JP4400641B2 - Radiation inspection apparatus and positron emission CT apparatus - Google Patents

Description

The present invention relates to a radiation inspection apparatus and a radiation inspection method using radiation, and more particularly to X-ray CT.
And positron emission computed tomography (positron emission computed tomography)
(Positron Emission Computed Tomography), hereinafter referred to as PET)
Or X-ray CT and single photon emission computed tomography (Single Photon Emission Computed Tomography),
The present invention relates to a radiation inspection apparatus and a radiation inspection method suitable for performing a radiation inspection by SPECT).

Examples of radiation examinations using the human body as a subject include X-ray CT, PET, and SPECT.
PET and SPECT measure the physical quantity of the integral value (flight direction) of the radiation emitted from the human body, and calculate and image the physical quantity of each voxel in the human body by back projecting the integral value. For this imaging, it is necessary to process enormous data. The rapid development of computer technology in recent years has made it possible to provide tomographic images of the human body at high speed and with high definition.

PET and SPECT can detect a function and metabolism at a molecular biology level that cannot be detected by X-ray CT or the like, and can provide a functional image in the body of the examinee.

PET is a positron emitting nuclide ( ¹⁵ O, ¹³ N, ¹¹ C, ¹⁸ F, etc., with a half-life of 2 to 110 minutes)
A radiopharmaceutical (hereinafter referred to as a “PET drug”) containing selenium is administered to a subject to be examined, and it is examined in which part of the body the PET drug is consumed. As an example of a drug for PET, fluorodeoxyglucose (2- [F-18] fluoro-2-deoxy-D-glucose,
¹⁸ FDG). ^{Since 18} FDG is highly accumulated in tumor tissue by sugar metabolism, it is used to identify a tumor site. A positron emitted from a positron emitting nuclide contained in a PET drug accumulated at a specific location is combined with an electron in a nearby cell and disappears to emit a pair of γ-rays having energy of 511 keV. These γ-rays are almost opposite to each other (180 ° ± 0.6 °
). If this pair of γ rays (referred to as γ ray pairs) is detected by a radiation detector, which 2
It can be seen whether positrons were emitted between the two radiation detectors. By detecting a large number of gamma ray pairs, a place where a lot of PET drug is consumed can be found. For example, since ¹⁸ FDG gathers in cancer cells with intense glucose metabolism as described above, it is possible to detect cancer foci by PET. In addition, the obtained data is obtained by using the filtered back projection method (Filtered Back Projection Method) described in pages 228 to 229 of the IEEE Transaction on Nuclear Science NS-21 volume. It is converted to the radiation generation density of γ-rays and contributes to imaging the generation position of γ rays (position where radionuclides accumulate, that is, the position of cancer cells).

SPECT is a substance that has the property of accumulating in a specific tumor or molecule, and a radiopharmaceutical containing a single photon emitting nuclide ( ⁹⁹ Tc, ⁶⁷ Ga, ²⁰¹ Tl, etc.) (referred to as SPECT drug) is administered to the subject. Γ-rays emitted from the nuclide are detected with a γ-ray detector. The energy of γ rays emitted from the single photon emitting nuclide is around several hundred keV. Since the SPECT drug accumulates in an affected area of cancer, the affected area of cancer can be identified. Also in the case of SPECT, the obtained data is converted into data of each voxel by a method such as filtered back projection. Note that transmission images are often taken even in SPECT. ⁹⁹ Tc,
⁶⁷ Ga, ²⁰¹ Tl is 6 hours to 3 days longer than the half-life of the radioisotope used for PET.

As described above, PET and SPECT can extract a site where radiopharmaceuticals are accumulated with good contrast in order to obtain a functional image using in-vivo metabolism, but there is a problem that the positional relationship with surrounding organs cannot be grasped. Therefore, in recent years, attention has been paid to a technique for performing a more advanced diagnosis by synthesizing a morphological image, which is a tomographic image obtained by X-ray CT, and a functional image, which is a tomographic image obtained by PET or SPECT. As an example of this technique, there is a technique described in JP-A-7-20245.

In the radiation inspection apparatus described in Japanese Patent Laid-Open No. 7-20245, an X-ray CT inspection apparatus and a PET inspection apparatus are installed in series, and the bed on which the examinee lies is moved horizontally to use both inspection apparatuses To examine the patient. That is, an X-ray CT examination is performed on the examinee using an X-ray CT examination apparatus, and then PET on the examinee is conducted using a PET examination apparatus.
Perform an inspection. The PET data and the X-ray CT data, which are the respective imaging data obtained by the two inspection apparatuses, are synthesized and the lesion position of the examinee is specified.

Japanese Laid-Open Patent Publication No. 9-5441 describes a radiation inspection apparatus in which an X-ray CT inspection apparatus and a SPECT inspection apparatus are arranged in series using a bed. X-ray CT data, which is imaging data obtained by each inspection apparatus, and SPECT data are combined to identify the lesion position of the examinee.

Japanese Patent Laid-Open No. 7-20245 Japanese Patent Laid-Open No. 9-5441

In the radiation inspection apparatus described in each of the above publications, two different inspections are performed in a state of being out of position. Naturally, both inspections have a time interval.

The object of the present invention is to improve the diagnostic accuracy of the subject, and even if the X-ray source is irradiated by the circumferential movement of the X-ray source, the X-ray source is located outside the radiation detector. they block the γ-rays emitted from the examinee, radiation detectors located in their right behind its no longer possible to detect γ-rays to provide a completely that a no radiological imaging apparatus and a radiographic inspection method There is.

A feature of the first invention to achieve the above object is that a plurality of radiation detectors are arranged in the longitudinal direction of the bed and around the bed and output a detection signal of γ rays, and the γ ray detector An X-ray source that is arranged outside and moves in the circumferential direction with respect to the longitudinal direction of the bed, and an X-ray detector that is a radiation detector that outputs an X-ray detection signal. Is located in a region formed between one end of the γ-ray detection unit and the other end of the γ-ray detection unit in the longitudinal direction of the bed, and passes X-rays emitted from the X-ray source A gap is formed between the γ-ray detection units in the longitudinal direction of the bed in a circumferential direction with respect to the longitudinal direction of the bed, and the γ-ray detection unit is moved while the X-ray source is moving. It is a radiation inspection apparatus characterized by not moving .

In the first invention, since at least a part of the X-ray detection unit is located in the region, even if the subject moves during the examination without moving the bed, the X-ray detection unit outputs the X-ray detection unit. Improving the accuracy of a tomographic image of a subject created using the first information obtained from the γ-ray detection signal and the second information obtained from the X-ray detection signal output from the X-ray detection unit. it can. This can improve diagnostic accuracy for the subject by using the tomographic image. Specifically, the position and size of the affected area of cancer can be recognized with high accuracy. In particular, cancer of lymph glands that are organelles can be diagnosed with high accuracy.

Specifically, the created tomogram includes first tomogram information created using the first information (for example, including an image of a site where a radiopharmaceutical is accumulated (an affected area of cancer)), a second It is created by synthesizing the second tomographic image information (for example, including a bone image) created using the information. Since the X-ray detection unit is located in the region, the first tomogram information and the second tomogram information can be synthesized with high accuracy, and the accuracy of the tomogram is improved.

ADVANTAGE OF THE INVENTION According to this invention, the diagnostic accuracy with respect to a test object, for example, the diagnostic accuracy of cancer, can be improved. Moreover, even if X-rays are irradiated by the circumferential movement of the X-ray source, the X-ray source is located outside the radiation detector, so that they block γ-rays emitted from the examinee, The possibility that the radiation detector located directly behind them cannot detect the gamma rays is completely eliminated.

In the radiological examination apparatus described in each of the above-mentioned publications, two different examinations are in a shifted state, that is, an examination for detecting X-rays transmitted through the subject is performed, and then the subject position is shifted. Thus, a test for detecting γ rays emitted from the subject is performed. In such a radiological examination described in each of the above-mentioned publications, the place where both examinations are inevitably shifted, so that the examinee moves between the examination apparatuses or the angle of the examinee changes. Thus, there arises a new problem that the correspondence between the respective image data obtained by both inspection apparatuses cannot be accurately taken. This new problem has been discovered by the inventors. As a result of various examinations of solutions for the new problem, the inventors have detected X-rays transmitted through the subject to which the radiopharmaceutical has been administered, and the subject at the position of the subject irradiating the X-ray. Image data created using the first information obtained from the γ-ray detection signal and second information obtained from the X-ray detection signal by detecting γ-rays emitted due to the radioactive drug in the It has been found that image data created using can be synthesized with high accuracy. The above problem can also be solved by the X-ray detection unit being located in a region formed between one end of the γ-ray detection unit and the other end of the γ-ray detection unit in the longitudinal direction of the bed. I found. Specific examples will be described below.

Example 1
A radiation inspection apparatus according to a preferred embodiment of the present invention will be described with reference to FIGS.
The radiation inspection apparatus 1 of the present embodiment includes an imaging device 2, a patient holding device 14, and a signal discriminating device 19.
, Coincidence device 26, computer (for example, workstation) 27, storage device 28
, A display device 29 and a general control device 47. The examinee holding device 14 includes a support member 15 and a bed 16 that is located on the upper end portion of the support member 15 and is installed on the support member 15 so as to be movable in the longitudinal direction. The imaging device 2 is installed in a direction perpendicular to the longitudinal direction of the bed 16, and includes a radiation detector annular body 3 and an X-ray source circumferential direction moving device 7. The radiation detector annular body 3 includes an annular holder 5 and a large number of radiation detectors 4 arranged in an annular shape inside the annular holder 5. A through hole 30 through which the bed 16 is inserted is formed inside the radiation detector 4 of the radiation detector annular body 3. A large number of radiation detectors 4 (total of about 10,000) are arranged in a plurality of rows in the annular holding portion 5 not only in the circumferential direction but also in the axial direction of the hole 30. A number of radiation detectors 4 included in the radiation detector annular body 3 constitute a cylindrical radiation detector 65.
In the present embodiment, all the radiation detectors 4 arranged annularly in the circumferential direction do not move in the circumferential direction and do not move in the axial direction of the hole 30. The radiation detector 4 is a semiconductor radiation detector, and a 5 mm cubic semiconductor element portion as a detection portion is made of cadmium tellurium (CdTe). The detector may be composed of gallium arsenide (GaAs) or cadmium tellurium zinc (CZT). The annular holding part 5 is installed on the support member 6. Support members 6 and 15 are
They are connected to each other and installed on the laboratory floor.

The X-ray source circumferential direction moving device 7 includes an X-ray source device 8 and an annular X-ray source device holding unit 13. The X-ray source device holding unit 13 is attached to the outer surface of the annular holding unit 5 at one end of the annular holding unit 5. An annular guide rail 12 is installed on one end surface of the X-ray source device holding unit 13. The guide rail 12 and the X-ray source device holding unit 13 surround the periphery of the hole 30. The X-ray source device 8 includes an X-ray source 9
, An X-ray source driving device 10 and an axially moving arm 11. The X-ray source driving device 10 includes a motor 17 and a power transmission mechanism (not shown) having a speed reduction mechanism in a casing.
The power transmission mechanism is connected to the rotating shaft of the motor 17. The axial movement arm 11 is attached to the casing of the X-ray source driving device 10 and extends into the hole 30. The X-ray source 9 is attached to the axial movement arm 11. The axial movement arm 11 expands and contracts in the axial direction of the hole 30 and moves the X-ray source 9 in the axial direction of the hole 30. The axial movement arm 11 is expanded and contracted by driving a motor 18 installed in the X-ray source driving apparatus 10. The X-ray source driving device 10 is attached to the guide rail 12 so as not to fall and move along the guide rail 12. Although not shown, the X-ray source driving device 10 has a pinion that receives a rotational force from the power transmission mechanism described above. The pinion meshes with a rack provided on the guide rail 12.

As shown in FIG. 3A, the X-ray source 9 includes a known X-ray tube 42, a radiation shield 43 and a shutter 44. The X-ray tube 42 is installed in a radiation shield 43 having an opening 46. A shutter 44 made of a radiation shielding material is rotatably attached to the radiation shielding body 43 by a shaft 45. Although not shown, the X-ray tube 42 includes an anode, a cathode, a current source for the cathode, and a voltage source for applying a voltage between the anode and the cathode in the outer cylinder. A high voltage power source 56 is connected to a current source and a voltage source via a switch 57. Electrons are emitted from the filament by passing a current from the current source to the cathode. The electrons are accelerated by a voltage (several hundred kV) applied between the cathode and the anode from the voltage source, and collide with the target anode (W, Mo, etc.). X-rays of about 30 keV to 80 keV are generated by the collision of electrons with the anode. The X-ray 67 is emitted from the opening 46 when the shutter 44 is open.

Each radiation detector 4 is connected to a corresponding signal discriminating device 19 by a wiring 23. One signal discriminating device 19 is provided for each radiation detector 4. A detailed configuration of the signal discriminating apparatus 19 is shown in FIG. The signal discriminating device 19 includes a changeover switch 31, a waveform shaping device 20,
A γ-ray discriminating device 21 and an X-ray detection signal processing device 22 for obtaining X-ray intensity are provided. The changeover switch 31 that is a changeover device has a movable terminal 32 and fixed terminals 33 and 34. The wiring 23 is connected to the movable terminal 32. The waveform shaping device 20 is connected to the fixed terminal 33 and the γ-ray discrimination device 21. The X-ray detection signal processing device 22 is connected to the fixed terminal 34. The positive terminal of the power supply 25 is connected to a wiring 23 connected to each radiation detector 4 provided in the radiation inspection apparatus 1 through a resistor. The negative terminal of the power supply 25 is connected to each radiation detector 4 via the power switch 24. The γ ray discriminating device 21 is connected to a computer 27 via a coincidence counting device 26. One coincidence device 26 is connected to the γ-ray discriminating device 21. The coincidence counting device 26 may be provided for each of several γ-ray discriminating devices 21. Each X-ray detection signal processing device 22 is connected to a computer 27. A storage device 28 and a display device 29 are connected to the computer 27. The signal discriminating device 19 is a signal processing device. This signal processing device includes a first signal processing device including an X-ray detection signal processing device 22, and a second signal processing device having a waveform shaping device 20 and a γ-ray discrimination device 21.

As shown in FIG. 5, the overall control device 47 includes an overall control unit 48, a detector power source control unit 49, and an X
A radiation source movement control unit 50, an X-ray emission control unit 51, a changeover switch control unit 52, and a bed movement control unit 53 are provided. A button switch 54 and an input device 55 are connected to the overall control device 47.

In this embodiment, an X-ray CT examination (an act of detecting with a radiation detector the X-ray 67 emitted from the X-ray source 9 and transmitted through the body of the examinee) and a PET examination (because of the PET drug) (The act of detecting γ-rays 68 emitted from the affected part 66 in the body of the examiner 35 with a radiation detector)
Is an example in which a single imaging device 2 is used.

Before specifically describing the inspection in this embodiment, the principle of radiation detection in this embodiment will be described. This example was made based on the following examination by the inventors. X-ray CT image (X
X-ray radiated from an X-ray source is irradiated to the subject in a specific direction for a predetermined time. X that penetrates the body
The operation (scanning) of detecting the line by the radiation detector is repeated, and the line is created based on the X-ray intensities detected by the plurality of radiation detectors. In order to obtain highly accurate X-ray CT image data, the X-ray CT examination releases the X-ray from the inside of the subject due to the radiopharmaceutical agent to detect the X-ray. It is desirable that γ rays do not enter. For this purpose, the inventor said that "in one radiation detector, the influence of γ rays can be ignored if the X-ray irradiation time to the subject is shortened corresponding to the incidence rate of γ rays". Based on these new findings, the X-ray irradiation time to the subject was shortened. In order to determine the irradiation time T of the X-ray, first, 1
Consider the incidence of gamma rays on two radiation detectors. PET administered to a subject in a PET examination
N (Bq) is the radioactivity in the body based on the radiopharmaceutical for use, and A is the penetration rate of the generated gamma rays in the body.
When the incidence rate obtained from the solid angle of one radiation detector is B and the sensitivity of the detection element is C, the rate α (number / sec) of γ rays detected by one radiation detector is given by equation (1). It is done. In the equation (1), the coefficient “2” means that a pair (two) of γ-rays are emitted when one positron is annihilated. The probability W that γ rays are detected by one detection element within the irradiation time T is given by equation (2) α = 2NABC (1)
It is done. By determining the irradiation time T so as to reduce the value of W in the expression (2), the influence of γ rays incident on one radiation detector becomes negligible during the X-ray CT examination.

W = 1−exp (−Tα) (2)
An example of the X-ray irradiation time T will be described below. Specific X based on formulas (1) and (2)
The irradiation time T of the line was determined. The intensity of radiation in the body due to the radiopharmaceutical administered to the subject in the PET examination is about 370 MBq at the maximum (N = 370 MBq), and the γ-ray passage rate A in the body is a water with a radius of 15 cm. Assuming that, it is about 0.6 (A = 0.6).
For example, considering a case where a radiation detector having a side of 5 mm is arranged in a ring shape with a radius of 50 cm, the incidence rate B obtained from the solid angle of one radiation detector is 8 × 10 ⁻⁶ (B = 8 × 10 ⁻⁶ ). It is. The detection sensitivity C of the radiation detector is about 0.6 (C = 0.6) at the maximum when a semiconductor radiation detector is used. From these values, the detection rate α of γ rays of one radiation detector is 2000.
It is about (number / sec). If the X-ray irradiation time T is 1.5 μsec, for example, the probability W that one radiation detector detects γ rays during X-ray detection is 0.003, and these γ rays can be almost ignored. When the radioactivity administered to the body is 360 MBq or less, if the X-ray irradiation time is 1.5 μsec or less, W <0.003, that is, the detection probability of γ rays is 0.3% or less and can be ignored.

Prior to performing a radiological examination, first, a PET drug is administered in advance to a subject to be examined 35 such as an injectable radioactivity of 370 MBq by a method such as injection. The PET drug is selected depending on the purpose of the examination (for example, grasping the location of cancer or examining the arterial flow of the heart). The PET drug administered to the examinee 35 gathers in an affected area (for example, an affected area of cancer) 66 of the examinee 35. The examinee 35 to whom the PET drug is administered is laid on the bed 16 of the examinee holding device 14.

An operator (for example, a radiographer) of the radiation inspection apparatus inputs an inspection target range to be examined for the examinee 35 and the number of X-ray CT examinations from the input device 55 before starting the radiation examination. These pieces of information are stored in a control device storage device (not shown) of the overall control device 47 and also input to the overall control unit 48. The length in the axial direction of the hole 30 in the inspection target range is shorter than the axial length of the radiation detector annular body 3, for example. The overall control unit 48 calculates the time required for the PET examination based on the information, and also the PET examination period, which is a γ-ray detection period, and the X-ray detection start time (X-ray CT examination start time) within the PET examination period. And an X-ray CT examination period that is an X-ray detection period. By this process, an example control schedule shown in FIG. 6 including the X-ray CT examination start time is created. The created control schedule information is stored in the control device storage device. The control schedule is displayed on a display device (not shown) so that the operator can see it. The control schedule is to perform four X-ray CT examinations during the PET examination period.

At the start of the radiation examination, the operator presses the button switch 54 to control the overall control unit 48.
An inspection start signal is input to. When the examination control signal is input, the overall control unit 48 outputs to the bed movement control unit 53 the bed movement start signal and information on the examination target range for the examinee 35 stored in the control device storage device. Based on the bed movement start signal and the examination target range information, the bed movement control unit 53 rotates a bed movement motor (not shown) that is provided on the support member 55 and moves the bed 16, and Inspection range is hole 30
The bed 16 is moved to enter.

In this state, an X-ray CT inspection and a PET inspection using the present embodiment are performed. These inspections are performed using the imaging device 2. Specific contents of these inspections will be described below.

The overall control device 47 controls power supply of the radiation detector 4, X-ray source movement control, bed movement control,
Switching control of the changeover switch 31 and X-ray emission control from the X-ray source 9 are performed. The functions of the overall control device 47 will be sequentially described below. First, the overall control unit 48 outputs a power ON signal to the detector power control unit 49 when an inspection start signal is input. The detector power supply control unit 49
When the power ON signal is input, the power switch 24 is closed. The voltage of the power supply 25 is applied to each radiation detector 4, and each radiation detector 4 becomes a state which can detect a gamma ray and an X-ray. A pair of 511 keV γ-rays 68 released from the body due to the PET drug accumulated in the affected part 66 of the examinee 35 closes the power switch 24, whereby each radiation detector of the radiation detector 65. 4 is detected. That is, the γ-ray detection period (see FIG. 6) is started by closing the power switch 24. The γ-ray detection period is a radiation detection period. A large number of gamma ray pairs are emitted in all directions from the affected area 66. The overall control unit 48 outputs an X-ray tube activation signal to the X-ray emission control unit 51 a predetermined time before the X-ray CT examination start time for the first X-ray CT examination in the control schedule. The X-ray emission control unit 51 receives the signal and outputs a first switch closing signal to close the switch 57. A voltage is applied from the high voltage power source 56 to the voltage source of the X-ray tube 42, and a current flows through the current source. Eventually, X-rays are generated in the X-ray tube 42 as described above. At this time, the shutter 44 is closed, and the X-rays are not emitted outside the X-ray source 9.

The γ rays 68 emitted from the examinee 35 inserted in the hole 30 and on the bed 16 as described above are detected by the radiation detectors 4 of the radiation detector 65. Each radiation detector 4 that has detected the γ-ray 68 outputs a γ-ray detection signal that is a detection signal. This γ-ray detection signal is input to the corresponding signal discriminating device 19 via the corresponding wiring 23 and processed as described later. The X-ray source 9 is housed in the X-ray source driving device 10 by contracting the axial movement arm 11 so as not to prevent the detection of the γ-ray 68 by the radiation detector 4.

Before outputting the X-ray CT examination start signal, the overall control unit 48 sends the first X-ray source movement control unit 50 the first signal.
An X-ray source movement signal is output. Upon receiving this signal, the X-ray source movement control unit 50 outputs a second switch closing signal. As a result, the second switch (not shown) connected to the motor 18 and also connected to the power source is closed, and the X-ray source 9 moves in the axial direction of the hole 30 by driving the motor 18. When the X-ray source 9 moves to a predetermined position within the inspection target range, the X-ray source movement control unit 50 outputs a second switch opening signal to open the second switch, so that the axial direction of the hole 30 X in
The movement of the radiation source 9 stops. Thereafter, the overall control unit 48 outputs an X-ray CT examination start signal to the X-ray source movement control unit 50, the X-ray emission control unit 51, and the changeover switch control unit 52. The X-ray emission control unit 51 outputs a shutter open signal and closes a second switch (not shown) that connects a shutter motor (not shown) and a power source. The shutter motor is driven to open the shutter 44 (see FIG. 3B). X-rays 67 generated by the X-ray tube 42 are emitted through the opening 46 and irradiated to the examinee 35 on the bed 16 in the form of a fan beam. The X-ray source movement control unit 50 outputs an X-ray source rotation start signal when an X-ray CT examination start signal is input, and closes a first switch (not shown) that connects the motor 17 and the power source. The pinion is rotated by the rotation of the motor 17. Accordingly, the X-ray source device 8 moves along the guide rail 12, and the X-ray source 9 moves around the patient 35 at a set speed. In this way, the X-ray CT examination is started.

The X-ray emission control unit 51 controls the emission time of the X-ray 67 from the X-ray source 9. That is, X
The line emission control unit 51 controls the opening and closing of the shutter by alternately outputting a shutter open signal and a shutter close signal at intervals of the first set time and the second set time during the X-ray CT examination,
The emission and stop of the X-ray 67 from the X-ray source 9 are controlled. By this control, the shutter 44 is
Open during the first set time and close during the second set time. As a result, X-rays are emitted from the X-ray source 9 in a pulse shape. The irradiation time T, which is the first set time, is set to, for example, 1 μsec so that the detection probability of the γ-ray 68 in the radiation detector 4 can be ignored. The second set time is a time T0 in which the X-ray source 9 moves between one radiation detector 4 and another radiation detector 4 adjacent to the radiation detector 4 in the circumferential direction, and the X-ray in the circumferential direction of the guide rail 12 It is determined by the moving speed of the source 9. The first and second set times are stored in the control device storage device.

The X-ray 67 irradiated to the examinee 35 and transmitted through the examinee 35 extends in the circumferential direction around the radiation detector 4 located 180 degrees from the X-ray source 9 with the axial center of the hole 30 as a base point. It is detected by a plurality of radiation detectors 4 positioned. These radiation detectors 4 output an X-ray detection signal that is a detection signal of the X-ray 67. This X-ray detection signal is input to the corresponding signal discriminating device 19 via the corresponding wiring 23. Those radiation detectors 4 that detect the X-rays in the radiation detector 65 are referred to as first radiation detectors 4 for convenience. Also,
For convenience, the radiation detector 4 that detects γ rays in the radiation detector 65 is referred to as a second radiation detector 4. During the X-ray CT examination, the X-ray source 9 is moved in the axial direction of the hole 30 in the examination target range because the axial movement arm 11 is extended under the control of the X-ray source movement control unit 50. When the X-ray 67 emitted from the X-ray source 9 is transmitted through the affected part 66 of the examinee 35, the first radiation detector 4 detects the X-ray 67 transmitted through the affected part.

Next, switching control of the changeover switch 31 will be described. In the signal discriminator 19, the γ-ray detection signal output from the second radiation detector 4 is transmitted to the γ-ray discriminator 21, and the X-ray detection signal output from the first radiation detector 4 is the X-ray detection signal. It is transmitted to the processing device 22. Such transmission of each detection signal is switched by switching control of the selector switch 31 of the signal discriminating device 19. The switching control for connecting the movable terminal 32 of the changeover switch 31 to the fixed terminal 33 or the fixed terminal 34 is the first changeover signal and the second changeover signal output from the changeover switch controller 52 after the X-ray CT inspection start signal is input. Based on. The movable terminal 32 is activated by the first switching signal.
Is connected to the fixed terminal 33, and the movable terminal 32 is connected to the fixed terminal 34 by the second switching signal. The changeover switch control unit 52 to which the X-ray CT examination start signal is inputted is the first radiation detector 4.
Is selected, a second switching signal is output to the selector switch 31 to which the selected first radiation detector 4 is connected, and the movable terminal 32 is connected to the fixed terminal 34.

Selection of the first radiation detector 4 is performed in the changeover switch control unit 52 as follows.
The changeover switch control unit 52 receives the detection signal of the encoder 58 (see FIG. 5) connected to the motor 17 to obtain the position of the X-ray source driving device 10, that is, the X-ray source 9 in the circumferential direction. The radiation detector 4 positioned 180 ° opposite to the position of the source 9 is selected using the stored data of the position of each radiation detector 4. Since the X-ray 67 radiated from the X-ray source 9 has a width that is the circumferential direction of the guide rail 12, the radiation detector 4 that detects the X-ray transmitted through the body of the examinee 35 is selected. In addition to the radiation detector 4, there exist a plurality in the circumferential direction. The changeover switch control unit 52 also selects the plurality of radiation detectors 4. These radiation detectors 4 are first radiation detectors. As the X-ray source 9 moves in the circumferential direction, the first radiation detector 4 also changes. As the X-ray source 9 moves in the circumferential direction, the first radiation detector 4 also appears to move in the pseudo circumferential direction. The changeover switch control unit 52
When another radiation detector 4 is selected on the basis of the detection signal of the encoder 58 during the movement of the X-ray source 9 in the circumferential direction, the second switch is connected to the changeover switch 31 connected to the new first radiation detector 4. A switching signal is output, and the movable terminal 32 is connected to the fixed terminal 34. Further, the changeover switch control unit 52 outputs a first changeover signal to the changeover switch 31 connected to the radiation detector 4 that is no longer the first radiation detector 4 as the X-ray source 9 moves in the circumferential direction. The movable terminal 32 is connected to the fixed terminal 33. The above switching control of the changeover switch is sequentially performed within the X-ray CT examination period.

When it is time to finish the first X-ray examination shown in FIG. 6, the overall control section 48 sends an X-ray CT examination end signal to the X-ray source movement control section 50, the X-ray emission control section 51, and the changeover switch control. Output to the unit 52. The functions of the three control units that have received the X-ray CT examination end signal will be described. The X-ray source movement control unit 50 first outputs an X-ray source rotation stop signal, opens the first switch, stops the rotation of the motor 17, and stops the turning of the X-ray source 9. The X-ray source movement control unit 50 outputs a second switch closing signal to close the second switch, reverses the motor 18 and contracts the axial telescopic arm 11 to make the X-ray source 9 the X-ray source driving device. 10 is housed. The X-ray emission control unit 51 closes the shutter 44 by outputting a shutter close signal. When the shutter 44 is closed, the irradiation of the examinee 35 with the X-ray 67 is stopped. The operation of closing the shutter 44 is performed immediately after inputting the X-ray CT examination end signal. The X-ray emission control unit 51 further outputs a first switch opening signal to open the switch 57 and stops the application of voltage from the high voltage power source 56 to the X-ray tube 42. The changeover switch control unit 52 outputs a first changeover signal to all changeover switches 31 in which the movable terminals 32 are connected to the fixed terminals 34, and connects the movable terminals 34 of those changeover switches 31 to the fixed terminals 33. To do.

In order to execute the second X-ray CT examination after the elapse of a set time after the end of the first X-ray CT examination, each control unit of the overall control device 47 performs the same control as described above. The overall control device 47 performs similar control for the third and fourth X-ray CT examinations. When the four X-ray CT examinations are finished and the remaining PET examinations are finished, the overall control unit 48 outputs a power OFF signal to the detector power source control unit 49 in order to finish the radiation examination. Upon receiving the signal, the detector power control unit 49 opens the power switch 24. Thereby, application of the voltage to each radiation detector 4 is stopped. The radiological examination is completed by the above control.

The control schedule information includes the bed movement start signal, the power ON signal, the X-ray tube activation signal, the first X-ray source movement signal, the X-ray CT examination start signal, and the X-ray CT examination end signal after the examination start signal is input. And time information for outputting each signal of the power OFF signal. In addition, each time information which outputs each signal of an X-ray tube starting signal, a 1st X-ray source movement signal, an X-ray CT inspection start signal, and an X-ray CT inspection end signal is an X-ray CT inspection performed within a radiation inspection period. Is included in the number of times. The overall control unit 48 outputs a corresponding control signal to the corresponding control unit in the overall control device 47 at each time specified by the time information included in the control schedule information.

In the radiation examination period, not only when the X-ray CT examination is not performed, but also when the X-ray CT examination is performed, the γ-ray 68 emitted from the affected part 66 of the examinee 35 by the second radiation detector 4. Can be detected. For this reason, in this embodiment, even during X-ray CT examination, PET
Inspections can be performed in parallel. In other words, the X-ray CT inspection can be performed during the PET inspection period.

The individual radiation detectors 4 of the radiation detection unit 65 become the first radiation detectors 4 when the relationship with the position of the X-ray source 9 is present, and the second radiation detectors 4 when there is another relationship. For this reason, each radiation detector 4 outputs both an X-ray detection signal and a γ-ray detection signal although they are separate.
The first radiation detector 4 detects the X-ray 67 that has passed through the examinee 35 during the first setting time of 1 μsec. As described above, the probability that the first radiation detector 4 detects the γ rays 68 emitted from the affected part 66 of the examinee 35 during 1 μsec is negligibly small. A number of gamma rays 68 generated in the affected area 66 of the examinee 35 due to the PET drug are not emitted in a specific direction, but are emitted in all directions. As described above, these γ-rays 68 are emitted in pairs in substantially opposite directions, and the second radiation detector 4 in any one of the radiation detectors 65.
Detected by.

The signal processing of the signal discriminator 19 when the X-ray detection signal and the γ-ray detection signal output from the radiation detector 4 are input will be described. As described above, the X-ray detection signal output from the first radiation detector 4 is input to the X-ray detection signal processing device 22 via the fixed terminal 34 of the changeover switch 31. The X-ray detection signal processing device 22 integrates the X-ray detection signals with a setting cycle by an integration device, and outputs an integrated value for each set cycle of the X-ray detection signals, that is, X-ray intensity information. The X-ray detection signal processing device 22 outputs X-ray detection position information that is the position of the radiation detector 4 connected to the X-ray detection signal processing device 22 together with the X-ray intensity information.

The γ-ray detection signal output from the second radiation detector 4 is a fixed terminal 33 of the changeover switch 31.
Is input to the waveform shaping device 20. The γ-ray detection signal input to the waveform shaping device 20 is
As shown in FIG. 7, the shape first falls abruptly and then approaches exponentially 0. The waveform shaping device 20 converts the γ-ray detection signal having the waveform shown in FIG. 7 into, for example, a temporal Gaussian distribution shown in FIG. 8 in order to smoothly process the γ-ray detection signal in the γ-ray discrimination device 21. It is converted into a γ-ray detection signal having a waveform and output. By the way, not all of the energy of 511 keV γ rays in the semiconductor element part of the radiation detector 4 is necessarily changed into electric charges. For this reason, γ
The line discriminating device 21 generates a pulse signal having a predetermined energy when a γ-ray detection signal having an energy equal to or higher than this energy set value is input, for example, with 450 keV lower than 511 keV as the first energy set value. . That is, the γ-ray discriminating device 21 is a device that generates a pulse signal having the above energy when a γ-ray detection signal having an energy equal to or higher than the first energy set value is input. The γ-ray discrimination device 21 is a γ-ray detection signal processing device, and adds time information and position information indicating the position of the radiation detector 4 connected to the γ-ray discrimination device 21 to the output pulse signal. The time information includes the time when the γ-ray detection signal is input to the γ-ray discriminator 21, and the pulse signal is the γ-ray discriminator 21.
Is any information of the time when it is output from.

As described above, in order to process the γ-ray detection signal equal to or higher than the first energy set value in the γ-ray discriminator 21, the first filter that allows the γ-ray detection signal equal to or higher than the first energy set value to pass is γ-ray discriminated. It is provided in the device 21 (or in front of the γ-ray discriminating device 21). γ ray discrimination device 21
Generates a pulse signal for the γ-ray detection signal that has passed through the first filter.

The coincidence counting device 26 receives the pulse signal output from the γ-ray discriminating device 21 of each signal discriminating device 19. The coincidence device 26 detects the two second gamma rays 68 that have detected each gamma ray 68 of the gamma ray pair.
Radiation detector (approximately 180 ° centered on the axial center of the hole 30 (strictly, 180 ° ± 0.6 °)
Simultaneous counting is performed using each pulse signal for each γ-ray detection signal output from a pair of second radiation detectors located at different positions, and a count value (γ-ray) for these γ-ray detection signals. Count information). The coincidence counting device 26 determines whether each pulse signal corresponds to the detection signal of each γ ray of the γ ray pair based on each time information given to the pulse signals. That is, the difference between two pieces of time information is set time (for example, 10
nsec), it is determined that the pulse signal is for a pair of γ rays 68 generated by the disappearance of one proton. Further, the coincidence counting device 26 converts each position information given to the pulse signals as data of each position of the corresponding pair of second radiation detectors 4, that is, position information of each γ-ray detection point.

Each γ ray discriminating device 21 and coincidence counting device 26 generate first information such as γ ray counting information and position information of each γ ray detection point with respect to a γ ray pair, which is used for reconstruction of tomographic images. A processing apparatus is configured. The X-ray detection signal processing device 22 is a second signal processing device that generates second information such as X-ray intensity information and X-ray detection position information used for reconstruction of a tomographic image. Specifically, the position information of the γ-ray detection point is position information of the radiation detector 4 that has detected γ-rays. Specifically, the X-ray detection position information is position information of the radiation detector 4 that has detected X-rays. The coincidence counting device 26 receives an output signal from each γ-ray discriminating device 21 which is a γ-ray detection signal processing device, and is necessary for the creation of first tomographic image information (specifically, PET image data). 1 information is output.

The computer 27 executes processing based on the processing procedure of steps 36 to 41 shown in FIG. The computer 27 that executes such processing creates first tomographic image information using the first information (specifically, the γ-ray counting information and the position information of the γ-ray detection point), and the second information (specifically, Specifically, the second tomographic image information (specifically, X-ray CT) using the X-ray intensity information and the X-ray detection position information).
Image data), and using the first tomogram information and the second tomogram information, tomogram data creation that creates third tomogram information (specifically, synthetic tomogram data) including those tomogram information Device. Count value information of the γ-ray detection signal counted by the coincidence device 26, position information of the γ-ray detection point output from the coincidence device 26, X output from the X-ray detection signal processor 22
The line intensity information and the X-ray detection position information given to the X-ray intensity are input (step 36).
. The input count value information of the γ-ray detection signal, position information of the γ-ray detection point, X-ray intensity information, and X-ray detection position information are stored in the storage device 28 (step 37).

Using the X-ray intensity information and the X-ray detection position information, a tomographic image of the cross section of the examinee 35 (hereinafter, the cross section refers to a cross section in a state where the examinee is standing) is reconstructed ( Step 38). The reconstructed tomographic image is referred to as an X-ray CT image. A specific process for the reconstruction of the tomographic image will be described.
First, using the X-ray intensity information, the attenuation rate of X-rays in each voxel in the body of the examinee 35 is calculated. In this embodiment, the X-ray attenuation rate in each voxel is calculated using each X-ray intensity information obtained from each X-ray detection signal detected in four X-ray CT examinations. This attenuation rate is stored in the storage device 28. In order to reconstruct the X-ray CT image, the radiation detector 4 that detects the position of the X-ray source 9 and the X-rays using the attenuation rate of the X-ray detection signal read from the storage device 28.
The line attenuation coefficient in the body of the examinee 35 between the position (obtained from the X-ray detection position information) is obtained. The position of the X-ray source 9 detected by the encoder 58 at the time of movement is
The X-ray intensity information is given to the computer 27 by the line detection signal processing device 22 and transmitted to the computer 27. The CT value in each voxel is calculated based on the value of the linear attenuation coefficient in each voxel obtained by the filtered back projection method using the linear attenuation coefficient. X-ray CT image data is obtained using these CT values and stored in the storage device 28. In step 38, an X-ray CT image in a cross section passing through the affected area where the PET drug is accumulated is also reconstructed.

A cross-sectional tomographic image of the examinee 35 including the affected part (for example, an affected part of cancer) is reconstructed using the count value of the γ-ray detection signal at the corresponding position (step 39). A tomographic image reconstructed using the count value of the γ-ray detection signal is referred to as a PET image. This process will be described in detail. Using the count value of the γ-ray detection signal read from the storage device 28, the pair of second radiation detectors 4 (identified from the position information of the γ-ray detection point) that detected the γ-rays generated by the annihilation of positrons. The number of γ-ray pairs generated in the body between each semiconductor element part (the number of γ-ray pairs generated in response to the disappearance of a plurality of positrons) is obtained. Using this number of γ-ray pairs generated, the γ-ray pair generation density in each voxel is obtained by the filtered back projection method. Based on these γ-ray pair generation densities, PET image data can be obtained. The PET image data is stored in the storage device 28.

The data of the PET image and the data of the X-ray CT image are synthesized, and the data of the synthesized tomographic image including both data is obtained and stored in the storage device 28 (step 40). By combining the PET image data at the position of the affected area and the X-ray CT image data at the position, the combined tomographic image data of the cross section of the examinee 35 at the position of the affected area is obtained. The synthesis of the PET image data and the X-ray CT image data can be performed easily and accurately by matching the position of the central axis of the hole 30 in both image data. In other words, since the PET image data and the X-ray CT image data are created based on the detection signal output from the shared radiation detector 4, alignment can be performed with high accuracy as described above. The composite tomogram data is called from the storage device 28 and output to the display device 29 (step 41) and displayed on the display device 29. Since the composite tomographic image displayed on the display device 29 includes the X-ray CT image, the position of the affected part in the PET image in the body of the examinee 35 can be easily confirmed. That is, since the X-ray CT image includes images of the internal organs and bones, the doctor can specify the position where the affected part (for example, an affected part of cancer) exists in relation to the internal organs and bones.

Since the X-ray CT image requires a plurality of scan data, the radiation detector 4 moves the X-ray source 9 along the guide rail 12 by using the X-ray source driving device 10, so that the amount of data required by the radiation detector 4 is obtained. Can be obtained. According to the circumferential scan of the X-ray source 9 as described above, the present embodiment obtains two-dimensional cross-section data related to the X-ray detection signal in one cross section of the examinee 35. Two-dimensional cross-section data relating to X-ray detection signals in other cross sections can be obtained by moving the X-ray source 9 in the axial direction of the hole 30 by expanding and contracting the axial movement arm 11. By stacking these two-dimensional cross-sectional data, three-dimensional cross-sectional data can be obtained. Using this three-dimensional cross-sectional data, three-dimensional X-ray CT image data can be obtained. It is also possible to perform an X-ray helical scan by continuously expanding and contracting the axial movement arm 11 in the axial direction of the hole 30 as the X-ray source 9 circulates. Even if the bed 16 is moved in the axial direction of the hole 30 instead of expanding and contracting the axial movement arm 11, two-dimensional cross-section data relating to X-ray detection signals in other cross sections can be obtained.

In this embodiment, since the radiation detection unit 65 is composed of a plurality of radiation detectors 4 that output both X-ray detection signals and γ-ray detection signals, the radiation detection unit 65 is a γ-ray detection unit and is an X-ray. It is also a detector. In the present embodiment, the X-ray detection unit is located in a region formed between one end of the γ-ray detection unit and the other end of the γ-ray detection unit in the longitudinal direction of the bed 16. The radiation detector 65 detects an X-ray 67 that is irradiated from the X-ray source 9 and passes through the examinee 35.
An X-ray detection unit that outputs a detection signal of the line 67, and PET from a site (affected part 66) through which the X-ray 67 in the examinee 35 passes at the position of the examinee 35 irradiating the X-ray 67 It is a γ-ray detection unit that detects γ-rays 68 emitted due to the medicine and outputs a detection signal of the γ-rays 68. The radiation imaging apparatus 2 having a γ-ray detection unit and an X-ray detection unit is a radiation detection device.

  According to the present embodiment, the following effects can be obtained.

(1) In the present embodiment, transmission through the examinee 35 is performed in parallel with the detection of γ-rays during a part of the radiological examination period for detecting γ-rays emitted from the examinee 35 as the subject. Since the detected X-ray is detected, the X-ray CT inspection can be performed while the PET inspection is performed. For this reason,
The total inspection time required for the radiation inspection for performing the PET inspection and the X-ray CT inspection can be shortened. In particular, when the X-ray CT inspection and the PET inspection are continuously performed as in JP-A-7-20245, and the X-ray CT inspection is performed a plurality of times, the first X-ray CT inspection and the first PET inspection are performed. After finishing, the following operations are performed. That is, PET at the end of the first PET inspection
The voltage application to the radiation detector (referred to as radiation detector A) of the inspection apparatus is stopped, the bed is moved, and the inspection object range of the examinee 35 is moved to the position of the X-ray CT inspection apparatus. Thereafter, a voltage is applied to a radiation detector (referred to as radiation detector B) of the X-ray CT apparatus to perform an X-ray XT examination. At the end of the X-ray CT examination, voltage application to the radiation detector B is stopped, the bed is moved, and the examination target range of the examinee 35 is moved to the position of the X-ray CT examination apparatus. Then again
A PET inspection is performed by applying a voltage to the radiation detector A. At the end of this PET inspection, application of voltage to the radiation detector A is stopped. Thereafter, these operations are repeated as necessary. As described above, in the radiation inspection in Japanese Patent Application Laid-Open No. 7-20245, it is necessary to carry out the movement of the bed, the application of the voltage of the radiation detector, and the application stop several times according to the number of X-ray CT inspections. Radiation inspection takes a long time.

(2) In this embodiment, since the X-ray CT examination is performed during a part of the radiological examination period, the radiation dose received by the examinee 35 by the X-ray irradiation during the X-ray CT examination is less than the allowable exposure dose. It becomes.

(3) Since the radiation detector 4 that detects γ-rays is used as the radiation detector 4 that detects X-rays, the radiation inspection apparatus 1 uses the radiation detector 4 that detects X-rays and the radiation detection that detects γ-rays. It is not necessary to provide the device 4 separately, the configuration can be simplified and the size can be reduced. The radiation detector 4 outputs both an X-ray detection signal and a γ-ray detection signal.

(4) Since a plurality of X-ray CT examinations are performed within the radiological examination period, if the examinee 35 moves within the radiological examination period, the X-ray detection signal in the state after movement Can be obtained. Therefore, the examinee 35 moved based on the γ-ray detection signal obtained during the radiological examination period and the respective X-ray detection signals obtained by a plurality of X-ray CT examinations performed during the radiological examination period. Even in this case, a tomographic image with high accuracy for the examinee 35 (including an image of an affected area, an image of a bone, a viscera, etc.)
Can be obtained. That is, since the influence when the examinee 35 moves appears in an X-ray CT image and a PET image, which will be described later, it is possible to obtain an accurate composite tomographic image as will be described later using both images including the influence. it can.

(5) In the present embodiment, the radiation detector 4 that detects γ-rays is used as the radiation detector 4 that detects X-rays (X-ray detection to obtain an X-ray detection signal obtains a γ-ray detection signal) This is performed using the radiation detector 4 that detects γ-rays). For this reason, the present embodiment uses an X-ray detection signal which is one output signal of the radiation detector 4 arranged in a ring shape, and an affected part (PET drug) including images of the internal organs and bones of the examinee 35. The first tomographic image (X-ray CT image) at the position of (integrated) can be reconstructed, and the affected part of the examinee 35 is used by using the γ-ray detection signal which is another output signal of the radiation detector 4 The second tomographic image (PET image) including the image can be reconstructed. First tomographic data and second
Since the tomographic data is reconstructed based on the output signal of the radiation detector 4 that detects both transmitted X-rays and γ-rays, the data of the first tomographic image and the data of the second tomographic image at the position of the affected area. Can be combined with high accuracy. For this reason, it is possible to easily obtain an accurate tomographic image (synthetic tomographic image) including images of the affected area, internal organs, bones and the like. According to this synthetic tomographic image, the position of the affected area can be accurately known in relation to the internal organs and bones. For example, by aligning the data of the first tomogram and the data of the second tomogram with the axial center of the hole 30 of the imaging device 2 as the center, image data obtained by easily synthesizing both tomograms can be obtained.

(6) In this embodiment, the X-ray detection unit detects X-rays irradiated from the X-ray source 9 and transmitted through the affected part of the examinee 35, and the position of the examinee 35 irradiating the X-rays In order for the γ-ray detector to detect γ-rays emitted from the site (affected part) through which X-rays pass through the body of the examinee 35 in the γ-ray detection unit, the examinee 35 is moved by the bed 16. X-ray CT inspection and PET inspection can be performed at the same position. During both examinations, the X-ray detection unit outputs an X-ray detection signal transmitted through the affected part of the examinee 35, and the γ-ray detection unit outputs a detection signal of γ-ray emitted from the affected part. In order to synthesize the first tomographic image data at the position of the affected area obtained based on the X-ray detection signal and the second tomographic image data at the position of the affected area obtained based on the γ-ray detection signal. Even if the examinee 35 moves on the bed 16 without being able to stand inside,
Those tomographic image data can be synthesized with high accuracy. That is, highly accurate synthetic tomographic image data can be obtained. Therefore, the diagnosis accuracy of the affected area can be improved by using the synthetic tomographic image data (synthetic tomographic image) at the position of the affected area displayed on the display device 29. In particular, even when an affected part exists in a place where an organ is complicated, the position of the affected part can be appropriately grasped by the synthetic tomographic image obtained in the present embodiment, and the diagnosis accuracy of the affected part is improved.

(7) In this embodiment, the X-ray source 9 can be moved in the axial direction of the radiation detection unit 65 during the radiation examination period by using the X-ray source axial movement device (for example, the axial movement arm 11). Without moving the examiner 35 in the axial direction of the radiation detection unit 65, the X-ray CT inspection can be performed on the inspection target range while performing the PET inspection on the inspection target range. When the X-ray CT examination for the examination target area is executed by moving the bed 16 without moving the X-ray source 9 in the axial direction, the position of the site where the PET drug is accumulated is also the same. Move in the axial direction. This means that the position where the γ ray pair is generated is moved in the axial direction, noise for the creation of PET image data increases, and accurate PET image data cannot be obtained. In this embodiment, since the position where the γ ray pair is generated does not move in the axial direction, highly accurate PET image data can be obtained, and the accuracy of the combined tomographic image data can be improved.

(8) In this embodiment, the radiation detectors 4 included in the radiation detector 65 can detect a plurality of pairs of γ rays emitted from the examinee 35 and move in the circumferential direction. X-rays emitted from 9 and transmitted through the examinee 35 can also be detected. For this reason, the prior art has required an imaging device for detecting X-rays and another imaging device for detecting γ-rays as an imaging device, but this embodiment is a single imaging device for detecting X-rays and γ-rays. Therefore, the configuration of the radiation inspection apparatus capable of performing both the X-ray CT inspection and the PET inspection can be simplified.

(9) In this embodiment, the X-ray detection signal necessary for creating the first tomographic image and the radiation detector 4 sharing the γ-ray detection signal necessary for creating the second tomographic image are used. Therefore, the time required for the examination of the examinee 35 (examination time) can be remarkably shortened. In other words, the X-ray detection signal necessary for creating the first tomographic image and the γ-ray detection signal necessary for creating the second tomographic image can be obtained in a short examination time. In the present embodiment, unlike the prior art, it is not necessary to move the examinee from an imaging device that detects transmitted X-rays to another imaging device that detects γ-rays. Contribute further.

(10) In this embodiment, since the X-ray source 9 is circulated and the radiation detection unit 65 is not moved in the circumferential direction and the axial direction of the hole 30, the X-ray source 9 does not move as compared with the motor necessary for moving the radiation detection unit 65.
The capacity of the motor that circulates the radiation source 9 can be reduced. The power consumption required to drive the latter motor can also be less than that of the former motor.

(11) Since the γ-ray detection signals input to the X-ray detection signal processing device 22, that is, the first signal processing device are remarkably reduced, highly accurate first tomographic image data can be obtained. Therefore, the position of the affected area can be known more accurately by using image data obtained by combining the data of the first tomographic image and the data of the second tomographic image.

(12) In this embodiment, since the X-ray source 9 circulates inside the radiation detection unit 65, the diameter of the annular holding unit 5 becomes large, and the radiation detector 4 can be installed in the circumferential direction inside the annular holding unit 5. The number of can be increased. An increase in the number of radiation detectors 4 in the circumferential direction brings about an improvement in sensitivity and resolution, and improves the resolution of the cross section of the examinee 35.

(13) In this embodiment, since the axial movement arm 11 to which the X-ray source 9 is attached and the X-ray source 9 are located inside the radiation detector 4, they are examined during X-ray CT examination. There is a possibility that the γ-rays emitted from 35 are blocked, and the radiation detector 4 located immediately behind them cannot detect the γ-rays, and detection data necessary for creating a PET image may be lost. But,
In the present embodiment, as described above, since the X-ray source 9 and the axially moving arm 11 circulate in the circumferential direction by the X-ray source driving device 10, the loss of data does not substantially cause a problem. In particular, X
The rotational speed of the radiation source 9 and the axial movement arm 11 is about 1 second / slice, which is sufficiently short compared with the time required for the PET inspection of the order of several minutes at the shortest. Even in this case, the loss of the data is not substantially a problem. When the X-ray CT inspection is not performed and the PET inspection is performed, the X-ray source 9 is accommodated in the X-ray source driving device 10, so that the X-ray source 9 and the axial movement arm 11 are used for γ-ray detection. It will not be an obstacle.

(14) In this embodiment, the X-ray detection unit is located in a region formed between one end of the γ-ray detection unit and the other end of the γ-ray detection unit in the longitudinal direction of the bed. Therefore, even if the subject moves during the examination, the first information obtained from the γ-ray detection signal output from the γ-ray detection unit and the X-ray detection signal output from the X-ray detection unit are obtained. The accuracy of the tomographic image of the subject created using the second information thus obtained can be improved. This can improve diagnostic accuracy for the subject by using the tomographic image. Specifically, the position and size of the affected area of cancer can be recognized with high accuracy. In particular, cancer of lymph glands that are organelles can be diagnosed with high accuracy.

Furthermore, the inspection time required to obtain an X-ray detection signal necessary for creating an X-ray CT image is as follows:
It is shorter than the inspection time required to obtain a γ imaging signal necessary for creating a PET image. Therefore, during the examination time for obtaining the γ-ray detection signal, the examinee is moved during the examination by always irradiating the examinee with X-rays from the X-ray source 9 to obtain the X-ray detection signal. Even in this case, it is possible to correct the deviation of the PET image data accompanying the swing of the examinee from the continuous image of the X-ray CT image obtained based on the X-ray detection signal.

In the first embodiment, the control function of the overall control device 47 may be implemented by the computer 27 using a program. In this case, the computer 27 having the control function is substantially an apparatus in which the tomographic image data creation device and the overall control device 47 are integrated.

In the first embodiment, the X-ray irradiation is performed in a fan beam shape, but the X-ray irradiation is not limited to this. For example, it is possible to obtain three-dimensional composite tomographic image data by irradiating X-rays in a cone beam shape. In the first embodiment, a semiconductor radiation detector to which CdTe is applied is used as the radiation detector 4, but a semiconductor radiation detector to which CZT, GaAs, or the like is applied can also be used. It is also possible to use a scintillator that is a radiation detector other than the semiconductor radiation detector. In the first embodiment, the X-ray source or the X-ray source and the radiation detector are swung around the subject. However, the subject may be rotated while the X-ray source and the radiation detector are fixed.

In the first embodiment, the inspection of the subject in the axial direction of the hole 30 is performed by moving the bed 16. On the other hand, the inspection can be performed by fixing the bed 16 and moving the imaging device in the axial direction. The arrangement of the radiation detectors is not limited to a cylindrical shape, and may be a polygonal cylinder such as a hexagon.

When the position of the affected part of the examinee 35 is not specified in advance, the bed 16 is moved and the PET examination is performed over the entire body of the examinee 35. While the PET inspection is being performed, the X-ray source 9 is circulated in the circumferential direction, and the X-ray CT inspection is performed on the place where the PET inspection is performed.

In the first embodiment, as shown in FIG. 6, the X-ray CT examination is performed four times. However, when the subject can be completely fixed, or the examination target range is narrow and the PET examination is completed in a short time, the X-ray is performed. CT
The number of inspections may be one.

In the first embodiment, the signal discriminating device 19A shown in FIG. 10 is used instead of the signal discriminating device 19 shown in FIG.
May be used. As shown in FIG. 10, the signal discriminating device 19 </ b> A includes a waveform shaping device 20, a γ-ray discriminating device 21, and a wave height analyzing device 58. The signal discriminating device 21 provided for each radiation detector 4 does not have the changeover switch 31, and the waveform shaping device 20 is connected to the corresponding radiation detector 4 by the wiring 23. The wave height analyzer 59 is connected to the waveform shaping device 20 and the computer 27. The γ-ray discriminating device 21 connected to the waveform shaping device 20 is connected to the coincidence counting device 26. The pulse height analyzer 59 is an X-ray detection signal processor.

When the signal discriminating device 19A is used, the X-ray emission control unit 51 outputs a shutter open signal when an X-ray CT inspection start signal is input, and outputs a shutter close signal when an X-ray CT inspection end signal is input. . For this reason, during the X-ray CT examination period, the shutter 44 is always open when irradiating X-rays, and the radiation detector 4 detects X-rays as well as γ-rays. The signal discriminating device 19A has a function of separately separating the X-ray detection signal and the γ-ray detection signal from the output signal of the radiation detector 4. That is, the signal discriminating device 19A has one radiation detector 4
It is an apparatus which discriminate | determines an energy from the X-ray detection signal and gamma-ray detection signal which were output from. The waveform shaping device 20 shapes the X-ray detection signal together with the γ-ray detection signal into a Gaussian distribution and outputs it. The γ-ray detection signal and the X-ray detection signal, which are outputs of the waveform shaping device 20, are input to the γ-ray discriminating device 21 and the wave height analyzing device 59. The γ-ray discriminator 21 needs to process the γ-ray detection signal, and the wave height analyzer 59 needs to process the X-ray detection signal. The γ ray discriminating device 21 exhibits the same function as the γ ray discriminating device 21 of the signal discriminating device 19. The energy of X-rays irradiated to the examinee 35 is 80
keV. When the X-ray detection signal having energy in the range of the second energy set value (70 keV) or more and the third energy set value (90 keV) or less is input from the waveform shaping device 20, the wave height analyzer 59 detects the X-ray. The integrated value for each signal setting period, that is, information on the X-ray intensity is output. The load on the pulse height analyzer 59 is significantly reduced by processing such a specific energy X-ray detection signal.

(Example 2)
Next, a radiation examination support method using the radiation examination apparatus 1 shown in FIG. 1 will be described with reference to FIG. The hospital, which is a medical institution, inputs the name of each examinee who undergoes a radiological examination for each day to the information terminal 63, and sends it to the server 60 of the radiological examination support provider via the hospital server 62 and communication line 64. Send it and request a radiological examination support provider for radiological examination. The transmitted radiation examination date and the name of each examinee for each radiation examination date are displayed on the display device of the information terminal 61 of the radiation examination support company. A radiation inspection apparatus 1 used for inspection owned by a radiation inspection support company is installed in the hospital. The PET drug is administered to the examinee 35 by the hospital. A radiographer who is an employee of a radiological examination support company lays the examinee 35 to whom the medicine is administered on the bed 16. When the radiologist presses button switch 54,
As described in the first embodiment, under the control of the overall control device 47, the radiation examination, that is, the PET examination and the X-ray CT examination for the corresponding examinee 35 using the radiation examination apparatus 1 is performed. By this radiation inspection, the γ-ray detection signal and the X-ray detection signal that are the outputs from the radiation detector 4 are processed as in the first embodiment. Each piece of information obtained by this process is input to the computer 27, and the process of FIG. 9 is executed to create synthetic tomographic data. The combined tomographic image data is output from the computer 27 to the server 60 together with information on the name of the patient to be examined, and is input to the information terminal 63 of the hospital that is the requester of the examination via the communication line 64 and the server 62 to the display device. Is displayed. The doctor of the hospital makes a diagnosis of the affected area by looking at the displayed synthetic tomography. Effects (1) to (13) produced in the embodiment because the radiation inspection is performed using the radiation inspection apparatus 1
Can be obtained. In particular, since the present embodiment performs the X-ray CT examination while performing the PET examination within the radiological examination period as described above, it can provide a hospital with a high-accuracy tomographic image including the affected area and bones. The doctor in the hospital can make an appropriate diagnosis of the affected area based on the tomographic image. In this radiation support method, the X-ray detection position and the γ-ray detection position are at least partially the same position (each of the radiation detectors 4 sharing at least a part of the plurality of radiation detectors 4 It can be said that a radiological examination is performed by outputting both X-ray and γ-ray detection signals.

In this embodiment, instead of the radiation inspection apparatus 1, any of the radiation inspection apparatuses 1A, 1B, 1C, and 1D in the embodiments described later may be used.

(Example 3)
A radiation inspection apparatus according to embodiment 3, which is another embodiment of the present invention, will be described with reference to FIGS. The radiation inspection apparatus 1A of the present embodiment includes an imaging device 2A and a patient holding device 14, and although not shown, the signal discrimination device 19, the coincidence counting device 26, the computer 27, and the like described in the first embodiment. A storage device 28 and a display device 29 are provided. The configuration of the examinee holding device 14 of the present embodiment is the same as the structure described in the first embodiment.

The imaging device 2A is installed in a direction perpendicular to the longitudinal direction of the bed 16, and includes a radiation detector annular body 3A, an X-ray source circumferential movement device 7, a drive device control device 70, and an X-ray source control device 71. Have The radiation detector annular body 3A includes an annular holder 5A and a large number of radiation detectors 4 arranged in an annular shape inside the annular holder 5A. As shown in FIGS. 12 and 13, the radiation detector annular body 3A is provided with a plurality of semicircular slits 69 as gaps in the axial direction. Specifically, these slits 69 are formed in the annular holding portion 5A. Except for the slit 69, a number of radiation detectors (semiconductor radiation detectors) 4 are installed inside the annular holding portion 5A as in the first embodiment. A large number of radiation detectors 4 included in the radiation detector annular body 3A constitute a cylindrical radiation detection unit 65A. The annular holding portion 5 </ b> A is installed on the support member 6.

The X-ray source circumferential direction moving device 7 of the present embodiment has the same configuration as that of the first embodiment. The X-ray source driving device 10 of the X-ray source device 8 is not shown in FIG. 12, but motors 17 and 18 (FIG. 1).
See). In the present embodiment, the X-ray source 9 and the axial movement arm 18 are disposed outside the radiation detector 65A, specifically, outside the radiation detector annular body 3A. The drive device control device 70 and the X-ray source control device 71 are installed on the outer peripheral surface of the annular holding portion 5A. In this embodiment, X
This is an example in which a line CT inspection and a PET inspection are performed using one imaging apparatus 2A.

Before performing the radiological examination, the PET drug is prepared by a method such as injection in the same manner as in Example 1.
It is administered to the examinee 35, which is the subject, so that the internally administered radioactivity becomes 370MBq.
The examinee 35 waits for a predetermined time until the PET drug diffuses into the body in a state where the medicine can be imaged and collects in the affected area 66. After the predetermined time has elapsed, the examinee 35 is laid on the bed 16 of the examinee holding device 14. The X-ray CT examination and the PET examination in the present embodiment are performed by using the imaging apparatus 2 </ b> A in a state where the bed 16 on which the examinee 35 lies is moved and the examinee 35 is inserted into the hole 30. .

The X-ray source controller 71 controls the X-ray emission time from the X-ray source 9. That is, the X-ray source control device 71 outputs an X-ray generation signal during the X-ray CT examination, and opens and closes provided between the anode (or cathode) of the X-ray tube 42 and the power source in the X-ray source 9. Close the device 57 (see FIG. 1)
When the first set time elapses, an X-ray stop signal is output to open the switch 57, and when the second set time elapses, the switch 57 is closed. A voltage is applied between the anode and the cathode during the first set time, and no voltage is applied during the second set time. By this control, X-rays 67 are emitted from the X-ray tube 42 in a pulse shape. The X-ray source 9 of this embodiment is not provided with the shutter 44 as in the first embodiment. The irradiation time T that is the first set time is the same as that in the first embodiment, and is set to 1 μsec, for example, so that the detection probability of γ rays at the radiation detector 4 can be ignored. The second set time is a time T0 in which the X-ray source 9 moves between one radiation detector 4 and another radiation detector 4 adjacent to the radiation detector 4 in the circumferential direction, and the X-ray in the circumferential direction of the guide rail 12 It is determined by the moving speed of the source 9. The first and second set times are stored in the X-ray source control device 71.

The X-rays 67 emitted from the X-ray source 9 pass through the slit 69 and enter the radiation detector 4 adjacent to the radiation detector 4 in the axial direction of the hole portion 30 at the position facing the slit 69.
The X-ray source 9 is mounted obliquely. Each slit 69 is an X-ray opening through which X-rays pass.
When starting the X-ray CT examination, the driving device controller 70 outputs a driving start signal, and closes the first switch (not shown) connected to the motor 17 and connected to the power source. When the current is supplied, the motor 17 rotates, and the rotational force is transmitted to the pinion via the power transmission mechanism, so that the pinion rotates. Since the pinion meshes with the rack of the guide rail 12, the X-ray source device 8, that is, the X-ray source 9 moves in the circumferential direction along the guide rail 12. The X-ray source 9 moves around the radiation detector annular body 3A at a set speed. At the end of the X-ray CT examination, the drive device controller 70 outputs a drive stop signal and opens the first switch. Thereby, the movement of the X-ray source 9 in the circumferential direction is stopped. The slit 69 is installed in a semicircular shape, and the movement of the X-ray source 9 is within this range. In the present embodiment, the radiation detection unit 65A does not move in the circumferential direction and does not move in the axial direction of the hole 30 as well. A known technique that does not hinder the movement of the X-ray source device 8 is applied to the transmission of the control signal from the X-ray source control device 71 that does not move and the driving device control device 70 to the moving X-ray source device 8.

The drive start signal output from the drive device controller 70 when starting the X-ray CT examination is input to the X-ray source controller 71. The X-ray source control device 71 performs X based on the input of the drive start signal.
Outputs line generation signal. Thereafter, the X-ray stop signal and the X-ray generation signal are repeatedly output.
By repeatedly outputting the X-ray stop signal and the X-ray generation signal, the X-ray source 9 emits X-rays during the first set time, that is, 1 μsec, and stops emitting X-rays during the second set time. . This X
The emission and stop of the line are repeated during the movement of the X-ray source 9 in the circumferential direction. The X-ray 67 emitted from the X-ray source 9 passes through the slit 69 in the form of a fan beam and has a hole 30.
It is irradiated to the examinee 35 inserted in the inside. By the movement of the X-ray source 9 in the circumferential direction, the examinee 35 on the bed 16 is irradiated with X-rays 67 from the surroundings. This X-ray 67 is obtained when the examinee 35
Are transmitted by the plurality of radiation detectors 4 positioned in the circumferential direction around the radiation detector 4 adjacent to the radiation detector 4 located 180 degrees from the slit 69 with the axial center of the hole 30 as a base point. Detected. These first radiation detectors 4 output the X-ray detection signal. This X-ray detection signal is input to the corresponding signal discriminating device 19 via the corresponding wiring 23.

The movement of the X-ray source 9 in the circumferential direction is completed within the slit 69 at the position of the slit 69 through which the X-ray 67 shown in FIG. After the completion, the driving device control device 70 closes a second switch (not shown) connected to the power source connected to the motor 18 of the X-ray source driving device 10. Thereby, the motor 18 is driven and the axial movement arm 11 is contracted, and the X-ray source 9 is moved to the position of the slit 69A. The emission of the X-ray 67 from the X-ray source 9 is stopped by the action of the X-ray source control device 71 when the axial movement arm 11 expands and contracts.

After the X-ray source 9 reaches the position of the slit 69 </ b> A, the X-ray source control device 71 moves from the X-ray source 9 to the X-ray source 9.
Line 67 is released. The X-ray 67 passes through the slit 69A and passes through the affected part 66 facing the slit 69A. The X-ray 67 transmitted through the affected part 66 is detected by the radiation detector 4.

From the affected part 66 of the examinee 35 on the bed 16 inserted into the hole 30, 511 keV γ rays 68 caused by the PET drug are emitted. A radiation detector (second radiation detector) 4 other than the first radiation detector 4 detects the γ-ray 68 and outputs a detection signal of the γ-ray 68. This γ-ray detection signal is input to the corresponding signal discriminating device 19 via the corresponding wiring 23.

The switching operation of the changeover switch 31 in the signal discriminating device 19 is performed by a drive device control device 70.
Controlled by. The drive device control device 70 performs the same control as the changeover switch control unit 52 in the first embodiment, and switches the connection of the movable terminal 32 to the fixed terminal 33 or the fixed terminal 34. When the drive device controller 70 selects another radiation detector 4 as the X-ray source 9 moves in the circumferential direction, the movable device is newly connected to the radiation detector 4 that becomes the first radiation detector 4. The terminal 32 is connected to the fixed terminal 34. The movable terminal 32 connected to the radiation detector 4 that is no longer the first radiation detector 4 as the X-ray source 9 moves in the circumferential direction is connected to the fixed terminal 33 by the driving device controller 70.

In the present embodiment, as in the first embodiment, the individual radiation detectors 4 in the radiation detection unit 65A are related to the position of the X-ray source 9, and when there are, the first radiation detector 4 is used. Sometimes it becomes the second radiation detector 4. For this reason, one radiation detector 4 outputs both an X-ray detection signal and a γ-ray detection signal although they are temporally separated. As described above, the probability that the first radiation detector 4 detects the γ-ray 68 emitted from the examinee 35 during the first setting time of 1 μsec is so small that it can be ignored.

When the position of the affected part 66 of the examinee 35 is not specified in advance, every range (the length in the axial direction of the radiation detection unit 65A) in which the PET examination can be performed on the whole body of the examinee 35 at once. Each PET inspection is performed. For each PET inspection, the X-ray source 9 is circulated in the circumferential direction, and an X-ray CT inspection is performed on the part where the PET inspection is performed. When the position of the affected part 66 of the examinee 35 is specified in advance by another examination, the bed 16 is moved and the position of the affected part 66 specified in advance is inserted into the hole 30, and the imaging apparatus 2 </ b> A. A PET examination and an X-ray CT examination are carried out on the vicinity of the affected area using.

The X-ray detection and γ-ray detection signals output from the radiation detector 4 are processed in the same manner as in the first embodiment by the signal discrimination device 19. The coincidence counting device 26 is a γ-ray discriminating device 21 of each signal discriminating device 19.
And the same processing as that in the first embodiment is executed. The computer 27 executes the processing of steps 36 to 41 shown in FIG. 9 described in the first embodiment, obtains the composite tomographic image data of the cross section at the position of the affected part 66 of the examinee 35 and obtains the composite tomographic image. The data is displayed on the display device 29.

In the present embodiment, the PET examination for detecting the γ-rays 68 emitted from the affected area 66 within the radiation examination period for obtaining the detection signal of the γ-rays 78 necessary for creating the tomographic image data of the examinee 35 is also provided. The X-ray CT examination for detecting the X-ray 67 transmitted through the examinee 35 is performed. The time required for the X-ray CT inspection is shorter than the time required for the PET inspection. X in this embodiment
The X-ray CT examination start signal of the drive device control device 70 is input when an operator such as a radiologist presses an X-ray CT examination start button on an operation panel (not shown). This is performed by the drive device controller 70 outputting the drive start signal described above. Also in this embodiment, as shown in FIG. 6, a plurality of X-ray CT examinations may be carried out within one radiation examination period.

In this embodiment, the X-ray source 9 is moved in the circumferential direction and passes through one slit 69.
The two-dimensional cross-sectional data in one cross section of the examinee 35 is obtained using the detection signal. Two-dimensional cross-sectional data in another cross section of the examinee 35 is obtained by moving the X-ray source 9 to the position of another slit 69 by extending and contracting the axial movement arm 11. By stacking these two-dimensional cross-sectional data, three-dimensional cross-sectional data can be obtained.

According to the present embodiment, the effects (1) to (11) and (14) produced in the embodiment can be obtained. In this example, the following effects (15) and (16) can be obtained. The radiation imaging apparatus 2A including the γ-ray detection unit and the X-ray detection unit is also a radiation detection device.

(15) In this embodiment, since the X-ray source 9 circulates outside the cylindrical radiation detection unit 65A, the diameter of the radiation detection unit is reduced. A pair of gamma rays emitted at the time of positron annihilation is 180 degrees ±
Since it is emitted at 0.6 degrees, the error is reduced and the image resolution is improved when the diameter of the radiation detector is reduced. In addition, the number of radiation detectors 4 can be reduced.

(16) In this embodiment, since the axial movement arm 11 and the X-ray source 9 to which the X-ray source 9 is attached are located outside the radiation detector 4, they are emitted from the examinee 35. The radiation detector 4 located immediately behind the lines is not able to detect the γ-rays, and the possibility of missing detection data necessary for creating a PET image is completely eliminated.

Example 4
A radiation inspection apparatus according to embodiment 4, which is another embodiment of the present invention, will be described with reference to FIGS. The radiation inspection apparatus 1B of the present embodiment includes an imaging apparatus 2B and a patient holding apparatus 14, and is not illustrated in FIG. 14, but is described in the γ-ray discrimination apparatus 21 illustrated in FIG. A coincidence counting device 26, a computer 27, a storage device 28 and a display device 29. Since the difference from the third embodiment resides in the image pickup apparatus 2B, the following description will mainly focus on the image pickup apparatus 2B.

The imaging device 2B includes a plurality of radiation detector annular bodies 3B, an X-ray source device 8A, and an X-ray detection device 77.
, A detector holding device 72, a circumferential guide rail 74, an X-ray source axial guide rail 75, and a detector axial guide rail 76.

The plurality of radiation detector annular bodies 3 </ b> B are independently installed on the support member 6 in the axial direction by the detector holding device 72. Each radiation detector annular body 3B includes an annular holding portion 5B.
A plurality of radiation detectors 4 are installed in the circumferential direction and the axial direction on the inner surface. The annular holding portion 5B is attached to the detector holding device 72. A gap 73 is formed between each of the radiation detector annular bodies 3B. An annular circumferential guide rail 74 is provided on the outer surface of each annular holding portion 5B. The X-ray source axial guide rail 75 and the detector axial guide rail 76 are provided to extend in the axial direction on the outer surface of each annular holding portion 5B at positions 180 ° apart from each other.

The X-ray source device 8 </ b> A includes an X-ray source driving device 10 and an X-ray source 9 provided in the X-ray source driving device 10. The X-ray source driving apparatus 10 includes a motor, a speed reduction mechanism, and two types of pinions for circumferential movement and axial movement, which are not shown in the casing. When the X-ray source device 8A moves in the circumferential direction, the speed reduction mechanism is connected to the circumferential movement pinion, and the driving force rotated by the motor is transmitted to the circumferential movement pinion. When the X-ray source device 8A moves in the axial direction, the speed reduction mechanism is connected to the axial movement pinion, and the driving force rotated by the motor is transmitted to the axial movement pinion. The circumferential movement pinion engages with a rack provided on the circumferential guide rail 74, and the axial movement pinion engages with a rack provided on the X-ray source axial guide rail 75. The X-ray source device 8A is movable in each direction on the outer surface side of the annular holding portion 3B. The X-ray source 9 is provided facing the annular holding portion 5B in the X-ray source device 8A.

The X-ray detection device 77 is connected to the X-ray source device 8A by a semicircular connecting member (not shown) outside the annular holding portion 5B. For this reason, when the X-ray source device 8A moves along the circumferential guide rail 74 in the circumferential direction of the annular holding portion 5B, the X-ray detection device 77 uses the X-ray source device 8A.
With the movement of the annular holding portion 5B along the circumferential guide rail 74 outside the annular holding portion 5B.
Move in the circumferential direction. When the X-ray source device 8A moves in the axial direction of the annular holding portion 5B along the X-ray source axial guide rail 75, the X-ray detector 77 moves in the detector axial direction along with the movement of the X-ray source device 8A. It moves along the guide rail 76 in the axial direction of the annular holding portion 5B outside the annular holding portion 5B. The X-ray detector 77 has a plurality of X-ray detectors 78 arranged in the circumferential direction of the hole 30. The plurality of X-ray detectors 78 constitute an X-ray detector. A plurality of X-ray detectors 78 may be arranged in the axial direction of the annular holding portion 5B.

The cylindrical γ-ray detection unit 80 includes the radiation detectors 4 provided in all the radiation detector annular bodies 3B.
Consists of. The X-ray detection unit is located in a region formed between one end of the γ-ray detection unit 80 and the other end of the γ-ray detection unit 80 in the longitudinal direction of the bed 16. The radiation detector 4 and the X-ray detector 78 are the semiconductor radiation detectors described in the first embodiment. In this embodiment, the X-ray source 9 is disposed outside the radiation detector annular body 3 </ b> B, that is, the γ-ray detection unit 80.

In the present embodiment, unlike the first and third embodiments in which the X-ray detection unit and the γ-ray detection unit are integrated, the X-ray detection unit and the γ-ray detection unit are provided separately. The configuration in which the X-ray detection unit and the γ-ray detection unit are separate is also applied to Examples 5 and 6 described later. The radiation imaging apparatus 2B having the γ-ray detection unit and the X-ray detection unit is also a radiation detection device.

The examinee 35 to whom the PET drug is administered is moved to a predetermined position in the hole 30 by moving the bed 16. When an operator such as a radiologist presses an X-ray CT examination start button on an operation panel (not shown), a drive device control device (not shown) and X
An X-ray CT inspection start signal is input to a radiation source control device (not shown), and the X-ray CT inspection in this embodiment is started. The X-ray source control device that has received the X-ray CT inspection start signal is supplied with the switch 57
Close (see FIG. 1). As a result, X-rays 67 are emitted from the X-ray source 9. The X-ray 67 emitted from the X-ray source 9 passes through the gap 73 and is irradiated to the examinee 35. The motor is rotated by the control of the driving device control device, and the X-ray source device 8A moves along the circumferential guide rail 74. The X-ray source device 8A and the X-ray detection device 77 move and rotate in a space 79 formed between adjacent detector holding devices 72. For this reason, the X-ray 67 emitted from the X-ray source 9
Is irradiated to the examinee 35 from around. The X-ray 67 transmitted through the examinee 35 is detected by the X-ray detector 78 of the X-ray detector. In order to move the X-ray source device 8A and the X-ray detection device 77 to the adjacent gap 73 (for example, the gap 73A), after the irradiation of the X-ray 67 to the examinee 35 through one gap 73 is completed, The X-ray source device 8 </ b> A is moved along the X-ray source axial direction guide rail 75. At that time, the X-ray detector 77 is connected to the detector axial guide rail 76.
Move along. When the X-ray source device 8 </ b> A moves along the X-ray source axial guide rail 75, the switch 57 is opened by the control of the X-ray source control device, so that X-rays are not emitted from the X-ray source 9. When the X-ray source device 8A reaches the adjacent gap 73A, the X-ray source device 8A and the X-ray detection device 77 are moved along the circumferential guide rail 74. At this time, X-rays 67 are emitted from the X-ray source 9 by the action of the X-ray source control device. The X-ray 67 passes through the gap 73A and is irradiated to the affected part 66 of the examinee 35. The X-ray 67 transmitted through the affected area 66 is detected by the radiation detector 78. The X-ray CT examination ends when the X-ray source device 8A reaches a predetermined position at the end of the X-ray CT examination.

Each radiation detector 4 of the γ-ray detection unit 80 detects the γ-ray 68 emitted from the affected part 66.
The γ-ray detection signal output from the radiation detector 4 is input to the γ-ray discrimination device 21 via the waveform shaping device 20. The γ-ray discriminating device 21 executes the processing shown in the first embodiment and outputs a pulse signal. The coincidence counting device 26 receives the pulse signal from the γ-ray discriminating device 21 of each signal discriminating device 19 and executes the same processing as in the first embodiment. The X-ray detection signal output from the X-ray detector 78 is processed by a signal processing device (not shown). The signal processing device outputs X-ray intensity information that is an integral value of the X-ray detection signal. The computer 27 for inputting the X-ray intensity information described above executes the processes of Steps 36 to 41 shown in FIG. Image data is obtained and the combined tomographic image data is displayed on the display device 29.

In the present embodiment, the PET examination for detecting the γ-rays 68 emitted from the affected area 66 within the radiation examination period for obtaining the detection signal of the γ-rays 78 necessary for creating the tomographic image data of the examinee 35 is also provided. The X-ray CT examination for detecting the X-ray 67 transmitted through the examinee 35 is performed. Also in this embodiment, as shown in FIG. 6, a plurality of X-ray CT examinations may be carried out within one radiation examination period.

According to the present embodiment, (1), (2), (4), (6), (7), (10) occurring in the third embodiment.
, (11) and (14) to (16) can be obtained. Furthermore, the following effects can also be obtained.

(17) In this embodiment, since the X-ray detection unit (specifically, the X-ray detector 78) is disposed between one end and the other end in the axial direction of the γ-ray detection unit 80, PET inspection is performed. The X-ray CT examination can be performed at the same position without moving the examinee 35 on the predetermined area of the examinee 35 being implemented. For this reason, even when the examinee 35 moves on the bed 16 during the examination, the first tomographic image data and the second tomographic image data at the position of the affected part can be accurately synthesized. For example, the data of the first tomographic image and the data of the second tomographic image can be easily and accurately synthesized by aligning the axial center of the hole 30 of the imaging device 2B. Therefore, even when an affected part exists in a place where an organ is complicated, the position of the affected part can be appropriately grasped by the tomographic image obtained in the present embodiment, and the diagnosis accuracy of the affected part is improved.

(18) In this embodiment, the selector switch 31 used in the first embodiment is not necessary. That means
The radiation detector 4 installed on the annular holding part 5B is connected to the γ-ray discriminating device 21 via the waveform shaping device 20 by the wiring 23. On the other hand, the X-ray detector 78 is directly connected to the signal processing device by wiring (not shown). Therefore, the circuit configuration is simplified. In addition, control of the changeover switch and the like is not necessary, and the control method can be simplified.

(19) In this embodiment, the X-ray source device 8A and the X-ray detection device 77 can be rotated 360 degrees. Therefore, in X-ray CT examination, it is possible to obtain data in the direction of 360 degrees in order to obtain one tomographic image, and the image quality of the X-ray CT image can be improved.

(20) In this embodiment, the X-ray source device 8 </ b> A and the X-ray detection device 77 with respect to the central axis of the hole 30.
Are arranged at opposite positions. Accordingly, it is possible to irradiate X-rays parallel to the cross-section when taking a two-dimensional cross-sectional image in the X-ray CT examination, and the image quality of the X-ray CT image can be improved.

(21) In this embodiment, X-rays can be irradiated parallel to the gap 73. Therefore, the gap 73
Can be minimized to a width approximately equal to the beam width. The gap 73 is a data defect area at the time of PET inspection, and by minimizing the width of the gap 73, the speed of the PET inspection and the image quality can be improved.

(22) In this embodiment, the X-ray detector 77 is provided independently of the radiation detector 4 for detecting γ-rays for PET inspection. Therefore, the arrangement pitch of the X-ray detectors 78 in the X-ray detector 77 can be arbitrarily set, and the resolution of the X-ray CT image can be easily increased.

(Example 5)
A radiation inspection apparatus according to embodiment 5, which is another embodiment of the present invention, will be described with reference to FIGS. The radiation inspection apparatus 1C of the present embodiment includes an imaging device 2C and a patient holding device 14, and is not illustrated in FIG. A coincidence counting device 26, a computer 27, a storage device 28 and a display device 29.
The radiation imaging apparatus 2C having the γ-ray detection unit and the X-ray detection unit is also a radiation detection device.

The image pickup apparatus 2C in the present embodiment is structurally configured to the image pickup apparatus 2A with the axially extendable arm 81.
And an X-ray detector 82 are added. However, the X-ray source device holding unit 13 is installed on a support member 83 that is detachably attached to the support member 6. The axial telescopic arm 81 is attached to the casing of the X-ray source driving device 10 at a position opposite to the axial telescopic arm 11 by 180 °. The X-ray detector 82 is installed at the tip of the axially extending arm 81, and includes a plurality of X-ray detectors 78 in the circumferential direction of the hole 30 as shown in FIG. The X-ray source circumferential direction moving device 7A in the present embodiment includes an X-ray source 9, an X-ray source driving device 10, an X-ray source device holding unit 13, axial telescopic arms 11, 81, and an X-ray detecting unit 82. A plurality of radiation detectors 4 arranged in a cylinder form a γ-ray detector 80A. The extension / contraction operation of the axial extension / contraction arm 81 is performed by driving the motor 18 in the same manner as the axial extension / contraction arm 11. The other configuration of the imaging device 2C has the same configuration as the imaging device 2A. The imaging apparatus 2C includes an X-ray imaging apparatus 84 and a γ-ray imaging apparatus 85. The X-ray imaging device 84 includes an X-ray source circumferential direction moving device 7 </ b> A, a drive device control device 70, an X-ray source control device 71, and a support member 83. The γ-ray imaging device 85 includes a radiation detector annular body 3 </ b> A and a support member 6.

The X-ray source 9 and the axial telescopic arm 11, the X-ray detector 82 and the axial telescopic arm 81 are
By moving the radiation source driving device 10 along the guide rail 12, the periphery of the examinee 35 on the bed 16 is moved within the range of the circumferential length of the slit 69 as in the third embodiment. The X-ray 67 emitted from the X-ray source 9 is irradiated to the examinee 35 to which the PET drug is administered through, for example, the slit 69 </ b> A and passes through the affected part 66. The X-ray 67 transmitted through the affected part 66 is
It is detected by the X-ray detector 78 of the X-ray detector 82. The X-ray source 9 and the X-ray detector 82 are
The axially extending and retracting arms 11 and 81 are expanded and contracted to move in the axial direction of the hole 30 in a state of facing each other. Gamma rays 68 released from the affected area 66 due to the PET drug are:
It is detected by the radiation detector 4 of the γ-ray detector 80A.

The X-ray detection signal output from the X-ray detector 78 and the γ-ray detection signal output from the radiation detector 4 are processed in the same manner as in the fourth embodiment. By this processing, the combined tomographic image data of the cross section at the position of the affected part 66 of the examinee 35 is obtained, and the combined tomographic image data is displayed on the display device 29.

According to the present embodiment, (1), (2), (4), (6), (7), (10) occurring in the fourth embodiment.
, (11), (14) to (18) and (20) to (22) can be obtained. The present embodiment further produces the following effects.

(23) In this embodiment, the X-ray source 9 and the X-ray detector 82 are attached to the X-ray source driving device 10 at a position facing each other, and the X-ray inspection is performed by the circumferential movement of the X-ray source driving device 10. It is a possible structure. Accordingly, during the X-ray CT examination, the movement of the X-ray source 9 and the X-ray detector 82 in the circumferential direction of the hole 30 can be controlled simultaneously, and the control method can be simplified.

(24) In the present embodiment, the X-ray imaging device 84 is detachable, and when it is removed,
An X-ray CT examination can be performed independently using the line imaging device 84.

(Example 6)
A radiation inspection apparatus according to embodiment 6, which is another embodiment of the present invention, will be described with reference to FIGS. The radiation examination apparatus 1D of the present embodiment includes an imaging apparatus 2D and a patient holding apparatus 14, and is not illustrated in FIG. A coincidence counting device 26, a computer 27, a storage device 28, and a display device 29.
Conceptually, the imaging device 2D is obtained by applying the X-ray imaging device 84 (FIG. 16) of the imaging device 2C to the imaging device 2B (FIG. 14). That is, the imaging device 2D includes an X-ray imaging device 84 and a γ-ray imaging device 85A. The γ-ray imaging device 85 </ b> A includes a plurality of radiation detector annular bodies 3 </ b> B, a support member 6, and a detector holding device 72 that installs each radiation detector annular body 3 </ b> B in the support member 6 in the fourth embodiment. In the present embodiment, the X-ray detector 82 and the axially extending / contracting arm 81 are arranged outside the radiation detector annular body 3B. In this embodiment, the X-ray source 9 and the X-ray detector 82 can be moved in the circumferential direction of the hole 30 by the X-ray source driving device 10 in a region other than the detector holding device 72. Although not shown, the X-ray detection unit 82 has the same configuration as that of the fifth embodiment. The radiation imaging apparatus 2D having the γ-ray detection unit and the X-ray detection unit is also a radiation detection device.

The X-ray detection signal output from the X-ray detector 78 and the γ-ray detection signal output from the radiation detector 4 are processed in the same manner as in the fourth embodiment. By this processing, the combined tomographic image data of the cross section at the position of the affected part 66 of the examinee 35 is obtained, and the combined tomographic image data is displayed on the display device 29.

According to the present embodiment, (1), (2), (4), (6), (7), (10) occurring in the fifth embodiment.
, (11), (14) to (18) and (20) to (24) can be obtained. In the present embodiment, the diameter of the radiation detector annular body can be reduced as compared with the fifth embodiment.

In Examples 1 to 5, at least a part of the X-ray detection unit may be positioned in a region formed between one end of the γ-ray detection unit and the other end of the γ-ray detection unit in the longitudinal direction of the recording bed. Good.

It is a longitudinal cross-sectional view of the radiation inspection apparatus used for the radiation inspection method which is a suitable Example of this invention. It is II-II sectional drawing of FIG. FIG. 1 is a longitudinal cross-sectional view of the X-ray source in FIG. 1, (A) is an explanatory view showing a state where the shutter is closed, and (B) is an explanatory view showing a state where the shutter is opened. It is a detailed block diagram of the signal discrimination apparatus in Example 1 shown in FIG. It is a detailed block diagram of the integrated control apparatus of FIG. It is explanatory drawing of the control schedule applied to the radiation inspection method of a present Example. It is explanatory drawing which shows the waveform of the gamma ray detection signal input into the waveform shaping apparatus of FIG. It is explanatory drawing which shows the waveform of the gamma ray detection signal output from the waveform shaping apparatus of FIG. It is a flowchart of the process sequence performed with the computer of FIG. It is a block diagram of the other Example of a signal discrimination apparatus. It is a block diagram of the transmission system of the tomogram data used for the radiological examination assistance method of Example 2 which is another Example of this invention. It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 3 which is one suitable Example of this invention. It is AA sectional drawing of FIG. It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 4 which is another Example of this invention. It is BB sectional drawing of FIG. It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 5 which is another Example of this invention. CC sectional drawing of FIG. It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 6 which is another Example of this invention. It is DD sectional drawing of FIG.

Explanation of symbols

1, 1A, 1B, 1C, 1D ... Radiation inspection apparatus, 2, 2A, 2B, 2C, 2D ... Imaging apparatus, 3, 3A, 3B ... Radiation detector annular body, 4 ... Radiation detector, 7, 7A ... X X-ray source device, 9 ... X-ray source, 10 ... X-ray source drive device, 11, 81 ... Axial telescopic arm, 12 ... Guide rail, 14 ... Holding subject Device, 16 ... bed, 19,
DESCRIPTION OF SYMBOLS 19A ... Signal discriminating device, 21 ... Gamma ray discriminating device, 22 ... X-ray detection signal processing device, 24 ... Power switch, 26 ... Simultaneous counting device, 27 ... Computer, 28 ... Storage device, 29 ... Display device,
DESCRIPTION OF SYMBOLS 30 ... Hole part, 31 ... Changeover switch, 32 ... Movable terminal, 38 ... Wave height analyzer, 42 ... X-ray tube, 44 ... Shutter, 47 ... General control apparatus, 48 ... General control part, 49 ... Detector power supply control part , 50... X-ray source movement control unit, 51... X-ray emission control unit, 52.
Bed movement control unit, 54 ... button switch, 65, 65A ... radiation detection unit, 66 ... affected part,
67 ... X-ray, 68 ... γ-ray, 69, 69A ... Slit, 70 ... Drive device controller, 71 ... X
Radiation source control device 72 ... Detector holding device 73, 73A ... Gap, 74 ... Circumferential guide rail, 75 ... X-ray source axial guide rail, 76 ... Detector axial guide rail, 77 ... X-ray detection device , 78... X-ray detector, 80, 80A... Γ-ray detector, 82... X-ray detector, 84.

Claims (29)

A plurality of radiation detectors are arranged in the longitudinal direction of the bed and around the bed and output a detection signal of γ-rays, and are arranged outside the γ-ray detection unit and are arranged in the longitudinal direction of the bed. An X-ray source that moves in the circumferential direction and an X-ray detector that is a radiation detector that outputs an X-ray detection signal,
The X-ray detection unit is located in a region formed between one end of the γ-ray detection unit and the other end of the γ-ray detection unit in the longitudinal direction of the bed,
A gap through which X-rays emitted from the X-ray source pass is formed between the γ-ray detection units in the longitudinal direction of the bed in the circumferential direction with respect to the longitudinal direction of the bed ,
The radiation inspection apparatus , wherein the γ-ray detection unit does not move while the X-ray source is moving .   The radiation inspection apparatus according to claim 1, further comprising a first X-ray source moving device that moves the X-ray source in a circumferential direction.   The radiation inspection apparatus according to claim 1, further comprising a second X-ray source moving device that moves the X-ray source in a longitudinal direction of the bed.   A first X-ray source moving device that moves the X-ray source in the circumferential direction, a second X-ray source moving device that moves the X-ray source in the longitudinal direction of the bed, the first X-ray source moving device, and the second X The radiation inspection apparatus according to claim 1, further comprising a control device that controls the radiation source moving device.   The radiation inspection apparatus according to claim 1, wherein the X-ray source is located in the region.   The γ-ray detection unit and the X-ray detection unit integrally form a radiation detection unit that is the γ-ray detection unit and the X-ray detection unit, and the radiation detection unit includes the γ-ray detection signal and The radiation inspection apparatus according to any one of claims 1 to 4, comprising a plurality of the radiation detectors that output both of the X-ray detection signals.   The radiation according to claim 1, wherein a plurality of the gaps are arranged at intervals in the longitudinal direction, and an X-ray source moving device that moves the X-ray source outside the γ-ray detection unit is provided. Inspection device.   A first guide device that guides the X-ray source moving device in the longitudinal direction; and a second guide device that guides the X-ray source moving device in a direction intersecting the first guide device around the γ-ray detection unit. The radiation inspection apparatus according to claim 7, further comprising:   The γ-ray detection unit and the X-ray detection unit are provided separately, the γ-ray detection unit includes a plurality of the radiation detectors that output the γ-ray detection signals, and the X-ray detection unit The radiation inspection apparatus according to claim 1, further comprising a plurality of radiation detectors that output X-ray detection signals.   The radiation inspection apparatus according to claim 9, wherein the X-ray detection unit is disposed inside the γ-ray detection unit.   The radiation inspection apparatus according to claim 9, wherein the X-ray detection unit is disposed outside the γ-ray detection unit.   6. A tomographic image creating apparatus for creating tomographic image information using first information obtained from the γ-ray detection signal and second information obtained from the X-ray detection signal. Item 10. The radiation inspection apparatus according to any one of Items 9 to 9.   Creating first tomogram information using first information obtained from the γ-ray detection signal, creating second tomogram information using second information obtained from the X-ray detection signal, and The radiological examination apparatus according to claim 1, further comprising a tomographic image creating apparatus that creates third tomographic image information including first tomographic image information and second tomographic image information. .   A first signal processing device for inputting γ-ray detection signals from the respective radiation detectors and outputting first information used for creating first tomographic image information including a site where radiopharmaceuticals are accumulated; A second signal processing device provided for each of the radiation detectors, which receives the X-ray detection signal from the detector and outputs second information used to create second tomographic image information including bone; The radiation inspection apparatus according to any one of claims 1, 6, and 9.   The radiation inspection apparatus according to claim 14, further comprising a tomographic image creation device that creates tomographic image information using the first information and the second information. The first signal processing device includes:
Input the γ-ray detection signal from the radiation detector, input a γ-ray detection signal processing device provided for each radiation detector, and each output signal from each γ-ray detection signal processing device, A counting device that outputs the position information of each of the pair of radiation detectors that have detected the γ-rays within the set time, and the count information of the detected γ-rays, which is the first information. And
The radiation inspection apparatus according to claim 14, further comprising a tomographic image creation device that creates tomographic image information using the position information, the count information, and the second information. A γ-ray detection signal processing apparatus that is provided for each of the radiation detectors and that receives a γ-ray detection signal from the radiation detector;
An X-ray detection signal processing device that is provided for each of the radiation detectors and that inputs the X-ray detection signal from the radiation detector;
A switching device connected to each of the plurality of radiation detectors and connecting the radiation detector to the γ-ray detection signal processing device or the X-ray detection signal processing device;
Switching control for selecting the radiation detector for detecting the X-ray based on the position of the X-ray source and controlling the switching device to connect the selected radiation detector to the X-ray detection signal processing device The radiation inspection apparatus according to claim 6, comprising the apparatus.   The radiation inspection apparatus according to any one of claims 1, 6, 9, and 17, wherein the radiation detector is a semiconductor radiation detector.   The radiation according to claim 17, wherein the switching control device controls the other switching device to connect the radiation detector other than the selected radiation detector to the γ-ray detection signal processing device. Inspection device. A plurality of radiation detectors are arranged in the longitudinal direction of the bed and around the bed and output a detection signal of γ-rays, and are arranged outside the γ-ray detection unit and are arranged in the longitudinal direction of the bed. An X-ray source that moves in the circumferential direction and an X-ray detector that is a radiation detector that outputs an X-ray detection signal,
The X-ray detection unit is located in a region formed between one end of the γ-ray detection unit and the other end of the γ-ray detection unit in the longitudinal direction of the bed,
A gap through which X-rays emitted from the X-ray source pass is formed between the γ-ray detection units in the longitudinal direction of the bed in the circumferential direction with respect to the longitudinal direction of the bed ,
The positron emission CT apparatus characterized in that the γ-ray detector does not move while the X-ray source is moving .   21. The positron emission CT apparatus according to claim 20, further comprising a first X-ray source moving device that moves the X-ray source in a circumferential direction.   The positron emission CT apparatus according to claim 20 or 21, further comprising a second X-ray source moving device that moves the X-ray source in a longitudinal direction of the bed.   The γ-ray detection unit and the X-ray detection unit integrally form a radiation detection unit that is the γ-ray detection unit and the X-ray detection unit, and the radiation detection unit includes the γ-ray detection signal and 23. The positron emission CT apparatus according to claim 20, comprising a plurality of the radiation detectors that output both of the X-ray detection signals.   A first signal processing device for inputting γ-ray detection signals from the respective radiation detectors and outputting first information used for creating first tomographic image information including a site where radiopharmaceuticals are accumulated; A second signal processing device provided for each of the radiation detectors, which receives the X-ray detection signal from the detector and outputs second information used to create second tomographic image information including bone; The positron emission CT apparatus according to claim 20. The first signal processing device includes:
Input the γ-ray detection signal from the radiation detector, input a γ-ray detection signal processing device provided for each radiation detector, and each output signal from each γ-ray detection signal processing device, A counting device that outputs the position information of each of the pair of radiation detectors that have detected the γ-rays within the set time, and the count information of the detected γ-rays, which is the first information. And
The radiation examination apparatus according to claim 24, further comprising a tomographic image creation device that creates tomographic image information using the position information, the count information, and the second information.   25. The positron emission CT apparatus according to claim 24, further comprising a tomographic image creation device that creates tomographic image information using the first information and the second information. A γ-ray detection signal processing apparatus that is provided for each of the radiation detectors and that receives a γ-ray detection signal from the radiation detector;
Each output signal from each of the γ-ray detection signal processing devices is input, and the positional information of the pair of radiation detectors that detected the γ-ray within a set time, and the count information of the detected γ-rays A counting device that outputs first information including:
An X-ray detection signal processing apparatus that is provided for each radiation detector and outputs the second information used to create second tomographic image information including bone by inputting the X-ray detection signal from the radiation detector. When,
A switching device connected to each of the plurality of radiation detectors and connecting the radiation detector to the γ-ray detection signal processing device or the X-ray detection signal processing device;
Switching control for selecting the radiation detector for detecting the X-ray based on the position of the X-ray source and controlling the switching device to connect the selected radiation detector to the X-ray detection signal processing device The positron emission CT apparatus according to claim 23, comprising: an apparatus.   The positron according to claim 27, wherein the switching control device controls the other switching device to connect the radiation detector other than the selected radiation detector to the γ-ray detection signal processing device. Emission CT device.   The positron emission CT apparatus according to claim 23, wherein the radiation detector is a semiconductor radiation detector.

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