computer device. For example, it may be connected to the console device 40 by the network connection circuit 44. For example, the function of the movement state detection function 54 may be executed by a server device on a network (not shown). In this case, at least a display device and an input interface may be installed in the examination room or the examination room, and the server device that executes the function of the movement state detection function 54 may communicate with the display device and the input interface via a network (not shown). Further, for the function of the movement state detection function 54, only some functions such as the splitting function 544 or / and the detection function 546 may be executed by the server device. In this case, the function of the movement state detection function 54 executed in the PET apparatus 1 (more specifically, the console device 40) and the function of the movement state detection function 54 executed by the server device may communicate with each other via a network (not shown) by the network connection circuit 44 to execute the entire function of the movement state detection function 54. The operations and processes of the function of the movement state detection function 54 in these cases may be made equivalent to the operations and processes of the function of the movement state detection function 54 in the above-described embodiment. Therefore, detailed descriptions of the operations and processes of the function of the movement state detection function 54 when it is executed outside the processing circuit 50 provided in the PET apparatus 1 are omitted.

[0067] In the above-described embodiment, the case where the movement state detection function 54 is applied to the PET apparatus 1 has been described as an example. However, this is merely an example, and the nuclear medicine diagnostic apparatus to which the movement state detection function 54 is applied is not limited to the PET apparatus. For example, the movement state detection function 54 may be applied to a PET-CT apparatus. In this case, the configuration, operation, and processing of the movement state detection function 54 may be made equivalent to those of the movement state detection function 54 in the above-described embodiment. Therefore, detailed description of the configuration, operation, and processing of the movement state detection function 54 when applied to a nuclear medicine diagnostic apparatus other than the PET apparatus 1 will be omitted.

[0068] The above-described embodiment can be expressed as follows. A nuclear medicine diagnostic apparatus comprising a processing circuitry, wherein the processing circuitry collects radiation data detected from radiation based on a radiopharmaceutical administered to a subject, divides the radiation data into a plurality of divided radiation data for each predetermined time width, and detects a movement state of a region of interest in the body of the subject based on each of the divided radiation data.

[0069] According to at least one of the embodiments described above, a collection unit (542) that collects radiation data (single list mode data) detected from radiation (gamma rays) based on a radiopharmaceutical administered to a subject (P), a division unit (544) that divides the radiation data into a plurality of divided radiation data (divided list mode data) for each predetermined time width, and a detection unit (546) that detects a movement state of a region of interest (ROI) in the body of the subject based on each of the divided radiation data are provided. Thus, in an examination (PET examination) that takes a medical image (PET image) of the subject, it is possible to quantitatively detect the movement state of the region of interest.

[0070] Although some embodiments have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, as well as in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0071] 1...PET apparatus, 10...gantry apparatus, 11...radiation detector, 11a...PET detection element, 12...count information collection unit, 13...frame, 14...control device, 30...bed apparatus, 31...base, 32...bed drive device, 33...top plate, 34...support frame, 40...console apparatus, 41...memory, 42...display, 43...input interface, 44...network connection circuit, 50...processing circuit, 51...system control function, 52...simultaneous count identification function, 53...image reconstruction function, 54...movement state detection function, 542...collection function, 544...division function, 546...detection function, 5461...reconstructed image generation function, 5462...sorting function, 5463...comparison function, 55...display control function

Claims

1. A collection unit that collects radiation data obtained by detecting radiation based on a radioactive agent administered to a subject; A division unit that divides the radiation data into a plurality of divided radiation data for each predetermined time width; A detection unit that detects a movement state of a region of interest in the body of the subject based on each of the divided radiation data; A nuclear medicine diagnostic apparatus comprising the above.

2. The detection unit includes: A reconstructed image generation unit that generates a reconstructed image representing the position of the region of interest based on the divided radiation data; An arrangement unit that arranges the generated reconstructed images in chronological order in the respiration of the subject; A comparison unit that compares the positions of the region of interest between at least two of the arranged reconstructed images; Comprising, Based on the compared comparison result, the movement state of the region of interest is detected. The nuclear medicine diagnostic apparatus according to Claim 1.

3. The arrangement unit arranges each of the generated reconstructed images based on the feature amount of each of the reconstructed images. The nuclear medicine diagnostic apparatus according to Claim 2.

4. The arrangement unit inputs each of the reconstructed images into a learning network to extract the feature amount including at least a movement component in the region of interest represented by each of the reconstructed images, and arranges each of the reconstructed images based on the similarity of the feature amounts. The nuclear medicine diagnostic apparatus according to Claim 3.

5. The comparison unit compares the position of the region of interest between a first reconstructed image that is the reconstructed image representing the maximum exhalation state in the respiration of the subject and a second reconstructed image that is the reconstructed image representing the maximum inhalation state in the respiration of the subject. The nuclear medicine diagnostic apparatus according to any one of Claims 2 to 4.

6. The comparison unit obtains a difference between the position of a first region of interest that is the region of interest represented by the first reconstructed image and the position of a second region of interest that is the region of interest represented by the second reconstructed image, and outputs information representing the obtained difference as the comparison result. The nuclear medicine diagnostic apparatus according to Claim 5.

7. A computer Collects radiation data obtained by detecting radiation based on a radioactive agent administered to a subject, Divides the radiation data into a plurality of divided radiation data for each predetermined time width, Based on each of the divided radiation data, detects a movement state of a region of interest in the body of the subject. Method for detecting movement state of region of interest.

8. A computer is caused to collect radiation data obtained by detecting radiation based on a radioactive agent administered to a subject, divide the radiation data into a plurality of divided radiation data for each predetermined time width, and detect a movement state of a region of interest in the body of the subject based on each of the divided radiation data. Program.

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