JP7246876B2 - PET-CT device, nuclear medicine diagnostic device and medical image diagnostic system - Google Patents

Description

Embodiments of the present invention relate to a PET-CT apparatus, a nuclear medicine diagnosis apparatus, and a medical image diagnosis system.

In medical image diagnostic systems such as PET (Positron Emission computed Tomography)-CT (Computed Tomography) equipment and PET-MRI (Magnetic Resonance Imaging) equipment, a plurality of different types of imaging obtained by each medical image diagnostic equipment A diagnostic image based on a medical image is used for image diagnosis. For example, in a medical image diagnostic system, a diagnostic image obtained by collecting and superimposing a morphological image and a functional image of a subject is displayed, or a diagnostic image obtained by correcting the other medical image using one medical image is displayed. That is, in such a medical image diagnostic system, the alignment accuracy between medical image diagnostic apparatuses affects the image quality and quantification of diagnostic images, which in turn affects diagnostic performance.

Therefore, it is a basic requirement for providing diagnostic images that the position of the subject in multiple medical images obtained by each medical image diagnostic apparatus matches with high accuracy. important in For this reason, in such a medical image diagnostic system, a plurality of medical image diagnostic apparatuses are arranged side by side so as to align the central axes of the detector fields of view, and the subject is placed on a table that moves in the direction of the central axis. It is common to design for moving between medical imaging equipment.

Here, conventionally, the top board on which the subject is placed has generally been designed to be sent out from the couch apparatus in a cantilevered state into the field of view of the detector. However, in this case, since the amount of feeding of the tabletop from the couch apparatus differs for each medical image diagnostic apparatus, the sagging of the tabletop also differs for each medical image diagnostic apparatus, and as a result, the position of the subject differs for each medical image. there was a case. Therefore, in recent years, a design has been adopted in which the same part of the subject imaged by each medical image diagnostic apparatus has the same sagging of the tabletop by means of a base mechanism that translates together with the couch apparatus.

Japanese Patent Application Laid-Open No. 2017-64400 JP 2006-187515 A

The problem to be solved by the present invention is to reduce the influence of sagging of the top plate.

A PET-CT apparatus according to an embodiment includes an X-ray CT apparatus, a PET apparatus, a tabletop, a support frame, a bed apparatus, and a controller. An X-ray CT apparatus scans a subject by irradiating the subject with X-rays. PET devices produce functional images based on gamma rays emitted from drugs administered to a subject. A subject is placed on the top plate. A support frame supports the top plate. A couch apparatus supports the support frame. The control unit controls the feeding amount of the support frame from the bed apparatus so that the relative distance between the tabletop and the support frame does not change during scanning by the X-ray CT apparatus or the PET apparatus.

FIG. 1 is a diagram showing the overall configuration of a PET-CT apparatus according to the first embodiment. FIG. 2A is a diagram showing the configuration of the PET gantry device according to the first embodiment. FIG. 2B is a diagram showing the configuration of the PET gantry device according to the first embodiment. FIG. 3 is a diagram showing the configuration of the CT gantry according to the first embodiment. FIG. 4 is a diagram showing the configuration of the console device according to the first embodiment. FIG. 5 is a diagram for explaining an example of bed control according to the first embodiment. FIG. 6A is a diagram for explaining an example of the processing of the determination function in the sagging suppression mode according to the first embodiment; FIG. 6B is a diagram for explaining an example of the processing of the determination function in the image quality priority mode according to the first embodiment; 7A and 7B are diagrams for explaining the positional deviation of the tabletop due to the difference in the scanning method according to the first embodiment. FIG. FIG. 8 is a flowchart for explaining an example of processing of the PET-CT apparatus according to the first embodiment. FIG. 9 is a diagram for explaining an example of processing of a decision function according to the second embodiment. FIG. 10 is a flowchart for explaining an example of processing of the PET apparatus according to the second embodiment.

Hereinafter, embodiments of a PET-CT apparatus, a nuclear medicine diagnostic apparatus, and a medical image diagnostic system will be described in detail with reference to the accompanying drawings. In the following description, a PET-CT apparatus will be described as an example of a medical image diagnostic system. Further, the PET-CT apparatus, nuclear medicine diagnosis apparatus, and medical image diagnosis system according to the present application are not limited to the embodiments shown below.

(First embodiment)
First, the overall configuration of the PET-CT apparatus according to the first embodiment will be explained using FIG. FIG. 1 is a diagram showing the overall configuration of a PET-CT apparatus according to the first embodiment. As shown in FIG. 1, the PET-CT apparatus according to the first embodiment includes a PET gantry device 1, a CT gantry device 2, a bed 3, and a console device 4. As shown in FIG.

The PET gantry device 1 detects a pair of gamma rays emitted from living tissue that has taken in the positron-emitting radionuclides administered to the subject P, thereby obtaining gamma-ray projection data (coincidence counts) for reconstructing a PET image. information). 2A and 2B are diagrams showing the configuration of the PET gantry device 1 according to the first embodiment.

The PET gantry device 1 has a PET detector 11, a coincidence counting circuit 12, etc., as shown in FIG. 2A. The PET detector 11 is a photon counting type detector that detects gamma rays emitted from the subject P. As shown in FIG. Specifically, the PET detector 11 is configured by arranging a plurality of PET detector modules 111 so as to surround the subject P in a ring shape.

For example, the PET detector module 111 is an Anger-type detector having a scintillator 111a, a photomultiplier tube (PMT) 111c, and a light guide 111b, as shown in FIG. 2B.

In the scintillator 111a, a plurality of scintillators such as NaI and BGO that convert incident gamma rays emitted from the subject P into visible light are arranged two-dimensionally, as shown in FIG. 2B. The photomultiplier tube 111c is a device that multiplies the visible light output from the scintillator 111a and converts it into an electric signal. ing. The light guide 111b is used to transmit visible light output from the scintillator 111a to the photomultiplier tube 111c, and is made of a plastic material or the like having excellent light transmittance.

The photomultiplier tube 111c is composed of a photocathode that receives scintillation light and generates photoelectrons, a multistage dynode that applies an electric field that accelerates the generated photoelectrons, and an anode that is an electron outflow port. Electrons emitted from the photocathode by the photoelectric effect are accelerated toward the dynode and collide with the surface of the dynode, ejecting a plurality of electrons. By repeating this phenomenon over multiple stages of dynodes, the number of electrons is avalanche-multiplied, and the number of electrons at the anode reaches about one million. In such an example, the gain factor of the photomultiplier tube 111c is 1,000,000 times. A voltage of 1000 volts or more is normally applied between the dynode and the anode for amplification using the avalanche phenomenon.

In this way, the PET detector module 111 converts gamma rays into visible light using the scintillator 111a, and converts the converted visible light into electrical signals using the photomultiplier tube 111c. count the number.

The coincidence circuit 12 shown in FIG. 2A is connected to each of the photomultiplier tubes 111c of the PET detector modules 111, respectively. Then, the coincidence counting circuit 12 generates coincidence counting information for determining the incident directions of the pair of annihilation gamma rays emitted from the positron from the output result of the PET detector module 111 . Specifically, the coincidence circuit 12 calculates the position of the center of gravity from the position of the photomultiplier tube 111c that converts the visible light output from the scintillator 111a into an electrical signal at the same timing and the intensity of the electrical signal. The incident position of pair annihilation gamma rays (the position of the scintillator 111a) is determined. The coincidence circuit 12 also calculates the energy value of the incident gamma ray by performing arithmetic processing (integration processing and differentiation processing) on the intensity of the electrical signal output from each photomultiplier tube 111c.

Then, the coincidence circuit 12 selects a combination in which the gamma ray incident timing (time) is within a certain time window width and both energy values are within a certain energy window width from the output results of the PET detector 11. Search (Coincidence Finding). For example, a time window width of 2 nsec and an energy window width of 350 keV to 550 keV are set as search conditions. Then, the coincidence counting circuit 12 generates coincidence counting information (Coincidence List) by treating the output result of the searched combination as information obtained by coincident counting two annihilated photons. Then, the coincidence counting circuit 12 transmits the coincidence counting information to the console device 4 shown in FIG. A line connecting two detection positions where two annihilation photons are coincidentally counted is called LOR (Line of Response). Also, the coincidence counting information may be generated by the console device 4 .

The coincidence circuit 12 can transmit the generated coincidence counting information to the console device 4 and can also transmit counting information obtained by counting gamma rays (for example, gamma ray count values) to the console device 4 . The coincidence circuit 12 can also generate only the gamma ray count value without generating the coincidence count information and transmit it to the console device 4 .

Returning to FIG. 1, the CT gantry 2 according to the present embodiment is a device for generating X-ray projection data for generating an X-ray CT image by detecting X-rays that have passed through a subject P. be. The CT gantry 2 can also generate X-ray projection data for generating a two-dimensional or three-dimensional scanogram.

FIG. 3 is a diagram showing the configuration of the CT gantry 2. As shown in FIG. The CT gantry 2 has an X-ray tube 21, an X-ray detector 22, a data acquisition circuit 23, etc., as shown in FIG. The X-ray tube 21 is a device that generates an X-ray beam and irradiates the subject P with the generated X-ray beam. The X-ray detector 22 is a device that detects X-rays that have passed through the subject P at a position facing the X-ray tube 21 . Specifically, the X-ray detector 22 is a two-dimensional array detector that detects two-dimensional intensity distribution data (two-dimensional X-ray intensity distribution data) of X-rays that have passed through the subject P. FIG. More specifically, in the X-ray detector 22, a plurality of rows of detection element arrays each having X-ray detection elements for a plurality of channels are arranged along the body axis direction of the subject P. As shown in FIG. The X-ray tube 21 and the X-ray detector 22 are supported inside the CT gantry 2 by a rotating frame (not shown).

The data acquisition circuit 23 is a DAS (Data Acquisition System), and performs amplification processing and A/D conversion processing on the two-dimensional X-ray intensity distribution data detected by the X-ray detector 22 to obtain X-rays. Generate projection data. The data acquisition circuit 23 then transmits the X-ray projection data to the console device 4 shown in FIG.

Returning to FIG. 1 , the bed 3 is a bed on which the subject P is placed, and has a top plate 31 , a support frame 32 and a bed device 33 . The bed 3 sequentially moves the subject to the imaging ports of the CT gantry 2 and the PET gantry 1 based on instructions received from the operator of the PET-CT apparatus via the console device 4 . That is, the PET-CT apparatus controls the bed 3 to first capture an X-ray CT image and then capture a PET image. Although FIG. 1 shows an example in which the CT gantry device 2 is arranged on the bed 3 side, the embodiment is not limited to this, and the PET gantry device 1 is arranged on the bed 3 side. It may be arranged.

The bed 3 moves the top plate 31 and the support frame 32 in the direction of the central axis of the field of view of the detector in the CT gantry 2 and the PET gantry 1 by a driving mechanism (not shown). In other words, the bed 3 moves the top plate 31 and the support frame 32 in a direction along the longitudinal direction of the top plate 31 and the support frame 32 . Details of movement of the top plate 31 and the support frame 32 in the bed 3 will be described later.

The console device 4 is a device that receives instructions from an operator and controls processing by the PET-CT apparatus. FIG. 4 is a diagram showing the configuration of the console device 4 according to the first embodiment. As shown in FIG. 4, the console device 4 includes a coincidence counting information storage circuit 41a, a gamma-ray volume data generation circuit 41b, a PET image generation circuit 41c, an X-ray projection data storage circuit 42a, and an X-ray volume data generation circuit. 42b, a scanogram generation circuit 42c, an X-ray CT image generation circuit 42d, a processing circuit 43, a storage circuit 44, an input interface 45, and a display 46.

In the embodiment shown in FIG. 4, the gamma-ray volume data generating circuit 41b is a processor that performs reconstruction processing on the coincidence counting information recorded in the coincidence counting information storage circuit 41a to generate gamma-ray volume data. Here, the gamma ray volume data generation circuit 41b calls a program corresponding to the reconstruction function from the storage circuit 44 and executes it, thereby realizing the reconstruction function. The PET image generation circuit 41c is a processor that performs image generation processing on the gamma ray volume data generated by the gamma ray volume data generation circuit 41b to generate a PET image. Here, the PET image generation circuit 41c calls a program corresponding to the image generation function from the storage circuit 44 and executes it to realize the image generation function.

4, the X-ray volume data generation circuit 42b is a processor that performs reconstruction processing on the X-ray projection data recorded in the X-ray projection data storage circuit 42a to generate X-ray volume data. . Here, the X-ray volume data generation circuit 42b calls a program corresponding to the reconstruction function from the storage circuit 44 and executes the reconstruction function, thereby realizing the reconstruction function. The scanogram generation circuit 42c is a processor that performs image generation processing on the X-ray volume data generated by the X-ray volume data generation circuit 42b to generate a scanogram. The X-ray CT image generation circuit 42d is a processor that performs image generation processing on the X-ray volume data generated by the X-ray volume data generation circuit 42b to generate an X-ray CT image. Here, the scanogram generation circuit 42c and the X-ray CT image generation circuit 42d each call a program corresponding to the image generation function from the storage circuit 44 and execute the image generation function, thereby realizing the image generation function.

The PET image generation circuit 41c, the scanogram generation circuit 42c, and the X-ray CT image generation circuit 42d are connected to the processing circuit 43, and output images generated by the image generation function to the processing circuit 43.

The processing circuit 43 performs a control function 43a and a decision function 43b. In the embodiment in FIG. 4, each processing function performed by the control function 43a and the decision function 43b of the constituent elements is recorded in the memory circuit 44 in the form of a computer-executable program. The processing circuit 43 is a processor that reads a program from the storage circuit 44 and executes it to implement a function corresponding to each program. In other words, the processing circuit 43 with each program read has each function shown in the processing circuit 43 of FIG. In FIG. 4, it is assumed that the processing functions performed by the control function 43a and the decision function 43b are realized by a single processing circuit. The functions may be realized by each processor executing a program. Note that the control function 43a in the first embodiment is an example of a control unit.

The coincidence counting information storage circuit 41 a stores the coincidence counting information transmitted from the coincidence counting circuit 12 . In addition, the coincidence counting information storage circuit 41a stores the count information transmitted from the coincidence counting circuit 12. FIG. The gamma-ray volume data generating circuit 41b reconstructs gamma-ray volume data from the coincidence counting information stored in the coincidence counting information storage circuit 41a by, for example, the FBP method or the successive approximation method. Here, the iterative approximation method includes the MLEM (Maximum Likelihood Expectation Maximization) method and the OSEM (Ordered Subset MLEM) method in which the convergence time is significantly shortened by improving the algorithm of the MLEM method. The PET image generation circuit 41c generates a PET image by performing image generation processing on the gamma ray volume data generated by the gamma ray volume data generation circuit 41b.

The X-ray projection data storage circuit 42 a stores the X-ray projection data transmitted from the data acquisition circuit 23 . Specifically, the X-ray projection data storage circuit 42a stores X-ray projection data for reconstructing scanograms and X-ray CT images. The X-ray volume data generating circuit 42b reconstructs the X-ray projection data stored in the X-ray projection data storage circuit 42a by, for example, an FBP (Filtered Back Projection) method or an iterative approximation method, thereby generating X-ray volume data. to reconfigure.

The scanogram generation circuit 42c generates a scanogram used for positioning the subject P, etc., by performing image generation processing on the X-ray volume data generated by the X-ray volume data generation circuit 42b. Further, the X-ray CT image generation circuit 42d performs image generation processing on the X-ray volume data stored in the X-ray volume data generation circuit 42b based on the imaging conditions (for example, slice width) determined by the imaging plan. , an X-ray CT image is generated in which a plurality of cross sections perpendicular to the body axis direction of the subject P are captured.

A processing circuit 43 controls the entire processing by the PET-CT apparatus. For example, the processing circuit 43 receives an operator's instruction via the input interface 45, and controls the PET gantry 1, the CT gantry 2, and the bed 3 according to the received instruction, thereby obtaining a scanogram. collection, main imaging, image reconstruction, image generation, and image display. That is, the processing circuit 43 reads out from the storage circuit 44 and executes the programs corresponding to the control function 43a and the determination function 43b, thereby executing each of the processes described above. Here, the processing circuit 43 according to the present embodiment reduces the influence of the sagging of the tabletop 31 by controlling the bed 3 described above. This point will be described in detail later.

The storage circuit 44 stores data used when the processing circuit 43 controls the entire processing by the PET-CT apparatus, PET image data, X-ray CT image data, and the like. The storage circuit 44 also stores programs executed by the processing circuit 43, the gamma ray volume data generation circuit 41b, and the like.

The input interface 45 includes a trackball, a switch button, a mouse, a keyboard, a touch pad for performing input operations by touching the operation surface, a touch monitor in which the display screen and the touch pad are integrated, an optical It is realized by a non-contact input circuit using a sensor, an audio input circuit, and the like. The input interface 45 is connected to the processing circuit 43 , converts an input operation received from an operator into an electric signal, and outputs the electric signal to the processing circuit 43 . It should be noted that the input interface 45 in this specification is not limited to having physical operation parts such as a mouse and a keyboard. For example, the input interface includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs the electrical signal to the processing circuit 43 .

The display 46 displays a GUI (Graphical User Interface) for the operator of the PET-CT apparatus to input various setting requests using the input interface 45, and displays PET images generated in the console apparatus 4, X-ray A CT image or the like is displayed. Also, the display 46 displays various messages and display information in order to notify the operator of the processing status and processing results. The display 46 also has a speaker and can output sound.

The overall configuration of the PET-CT apparatus according to the first embodiment has been described above. With such a configuration, the PET-CT apparatus according to the first embodiment makes it possible to reduce the influence of sagging of the tabletop. Specifically, the PET-CT apparatus according to the first embodiment includes a tabletop 31 on which a subject is placed, a support frame 32 that supports the tabletop 31, and a bed device 33 that supports the support frame 32. and controls the feed amount of the support frame 32 from the bed device 33 so that the relative distance between the tabletop 31 and the support frame 32 does not change during scanning by the CT gantry 2 or the PET gantry 1. This reduces the influence of sagging on the top plate.

As described above, in the case of a design in which the table is cantilevered from the couch into the field of view of the detector, the amount of the table sent out from the couch differs from one medical image diagnostic apparatus to another (for example, PET). (because the feeding amount of the top board during scanning differs between the gantry 1 and the CT gantry 2), the sagging of the top board also differs for each medical image diagnostic apparatus, and as a result, the position of the subject differs in each medical image. there was a case. Therefore, in the present embodiment, a support frame 32 that supports the top plate 31 and can be sent out in the same direction as the direction in which the top plate 31 is sent out is provided between the bed device 33 and the top plate 31. By controlling the feeding of the support frame 32 so that the sag of the top plate 31 is the same for the same part of the subject imaged by the 1 and the CT gantry 2, the influence of the sag of the top plate is reduced. do.

FIG. 5 is a diagram for explaining an example of control of the bed 3 according to the first embodiment. For example, as shown in FIG. 5, the bed 3 has a support frame 32 supported by a bed device 33 and a top plate 31 supported by the support frame 32 . Here, the bed 3 includes a slide mechanism for independently feeding out (sliding) the top plate 31 and the support frame 32 in the longitudinal direction. The slide mechanism that slides the top plate 31 in the longitudinal direction and the slide mechanism that slides the support frame 32 in the longitudinal direction each have a driving device realized by, for example, a servomotor. Each driving device is controlled by the control function 43a, and the generated power causes the top plate 31 and the support frame 32 to slide in the longitudinal direction.

Here, the control function 43a controls each driving device according to the control content determined by the determination function 43b. For example, the determination function 43b can support the operator during scanning by the CT gantry 2 or the PET gantry 1 based on an operator's instruction via the input interface 45 or preset information. It is decided to move the frame 32 by a distance corresponding to the distance between the detector centers of the CT gantry 2 and the PET gantry 1 in the delivery direction of the top plate.

In such a case, the control function 43a first controls the bed 3 from the state shown in the upper diagram of FIG. 5 to the state shown in the middle diagram, for example. That is, the control function 43a drives the driving device in the slide mechanism for sliding the top plate 31 in the longitudinal direction according to the control contents determined by the determination function 43b, thereby moving the top plate 31 from the support frame 32 to the direction indicated by the arrow 61. Control to send out in the direction of As a result, the control function 43 a inserts the imaging region of the subject P into the imaging port of the CT gantry 2 .

Then, the control function 43a controls the CT gantry 2 to pick up an X-ray CT image. Here, the control function 43a captures an X-ray CT image by a step-and-shoot method in which the table 31 on which the subject P is placed is moved step by step in the longitudinal direction to capture an image for each part. Alternatively, the X-ray CT image may be captured by a continuous movement method in which the table 31 on which the subject P is placed is moved in the longitudinal direction.

After imaging the X-ray CT image, the control function 43a moves the support frame 32 to the bed while the top board 31 is still being sent out from the support frame 32, as shown in the lower diagram of FIG. By sliding from the device 33 , the imaging region of the subject P is inserted into the imaging port of the PET gantry device 1 . Here, the control function 43a, as shown in the lower diagram of FIG. move distance. In other words, the control function 43a moves the support frame 32 by a distance "a" so that the same part in the body axis direction of the subject P is imaged when the X-ray CT image is captured and when the PET image is captured. The extension amount of the top plate 31 from the support frame 32 is the same. The support frame 32 is formed of a strong member and structure so that it does not sag like the top plate 31 even when it is sent out from the bed device 33 in the longitudinal direction.

Then, the control function 43a captures a PET image by, for example, horizontally moving the table top 31 in a direction opposite to that when capturing an X-ray CT image. In such a case, the control function 43a, after capturing an image of a part of the subject, horizontally moves the subject by a predetermined amount of movement while the image capturing is stopped, captures an image of another part, and repeats such movement and image capturing. A step-and-shoot method may be used to image a wide range of the subject, or a continuous movement method may be used to perform imaging while moving the tabletop 31 on which the subject P is placed in the longitudinal direction.

As described above, in the PET-CT apparatus according to the first embodiment, the bed 3 includes the top plate 31, the support frame 32, and the bed device 33, and the same part of the subject P in the body axis direction is imaged. By controlling the extension amount of the top plate 31 from the support frame 32 to be the same, the influence of the top plate 31 sagging is reduced.

Furthermore, in the PET-CT apparatus according to the first embodiment, by sliding the support frame 32 without sliding the bed apparatus 33, the installation space of the apparatus can be narrowed and the imaging protocol can be efficiently set. can allow for flexible wire configuration. For example, when the bed device 33 is slid, a slide mechanism for sliding the bed device 33 is installed on the floor of the examination room, which requires a large area and requires a large-scale installation work. On the other hand, in the PET-CT apparatus according to the first embodiment, there is no need to install a slide mechanism for sliding the bed device 33, so that the installation space can be narrowed and the labor for the installation work can be reduced. can be made

Furthermore, the slide mechanism for sliding the bed device 33 may become an obstacle at the feet of the subject and the operator. It can be a constraint for efficient conductor setting in On the other hand, in the PET-CT apparatus according to the first embodiment, there are no obstacles around the bed 3, enabling efficient lead wire setting in the imaging protocol.

Furthermore, if the slide mechanism for sliding the bed device 33 is installed on the floor, there is a risk of malfunction due to the operator accidentally stepping on the bed device 33 or accumulation of dust and dirt. However, the PET-CT apparatus according to the first embodiment does not cause such a problem.

(Modification 1)
In the above-described embodiment, an example in which a PET image is captured by moving the support frame 32 by the same distance as the distance between the center positions of the detectors after capturing an X-ray CT image has been described. That is, in the above-described embodiment, the difference in relative sagging of the top plate 31 during imaging by the PET gantry device 1 and during imaging by the CT gantry device 2 is eliminated, and the situation of sag during imaging is adjusted. An example of making them identical has been described.

However, the PET-CT apparatus according to the first embodiment can also reduce the absolute amount of sag in the top plate 31. FIG. In such a case, the decision function 43b decides the control of the bed 3 so as to minimize the feeding amount of the tabletop 31 from the support frame 32 during imaging. Hereinafter, the control for minimizing the feed amount of the table top 31 from the support frame 32 during imaging will be referred to as "sagging suppression mode".

For example, in the sag suppression mode, the decision function 43b decides to perform control so that the support frame 32 is sent out from the bed device 33 before imaging with the CT gantry device 2 shown in the middle diagram of FIG. . That is, the decision function 43b decides the contents of control for sending out the support frame 32 to the vicinity of the detector of the CT gantry 2 when the table top 31 is sent out from the support frame 32 .

Here, the determination function 43 b determines the feed amount of the support frame 32 with respect to the detector of the CT gantry 2 according to the position of the PET detector 11 . FIG. 6A is a diagram for explaining an example of the processing of the determination function 43b in the sagging suppression mode according to the first embodiment. For example, the decision function 43b decides to move the support frame 32 to the bed 3 side end 63 of the PET detector 11, as shown in FIG. 6A. Then, the determination function 43b sets the position P1 (not shown), which is the same distance as the distance between the center positions of the detectors, from the end portion 63 toward the bed 3 as the position of the support frame 32 at the time of imaging the X-ray CT image. decide.

That is, the determination function 43b determines the control contents to feed the support frame 32 to the position P1 before imaging with the CT gantry 2, and to feed the support frame 32 to the end portion 63 after imaging the X-ray CT image. decide. As a result, the PET-CT apparatus according to the first embodiment minimizes the degree of sagging of the tabletop when capturing an X-ray CT image and when capturing a PET image. It is possible to make the situation of sauce the same.

Note that if the position P1 is a position that affects the imaging of the X-ray CT image (for example, if scattering occurs due to the support frame 32), the determination function 43b determines the position of the support frame at the time of imaging the X-ray CT image. 32 is determined as a position P2 (not shown) that does not affect imaging. Then, the determination function 43b determines the position of the support frame 32 when the PET image is captured by moving the position of the end portion 63 in the direction of the bed 3 by a distance corresponding to the distance from the position P1 to the position P2. decide.

(Modification 2)
In addition, the PET-CT apparatus according to the first embodiment can reduce the absolute amount of sag in the top plate 31 and also suppress deterioration in image quality. For example, as shown in FIG. 6A, if the support frame 32 is extended to the edge 63 of the PET detector 11, the image quality of the PET image may be degraded. Therefore, the determination function 43b controls the bed 3 so as to move the support frame 32 closer to the bed 3 than the position corresponding to the PET detector 11 in order to prevent the quality of the PET image from deteriorating. decide. Hereinafter, the control for suppressing deterioration of image quality will be referred to as "image quality priority mode".

FIG. 6B is a diagram for explaining an example of processing of the determination function 43b in the image quality priority mode according to the first embodiment. For example, in the image quality priority mode, the decision function 43b decides to move the support frame 32 to the boundary 64 between the CT gantry 2 and the PET gantry 1, as shown in FIG. 6B. Then, the determination function 43b determines a position P3 (not shown), which is the same distance as the distance between the center positions of the detectors from the boundary 64 to the bed 3 side, as the position of the support frame 32 during imaging of the X-ray CT image. do.

That is, the decision function 43b decides the control contents to send the support frame 32 to the position P3 before imaging with the CT gantry 2, and to send the support frame 32 to the boundary 64 after imaging the X-ray CT image. do. As a result, the PET-CT apparatus according to the first embodiment suppresses the deterioration of the image quality while suppressing the degree of sagging of the tabletop when capturing an X-ray CT image and when capturing a PET image. It is possible to make the situation of sagging at the time of imaging the same.

Note that if the position P3 is a position that affects the imaging of the X-ray CT image (for example, if scattering occurs due to the support frame 32), the determination function 43b determines whether the support frame at the time of imaging the X-ray CT image 32 is determined as a position P4 (not shown) that does not affect imaging. Then, the determination function 43b determines a position obtained by moving the position of the boundary 64 in the direction of the bed 3 by a distance corresponding to the distance from the position P3 to the position P4 as the position of the support frame 32 when the PET image is taken. do.

The decision function 43b decides which of the sagging suppression mode and the image quality priority mode is to be controlled based on a mode according to an operator's instruction via the input interface 45 or a preset mode. The control function 43a controls the bed 3 according to the mode determined by the determination function 43b.

(Modification 3)
In the above-described embodiment, a case has been described in which the support frame 32 is sent out from the bed device 33 before capturing an image, and the top plate 31 is sent out from the support frame 32 during image capture. However, the embodiment is not limited to this, and the timing, absolute length, speed, etc. of sending out the support frame 32 and the sending out of the top board 31 can be arbitrarily changed. That is, if it is possible to control the same part of the subject to be imaged by the PET gantry 1 and the CT gantry 2 so that the tabletop 31 has the same sagging, what kind of control is performed? may be

For example, the determination function 43b determines the delivery of the top plate 31 and the support frame 32 so as to eliminate the positional deviation of the top plate 31 due to the difference between the scanning method by the CT gantry device 2 and the scanning method by the PET gantry device 1. control can be determined. First, the positional deviation of the top plate 31 due to the difference between the scanning method by the CT gantry 2 and the PET gantry 1 will be described. In the PET-CT apparatus, different imaging methods are often used when imaging images with the gantry device 2 for CT and the gantry device 1 for PET. For example, in a PET-CT apparatus, a PET image is captured by a step-and-shoot method, and an X-ray CT image is captured by a continuous movement method.

FIG. 7 is a diagram for explaining positional deviation of the tabletop 31 due to different scanning methods according to the first embodiment. Here, bed 1, bed 2, and bed 3 in FIG. 7 indicate image pickup positions by the step-and-shoot method. In FIG. 7, after moving the support frame 32 toward the PET gantry 1 side, the PET images of the beds 1 to 3 are returned to the support frame 32 by the step-and-shoot method while the top board 31 that has been sent out is returned to the support frame 32 in this order. The sagittal plane of the bed-by-bed image is shown for the imaging of . That is, FIG. 7 shows a cross section in the body axis direction in which the bed 1 side is the subject's foot side and the bed 3 side is the subject's head side. Further, the line L1 in FIG. 7 indicates the position of the tabletop during imaging by the continuous movement method, and the line L2 indicates the position of the tabletop during imaging by the step-and-shoot method.

The degree of top plate sagging varies depending on the amount of feeding of the top plate 31 from the support frame 32 . That is, when the bed 1 is scanned (when the tabletop 31 is fed by a large amount), the weight of the subject exerts a large influence on the tabletop 31, and the tabletop sag in the scan area is also large. However, each time the amount of feeding of the tabletop 31 from the support frame 32 decreases (every time images are taken from bed 2 and bed 3), the influence of the weight of the subject on the tabletop 31 decreases, and the scan area The degree of the top plate sag in

Therefore, in imaging by the step-and-shoot method, as indicated by line L2 in FIG. , bed 3, the position of the top plate becomes higher and the inclination becomes gentler.

On the other hand, even in the case of imaging by the continuous movement method, the position of the top plate on the head side (bed 3 side) where the feeding amount of the top plate 31 is small is high, and the position of the top plate on the foot side (bed 1 side) where the feeding amount of the top plate 31 is large is high. Lower the plate position. However, the slice width of the X-ray CT image captured by the continuous movement method when viewed on the sagittal plane is very thin, and the cross-sectional image converges on the center of the X-ray detector 22. . Therefore, the tabletop 31 when viewing the X-ray CT image in the sagittal plane is a continuous straight line with a higher head side and a lower foot side as indicated by line L1 in FIG.

As described above, when the scanning method by the CT gantry device 2 and the scanning method by the PET gantry device 1 are different, the position of the top plate 31 in the image is shifted. Therefore, the decision function 43b decides the control of sending out the top plate 31 and the support frame 32 so as to eliminate the displacement of the top plate 31 due to the difference in the scanning method.

For example, the decision function 43b decides control to execute continuous movement imaging by sending out the support frame 32 . That is, the determination function 43b continuously moves the support frame 32 while the top plate 31 is fed out from the support frame 32 by the same feeding amount as the feeding amount of the top plate 31 in each bed in the step-and-shoot method. Control is determined so as to pick up an X-ray CT image at a position corresponding to each bed. The control function 43a controls the bed 3 according to the control content determined by the determination function 43b. The example described above is merely an example, and the PET-CT apparatus can perform various other controls on the bed 3 .

Next, an example of the procedure of processing by the PET-CT apparatus will be described with reference to FIG. FIG. 8 is a flowchart for explaining an example of processing of the PET-CT apparatus according to the first embodiment. Note that FIG. 8 shows the processing when the mode is determined and control is performed according to the mode. Here, steps S103 to S106 in FIG. 8 are realized by the processing circuit 43 calling and executing a program corresponding to the control function 43a from the storage circuit 44. FIG. Steps S101, S102, and S107 in FIG. 8 are realized by the processing circuit 43 calling and executing a program corresponding to the determination function 43b from the storage circuit 44. FIG.

As shown in FIG. 8, in the PET-CT apparatus, the processing circuit 43 determines whether or not the sagging suppression mode is set (step S101). Here, if it is the sagging suppression mode (Yes at step S101), the processing circuit 43 determines the amount of movement of the support frame 32 based on the position of the detector (step S102). On the other hand, if the mode is not the droop suppression mode (No at step S101, image quality priority mode), the processing circuit 43 determines the amount of movement of the support frame 32 based on the gantry position (step S107).

After determining the movement amount of the support frame 32 in step S102 or step S107, the processing circuit 43 moves the support frame 32 (step S103). Then, the processing circuit 43 controls the movement of the tabletop 31 to acquire an X-ray CT image (step S104).

After that, the processing circuit 43 moves the support frame 32 so that the feeding amount of the top plate 31 becomes the same (step S105). Then, the processing circuit 43 controls to acquire PET images while controlling the movement of the tabletop 31 (step S106).

As described above, according to the first embodiment, the CT gantry 2 scans the subject by irradiating the subject with X-rays. A PET gantry device 1 generates a functional image based on gamma rays emitted from a drug administered to a subject. A subject is placed on the top plate 31 . A support frame 32 supports the top plate. A couch device 33 supports the support frame. The control function 43a adjusts the feed amount of the support frame 32 from the bed device 33 so that the relative distance between the tabletop 31 and the support frame 32 does not change during scanning by the CT gantry 2 or the PET gantry 1. Control. Therefore, the PET-CT apparatus according to the first embodiment eliminates the difference in the relative sagging of the top plate 31 between the time of imaging by the PET gantry device 1 and the time of imaging by the CT gantry device 2, To make it possible to equalize the situation of sagging at the time of imaging, and to reduce the influence of sagging of a top plate.

Further, according to the first embodiment, the control function 43a moves the support frame 32 to the position of the CT gantry 2 in the feed-out direction of the top plate 31 during scanning by the CT gantry 2 or the PET gantry 1. and the PET gantry device 1 by a distance corresponding to the distance between the centers of the detectors. Therefore, the PET-CT apparatus according to the first embodiment can easily control the relative sagging of the tabletop 31 between the time of imaging by the PET gantry device 1 and the time of imaging by the CT gantry device 2. make it possible to eliminate the difference between

Further, according to the first embodiment, the control function 43a moves the support frame 32 to a position corresponding to the PET detector 11 of the PET gantry 1 during scanning by the PET gantry 1. mode (sagging suppression mode) and a second mode (image quality priority mode) in which the support frame 32 is moved closer to the bed device 33 than the position corresponding to the PET detector 11, and the PET gantry device 1 The feed amount of the support frame 32 during scanning by the CT gantry 2 is determined according to the mode executed during scanning by . Therefore, the PET-CT apparatus according to the first embodiment makes it possible to perform imaging according to the situation while reducing the influence of the sagging of the tabletop 31. FIG. In addition, since the support frame 32 can be inserted into the imaging openings of the CT gantry 2 and the PET gantry 1, the degree of sagging of the top plate 31 can be reduced compared to the case where the bed device 33 is slid. can be further reduced.

Further, according to the first embodiment, the control function 43a controls the top plate 31 so as to eliminate the positional deviation of the top plate 31 due to the difference between the scanning method by the CT gantry device 2 and the scanning method by the PET gantry device 1. It controls the feeding of the plate 31 and the support frame 32 . Therefore, the PET-CT apparatus according to the first embodiment makes it possible to reduce the displacement of the top plate 31 due to the scanning method.

(Second embodiment)
In the first embodiment described above, the case where the PET-CT apparatus includes the bed 3 having the top plate 31, the support frame 32, and the bed device 33 has been described as an example. In the second embodiment, an example in which a PET apparatus includes a bed 3 having a top board 31, a support frame 32, and a bed device 33 will be described. The PET apparatus according to the second embodiment has the same configuration as the PET-CT apparatus according to the first embodiment shown in FIG. The line volume data generation circuit 42b, the scanogram generation circuit 42c, and the X-ray CT image generation circuit 42d are omitted, and the processing in the control function 43a and decision function 43b is partially different. Therefore, the same reference numerals as in FIG. 1 are assigned to the points having the same functions as the configuration described in the first embodiment, and the description thereof is omitted.

The control function 43 a according to the second embodiment controls the amount of feeding of the support frame 32 from the bed device 33 based on the position of the PET detector 11 . That is, the determination function 43 b according to the second embodiment determines the amount of feed of the top plate 31 from the support frame 32 by determining the amount of feed of the support frame 32 based on the position of the PET detector 11 .

For example, the decision function 43b decides to execute the control of the support frame 32 in the sag suppression mode described above. In such a case, the decision function 43b decides to move the support frame 32 to the position of the end of the PET detector 11 on the bed 3 side. Also, for example, the decision function 43b decides to execute control of the support frame 32 in the image quality priority mode described above. In such a case, the decision function 43b decides to move the support frame 32 to the position of the end of the PET gantry device 1 on the bed 3 side. The control function 43a controls the bed 3 according to the mode determined by the determination function 43b.

Furthermore, the determination function 43b according to the second embodiment can also determine the feed amount of the support frame 32 based on the information of the detection area used for imaging in the PET detector 11 . For example, in a Total-Body PET apparatus capable of scanning the whole body of a subject, when collecting a PET image using only a partial area of the PET detector 11 as the detection area, the determination function 43b determines the detection area , the feed amount of the support frame 32 is determined based on the position of .

FIG. 9 is a diagram for explaining an example of processing of the determination function 43b according to the second embodiment. For example, the determination function 43b acquires the positional information of the detection area in the PET detector 11. FIG. Based on the acquired position information, the determination function 43b then determines to move the support frame 32 to the end of the detection area of the PET detector 11 on the bed 3 side, as shown in FIG. The control function 43a controls the bed 3 according to the control content determined by the determination function 43b.

For example, imaging of PET images by a total-body PET apparatus requires an extremely large amount of data. When acquiring a PET image of a specific site using such a total-body PET apparatus, there may be a case where the detection area of the PET detector 11 is limited to a part in order to reduce the amount of data. In such a case, by performing the control described above, the PET apparatus according to the second embodiment can suppress the amount of data while suppressing the degree of sagging of the top plate 31 . In addition, below, the control which suppresses data amount is described as "data amount suppression mode."

Further, the determination function 43b according to the second embodiment determines the feed amount of the support frame 32 from the couch device 33 further based on the position information of the imaging target region of the subject. For example, the determination function 43b acquires position information of the imaging target region of the subject based on the imaging protocol and input information via the input interface 45 . Then, the determination function 43b determines the feed amount of the support frame 32 based on the relative positional relationship between the position of the detection region and the imaging target region. The control function 43a controls movement of the support frame 32 based on the delivery amount determined by the determination function 43b.

Next, an example of the procedure of processing by the PET apparatus will be described with reference to FIG. FIG. 10 is a flowchart for explaining an example of processing of the PET apparatus according to the second embodiment. Note that FIG. 10 shows processing in which the detection area and mode are determined and control is performed according to the determination result. Here, steps S204 and S205 in FIG. 10 are realized by the processing circuit 43 calling and executing a program corresponding to the control function 43a from the storage circuit 44. FIG. Steps S201 to S203 and step S206 in FIG. 10 are realized by the processing circuit 43 calling and executing a program corresponding to the determination function 43b from the storage circuit 44. FIG.

As shown in FIG. 10, in the PET apparatus, the processing circuit 43 determines whether or not the detection area is the entire PET detector 11 (step S201). Here, if the detection area is not the entire PET detector 11 (No at step S201), the processing circuit 43 determines whether or not it is in the data amount reduction mode (step S202). Here, if it is the data amount reduction mode (Yes at step S202), the processing circuit 43 determines the amount of movement of the support frame 32 based on the position of the detection area (step S203).

On the other hand, if the detection area is the entire PET detector 11 (Yes at step S201) and if the data amount reduction mode is not set (No at step S202), the processing circuit 43 sets the amount of movement of the support frame 32 to a preset value. Determine (step S206).

After determining the amount of movement of the support frame 32 in step S203 or step S206, the processing circuitry 43 moves the support frame 32 (step S204). Then, the processing circuit 43 controls to acquire PET images while controlling the movement of the tabletop 31 (step S205).

As described above, according to the second embodiment, the top plate 31 is placed with the subject. A support frame 32 supports the top plate. A couch device 33 supports the support frame. PET detectors 11 are arranged in a ring shape in the circumferential direction. The control function 43 a controls the amount of feeding of the support frame 32 from the couch device 33 based on the position of the PET detector 11 . Therefore, the PET apparatus according to the second embodiment can reduce the degree of sagging of the top plate 31 and reduce the influence of the sagging of the top plate 31 .

Also, according to the second embodiment, the control function 43 a is configured to move the support frame 32 to the position corresponding to the PET detector 11 in the first mode and to move the couch device 33 to the position corresponding to the PET detector 11 . , and the second mode in which the support frame 32 is moved to the side closer to the . Therefore, the PET apparatus according to the second embodiment makes it possible to perform imaging according to the situation while reducing the influence of sagging of the tabletop 31 .

Further, according to the second embodiment, the control function 43a controls the feeding amount of the support frame 32 from the couch device 33 further based on the position information of the imaging target region of the subject. Therefore, the PET apparatus according to the second embodiment enables control according to the imaging target region.

(Third embodiment)
Now, although the first and second embodiments have been described so far, various different modes other than the above-described first and second embodiments may be implemented.

In the first embodiment described above, the PET-CT apparatus has been described as an example of the medical image diagnostic system. However, the embodiments are not limited to this, and may be applied to other medical image diagnostic systems such as PET-MR devices, for example. That is, the above-described embodiment includes a first medical image diagnostic apparatus that generates a first medical image of a subject, and a second medical image that generates a second medical image that is different in type from the first medical image of the subject. It can be applied to a medical image diagnostic system provided with two medical image diagnostic apparatuses.

In such a case, a medical image diagnostic system including the first medical image diagnostic apparatus and the second medical image diagnostic apparatus includes the bed 3 and the processing circuit 43 described above. Then, the processing circuit 43 executes the processing of the control function 43a and the determination function 43b described above.

Further, in the first embodiment described above, the case where the bed device 33 is fixed to the floor surface has been described as an example. However, the embodiment is not limited to this, and the bed device 33 may be slid by a slide mechanism. In such a case, for example, when an electrocardiograph or the like is attached to the subject, by arranging the electrocardiogram monitor or the like on the bed device 33 , the bed device 33 is moved together with the movement of the support frame 32 . It is possible to prevent an electric meter or the like from coming off the subject.

Further, in the first embodiment described above, an example in which imaging by the PET gantry device 1 is performed after imaging by the CT gantry device 2 has been described. However, embodiments are not limited to this, and the order of imaging may be reversed. Further, the feeding direction of the top board 31 at the time of imaging may be from the side of the bed 3 to the side of the gantry device, or may be the opposite direction. Also, the support frame 32 may be moved out during imaging to perform imaging, and the moving direction may be from the side of the bed 3 to the side of the gantry device, or vice versa.

Further, in the above-described embodiment, the case where the subject is inserted into the imaging port from the head side has been described as an example. However, the embodiment is not limited to this, and for example, it may be inserted into the imaging port from the subject's foot side.

In addition, the term "processor" used in the above description includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an application specific integrated circuit (ASIC), a programmable logic device ( For example, it means circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA). The processor implements its functions by reading and executing programs stored in the storage circuit 420 . Note that instead of storing the program in the memory circuit 420, the program may be configured to be directly installed in the circuit of the processor. In this case, the processor implements its functions by reading and executing the program embedded in the circuit. Note that each processor of the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as one processor by combining a plurality of independent circuits to realize its function. good.

Here, the processing program executed by the processor is preinstalled in a ROM (Read Only Memory), storage unit, or the like and provided. This processing program is a file in a format that can be installed in these devices or a format that can be executed on a CD (Compact Disk)-ROM, FD (Flexible Disk), CD-R (Recordable), DVD (Digital Versatile Disk). may be stored and provided in a computer-readable storage medium such as Also, this processing program may be stored on a computer connected to a network such as the Internet, and may be provided or distributed by being downloaded via the network. For example, this processing program is composed of modules including each functional unit described later. As actual hardware, the CPU reads out a program from a storage medium such as a ROM and executes it, so that each module is loaded onto the main storage device and generated on the main storage device.

Also, each component of each device illustrated in the above-described embodiment is functionally conceptual, and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution and integration of each device is not limited to the one shown in the figure, and all or part of them can be functionally or physically distributed and integrated in arbitrary units according to various loads and usage conditions. Can be integrated and configured. Furthermore, all or any part of each processing function performed by each device can be implemented by a CPU and a program analyzed and executed by the CPU, or implemented as hardware based on wired logic.

According to at least one embodiment described above, it is possible to reduce the influence of sagging of the top plate.

While several embodiments of the invention have been described, these embodiments have been 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 modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

REFERENCE SIGNS LIST 1 PET cradle device 2 CT cradle device 31 Top plate 32 Support frame 33 Bed device 43 Processing circuit 43a Control function 43b Decision function

Claims (6)

an X-ray CT apparatus for scanning a subject by irradiating the subject with X-rays;
a PET device that produces functional images based on gamma rays emitted from a drug administered to a subject;
a top plate on which the subject is placed;
a support frame that supports the top plate;
a bed device that supports the support frame;
The bed device is arranged so that the relative distance between the tabletop and the support frame does not change when scanning the same part of the subject during scanning by the X-ray CT apparatus and scanning by the PET apparatus. a control unit that controls the amount of delivery of the support frame from
with
During scanning by the PET device, the control unit moves the support frame to a position corresponding to the detector of the PET device in a first mode and to a position closer to the bed device than the position corresponding to the detector. and a second mode in which the support frame is moved to the side, and the amount of movement of the support frame from the couch device during scanning by the X-ray CT device according to the mode executed during scanning by the PET device. A PET-CT machine that determines the During scanning by the X-ray CT apparatus and during scanning by the PET apparatus, the control unit moves the support frame between the detector centers of the X-ray CT apparatus and the PET apparatus in the delivery direction of the tabletop. 2. The PET-CT apparatus according to claim 1, wherein the PET-CT apparatus is controlled to move by a distance corresponding to the distance of . The control unit controls feeding of the top plate and the support frame so as to eliminate positional deviation of the top plate due to a difference between a scanning method by the X-ray CT apparatus and a scanning method by the PET apparatus. Item 1. The PET-CT apparatus according to item 1. a top plate on which the subject is placed;
a support frame that supports the top plate;
a bed device that supports the support frame;
a detector arranged in a ring shape;
a control unit for controlling the feed amount of the support frame from the couch device based on the position of the detection area used for imaging in the detector;
with
The control unit has a first mode of moving the support frame to a position corresponding to the detector, and a second mode of moving the support frame to a side closer to the bed apparatus than the position corresponding to the detector. Nuclear medicine diagnostic equipment that switches between modes . 5. The nuclear medicine diagnostic apparatus according to claim 4 , wherein said control unit controls the amount of movement of said support frame from said couch apparatus, further based on position information of an imaging target region of said subject. a first medical imaging diagnostic apparatus that generates a first medical image of a subject;
a second medical image diagnostic apparatus that generates a second medical image of a different type from the first medical image of the subject;
a top plate on which the subject is placed;
a support frame that supports the top plate;
a bed device that supports the support frame;
Relative distance between the top plate and the support frame when scanning the same part of the subject when scanning by the first medical image diagnostic apparatus and when scanning by the second medical image diagnostic apparatus a control unit for controlling the feed-out amount of the support frame from the couch device so as not to change;
with
During scanning by the second medical image diagnostic apparatus, the control unit includes a first mode for moving the support frame to a position corresponding to the detector of the second medical image diagnostic apparatus; Switching between a second mode of moving the support frame to a side nearer to the couch apparatus than the corresponding position, and switching the first medical image diagnostic apparatus according to a mode executed during scanning by the second medical image diagnostic apparatus. A medical diagnostic imaging system that determines the amount of movement of the support frame from the couch device during scanning by an imaging diagnostic device.

Images