Positron emission tomography apparatus, method and program

Abstract

To appropriately manage the state of a PET detector.SOLUTION: A positron emission tomographic apparatus according to an embodiment comprises a plurality of PET detector units, an acquisition unit, a first detection unit, and a second detection unit. The plurality of PET detector units are arranged in a ring shape. The acquisition unit acquires, for each of the plurality of PET detector units, state information indicating the state of the PET detector unit. When an index value indicating the state of a unit or the entirety of the plurality of PET detector units exceeds a threshold, the first detection unit detects abnormality based on the state information. The second detection unit detects, based on the state information, a state where the abnormality is not detected, the state where an index value indicating the state of at least two PET detector units of the plurality of PET detector units is different from an index value indicating the state of at least two other PET detector units.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The embodiments disclosed in the present specification and drawings relate to a positron emission tomography apparatus, method, and program. [Background technology]

[0002] Conventionally, a Positron Emission Tomography (PET) device includes a PET detector that detects gamma rays emitted by annihilation of a positron and an electron emitted from a tracer administered to a subject P. Generally, in such a PET device, a quality check (QC) is performed on a daily basis to manage the condition of the PET detector. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-147604 A [Patent Document 2] Special Publication No. 2003-523219 [Patent Document 3] JP 2005-106562 A Summary of the Invention [Problem to be solved by the invention]

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to appropriately manage the state of a PET detector. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0005] A PET device according to an embodiment includes a plurality of PET detector units, an acquisition unit, a first detection unit, and a second detection unit. The plurality of PET detector units are arranged in a ring shape. The acquisition unit acquires status information indicating a status of each of the plurality of PET detector units. The first detection unit detects an abnormality when an index value indicating a status of the plurality of PET detector units alone or as a whole exceeds a threshold based on the status information. The second detection unit detects a state in which the abnormality is not detected and index values ​​indicating the status of at least two of the plurality of PET detector units are different from index values ​​indicating the status of at least two other PET detector units based on the status information. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a PET apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the state of parameter values ​​of each of a plurality of detector units included in the PET detector according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of state detection of the PET detector 14 performed by the second detection function according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing a processing procedure of the processing performed by the acquisition function and the second detection function according to the first embodiment. [Diagram 5] FIG. 5 is a diagram showing an example of state detection of the PET detector performed by the second detection function according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of a PET device will be described in detail with reference to the drawings.

[0008] (First embodiment) FIG. 1 is a diagram showing an example of the configuration of a PET apparatus according to the first embodiment.

[0009] For example, as shown in FIG. 1, a PET device 100 according to this embodiment includes a gantry device 10 and a console device 20.

[0010] The gantry 10 detects gamma rays emitted by annihilation of positrons and electrons emitted from a tracer administered to the subject P, and collects counting information by counting the detected gamma rays. Here, the gantry 10 has a cylindrical opening formed to penetrate the gantry 10 in the horizontal direction, and detects gamma rays emitted from the subject P placed in the opening. In the following, the direction along the axis of the cylindrical opening of the gantry 10 is defined as the Z-axis direction, the horizontal direction perpendicular to the Z-axis direction is defined as the X-axis direction, and the vertical direction perpendicular to the Z-axis direction is defined as the Y-direction.

[0011] Specifically, the gantry 10 includes a tabletop 11 , a bed 12 , a bed driving mechanism 13 , a PET detector 14 , a counting information collecting circuit 15 , a current information collecting circuit 16 , and a bed control circuit 17 .

[0012] The top board 11 is a bed on which the subject P is placed. For example, the top board 11 is formed in a rectangular flat plate shape and is disposed so that the longitudinal direction is parallel to the Z-axis direction.

[0013] The bed 12 supports the top board 11 so as to be movable in the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0014] The bed driving mechanism 13 is provided inside or outside the bed 12, and moves the top board 11 supported by the bed 12. For example, when imaging the subject P, the bed driving mechanism 13 moves the top board 11 on which the subject P is placed to an opening of the gantry device 10. For example, the bed driving mechanism 13 moves the top board 11 on the bed 12 while the position of the bed 12 is fixed. Alternatively, for example, the bed driving mechanism 13 moves the bed 12 arranged on a moving base together with the top board 11.

[0015] The PET detector 14 detects gamma rays emitted by annihilation of positrons and electrons emitted from a tracer administered to the subject P, and converts the detected gamma rays into an electrical signal and outputs it. Specifically, the PET detector 14 includes a plurality of detector units 14a arranged in a ring shape centered on the Z axis so as to surround an opening formed in the gantry device 10, and each detector unit 14a detects gamma rays.

[0016] The counting information collecting circuit 15 collects counting information by counting gamma rays based on the electrical signals output from each detector unit 14a of the PET detector 14. Specifically, the counting information collecting circuit 15 converts the electrical signals output from the PET detector 14 into digital signals to generate counting information including the detection position, energy, and detection time of the gamma rays. Then, the counting information collecting circuit 15 stores the generated counting information in the memory 23.

[0017] The console device 20 receives various operations for the PET device 100 from an operator, and controls the operation of the PET device 100 based on the received operations. Specifically, the console device 20 includes an input interface 21, a display 22, a memory 23, and a processing circuit 24. Here, each unit included in the console device 20 is connected via a bus. Note that, although an example in which the gantry device 10 and the console device 20 are separate entities will be described here, the console device 20 or some of the components of the console device 20 may be included in the gantry device 10.

[0018] The input interface 21 receives various input operations from an operator, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuit 24. For example, the input interface 21 is realized by a mouse, a keyboard, a trackball, a switch, a button, a joystick, a touchpad for performing input operations by touching an operation surface, a touch screen in which a display screen and a touchpad are integrated, a non-contact input circuit using an optical sensor, a voice input circuit, and the like for setting imaging conditions and a region of interest (ROI), and the like. Note that, for example, the input interface 21 may be provided in the gantry device 10. Also, for example, the input interface 21 may be configured by a tablet terminal or the like capable of wireless communication with the main body of the console device 20. Also, the input interface 21 is not limited to only those having physical operation parts 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 console device 20 and outputs the electrical signal to the processing circuit 24 is also included in the input interface 21.

[0019] The display 22 displays various information. For example, the display 22 outputs a PET image generated by the processing circuit 24, a GUI (Graphical User Interface) for receiving various operations from an operator, and the like. For example, the display 22 is a liquid crystal display or a CRT (Cathode Ray Tube) display. Note that, for example, the display 22 may be provided in the gantry device 10. Also, for example, the display 22 may be a desktop type, or may be configured as a tablet terminal or the like capable of wireless communication with the console device 20 main body.

[0020] The memory 23 stores various data used in the PET device 100. For example, the memory 23 is realized by a semiconductor memory element such as a random access memory (RAM) or a flash memory, a hard disk, an optical disk, or the like.

[0021] The processing circuitry 24 controls the overall operation of the PET device 100. Specifically, the processing circuitry 24 has a coincidence counting information generating function 24a, an image reconstruction function 24b, a control function 24c, an acquisition function 24d, a first detection function 24e, and a second detection function 24f.

[0022] The coincidence information generating function 24a generates coincidence information using the counting information collected by the counting information collecting circuit 15. Specifically, the coincidence information generating function 24a refers to the counting information stored in the memory 23, and searches for a set of counting information in which pair annihilation gamma rays are counted substantially simultaneously, based on the detection time of each piece of counting information. Then, the coincidence information generating function 24a generates coincidence information that associates the searched sets of counting information, and stores the generated coincidence information in the memory 23.

[0023] The image reconstruction function 24b reconstructs a PET image based on the coincidence information generated by the coincidence information generation function 24a. Specifically, the image reconstruction function 24b reads out the coincidence information stored in the memory 23, and performs back projection processing using the read out coincidence information as projection data to reconstruct the PET image. The image reconstruction function 24b also stores the reconstructed PET image in the memory 23.

[0024] The control function 24c controls each part of the gantry device 10 and the console device 20, thereby performing overall control of the PET device 100. For example, the control function 24c controls the bed driving mechanism 13 to move the tabletop 11. Also, for example, the control function 24c controls the counting information collecting circuit 15 to collect counting information of pair annihilation gamma rays emitted from the subject P.

[0025] The acquisition function 24d, the first detection function 24e, and the second detection function 24f will be described in detail later.

[0026] For example, the processing circuitry 24 is realized by a processor. In this case, the processing functions of the processing circuitry 24 are stored in the memory 23 in the form of programs executable by a computer. The processing circuitry 24 then realizes the processing functions corresponding to each program by reading and executing each program from the memory 23. In other words, the processing circuitry 24 has each processing function shown in the processing circuitry 24 in FIG. 1 when each program is read.

[0027] The above describes an example of the configuration of the PET device 100 according to the first embodiment. As described above, in the PET device 100 according to this embodiment, the PET detector 14 includes a plurality of detector units 14a arranged in a ring shape.

[0028] Generally, in such a PET device 100, the state of the PET detector 14 is managed by performing QC on a daily basis.

[0029] In QC, typically, a parameter value indicating the state of each of the multiple detector units 14a included in the PET detector 14 is acquired, and the state of the PET detector 14 is evaluated from the parameter value of the detector unit 14a alone and the average value of the parameter values ​​of all the detector units 14a. Here, the parameter value indicating the state of the detector unit 14a is, for example, temperature, energy, time information, etc.

[0030] However, in this type of QC, since standard values ​​are set for the parameter values ​​of the detector unit 14a alone and the average value of the parameter values ​​of all the detector units 14a, there may be cases where the state of the PET detector 14 cannot be properly managed.

[0031] FIG. 2 is a diagram showing an example of the state of parameter values ​​of each of a plurality of detector units 14a included in the PET detector 14 according to the first embodiment.

[0032] For example, as shown in FIG. 2, in a PET detector 14, due to deterioration over time or failure of individual detector units 14a, biases in parameter values ​​such as temperature, energy, and time information may occur among the multiple detector units 14a, or differences in parameter values ​​may occur between opposing detector units 14a.

[0033] In this way, when a deviation occurs in the parameter values ​​in the multiple detector units 14a or when a difference occurs in the parameter values ​​between opposing detector units 14a, this may affect image quality, and therefore it is necessary to perform calibration of the PET detector 14. Here, calibration refers to correcting the parameter values ​​of each detector unit 14a included in the PET detector 14 to appropriate values.

[0034] However, in the above-mentioned QC, standard values ​​are set for the parameter values ​​of the detector unit 14a alone and the average value of the parameter values ​​of all the detector units 14a, so even if the PET detector 14 is in a state in which it may affect the image, the detector unit 14a alone or as a whole may fall within the QC standard. For this reason, the above-mentioned QC may not be able to appropriately manage the state of the PET detector 14.

[0035] For this reason, the PET device 100 according to this embodiment is configured to be able to appropriately manage the state of the PET detector .

[0036] Specifically, the acquisition function 24d of the processing circuitry 24 acquires a parameter value indicating the state of each of the detector units 14a. Here, the acquisition function 24d is an example of an acquisition unit. The detector unit 14a is an example of a PET detector unit. The parameter value is an example of state information.

[0037] Furthermore, a first detection function 24e of the processing circuit 24 detects an abnormality when an index value indicating the state of each or the entirety of the multiple detector units 14a exceeds a threshold value based on the parameter value acquired by the acquisition function 24d. Here, the first detection function 24e is an example of a first detection unit.

[0038] Further, the second detection function 24f of the processing circuit 24 detects, based on the parameter values ​​acquired by the acquisition function 24d, a state in which no abnormality is detected by the first detection function 24e and an index value indicating the state of at least two of the multiple detector units 14a is different from an index value indicating the state of at least two other detector units 14a. Here, the second detection function 24f is an example of a second detection unit.

[0039] According to such a configuration, even if no abnormality is detected in the index values ​​indicating the individual or overall state of the multiple detector units 14a, it is possible to detect a state in which the index values ​​of the multiple detector units 14a are biased or the difference between the index values ​​is large. As a result, in this embodiment, the state of the PET detector 14 can be appropriately managed.

[0040] The above-mentioned acquisition function 24d, first detection function 24e, and second detection function 24f will be described in detail below.

[0041] First, the acquisition function 24d acquires parameter values ​​indicating the state of each detector unit 14a at any time while the PET device 100 is operating. Then, the acquisition function 24d stores the acquired parameter values ​​in the memory 23 at each acquisition point in time.

[0042] For example, the acquisition function 24d acquires at least one of temperature, energy, and time information as the parameter value. Here, the energy is, for example, energy resolution, energy peak value, etc. Furthermore, the time information is, for example, time resolution, delay time, etc. Furthermore, the time resolution is the variation in the difference in detection time between opposing detector units, and the delay time is the amount of deviation in detection time of the energy peak value between opposing detector units.

[0043] Next, when QC is performed, the first detection function 24e detects an abnormality in the PET detector 14 based on the parameter values ​​of each detector unit 14a acquired by the acquisition function 24d in response to instructions from a user, etc.

[0044] Specifically, the first detection function 24e refers to the parameter values ​​of each detector unit 14a stored in the memory 23, and detects an abnormality when the parameter value of any of the detector units 14a among the multiple detector units 14a exceeds a first threshold value, or when the average value of the parameter values ​​of all the detector units 14a exceeds a second threshold value. Here, the first threshold value and the second threshold value are set according to the standard value of QC. In addition, the first threshold value and the second threshold value may be the same value or may be different values. Then, when the first detection function 24e detects an abnormality, it notifies the display 22 or the like that the PET detector 14 needs to be calibrated.

[0045] Next, the second detection function 24f detects the state of the PET detector 14 by analyzing the parameter values ​​of each detector unit 14a acquired by the acquisition function 24d at any time while the PET device 100 is operating.

[0046] In this embodiment, the second detection function 24f detects a state in which an index value indicating the state of at least two of the multiple detector units 14a is different from an index value indicating the state of at least two detector units 14a other than the at least two detector units 14a.

[0047] Here, for example, the at least two detector units 14a are at least two detector units 14a arranged adjacent to each other, or two detector units 14a arranged opposite each other, and the index value is a parameter value itself indicating the state of the detector unit 14a, or a value calculated from the parameter value.

[0048] Specifically, the second detection function 24f refers to the parameter values ​​of each detector unit 14a stored in the memory 23, and calculates an index value indicating the state of the detector units 14a for each set of at least two detector units 14a. Then, the second detection function 24f detects a state in which the index value of any set is different from the index values ​​of the other sets.

[0049] For example, the second detection function 24f detects a state in which the index values ​​for each set of at least two detector units 14a are different based on a threshold value that is lower than the threshold value used by the first detection function 24e.

[0050] Fig. 3 is a diagram showing an example of state detection of the PET detector 14 performed by the second detection function 24f according to the first embodiment. Here, the horizontal axis shown in Fig. 3 indicates the number of each of the multiple detector units 14a included in the PET detector 14, and the vertical axis indicates the temperature of the detector unit 14a.

[0051] For example, as shown in FIG. 3, it is assumed that each detector unit 14a included in the PET detector 14 is divided into a plurality of regions, each region consisting of a predetermined number of adjacent detector units 14a, as a hardware configuration.

[0052] In such a case, for example, the second detection function 24f calculates the average temperature of the detector unit 14a for each region. If the average temperature of any region exceeds a threshold, the second detection function 24f determines that the temperature of the detector unit 14a in that region is different from the temperatures of the detector units 14a in the other regions.

[0053] Although an example in which the parameter value is temperature has been described here, the parameter value used by the second detection function 24f may be energy or time information, etc.

[0054] Furthermore, the state detection of the PET detector 14 performed by the second detection function 24f is not limited to the above example.

[0055] For example, the second detection function 24f may determine that the index values ​​indicating the states of at least two of the multiple detector units 14a are different when the index values ​​indicating the states of at least two detector units 14a other than the at least two detector units 14a differ by a predetermined value or more.

[0056] Alternatively, for example, the second detection function 24f may identify the maximum and minimum values ​​among the average values ​​of the parameter values ​​calculated for each region of the detector unit 14a, and calculate the difference between the identified maximum and minimum values.The second detection function 24f may then compare the calculated difference with the average value of the parameter values ​​of all the detector units 14a, and if the ratio or difference between them exceeds a threshold, determine that the index value of the detector unit 14a in one region is different from the index value of the detector unit 14a in the other regions.

[0057] After detecting the state of the PET detector 14 in this manner, the second detection function 24f determines whether or not calibration of the PET detector 14 is required, depending on the detected state of the PET detector 14.

[0058] Specifically, when the second detection function 24f detects a state in which an index value indicating the state of at least two of the multiple detector units 14a included in the PET detector 14 is different from an index value indicating the state of at least two detector units 14a other than the at least two detector units 14a, it determines that calibration is necessary, and in other cases, it determines that calibration is not necessary.

[0059] When the second detection function 24f determines that calibration of the PET detector 14 is necessary, it notifies the user of a suggestion to perform calibration on the display 22, etc. When the second detection function 24f determines that calibration of the PET detector 14 is not necessary, it does not notify the user of a suggestion to perform calibration, and allows the user to continue using the device.

[0060] This makes it possible to calibrate the PET detector 14 when the state of multiple detector units 14a that are positioned adjacently or facing each other, which may affect image quality, changes, so that the performance of the PET device 100 is not deteriorated.

[0061] FIG. 4 is a flowchart showing the procedure of the processing performed by the acquisition function 24d and the second detection function 24f according to the first embodiment.

[0062] In this embodiment, abnormality detection by the first detection function 24e is performed when QC is performed, while status detection of the PET detector 14 by the second detection function 24f is performed at any time while the PET device 100 is operating, as described below.

[0063] For example, as shown in FIG. 4, the acquisition function 24d acquires parameter values ​​indicating the state of each detector unit 14a at any time while the PET device 100 is in operation (step S1).

[0064] Furthermore, the second detection function 24f analyzes the parameter values ​​of each detector unit 14a acquired by the acquisition function 24d at any time while the PET device 100 is operating, to detect the state of the PET detector 14 (step S2).

[0065] Thereafter, the second detection function 24f determines whether or not it is necessary to perform calibration of the PET detector 14, depending on the detected state of the PET detector 14 (step S3).

[0066] Then, when the second detection function 24f determines that the calibration of the PET detector 14 needs to be performed (Yes at step S3), it notifies the display 22 or the like of a suggestion to perform the calibration (step S4).

[0067] On the other hand, when it is determined that the calibration of the PET detector 14 is not necessary (Yes in step S3), the second detection function 24f does not notify the suggestion to perform the calibration, and allows the use of the device to continue.

[0068] The above describes the acquisition function 24d, the first detection function 24e, and the second detection function 24f of the processing circuitry 24. As described above, when the processing circuitry 24 is realized by a processor, the processes performed by the acquisition function 24d, the first detection function 24e, and the second detection function 24f are realized, for example, by the processing circuitry 24 reading out from the memory 23 a program corresponding to each processing function and executing it.

[0069] As described above, in the first embodiment, the acquisition function 24d acquires state information of each of the multiple detector units 14a for each of the multiple detector units 14a. Furthermore, the first detection function 24e detects an abnormality when an index value indicating the state of each or the entire multiple detector units 14a exceeds a threshold value based on the state information acquired by the acquisition function 24d. Furthermore, the second detection function 24f detects a state in which no abnormality is detected by the first detection function 24e and the index value indicating the state of at least two of the multiple detector units 14a is different from the index value indicating the state of at least two other detector units 14a based on the state information acquired by the acquisition function 24d.

[0070] According to such a configuration, even if no abnormality is detected in the index values ​​indicating the individual or overall state of the multiple detector units 14a, it is possible to detect a state in which the index values ​​of the multiple detector units 14a are biased or the difference between the index values ​​is large by comparing the index values ​​of each set of at least two detector units 14a. As a result, in the first embodiment, the state of the PET detector 14 can be appropriately managed.

[0071] In the first embodiment, even if the parameter values ​​of the multiple detector units 14a are within the QC standard, the implementation of calibration is suggested when there is a tendency in the parameter values ​​of the detector units 14a, thereby preventing deterioration of image quality. This reduces the burden of device management.

[0072] Although the first embodiment has been described above, the above-mentioned PET device 100 can be implemented by appropriately modifying a part of its configuration. Therefore, the following describes modifications of the first embodiment as other embodiments. Note that the following embodiments will be described with a focus on differences from the first embodiment, and detailed descriptions of overlapping contents already described will be omitted.

[0073] Second embodiment For example, in the above-described first embodiment, an example has been described in which the state of the PET detector 14 is detected based on one type of parameter value, but the embodiment is not limited to this.

[0074] For example, the state of the PET detector 14 may be detected based on a plurality of types of parameter values. Such an example will be described below as a second embodiment.

[0075] In this embodiment, the acquisition function 24d acquires a first parameter value and a second parameter value different in type from the first parameter value as parameter values ​​indicating the state of the detector unit 14a. Here, the acquisition function 24d is an example of an acquisition unit. The first parameter value is an example of first state information, and the second parameter value is an example of second state information.

[0076] In addition, the second detection function 24f calculates a first index value from the first parameter value and a second index value from the second parameter value as index values ​​for at least two detector units 14a, and detects a state in which the index values ​​are different based on the difference between the first parameter value and the second parameter value.

[0077] Fig. 5 is a diagram showing an example of state detection of the PET detector 14 performed by the second detection function 24f according to the second embodiment. Here, the horizontal axis shown in Fig. 5 indicates the number of each of the multiple detector units 14a included in the PET detector 14, and the vertical axis indicates temperature and time information of the detector unit 14a.

[0078] For example, as shown in FIG. 5, in multiple detector units 14a, the trend of the detector's time information may change independently of the temperature trend, resulting in a large difference between the maximum value and average value of the time information.

[0079] In such a case, for example, the second detection function 24f determines that the time information is different between at least two detector units 14a among the multiple detector units 14a and at least two detector units 14a other than the at least two detector units 14a when the magnitude of the difference in time information is equal to or greater than the conversion value of the time information calculated from the temperature difference. In this case, for example, the second detection function 24f calculates the conversion value of the time information by the temperature difference x 5 [ps / °C].

[0080] Then, for example, when the second detection function 24f detects a state in which the time information is different, it notifies a suggestion to perform calibration on the display 22 or the like so as to calibrate only the time information.

[0081] According to such a configuration, even if no abnormality is detected in the index values ​​indicating the individual or overall state of the multiple detector units 14a, it becomes possible to detect a state in which the index values ​​of the multiple detector units 14a are biased or the difference between the index values ​​is large due to differences in the tendencies of the multiple index values. As a result, the state of the PET detector 14 can be appropriately managed in the second embodiment as well.

[0082] (Third embodiment) Also, for example, in the above-mentioned first embodiment, an example of detecting a state in which index values ​​at the same time point are different between at least two detector units 14a and at least two other detector units 14a has been described, but the embodiment is not limited to this. For example, a state in which index values ​​at different times are different for at least two detector units 14a may be detected. Hereinafter, such an example will be described as a third embodiment.

[0083] In this embodiment, the second detection function 24f may detect a state in which an index value indicating the state of at least two of the multiple detector units 14a is different from an index value indicating the state of the at least two detector units 14a at a past point in time.

[0084] Specifically, the second detection function 24f refers to the parameter values ​​of each detector unit 14a stored in the memory 23, calculates the most recent index value from the most recently acquired parameter values ​​for each set of at least two detector units 14a, and further calculates past index values ​​from parameter values ​​acquired before the most recent one. For example, the second detection function 24f calculates the past index value from the parameter values ​​at the time when QC was performed last time.

[0085] The second detection function 24f detects a state in which the most recent index value differs from the past index value for each set of the detector units 14a. At this time, for example, the second detection function 24f determines that the index values ​​are different when the most recent index value differs from the past index value by a predetermined value or more.

[0086] According to such a configuration, even if no abnormality is detected in the index values ​​indicating the individual or overall state of the multiple detector units 14a, it is possible to detect a state in which the index values ​​of the multiple detector units 14a are biased or the difference between the index values ​​has become large by comparing with past time points. As a result, the state of the PET detector 14 can be appropriately managed in the third embodiment as well.

[0087] In the third embodiment, even if the condition of the detector units 14a is predicted to deteriorate due to changes over time in the multiple detector units 14a, the implementation of calibration is suggested to prevent deterioration of image quality, thereby reducing the burden of device management.

[0088] (Other embodiments) In the above embodiment, an example in which the state is detected for each detector unit 14a has been described, but the embodiment is not limited to this. For example, if each detector unit 14a included in the PET detector 14 is composed of a plurality of detector modules 14b arranged in the Z-axis direction, the state may be detected for each detector module 14b. In this case, the detector module 14b is an example of a PET detector unit.

[0089] In the above-described embodiment, an example has been described in which the acquisition unit, the first detection unit, and the second detection unit in this specification are realized by the acquisition function 24d, the first detection function 24e, and the second detection function 24f of the processing circuit 24, but the embodiment is not limited to this. For example, the acquisition unit, the first detection unit, and the second detection unit in this specification may be realized by only hardware, only software, or a combination of hardware and software, in addition to being realized by the acquisition function 24d, the first detection function 24e, and the second detection function 24f described in the embodiment.

[0090] In the above-described embodiment, the processing circuit is not limited to being realized by a single processor, but may be configured by combining multiple independent processors, and each processor may execute a program to realize each processing function. Each processing function of the processing circuit may be appropriately distributed or integrated into a single or multiple processing circuits. Each processing function of the processing circuit may be realized by a mixture of hardware such as a circuit and software. Here, an example in which a program corresponding to each processing function is stored in a single memory has been described, but the embodiment is not limited to this. For example, a configuration in which a program corresponding to each processing function is distributed and stored in multiple memories, and a processing circuit reads out and executes each program from each memory, may be used.

[0091] The term "processor" used in the description of the above-mentioned embodiment means a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). Here, instead of storing a program in a memory, the program may be directly embedded in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit. Furthermore, each processor in the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as a single processor by combining multiple independent circuits to realize its function.

[0092] Here, the program executed by the processor is provided in advance in a ROM (Read Only Memory) or the like. The program may be provided by being recorded in a computer-readable non-transitory storage medium such as a CD (Compact Disk)-ROM, a FD (Flexible Disk), a CD-R (Recordable), or a DVD (Digital Versatile Disk) in a format that can be installed in these devices or in a format that can be executed. The program may also be provided or distributed by being stored on a computer connected to a network such as the Internet and downloaded via the network. For example, the program is composed of modules including each of the above-mentioned processing functions. As actual hardware, a CPU reads out the program from a storage medium such as a ROM and executes it, so that each module is loaded onto a main storage device and generated on the main storage device.

[0093] In the above-described embodiment, each component of each device shown in the figure is a functional concept, and does not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution or integration of each device is not limited to that shown in the figure, and all or a part of it can be functionally or physically distributed or integrated in any unit according to various loads, usage conditions, etc. Furthermore, all or any part of each processing function performed by each device can be realized by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

[0094] Furthermore, among the processes described in the above-mentioned embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by a known method. In addition, the information including the processing procedures, control procedures, specific names, various data and parameters shown in the above documents and drawings can be changed arbitrarily unless otherwise specified.

[0095] According to at least one of the embodiments described above, the state of the PET detector can be appropriately managed.

[0096] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0097] 100 PET equipment 10 Mounting device 14 PET detector 14a Detector unit 20 Console device 24 Processing circuit 24d acquisition function 24e First detection function 24f Secondary detection function

Claims

1. A plurality of PET detector units arranged in a ring shape; an acquisition unit that acquires, for each of the plurality of PET detector units, status information indicating a status of the PET detector unit; a first detection unit that detects an abnormality when an index value indicating a state of each of the plurality of PET detector units or the entirety of the plurality of PET detector units exceeds a threshold based on the state information; a second detection unit that, when detecting a state in which the abnormality is not detected and index values ​​indicating states of at least two of the plurality of PET detector units are different from index values ​​indicating states of at least two other PET detector units based on the state information, notifies a suggestion to perform calibration of the PET detector units; Equipped with the acquisition unit acquires, as the status information, first status information and second status information of a different type from the first status information; The second detection unit calculates time information from the first status information as the index value for each of the at least two PET detector units and the at least two other PET detector units, and calculates a temperature from the second status information, and when the magnitude of the difference in the time information between the at least two PET detector units and the at least two other PET detector units is equal to or greater than a conversion value of the time information calculated from the difference in temperature, the second detection unit notifies a suggestion to perform the calibration.

2. The second detection unit detects a state in which the index value is different based on a threshold value that is lower than the threshold value used by the first detection unit.

2. A positron emission tomography apparatus according to claim 1.

3. the second detection unit detects a state in which an index value indicating a state of at least two PET detector units among the plurality of PET detector units is different from an index value indicating a state of at least two PET detector units other than the at least two PET detector units; 3. A positron emission tomography apparatus according to claim 1 or 2.

4. the second detection unit detects a state in which an index value indicating a state of at least two PET detector units among the plurality of PET detector units is different from an index value indicating a state of the at least two PET detector units at a past time point; 3. A positron emission tomography apparatus according to claim 1 or 2.

5. The at least two PET detector units are at least two PET detector units arranged adjacent to each other or two PET detector units arranged opposite each other. A positron emission tomography apparatus according to any one of claims 1 to 4.

6. A method applied to a positron emission tomography apparatus having a plurality of PET detector units arranged in a ring shape, comprising: an acquisition step of acquiring status information indicating a status of each of the plurality of PET detector units; a first detection step of detecting an abnormality when an index value indicating a state of each of the plurality of PET detector units or the entirety of the plurality of PET detector units exceeds a threshold based on the state information; a second detection step of notifying a suggestion to perform calibration of the PET detector units when a state in which the abnormality is not detected and index values ​​indicating states of at least two of the plurality of PET detector units are different from index values ​​indicating states of at least two other PET detector units are detected based on the state information; Including, The acquiring step acquires, as the status information, first status information and second status information of a different type from the first status information, The second detection step calculates time information from the first status information as the index value for each of the at least two PET detector units and the at least two other PET detector units, and calculates temperature from the second status information, and when the magnitude of the difference in the time information between the at least two PET detector units and the at least two other PET detector units is equal to or greater than a conversion value of the time information calculated from the difference in temperature, notifies a suggestion to perform the calibration.

7. A program applied to a positron emission tomography apparatus having a plurality of PET detector units arranged in a ring shape, an acquisition step of acquiring status information indicating a status of each of the plurality of PET detector units; a first detection step of detecting an abnormality when an index value indicating a state of each of the plurality of PET detector units or the entirety of the plurality of PET detector units exceeds a threshold based on the state information; a second detection step of notifying a suggestion to perform calibration of the PET detector units when detecting a state in which the abnormality is not detected and index values ​​indicating states of at least two of the plurality of PET detector units are different from index values ​​indicating states of at least two other PET detector units based on the state information; Run the following on your computer: the acquiring step includes acquiring, as the status information, first status information and second status information of a different type from the first status information; The second detection procedure is a program that calculates time information from the first status information as the index value for each of the at least two PET detector units and the at least two other PET detector units, calculates temperature from the second status information, and notifies a suggestion to perform the calibration when the magnitude of the difference in the time information between the at least two PET detector units and the at least two other PET detector units is equal to or greater than a conversion value of the time information calculated from the difference in temperature.

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