JP7249831B2 - MEDICAL IMAGE DIAGNOSTIC DEVICE AND INSPECTION IMAGE GENERATION METHOD - Google Patents

Description

TECHNICAL FIELD Embodiments of the present invention relate to a medical image diagnostic apparatus and an inspection image generation method.

Recently, a composite device (hereinafter referred to as a SPECT-CT device) has been developed that integrates an X-ray CT (Computed Tomography) device for reconstructing morphological images and a SPECT (Single Photon Emission computed Tomography) device for reconstructing functional images. It is

According to the SPECT-CT apparatus, the subject can undergo two kinds of examinations in one examination, so the burden on the subject can be reduced. Moreover, since the user can simultaneously refer to the morphological image and the functional image of the same part of the subject, it is possible to perform highly accurate image diagnosis.

By the way, if imaging becomes impossible after administration of radiopharmaceuticals due to malfunction of the gamma ray detector of the SPECT apparatus, the subject will be exposed to unnecessary radiation, and the quality of medical services will be degraded. In addition, when artifacts occur in scintigrams due to defects in the gamma ray detector, misdiagnosis without being noticed by the user can lead to medical accidents. Therefore, for quality control of the gamma ray detector, it is preferable to perform a daily inspection of the SPECT apparatus at the start of work (hereinafter referred to as start-up inspection). Inspection items in the start-up inspection of SPECT equipment include, for example, energy peaks due to the nuclide used, abnormal accumulation of gamma ray detectors, presence or absence of defects, uniformity, rotation center, etc. For example, visual recognition of a misaligned image can be mentioned.

However, in this type of pre-work inspection, which is performed every time the SPECT system starts work, a vial or syringe containing a solution of radioisotope (RI), which is the radiation source for the pre-work inspection, is used. . For this reason, the engineer needs to be present at each start-up inspection to install the radiation source for the start-up inspection, and is exposed to radiation from the radiation source each time the start-up inspection is performed. In addition, since the radiation source for the start-up inspection uses a radiation source with a dose equivalent to that of the RI administered to the subject during normal imaging, it takes time to accumulate the counts required for imaging. Unfortunately, it may take a long time, such as 30 minutes to an hour or more. In addition, since the RI is prepared every time as a radiation source for the start-up inspection, the start-up inspection is costly.

U.S. Pat. No. 8,049,175

A problem to be solved by the present invention is to perform a start-up inspection of a gamma ray detector without using RI.

A medical image diagnostic apparatus according to an embodiment includes an X-ray tube, an X-ray detector, a gamma ray detector, and a generator. The X-ray tube emits X-rays. The X-ray detector detects X-rays emitted from the X-ray tube. A gamma ray detector detects gamma rays emitted from a radiation source administered to a subject. The generator generates image data by detecting X-rays emitted from the X-ray tube with a gamma ray detector.

1 is an external view showing an example of a SPECT-CT apparatus according to one embodiment; FIG. FIG. 2 is a block diagram showing a configuration example of a SPECT-CT apparatus; FIG. 4 is an explanatory diagram showing an example of a case where an X-ray detector detects X-rays emitted from an X-ray tube; FIG. 4 is an explanatory diagram showing an example of a first method for inspection imaging according to the present embodiment; (a) is an explanatory diagram showing an example of the second method of inspection imaging according to the present embodiment, and (b) is an explanatory diagram showing another example of the second method of inspection imaging according to the present embodiment. Explanatory drawing which shows an example of the SPECT image for inspection. (a) is an explanatory diagram showing a first modification of the first method and the second method of inspection imaging, and (b) is an explanation showing a second modification of the first method and the second method of inspection imaging. figure. FIG. 5 is a diagram for explaining inspection imaging for checking rotation center shift; 4 is a flow chart showing an example of a procedure for performing a start-up inspection of a gamma ray detector without using RI by the SPECT-CT apparatus according to the present embodiment;

Hereinafter, embodiments of a medical image diagnostic apparatus and an inspection image generation method will be described in detail with reference to the drawings.

In the following description, an example of a case of using a composite apparatus (SPECT-CT apparatus) of a SPECT apparatus and an X-ray CT apparatus as the medical image diagnostic apparatus according to the embodiment will be shown.

FIG. 1 is an external view showing an example of a SPECT-CT apparatus 10 according to one embodiment. FIG. 2 is a block diagram showing one configuration example of the SPECT-CT apparatus 10. As shown in FIG.

The SPECT-CT device 10 has a gamma ray scanner device 20, an X-ray scanner device 30, a console 50, and a bed device 40. The SPECT-CT apparatus 10 is an example of a medical image diagnostic apparatus. Note that the console 50 need only be connected to the gamma-ray data acquisition circuit 24 and the X-ray data acquisition circuit 34 so that data can be transmitted and received. good.

As shown in FIG. 1, the gamma ray scanner device 20 and the X-ray scanner device 30 have a SPECT pedestal 21 and an X-ray CT pedestal 31, respectively. The SPECT pedestal 21 and the X-ray CT pedestal 31 respectively have cylindrical hollow portions 21a and 31a into which the top plate 41 is transferred. The SPECT mount 21 has a rotating mount and a fixed mount that rotatably supports the rotating mount. The X-ray CT pedestal 31 also has a rotating pedestal and a fixed pedestal.

As shown in FIG. 1, in this embodiment, the longitudinal direction of the top plate 41 of the bed device 40 is the z-axis direction, and the axial direction perpendicular to the z-axis direction is the x-axis direction. The axial direction perpendicular to the z-axis direction and perpendicular to the floor surface is defined as the y-axis direction.

The gamma ray scanner device 20 has a collimator 22, a gamma ray detector 23 to which the collimator 22 is detachably mounted, and a gamma ray data acquisition circuit 24 in a SPECT mount 21 (see FIG. 2).

The gamma ray scanner device 20 has the same configuration as, for example, a gamma ray detector rotating type SPECT device. FIG. 1 shows an example in which the gamma ray scanner device 20 has a configuration similar to a two-detector type gamma ray detector rotating SPECT device. good.

The collimator 22 is made of a material such as lead or tungsten that does not easily transmit radiation, and is provided with an opening for defining the incident angle of photons. The spatial resolution and sensitivity of the gamma ray scanner device 20 change according to the type of collimator 22 . The type of collimator 22 differs depending on the thickness of partition walls, the number of apertures, the field of view, the focal position, and the like. Types of collimators 22 that can be used for the gamma ray detector 23 include, for example, parallel hole collimators, fan beam collimators, cone beam collimators, astigmatic collimators, pinhole collimators, diverging collimators, converging collimators, and slant hole collimators. Various can be used.

Two gamma ray detectors 23 are held on a rotating frame of the SPECT frame 21 . The two gamma ray detectors 23 are integrally rotated around the rotation axis r by rotating the rotary gantry around the predetermined rotation axis r (z-axis). The rotating pedestal has a rotating plate rotatably supported with respect to the fixed pedestal. The gamma ray detector 23 is held on the rotating plate of this rotating gantry. The fixed pedestal is composed of a housing fixed to a base. The rotating cradle and the fixed cradle are covered, for example, by a cradle cover. A hollow portion 21a that encloses an imaging region is provided in the central portion of the rotary pedestal, the fixed pedestal, and the pedestal cover that covers them.

The gamma ray detector 23 detects gamma rays emitted from RI (radioisotope, radiation source) such as technetium administered to a subject (for example, a patient). The gamma ray detector 23 may be a scintillator type detector or a semiconductor type detector.

When the gamma ray detector 23 is a scintillator type detector, the gamma ray detector 23 includes a scintillator that emits an instantaneous flash of light when the gamma ray collimated by the collimator 22 is incident, a light guide, and the light emitted from the scintillator. It has a plurality of photomultiplier tubes arranged two-dimensionally for detection, an electronic circuit for a scintillator, and the like. The scintillator is composed of, for example, thallium-activated sodium iodide NaI (Tl).

The electronic circuit for the scintillator acquires incident position information of the gamma rays within the detection plane composed of the multiple photomultiplier tubes based on the outputs of the multiple photomultiplier tubes each time an event of incident gamma rays occurs. (Position information), incident intensity information and incident time information are generated and output to the processing circuit 55 of the console 50 . This position information may be two-dimensional coordinate information within the detection plane, or the detection plane may be virtually divided in advance into a plurality of divided regions (primary cells) (for example, divided into 128×128 cells). ), and information indicating to which primary cell the incident occurred.

On the other hand, when the gamma ray detector 23 is a semiconductor type detector, the gamma ray detector 23 includes a plurality of gamma ray detection semiconductor elements (hereinafter referred to as (referred to as a semiconductor element), electronic circuits for semiconductors, and the like. The semiconductor element is made of CdTe or CdZnTe (CZT), for example.

The semiconductor electronic circuit generates incident position information, incident intensity information, and incident time information based on the output of the semiconductor element each time a gamma ray incident event occurs, and outputs the information to the processing circuit 55 . This positional information is information indicating which semiconductor element among a plurality of semiconductor elements (eg, 128×128 pieces) the light is incident on.

That is, the gamma ray detector 23 outputs incident position information, incident intensity information, and incident time information for each event. The positional information is at least one of information indicating which position of the primary cell the gamma ray is incident on and information on two-dimensional coordinates within the detection plane.

The imaging timing of the gamma ray detector 23 is controlled by the processing circuit 55 .

The gamma ray data acquisition circuit 24 is configured, for example, by a printed circuit board and is controlled by a processing circuit 55 to acquire the respective outputs of the two gamma ray detectors 23, for example in list mode, and output the acquired projection data to the console 50. do. In the list mode, gamma ray detection position information, intensity information, information indicating the relative position between the gamma ray detector 23 and the subject (position and angle of the gamma ray detector 23, etc.), and gamma ray detection time are displayed for each gamma ray incident event. to be collected.

On the other hand, the X-ray scanner device 30 has an X-ray tube 32 , an X-ray movable aperture 32 a , an X-ray detector 33 and an X-ray data acquisition circuit 34 in an X-ray CT frame 31 .

The X-ray tube 32 is a vacuum tube that generates X-rays by irradiating thermal electrons from a cathode (filament) to an anode (target) by applying a high voltage from a high voltage device.

The X-ray scanner device 30 may have a configuration similar to that of a single-tube type X-ray CT device, or a so-called multiple scanner device in which a plurality of pairs of X-ray tubes and detectors are mounted on a rotating ring. The configuration may be similar to that of a tube-type X-ray CT apparatus. Also, hardware for generating X-rays is not limited to the X-ray tube 32 . For example, in place of the X-ray tube 32, a focus coil for converging the electron beam generated from the electron gun and a deflection coil for electromagnetic deflection collide with the deflected electron beam surrounding the half circumference of the object to generate X-rays. X-rays may be generated using a configuration similar to that of the fifth-generation CT, including a target ring for generating X-rays.

The X-ray movable diaphragm 32a is a lead plate or the like for narrowing down the X-ray irradiation range, and forms a slit by combining a plurality of lead plates or the like. The X-ray movable diaphragm 32a is controlled by the processing circuit 55 to change the X-ray irradiation range.

For example, the X-ray movable diaphragm 32 a can be positioned at a position that directs the X-ray emitted from the X-ray tube 32 to the X-ray detector 33 . Also, the X-ray movable diaphragm 32 a according to this embodiment can be positioned at a position where the X-ray emitted from the X-ray tube 32 is directed to the gamma ray detector 23 .

The X-ray detector 33 detects X-rays emitted from the X-ray tube 32 and passing through the subject, and outputs an electrical signal corresponding to the X-ray dose to the DAS 18 . The X-ray detector 33 has a plurality of X-ray detection element arrays in which a plurality of X-ray detection elements are arranged in the channel direction along one circular arc centering on the focal point of the X-ray tube 32 . Further, the X-ray detector 33 has a structure in which a plurality of X-ray detection element rows (for example, 320 rows) in which a plurality of X-ray detection elements are arranged in the channel direction are arranged in the slice direction (column direction, row direction). have.

Also, the X-ray detector 33 is, for example, an indirect conversion type detector having a grid, a scintillator array, and a photosensor array. The scintillator array has a plurality of scintillators, and each scintillator has a scintillator crystal that outputs a photon amount of light corresponding to the amount of incident X-rays. The grid has an X-ray shielding plate arranged on the surface of the scintillator array on the X-ray incident side and having a function of absorbing scattered X-rays. Note that the grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator). The photosensor array has a function of converting the amount of light from the scintillator into an electrical signal, and includes photosensors such as photomultiplier tubes (PMTs).

Note that the X-ray detector 33 may be a direct conversion detector having a semiconductor element that converts incident X-rays into electrical signals.

An X-ray data acquisition circuit (DAS (Data Acquisition System)) 34 includes an amplifier that amplifies an electric signal output from each X-ray detection element of the X-ray detector 33, and an analog-to-digital conversion ( and an A/D converter for AD conversion) to generate detection data. The X-ray data acquisition circuit 34 is a conversion board composed of a plurality of signal processing boards (hereinafter referred to as AD conversion boards) having signal processing circuits such as IV converters and AD converters for receiving data from X-ray detection elements. have a group. Detected data generated by the x-ray data acquisition circuit 34 is transferred to the console 50 .

The rotating gantry of the X-ray CT gantry 31 rotates around the same rotation axis as the rotating gantry of the SPECT gantry 21 . The rotating frame of the X-ray CT frame 31 is an annular frame that supports the X-ray tube 32 and the X-ray detector 33 facing each other and rotates the X-ray tube 32 and the X-ray detector 33 around the z-axis. be. In addition to the X-ray tube 32 and X-ray detector 33 , the rotating gantry also supports a high voltage device and an X-ray data acquisition circuit 34 . The detection data generated by the X-ray data acquisition circuit 34 is transmitted by optical communication from a transmitter having a light-emitting diode (LED) provided on the rotating pedestal to a photodiode provided on the fixed pedestal of the X-ray CT pedestal 31. , and forwarded to the console 50 . The method of transmitting the detected data from the rotating gantry of the X-ray CT gantry 31 to the fixed gantry is not limited to optical communication, and any method of non-contact data transmission may be adopted.

The bed device 40 is a device for placing and moving a subject to be scanned, and includes a tabletop 41, a base, a bed driving device, and a support frame.

The base is a housing that supports the support frame so as to be movable in the vertical direction (y direction). The bed driving device is a motor or actuator that moves the table 41 on which the subject is placed in the long axis direction (z direction) of the table 41 . A top plate 41 provided on the upper surface of the support frame is a plate on which the subject is placed.

The bed driving device may move the support frame in addition to the top plate 41 in the long axis direction (z direction) of the top plate 41 . Further, the bed drive device may move the base of the bed device 40 together.

The console 50 is composed of, for example, a general personal computer or workstation, and has an input interface 51 , a display 52 , a memory circuit 53 , a network connection circuit 54 and a processing circuit 55 . Note that the console 50 may not be provided independently. may be provided.

The input interface 51 is composed of general input devices such as a trackball, switch button, mouse, keyboard, numeric keypad, etc., and outputs operation input signals corresponding to user's operations to the processing circuit 55 . For example, the user can specify the region to be imaged and the RI used in the examination via the input interface 51 .

The display 52 is composed of a general display output device such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display.

The storage circuit 53 has a configuration including a processor-readable recording medium such as a magnetic or optical recording medium or a semiconductor memory. A part or all of the programs and data in these recording media may be configured to be downloaded by communication via an electronic network.

The network connection circuit 54 is composed of, for example, a network card having a predetermined printed circuit board, and implements various information communication protocols according to the form of the network. The network connection circuit 54 connects the nuclear medicine diagnosis apparatus 1 and other devices according to these various protocols. An electrical connection via an electronic network or the like can be applied to this connection. The term “electronic network” as used herein refers to all information communication networks using telecommunication technology, including wireless/wired hospital LANs (Local Area Networks), Internet networks, telephone communication networks, optical fiber communication networks, cable networks, etc. Including communication networks and satellite communication networks.

The processing circuit 55 is a processor that reads out and executes a program stored in the storage circuit 53 to perform processing for performing a start-up inspection of the gamma ray detector 23 without using RI.

As shown in FIG. 2 , the processor of the processing circuit 55 implements an inspection imaging control function 551 , an image generation function 552 and a rotation control function 553 . Each of these functions is stored in the memory circuit 53 in the form of a program.

The inspection imaging control function 551 controls the gamma ray scanner device 20 and the X-ray scanner device 30, and performs imaging ( hereinafter referred to as inspection imaging) is executed.

The image generation function 552 generates image data based on the output of the gamma ray detector 23 that has detected the X-rays emitted from the X-ray tube 32 . For example, when inspection imaging is performed, the image generation function 552 generates image data for inspection of the gamma ray detector 23 based on the output of the gamma ray detector 23 that has detected X-rays emitted from the X-ray tube 32. , based on this image data, a SPECT image for inspection of the gamma ray detector 23 (hereinafter referred to as an inspection SPECT image) is generated and displayed on the display 52 . The image generation function 552 is an example of a generation unit.

The inspection SPECT image is at least an image for determining the presence or absence of abnormal accumulation of the gamma ray detector 23, an image for determining the presence or absence of loss, an image for determining uniformity, and an image for misalignment of the rotation center of the gamma ray detector 23. Contains one image.

In checking for abnormal accumulation and loss, it is checked whether there is a place where the count is overestimated or a place where the count is not included at all in the PMT of the gamma ray detector 23 . In the confirmation of uniformity, it is confirmed whether the emitted radiation can be uniformly detected on the detection surface of the gamma ray detector 23, and whether there is unevenness or an unintended decrease in brightness. For example, uniformity is lost if the gamma ray detector 23 rolls or flexes during rotation.

By checking the SPECT image for inspection generated based on the X-rays emitted from the X-ray tube 32 without using the RI for inspection, the user can check the presence or absence of abnormal accumulation, defect, and uniformity of the gamma ray detector. The gamma ray detector 23 can be inspected at the beginning of work by visually checking the performance and rotation center deviation.

In addition, the image generation function 552 may analyze the SPECT image for inspection captured this time and, if an abnormality is detected, display an image to that effect on the display 52 .

The rotation control function 553 is controlled by the inspection imaging control function 551 at the time of inspection imaging for confirming rotation center shift, so that the X-ray tube 32 and the gamma ray detector 23 rotate on the xy plane coordinates orthogonal to the rotation axis. The rotation of the X-ray tube 32 and the rotation of the gamma ray detector 23 are synchronized so as to face each other. This rotation synchronization will be described later with reference to FIG.

FIG. 3 is an explanatory diagram showing an example in which the X-ray detector 33 detects X-rays emitted from the X-ray tube 32. As shown in FIG.

As shown in FIG. 3, the X-rays emitted from the X-ray tube 32 are usually regulated in an irradiation range so as to irradiate the X-ray detector 33 by the X-ray movable diaphragm 32a. At this time, the direct X-ray flux 61 irradiates the X-ray detector 33 and does not irradiate the gamma ray detector 23 .

On the other hand, when the direct beam of X-rays 61 irradiates the X-ray detector 33 , scattered X-rays are considered to irradiate the gamma-ray detector 23 .

Therefore, the SPECT-CT apparatus 10 according to the present embodiment generates an inspection image using X-rays emitted from the X-ray tube 32 without using RI during inspection imaging.

FIG. 4 is an explanatory diagram showing an example of the first method of inspection imaging according to the present embodiment. A first method of inspection imaging is a method of performing inspection imaging using scattered X-rays. As shown in FIG. 4 , when a direct beam of X-rays 61 irradiates the X-ray detector 33 , a scattered beam of X-rays 62 irradiates the gamma-ray detector 23 .

In the first inspection imaging method, the inspection imaging control function 551 causes the X-ray detector 33 to be directly irradiated with the beam of rays 61 from the X-ray tube 32 via the X-ray movable diaphragm 32a. At this time, the gamma ray detector 23 detects scattered X-rays emitted from the X-ray tube 32 . In addition, the image generation function 552 generates inspection image data based on the output of the gamma ray detector 23 based on the scattered radiation, and generates inspection SPECT images of the gamma ray detector 23 based on this inspection image data. to display on the display 52.

FIG. 5A is an explanatory diagram showing an example of the second method of inspection imaging according to the present embodiment, and FIG. 5B is an explanation showing another example of the second method of inspection imaging according to the present embodiment. It is a diagram.

A second method of inspection imaging is a method of performing inspection imaging using direct X-ray rays.

In the second inspection imaging method, the inspection imaging control function 551 causes the gamma ray detector 23 to be directly irradiated with the beam 61 from the X-ray tube 32 via the X-ray movable diaphragm 32a. At this time, the gamma ray detector 23 detects the direct rays of X-rays emitted from the X-ray tube 32 .

If the intensity of the direct X-ray emitted from the X-ray tube 32 is too strong for the gamma ray detector 23, it is preferable to use a filter for attenuating the intensity. For example, the radiation source side filter 35 may be provided near the X-ray movable diaphragm 32a, and the radiation source side filter 35 may be moved to attenuate the intensity of direct rays directed from the X-ray tube 32 to the gamma ray detector 23 (FIG. 5). (a)).

Alternatively, the detector-side filter 25 may be provided near the gamma-ray detector 23 to attenuate the intensity of direct rays from the X-ray tube 32 toward the gamma-ray detector 23 (see FIG. 5(b)). reference). The detector-side filter 25 may be provided on or near the front surface of the collimator 22 (see FIG. 5B), or may be attached on the front surface of the gamma ray detector 23 in place of the collimator 22 .

Also, the source-side filter 35 and the detector-side filter 25 may be used together. The source-side filter 35 and the detector-side filter 25 are formed by processing a material such as aluminum that attenuates X-rays.

In the second method of inspection imaging, the image generation function 552 generates inspection image data based on the output of the gamma ray detector 23 based on direct rays, and based on this inspection image data, the gamma ray detector 23 is generated and displayed on the display 52 .

FIG. 6 is an explanatory diagram showing an example of a SPECT image for inspection. On the detection surface of the gamma ray detector 23 , the X-ray energy irradiated is higher at a position closer to the X-ray CT stand 31 and closer to the X-ray tube 32 than at a position farther from the X-ray CT stand 31 . FIG. 6 shows an example in which inspection SPECT images are generated such that the higher the energy, the darker the color.

It should be noted that the geometrical conditions and X-ray conditions such as the X-ray tube 32, the X-ray movable aperture 32a, the gamma-ray detector 23, etc. at the time of inspection imaging and the inspection SPECT image (reference image) under these geometrical conditions are prepared in advance. , and an RI_SPECT image obtained by inspection imaging using a conventional RI may be stored in the storage circuit 53 in association with each other. In this case, the image generation function 552 simultaneously displays the SPECT image for inspection captured this time and the reference image associated with the same geometrical conditions and X-ray conditions as this imaging on the display 52 by parallel display or the like. can be made

FIG. 7A is an explanatory diagram showing a first modification of the first method and the second method of inspection imaging, and FIG. 7B is a second modification of the first method and the second method of inspection imaging. FIG. 4 is an explanatory diagram showing an example;

In the first method and the second method of inspection imaging shown in FIGS. 4 and 5, respectively, as shown in FIG. There is a large difference in the energy of X-rays irradiated at a distant position. Therefore, regardless of whether the first inspection imaging method using scattered rays or the second inspection imaging method using direct rays is used, the gamma ray detector 23 and the collimator 22 are rotated together. Aiming at the X-ray tube 32 (see FIG. 7(a)), or attaching a collimator 22 pointing at the X-ray tube 32 (FIG. 7(b)), the emitted X-rays within the detection plane of the gamma ray detector 23 The difference in energy may be small.

In the first inspection imaging method shown in FIG. 4, scattered X-rays attenuated by the collimator 22 irradiate the gamma ray detector 23 . In this case, the detected peak is not a sharp peak, but rather a peak with a certain width. However, the window width and window level are set so as to detect such a broad X-ray width. can be detected without problems. In addition, X-rays that do not have sharp peaks may not be used as long as inspection SPECT images are generated in the start-up inspection. Moreover, it can be said that detecting a wider band can support various inspections.

On the other hand, when applying the first modified example or the second modified example shown in FIGS. 7A and 7B to the second inspection imaging method using direct rays, Even if attenuated by at least one of the filters 25, the gamma ray detector 23 is illuminated by a direct ray of X-rays having a relatively sharp peak. In this case, for example, by setting the window width and the window level in detail according to the inspection site of the subject for the next actual SPECT imaging, it is possible to confirm the actual SPECT imaging in advance.

FIG. 8 is a diagram for explaining inspection imaging for checking rotation center shift.

The rotation control function 553 is controlled by the inspection imaging control function 551 to rotate the X-ray tube 32 and the gamma rays so that the X-ray tube 32 and the gamma ray detector 23 face each other on the xy plane coordinates orthogonal to the rotation axis. Synchronize the rotation of the detector 23; The image generation function 552 generates image data based on X-rays detected by the gamma ray detector 23 during synchronous rotation of the X-ray tube 32 and gamma ray detector 23 . At this time, the first method of inspection imaging may be used, or the second method may be used. Alternatively, the first modified example or the second modified example illustrated in FIG. 7 may be used.

The inspection imaging control function 551 performs inspection imaging by causing the X-ray tube 32 and the gamma ray detector 23 to face each other and synchronously rotating them for each condition that causes sagging or bending of the gamma ray detector 23 . The image generation function 552 obtains data for correcting the deviation of the center of rotation based on the image data obtained for each condition, generates an image showing the data, and displays it on the display 52 . Conditions that cause sag and deflection of the gamma ray detector 23 include, for example, rotational speed. In addition, when checking the gamma ray detector 23 for sagging or bending, it is preferable to take still images at predetermined angles.

Next, an example of the operation of the SPECT-CT apparatus 10 according to this embodiment will be described.

FIG. 9 is a flow chart showing an example of the procedure when the SPECT-CT apparatus 10 according to the present embodiment performs the start-up inspection of the gamma ray detector 23 without using RI. In FIG. 9, numerals attached to S indicate respective steps of the flow chart.

First, in step S<b>1 , the inspection imaging control function 551 causes the X-ray tube 32 to emit X-rays. Next, in step S<b>2 , the gamma ray detector 23 detects X-rays emitted from the X-ray tube 32 .

Next, in step S3, the image generation function 552 generates image data based on the output of the gamma ray detector 23 based on X-rays. Then, in step S<b>4 , the image generation function 552 generates an inspection image (inspection SPECT image) of the gamma ray detector 23 based on the image data, and displays it on the display 52 .

By the above procedure, the start-up inspection of the gamma ray detector 23 can be performed without using RI.

The gamma ray detector 23 of the SPECT-CT apparatus 10 according to this embodiment detects scattered rays or direct rays of X-rays emitted from the X-ray tube 32 of the X-ray scanner device 30, and an image based on the detected X-rays is detected. data can be generated.

Therefore, it is possible to cause the gamma ray detector 23 to detect X-rays without using RI at the time of start-up inspection. Therefore, the technician is extremely safe without being exposed to radiation from RI every time an inspection is performed at the start of work. In addition, the engineer does not need to be present to install the radiation source for the start-of-work inspection every time the start-of-work inspection is performed, which reduces the burden on the engineer. In addition, X-ray can be imaged in a much shorter time than RI, which requires a long time to image, so that the time required for the start-up inspection can be greatly shortened. Also, since it is not necessary to purchase an RI for the start-up inspection, the cost for the start-up inspection can be reduced.

Further, by comparing the image data based on the X-rays detected by the gamma ray detector 23 over time, it becomes possible to detect an abnormality of the X-ray tube 32 .

According to at least one embodiment described above, the start-up inspection of the gamma ray detector 23 can be performed without using RI.

In the above embodiment, the word "processor" is, for example, a dedicated or general-purpose CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), Circuits such as programmable logic devices (eg, Simple Programmable Logic Devices (SPLDs), Complex Programmable Logic Devices (CPLDs), and FPGAs) shall be meant. The processor implements various functions by reading and executing programs stored in the storage medium.

Further, in the above embodiments, an example of a case where a single processor of the processing circuit realizes each function is shown, but a processing circuit is configured by combining a plurality of independent processors, and each processor realizes each function. good too. Further, when a plurality of processors are provided, a storage medium for storing programs may be provided individually for each processor, or a single storage medium may collectively store programs corresponding to the functions of all processors. good too.

It should be noted that although several embodiments of the invention have been described, these embodiments are provided 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.

1 nuclear medicine diagnosis device 10 SPECT-CT device 11 X-ray tube 20 gamma ray scanner device 21 SPECT stand 22 collimator 23 gamma ray detector 25 detector side filter 30 X-ray scanner device 31 X-ray CT stand 32 X-ray tube 32a X Ray movable diaphragm 33 X-ray detector 35 Source-side filter 50 Console 55 Processing circuit 61 Direct beam 62 Scattered beam 551 Inspection imaging control function 552 Image generation function 553 Rotation control function

Claims (9)

an X-ray tube that emits X-rays;
an X-ray detector that detects the X-rays emitted from the X-ray tube;
a gamma ray detector that detects gamma rays emitted from a radiation source administered to a subject;
A generation unit that generates image data by detecting the X-rays emitted from the X-ray tube with the gamma -ray detector, and generates an image for inspection of the gamma-ray detector based on the image data. and,
A medical diagnostic imaging device with The gamma ray detector is
detecting scattered radiation of the X-ray emitted from the X-ray tube;
The generating unit
generating the image data based on the output of the gamma ray detector based on the scattered radiation;
The medical image diagnostic apparatus according to claim 1. an X-ray aperture that directs the X-rays emitted from the X-ray tube to the gamma ray detector;
further comprising
The gamma ray detector is
detecting a direct ray of the X-ray emitted from the X-ray tube;
The generating unit
generating the image data based on the output of the gamma ray detector based on the direct rays;
The medical image diagnostic apparatus according to claim 1. a source-side filter provided near the X-ray diaphragm for attenuating the intensity of the direct rays directed from the X-ray tube to the gamma ray detector;
4. The medical image diagnostic apparatus according to claim 3, further comprising: a detector-side filter provided near the gamma-ray detector for attenuating the intensity of the direct rays directed from the X-ray tube to the gamma-ray detector;
The medical image diagnostic apparatus according to claim 3 or 4, further comprising: The detector-side filter is
attached to the front of a collimator attached to the front of the gamma ray detector;
The medical image diagnostic apparatus according to claim 5. the X-ray tube and the gamma ray detector rotate about the same axis of rotation;
a rotation control unit for synchronizing the rotation of the X-ray tube and the gamma-ray detector so that the X-ray tube and the gamma-ray detector face each other on an in-plane coordinate orthogonal to the rotation axis;
further comprising
The generating unit
generating the image data based on the X-rays detected by the gamma-ray detector during synchronous rotation of the X-ray tube and the gamma-ray detector;
The medical image diagnostic apparatus according to any one of claims 1 to 6 . The image for inspection of the gamma ray detector is
At least one of an image for determining the presence or absence of abnormal accumulation of the gamma ray detector, an image for determining the presence or absence of loss, an image for determining uniformity, and an image for deviation of the rotation center,
The medical image diagnostic apparatus according to claim 1 . An inspection image generation method for generating an inspection image of a gamma ray detector that detects gamma rays emitted from a radiation source administered to a subject, comprising:
a step in which the gamma ray detector detects X-rays emitted from an X-ray tube;
generating image data for inspection of the gamma ray detector based on the output of the gamma ray detector based on the X-rays;
An inspection image generation method comprising:

Images