JP2005121673A - Positron emission ct device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positron emission CT device with a simplified device structure. <P>SOLUTION: An imaging device 2 of a radiation inspection device 1 comprises radiation detector annular bodies 3A and 3B, and an X-ray source 9 going round along the annular bodies and outside the annular bodies. The annular bodies 3A and 3B include a multitude of radiation detectors 4 annularly installed inside an annular hold part 5. Between the annular bodies 3A and 3B, a slit 36 is formed allowing X rays emitted from the X-ray source 9 to pass therethrough. A bed 16 with an examinee 35 thereon is inserted into a hole part 30 of the annular bodies 3 to execute X-ray CT inspection and PET inspection. The plurality of radiation detectors 4 annularly disposed make it possible to detect a plurality of γ-ray pairs emitted from the examinee 35 while making it possible to detect X rays emitted from the circumferentially moving X-ray source 9 and transmitted by the examinee 35. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a positron emission CT apparatus (Positron Emission Computed Tomography, hereinafter referred to as PET).

The inspection technique using radiation can inspect the inside of a subject nondestructively. X-ray CT, PET, and single photon emission computed tomography (Single Photon Emission Computed Tomography (Single Photon)
Emission Computed Tomography)), hereinafter referred to as SPECT). All of these techniques 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 a huge amount of 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.

  X-ray CT irradiates the examinee with X-rays from the X-ray source, measures the intensity of the X-rays that have passed through the body of the examinee, and obtains cross-sectional shape information on the examinee from the X-ray passage rate in the body. This is a technique for imaging, that is, obtaining a tomographic image of the examinee. The X-ray intensity that has passed through the body of the examinee is measured by a radiation detector arranged on the opposite side of the X-ray source with respect to the examinee, and the X-ray source and the radiation detector are measured using the measured X-ray intensity. Find the linear attenuation coefficient between The X-ray source and the radiation detector are simultaneously turned around the examinee to obtain the distribution of the linear attenuation coefficient in the body. Using this linear attenuation coefficient, the linear attenuation coefficient of each voxel is obtained using a filtered back projection method (Filtered BackProjection Method) described in Non-Patent Document 1, and the value is converted into a CT value. A radiation source often used for X-ray CT is about 80 keV.

  On the other hand, 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.

In PET, a radiopharmaceutical containing a positron emitting nuclide ( ¹⁵ O, ¹³ N, ¹¹ C, ¹⁸ F, etc.) and a substance having a property of collecting in specific cells in the body is administered to a subject to be examined. It is a method to check which part of the body is consumed a lot. An example of a radiopharmaceutical is 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 radiopharmaceutical 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 emitted in directions almost opposite to each other (180 ° ± 0.6 °). If this pair of γ-rays is detected by a γ-ray detector, it can be seen between which two γ-ray detectors the positrons are emitted. By detecting these many gamma ray pairs, it is possible to know where the radiopharmaceutical is consumed much. 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. The obtained data is converted into the radiation generation density of each voxel by the filtered back projection method shown above, and the generation position of the γ-ray (the position where the radionuclide accumulates, that is, the position of the cancer cell) is imaged. To contribute. ¹⁵ O, ¹³ N, ¹¹ C, and ¹⁸ F used in PET are radioisotopes with a short half-life of 2 to 110 minutes.

  In the inspection by PET, γ rays generated at the time of positron annihilation attenuate in the body of the examinee, so a transmission image is captured and corrected. The transmission image is a method of measuring the attenuation rate of γ-rays in the body by making γ-rays incident on a radiation source using, for example, cesium and measuring the intensity of the γ-rays transmitted through the body of the examinee. By using the obtained γ-ray attenuation rate to estimate the γ-ray attenuation rate in the body and correcting the data obtained by PET, it is possible to obtain a more accurate PET image.

In SPECT, a radiopharmaceutical containing a single photon emitting nuclide is administered to a subject to be examined, and γ rays emitted from the nuclide are detected by a γ ray detector. The energy of γ rays emitted from single-photon emission nuclides often used at the time of inspection by SPECT is around several hundred keV. In the case of SPECT, since a single gamma ray is emitted, the angle incident on the gamma ray detector cannot be obtained. Therefore, angle information is obtained by detecting only γ rays incident from a specific angle using a collimator. SPECT is a substance that accumulates in a specific tumor or molecule, and a radiopharmaceutical containing a single photon emitting nuclide (such as ⁹⁹ Tc, ⁶⁷ Ga, ²⁰¹ Tl, etc.) is administered to a subject, and γ generated from the radiopharmaceutical. This is an inspection method that detects a line and identifies a place where a large amount of radiopharmaceutical is consumed (for example, a place where cancer cells are present). 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 used for SPECT 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 that is a tomographic image obtained by X-ray CT and a functional image that is a tomographic image obtained by PET or SPECT. As an example of this technology, there is a technology described in Patent Document 1.

  The radiation inspection apparatus described in Patent Document 1 has an X-ray CT inspection apparatus and a PET inspection apparatus installed in series, moves the bed on which the examinee lies horizontally, and uses both inspection apparatuses to examine the patient. Perform the inspection. In this case, the time interval between the two examinations is short, and the examinee hardly moves on the bed, so the correspondence between the PET data, which is the imaging data obtained by the two examination apparatuses, and the X-ray CT data can be known. Using the information on the correspondence relationship, the PET data and the X-ray CT data are synthesized, and the lesion position of the examinee is specified.

  Patent Document 2 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 I Triple E Transaction on Nuclear Science, NS-21, 21

  In the radiological examination apparatus described in each of the above publications, the positional relationship between the two imaging data seems to be clear at first glance. However, there is a possibility that the examinee who is the subject moves between the two examination apparatuses. is there. The resolution of a recent PET inspection apparatus is about 5 mm, and the resolution of an X-ray CT inspection apparatus is about 0.5 mm, which is about an order of magnitude smaller than that. For this reason, if the examinee moves between the two examination apparatuses or the angle of the examinee changes, the correspondence between the respective image data obtained by both examination apparatuses becomes unclear. As a result, for example, after each image data is reconstructed, a feature region existing in each image is extracted in common, and the positional relationship of each image is obtained from the positional relationship of the feature region, and alignment is performed. Need arises. In addition, these radiation inspection apparatuses include two imaging apparatuses each having a radiation detector and the like, and thus the apparatus configuration is complicated.

  An object of the present invention is to provide a positron emission CT apparatus having a simplified apparatus configuration.

A feature of the present invention that achieves the above object is that an imaging apparatus includes a radiation detector annular body having a plurality of radiation detectors arranged in an annular shape, and a radiation detector annular body in a radial direction of the radiation detector annular body. An X-ray source that is disposed outside and emits X-rays, and an X-ray source moving unit that moves the X-ray source in the circumferential direction of the radiation detector annular body. The radiation detector transmits the subject. Output a first detection signal that is a detection signal of X-rays and a second detection signal that is a detection signal of γ rays emitted from the subject,
A slit for passing X-rays emitted from the X-ray source toward the inside of the radiation detector annular body is formed between the radiation detectors of the radiation detector annular body.

  Since a plurality of radiation detectors are arranged in an annular shape, these radiation detectors can detect a plurality of pairs of γ rays emitted from the subject and are emitted from an X-ray source moving in the circumferential direction. X-rays that have passed through the subject can also be detected. For this reason, the configuration of the radiation inspection apparatus can be simplified. Further, the X-ray source is disposed outside the radiation detector annular body in the radial direction of the radiation detector annular body, and allows X-rays emitted from the X-ray source to pass inward from the radiation detector annular body. Since the slit is formed between the radiation detectors of the radiation detector annular body, the positron emission CT apparatus can be miniaturized.

  Preferably, a collimator through which X-rays pass is disposed between the slit and the radiation detector, and the radiation detector is disposed around the collimator. According to this, X-ray incidence to the radiation detector 4 adjacent to the slit can be blocked by the radiation shielding function of the collimator.

  According to the present invention, the configuration of a positron emission CT apparatus can be simplified.

  Embodiments of the present invention will be described with reference to the drawings.

(Example 1)
A radiation inspection apparatus according to a preferred embodiment of the present invention will be described with reference to FIGS. The radiation examination apparatus 1 of the present embodiment includes an imaging device 2, a patient holding device 14, a signal discriminating device 19, a coincidence counting device 26, a computer (for example, a workstation) 27, a storage device 28, and a display device 29. Yes. 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, an X-ray source circumferential movement device 7, a drive device control device 17, and an X-ray source control device 18. Have 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 not only in the circumferential direction but also in the axial direction of the hole 30 in the annular holding portion 5. 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. The support members 6 and 15 are connected to each other and installed on the floor of the examination room. The drive device control device 17 and the X-ray source control device 18 are installed on the outer surface of the annular holder 5.

  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. A scan rail 12, which is an annular guide rail, is installed on one end surface of the X-ray source device holding unit 13. The scan rail 12 and the X-ray source device holding unit 13 surround the hole 30. The X-ray source device 8 includes an X-ray source 9, an X-ray source driving device 10, and an axial movement arm 11. Although not shown, the X-ray source driving device 10 includes a first motor and a power transmission mechanism having a speed reduction mechanism in the casing. The power transmission mechanism is coupled to the rotation shaft of the first motor. 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 the operation of a second motor (not shown) installed in the X-ray source driving device 10. The X-ray source driving device 10 is attached to the scan rail 12 so as not to fall and move along the scan 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. This pinion meshes with a rack provided on the scan rail 12.

  Although not shown, the X-ray source 9 has a known X-ray tube. The X-ray tube includes an anode, a cathode, a cathode current source, and a voltage source for applying a voltage between the anode and the cathode in an outer cylinder. The cathode is a tungsten filament. 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 80 keV are generated by the collision of the electrons with the anode. This X-ray is emitted from the X-ray source 9.

  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 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 a signal processing device 22 for obtaining X-ray intensity. 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 signal processing device 22 is connected to the fixed terminal 34. The minus terminal of the power source 25 is connected to the wiring 23 via the resistor 24, and the plus terminal of the power source 25 is connected to the radiation detector 4. 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 device 26 may be provided for each of several γ-ray discriminating devices 21. Each 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. The signal processing device includes a first signal processing device including a signal processing device 22, and a second signal processing device including a waveform shaping device 20 and a γ-ray discrimination device 21.

  In this embodiment, X-ray CT examination (act of detecting with a radiation detector X-rays emitted from the X-ray source 9 and transmitted through the body of the examinee) and PET examination (because of the radiopharmaceutical for PET) This is an example in which a single imaging device 2 is used to perform the action of detecting γ-rays radiated from the body of the examinee with a radiation detector.

Prior to performing the radiological examination, first, the above-described radiopharmaceutical for PET is applied to the subject to be examined 35 by a method such as injection in advance so that the in-vivo radioactivity is 370 MBq. It is administered to the examiner 35. The radiopharmaceutical is selected according to the examination purpose (for example, grasping the location of cancer or examining the arterial flow of the heart). The examinee 35 waits for a predetermined time until the radiopharmaceutical is diffused into the body in a state where the radiopharmaceutical can be imaged and collected in the affected area. The radiopharmaceutical collects in the affected area (for example, the affected area of cancer) of the examinee 35 as the predetermined time elapses. After the predetermined time has elapsed, the examinee 35 is laid on the bed 16 of the examinee holding device 14. Depending on the type of examination, the radiopharmaceutical may be administered to the examinee 35 laid on the bed 16. In addition, when ¹⁵ O having a half-life of 2 minutes is used, imaging is performed by the imaging device 2 while being administered to the examinee 35.

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 images (tomographic images including visceral and bone images of the subject obtained by X-ray CT) are obtained by scanning X-rays emitted from an X-ray source in a specific direction for a predetermined time. The operation (scan) of irradiating the subject and detecting the X-rays transmitted through the body by the radiation detector is repeated, and is created based on the intensities of the X-rays detected by the plurality of radiation detectors. In order to obtain highly accurate X-ray CT image data, the X-ray CT examination is released from the inside of the subject due to the PET radiopharmaceutical to the X-ray detection radiation detector. It is desirable that γ rays do not enter. For this purpose, the inventor says 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, the incidence rate of γ rays to one radiation detector is considered. Incidence rate obtained from the radioactivity in the body based on the PET radiopharmaceutical administered to the subject in the PET examination, N (Bq), and the passing rate of the generated γ rays from the solid angle of one radiation detector A 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). In the equation (1), the coefficient “2” means that a pair of (2) γ-rays are emitted when one positron annihilates α = 2NABC (1)
doing. The probability W that γ rays are detected by one detection element within the irradiation time T is given by equation (2). By determining the irradiation time T so as to reduce the value of W in the equation (2), X-ray CT
W = 1−exp (−Tα) (2)
At the time of inspection, the influence of γ rays incident on one radiation detector is negligible.

An example of the X-ray irradiation time T will be described below. A specific X-ray irradiation time T was determined based on the equations (1) and (2). The maximum radiation intensity in the body due to the radiopharmaceutical administered to the subject in the PET examination is about 370 MBq (N = 370 MBq). 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 irradiation time T of X-rays 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.

  An X-ray CT inspection and a PET inspection using the present embodiment to which the above principle is applied will be specifically described. In the X-ray CT examination and the PET examination in this embodiment, the examination subject 35 is inserted into the hole 30 by moving the bed 16 on which the examination subject 35 to which the PET radiopharmaceutical has been administered is moved. This is performed using the imaging device 2.

The X-ray source control device 18 controls the emission time of X-rays from the X-ray source 9. That is, the X-ray source control device 18 outputs an X-ray generation signal during the X-ray CT examination, and is a switch provided between the anode (or cathode) of the X-ray tube in the X-ray source 9 and the power source. (Hereinafter referred to as X-ray source switch not shown) is closed, an X-ray stop signal is output when the first set time elapses, the X-ray source switch is opened, and X-rays elapse when the second set time elapses. The control of closing the source switch is repeated. 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 are emitted from the X-ray tube in pulses. The irradiation time T that is the first set time is, for example, 1 so that the detection probability of γ rays at the radiation detector 4 can be ignored.
Set to μsec. 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 scan 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.

When starting the X-ray CT examination, the driving device control device 17 outputs a driving start signal and is connected to the first motor of the X-ray source driving device 10 and connected to the power source (hereinafter referred to as the first motor). Close the switch. When the current is supplied, the first motor 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 scan rail 12, the X-ray source device 8, that is, the X-ray source 9 moves in the circumferential direction along the scan rail 12. The X-ray source 9 moves around the examinee 35 at a set speed while being inserted into the hole 30. At the end of the X-ray CT examination, the drive device controller 17 outputs a drive stop signal to open the first motor switch. Thereby, the movement of the X-ray source 9 in the circumferential direction is stopped. 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. A known technique that does not hinder the movement of the X-ray source device is applied to the transmission of the control signal from the X-ray source control device that does not move and the driving device control device to the moving X-ray source device.

  The drive start signal output from the drive device controller 17 when starting the X-ray CT examination is input to the X-ray source controller 18. The X-ray source control device 18 outputs an X-ray generation signal based on the input of the drive start 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. . The emission and stop of the X-ray are repeated during the movement period of the X-ray source 3 in the circumferential direction. The X-rays emitted from the X-ray source 9 are irradiated to the examinee 35 inserted into the hole 30 in a fan beam shape. 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 from the surroundings. The X-ray passes through the examinee 35 and then has a plurality of radiations positioned in the circumferential direction around the radiation detector 4 at a position 180 degrees from the X-ray source 9 with the axial center of the hole 30 as a base point. It is detected by the detector 4. These radiation detectors 4 output X-ray detection signals (hereinafter referred to as X-ray imaging signals). This X-ray imaging signal is input to the corresponding signal discriminating device 19 via the corresponding wiring 23. Those radiation detectors 4 that detect the X-rays are referred to as first radiation detectors 4 for convenience.

  From the examinee 35 on the bed 16 inserted into the hole 30, 511 keV γ-rays resulting from the radiopharmaceutical for PET are emitted. The radiation detectors 4 other than the first radiation detector 4 detect the γ rays emitted from the examinee 35 and output a detection signal (hereinafter referred to as a γ ray imaging signal) of the γ rays. This γ-ray imaging signal is input to the corresponding signal discriminating device 19 via the corresponding wiring 23. The radiation detector 4 that detects γ rays is referred to as a second radiation detector 4 for convenience.

  In the signal discriminating device 19, the γ-ray imaging signal output from the second radiation detector 4 is transmitted to the γ-ray discriminating device 21, and the X-ray imaging signal output from the first radiation detector 4 is the signal processing device 22. To be told. Such transmission of each imaging signal is performed by a switching operation of the selector switch 31 of the signal discriminating apparatus 19. The switching operation for connecting the movable terminal 32 of the switch 31 to the fixed terminal 33 or the fixed terminal 34 is performed based on a switching control signal that is an output of the drive device control device 17. The drive device control device 17 controls the movement operation of the X-ray source device 10 as described above. At the same time, the drive device control device 17 selects the first radiation detector 4 and connects to the first radiation detector 2. The movable terminal 32 of the changeover switch 31 is connected to the fixed terminal 34.

  Selection of the first radiation detector 4 will be described. An encoder (not shown) is connected to the first motor in the X-ray source driving apparatus 10. The drive device control device 17 inputs the detection signal of the encoder to determine the position of the X-ray source drive device 10 in the circumferential direction, that is, the X-ray source 9, and is positioned 180 ° opposite to the position of the X-ray source 9. The radiation detector 4 is selected using the stored position data of each radiation detector 4. Since the X-rays emitted from the X-ray source 9 have a width that is the circumferential direction of the scan rail 12, the radiation detector 2 that detects X-rays 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 drive device control device 17 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. When the drive device control device 17 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 17.

  It can be said that the first radiation detector 4 is the radiation detector 4 connected to the signal processing device 22 by the changeover switch 31. It can also be said that the second radiation detector 4 is the radiation detector 4 connected to the γ-ray discriminating device 21 by the changeover switch 31. The individual radiation detectors 4 installed on the annular holding unit 5 become the first radiation detectors 4 in some cases and the second radiation detectors 4 in other cases because of the relationship with the position of the X-ray source 9. . Therefore, one radiation detector 4 outputs both an X-ray imaging signal and a γ-ray imaging signal although they are separate.

The first radiation detector 4 detects X-rays that have been irradiated from the X-ray source 9 and transmitted through the examinee 35 during the first setting time of 1 μsec. As described above, the probability that the first radiation detector 4 detects γ rays emitted from the examinee 35 during 1 μsec is negligibly small. A large number of gamma rays generated in the body of the examinee 35 due to the radiopharmaceutical are not emitted in a specific direction but are emitted in all directions. As described above, these γ-rays are emitted in pairs in substantially opposite directions (180 ° ± 0.6 °) and detected by any second radiation detector 4 of the radiation detector annular body 3. Is done.

  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. When the position of the affected area of the examinee 35 is specified in advance by another examination, the bed 16 is moved to insert the position of the affected area specified in advance into the hole 30 and the imaging device 2 is used. A PET examination and an X-ray CT examination are performed on the vicinity of the affected part.

  The signal processing of the signal discriminating device 19 when the X-ray imaging signal and the γ-ray imaging signal output from the radiation detector 4 are input will be described. As described above, the X-ray imaging signal output from the first radiation detector 4 is input to the signal processing device 22 by the action of the changeover switch 31. The signal processing device 22 integrates the input X-ray imaging signal by the integrating device, and outputs an integrated value of the X-ray imaging signal, that is, information on the intensity of the X-ray imaging signal.

The γ-ray imaging signal output from the second radiation detector 4 is input to the waveform shaping device 20 by the action of the changeover switch 31. As shown in FIG. 4, the γ-ray imaging signal input to the waveform shaping device 20 has a shape that suddenly falls first and then approaches 0 exponentially. The γ-ray discriminating device 21 that receives the output signal of the waveform shaping device 20 cannot process a γ-ray imaging signal having a waveform as shown in FIG. For this reason, the waveform shaping device 20 converts the γ-ray imaging signal having a waveform as shown in FIG. 4 into a γ-ray imaging signal having a temporal Gaussian distribution waveform as shown in FIG. As described above, the energy of γ-rays generated in the body by positron annihilation from positrons emitted from the radiopharmaceutical for PET is 511 keV. However, not all γ-ray energy is converted into electric charges in the semiconductor element portion. For this reason, the γ-ray discriminating apparatus 21 has a predetermined value when an imaging signal having an energy equal to or higher than the energy setting value (referred to as the first energy setting value) is input, for example, with an energy setting value of 450 keV lower than 511 keV. A pulse signal having energy is generated. That is, the γ-ray discriminating device 21 is a device that generates a pulse signal having the above energy when an imaging signal (γ-ray imaging signal) having an energy equal to or higher than the first energy set value is input.

  As described above, in order to process a γ-ray imaging signal having a specific energy in the γ-ray discriminating apparatus 21, a filter that passes an imaging signal in a predetermined energy range is provided in the γ-ray discriminating apparatus 21 (or γ-ray discrimination). It is good to provide in the front | former stage of the apparatus 21). A first filter is provided in the γ-ray discriminating device 21 that allows an imaging signal having an energy equal to or higher than the first energy set value to pass and prevents an imaging signal having an energy lower than the set value from passing. The γ-ray discriminating device 21 generates a pulse signal for the imaging signal that has passed through the first filter.

  The coincidence counting device 26 receives the pulse signals output from the γ ray discriminating device 21 of each signal discriminating device 19, performs coincidence using these pulse signals, and obtains a count value for the γ ray imaging signal. Further, the coincidence counting device 26 has two detection points (approximately 180 ° centered on the axis of the hole 30 (strictly speaking, the center of the hole 30) by detecting the pair of γ rays by the pair of pulse signals for the pair of γ rays. 180 ° ± 0.6 °) is converted into data as position information for gamma ray detection.

  The computer 27 executes processing based on the processing procedure of steps 21 to 28 shown in FIG. The computer 27 that executes such processing is a tomographic image data creation device. The count value of the γ-ray imaging signal counted by the coincidence device 26, the position information of the detection point output from the coincidence device 26, and the intensity of the X-ray imaging signal output from the signal processing device 22 are input ( Step 21). The input count value of the γ-ray imaging signal, position information of the detection point, and the intensity of the X-ray imaging signal are stored in the storage device 28 (step 22).

  Using the intensity of the X-ray imaging signal stored in the storage device 28, the attenuation rate of X-rays in each voxel in the body of the examinee 35 is calculated (step 23). This attenuation rate is stored in the storage device 28.

A tomographic image of the cross section of the examinee 35 is reconstructed using the attenuation rate of the X-ray imaging signal at the corresponding position (step 24). A tomographic image reconstructed using the attenuation rate of the X-ray imaging signal is referred to as an X-ray CT image. In order to reconstruct the X-ray CT image, the attenuation rate of the X-ray imaging signal read from the storage device 28 is used to connect the X-ray source 9 and the semiconductor element portion of the radiation detector 4 that detects X-rays. A linear attenuation coefficient in the body of the examinee 35 in the meantime is obtained. Using this linear attenuation coefficient, the linear attenuation coefficient of each voxel is obtained by the filtered back projection method. The CT value in each voxel is obtained using the value of the linear attenuation coefficient of each voxel. X-ray CT image data is obtained using these CT values. The X-ray CT image data is stored in the storage device 28.

  Since γ-rays generated in the affected area are absorbed and attenuated while passing through the body, these effects are estimated from the above-mentioned attenuation rate data, and the count value of the γ-ray imaging signal is corrected to achieve higher accuracy. It is also possible to obtain a count value of a gamma ray imaging signal. In step 25, the count value of the γ-ray imaging signal is corrected. An example of a correction method related to the count value of the γ-ray imaging signal will be described below. First, a tomographic image of the examinee 35 is reconstructed using the attenuation rate of the X-ray imaging signal, and CT values at each position in the body are obtained. From the obtained CT value, the material composition at each position is estimated. Then, the linear attenuation coefficient at each position at 511 keV is estimated from the material composition data. Using the obtained linear attenuation coefficient data, a linear attenuation coefficient between a pair of semiconductor element portions in which a pair of γ rays is detected is obtained by a forward projection method. The data difference due to internal attenuation is corrected by multiplying the reciprocal of the obtained linear attenuation coefficient by the count value of the γ-ray imaging signal.

  A cross-sectional tomographic image of the examinee 35 including the affected part (for example, an affected part of cancer) is reconstructed using the corrected count value of the γ-ray imaging signal at the corresponding position (step 26). A tomographic image reconstructed using the count value of the γ-ray imaging signal is referred to as a PET image. This process will be described in detail. Each semiconductor element section of the pair of radiation detectors 4 (specified from the position information of the detection points) that detects the γ-rays generated by the annihilation of positrons using the count value of the γ-ray imaging signal read from the storage device 28 The number of γ-ray pairs generated in the body (number of γ-ray pairs generated in response to the disappearance of a plurality of positrons) is calculated. 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 27). The synthesis of the PET image data and the X-ray CT image data can be easily and accurately performed by matching the position of the central axis of the hole 30 in both image data. That is, since the PET image data and the X-ray CT image data are created based on the imaging signal output from the shared radiation detector 4, alignment can be performed with high accuracy as described above. The composite tomographic data is called from the storage device 28 and output to the display device 29 (step 28), and displayed on the display device 29. Since the composite tomographic image displayed on the display device 29m 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 scan 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. By this circumferential scanning of the X-ray source 9, the present embodiment obtains two-dimensional cross-sectional data related to the X-ray imaging signal in one transverse section of the examinee 35. Two-dimensional cross-section data relating to X-ray imaging 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 section data, three-dimensional section data can be obtained. Using this three-dimensional cross-sectional data, three-dimensional X-ray CT image data can be obtained. Moreover, 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 imaging signals in other cross sections can be obtained.

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

  (1) In this embodiment, a plurality of radiation detectors 4 provided on the radiation detector annular body 3 are arranged in an annular shape. In this embodiment, the radiation detectors 4 arranged in an annular shape can detect a plurality of pairs of γ rays emitted from the examinee 35 as the subject, and the X-ray source 9 moves in the circumferential direction. X-rays emitted from the patient and transmitted through the examinee 35 can also be detected. For this reason, the prior art requires an imaging device that detects transmitted X-rays and another imaging device that detects γ-rays as an imaging device. However, in this embodiment, only one imaging device is required, and X-ray CT is required. The configuration of a radiation inspection apparatus that can perform both inspection and PET inspection can be simplified.

  (2) In the present embodiment, an X-ray imaging signal that is a detection signal of X-rays (referred to as transmitted X-rays) transmitted through the body of the examinee 35 by each of the radiation detectors 4 arranged in an annular shape, and a radiopharmaceutical Both γ-ray imaging signals, which are detection signals of γ-rays emitted from the body due to the above, are output. Such a configuration also contributes to further simplification of the configuration of the radiation inspection apparatus and miniaturization of the radiation inspection apparatus.

  (3) In the present embodiment, a first tomographic image including a visceral and bone image of the examinee 35 using an X-ray imaging signal which is one output signal of the radiation detector 4 arranged in a ring shape. (X-ray CT image) can be reconstructed, and a second tomographic image (PET) including an image of the affected area of the examinee 35 using a γ-ray imaging signal which is another output signal of the radiation detector 4 Image) can be reconstructed. Since the data of the first tomogram and the data of the second tomogram are reconstructed based on the output signal of the radiation detector 2 that detects both transmitted X-rays and γ-rays, Two tomographic image data can be accurately aligned and synthesized. For this reason, it is possible to easily obtain an accurate tomographic image (synthetic tomographic image) including images of the affected area, internal organs and bones. According to this synthetic tomographic image, the position of the affected part can be accurately known in relation to the internal organs and bones. For example, by aligning the data of the first tomographic image and the data of the second tomographic image with the axial center of the hole 30 of the imaging device 2 as the center, it is possible to easily obtain image data obtained by combining the two tomographic images.

  (4) This embodiment can be obtained from the radiation detector 4 that shares the imaging signal necessary for creating the first tomographic image and the imaging signal necessary for creating the second tomographic image. Therefore, the time (inspection time) required for the examination of the examinee 35 can be significantly shortened. In other words, in a short inspection time, an imaging signal necessary for creating the first tomographic image and an imaging signal necessary for creating the second tomographic image can be obtained. In the present embodiment, unlike the prior art, it is not necessary to move the examinee from an imaging apparatus that detects transmitted X-rays to another imaging apparatus that detects γ-rays, and the probability that the examinee moves can be reduced. . Eliminating the necessity of moving the examinee from the imaging device that detects transmitted X-rays to another imaging device that detects γ rays also contributes to shortening the examination time of the examinee.

  (5) In this embodiment, the X-ray source 9 is circulated so that the radiation detector annular body 3, that is, the radiation detector 4 is not moved in the circumferential direction and the axial direction of the hole 30. The capacity of the motor for rotating the X-ray source 9 can be reduced as compared with the motor necessary for the movement. The power consumption required to drive the latter motor can also be less than that of the former motor.

  (6) Since the γ-ray imaging signal input to the signal processing device 22, that is, the first signal processing device is remarkably reduced, highly accurate first tomographic image data can be obtained. For this reason, the position of the affected part 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.

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

  (8) 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 emitted from the examinee 35. There is a possibility that the radiation detector 4 positioned immediately behind the lines will not be able to detect the γ-rays, and detection data necessary for creating a PET image may be lost. However, in the present embodiment, since the X-ray source 9 and the axial movement arm 11 circulate in the circumferential direction by the X-ray source driving device 10 as described above, data loss is not a problem in practice. . In particular, the revolving speed of the X-ray source 9 and the axial movement arm 11 is about 1 second / 1 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. Further, when the X-ray CT examination is not performed, the apparatus related to the X-ray CT examination is removed from the radiation detector 4 and stored. For example, in this embodiment, the X-ray source 9 is stored in the X-ray source driving device 10.

  Furthermore, the inspection time required to obtain an X-ray imaging signal necessary for creating an X-ray CT image 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 imaging signal, the examinee is moved during the examination by always irradiating the examinee with X-rays from the X-ray source 3 to obtain the X-ray imaging signal. Even in this case, it is possible to correct the deviation of the data of the PET image accompanying the swing of the examinee from the continuous image of the X-ray CT image obtained based on the X-ray imaging signal.

(Example 2)
A radiation inspection apparatus 1A according to embodiment 2, which is another embodiment of the present invention, will be described below with reference to FIGS. The radiation inspection apparatus 1A is obtained by replacing the imaging apparatus 2 in the radiation inspection apparatus 1 of the first embodiment with an imaging apparatus 2A, and further replacing the signal discriminating apparatus 19 with a signal discriminating apparatus 19A. The other configuration of the radiation inspection apparatus 1A is the same as that of the radiation inspection apparatus 1. Since the radiation inspection apparatus 1A is provided with the signal discriminating apparatus 19A, the computer 27 executes the processing shown in FIG. The imaging device 2A has a configuration in which the driving device control device 17 and the X-ray source control device 18 of the imaging device 2 in Embodiment 1 are replaced with the driving device control device 17A and the X-ray source control device 18A, respectively. The other configuration of the imaging device 2A is the same as that of the imaging device 2.

  As shown in FIG. 8, 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 38. The signal discriminating device 21 provided for each radiation detector 4 does not have the changeover switch 31 and is connected to the corresponding radiation detector 4 by the wiring 23. The wiring 23 is connected to the waveform shaping device 20 of the signal discriminating device 19A. The wave height analyzer 38 is connected to the waveform shaping device 20 and the computer 27. The γ ray discriminating device 21 is connected to a computer 27 via a coincidence counting device 26. The signal discriminating device 19A is a signal processing device, and includes a first signal processing device having a wave height analyzing device 38, and a second signal processing device having a waveform shaping device 20 and a γ-ray discriminating device 21. A drive device control device 17A and an X-ray source control device 18A are installed in the annular holding portion 5.

  The present embodiment is an example in which an X-ray CT inspection and a PET inspection are performed using a single imaging apparatus 2A. The examinee 35 to which the radiopharmaceutical for PET is administered and lies on the bed 16 is inserted into the hole 30 by the movement of the bed 16. The radiation detector 4 detects 511 keV γ rays emitted from the affected part of the examinee 35. On the other hand, X-rays (80 keV) emitted from the X-ray source 9 are detected by the radiation detector 4 after passing through the examinee 35. The X-ray source 9 circulates around the examinee 35 along the scan rail 12 by the X-ray source driving device 10. For this reason, the examinee 35 is irradiated with X-rays from any position in the circumferential direction. The drive device control device 17A of this embodiment controls the movement of the X-ray source drive device 10 by outputting a drive start signal and a drive stop signal, similarly to the drive device control device 17 of the first embodiment. However, the drive device control device 17A does not perform the switching control of the changeover switch 31 performed by the drive device control device 17. As in the first embodiment, the X-ray source control device 18A outputs an X-ray generation signal that closes the X-ray source switch and outputs an X-ray stop signal that opens the X-ray source switch. However, like the X-ray source control device 18 of the first embodiment, the X-ray source control device 18A generates X-rays only during a first set time in which the incidence of γ rays on the radiation detector 4 can be ignored. Control is not performed. Therefore, in this embodiment, the radiation detector 4 that detects X-rays also detects γ-rays. Therefore, in the present embodiment in which the X-ray CT inspection and the PET inspection are performed with one imaging apparatus 2A, each radiation detector 4 outputs an output signal including an X-ray imaging signal and a γ-ray imaging signal. The output signal from the radiation detector 4 is input to the corresponding signal discriminating device 19A.

  The function of the signal discriminating device 19A will be described below. The signal discriminating device 19A has a function of separately separating the X-ray imaging signal and the γ-ray imaging signal from the output signal of the radiation detector 4. That is, the signal discriminating apparatus 19A is an apparatus that discriminates energy between the X-ray imaging signal and the γ-ray imaging signal detected by one radiation detector 4. Note that the time interval at which the X-ray source 9 emits X-rays is longer than the operation time window Δτ of the signal discriminating device 19A. The waveform shaping device 20 of the signal discriminating device 19A outputs the X-ray imaging signal as well as the γ-ray imaging signal shaped into the Gaussian distribution described in the first embodiment, with the waveform shaping device 20 shaping the waveform into a Gaussian distribution. The As shown in FIG. 5, an X-ray imaging signal shaped into a signal having a temporal Gaussian distribution waveform is also output.

  The γ-ray imaging signal and the X-ray imaging signal that are the outputs of the waveform shaping device 20 are input to the γ-ray discriminating device 21 and the wave height analyzing device 38. It is necessary that the γ-ray discriminating device 21 processes the γ-ray imaging signal and the wave height analyzer 38 processes the X-ray imaging signal. For this reason, the following devices are made in this embodiment.

  The γ-ray discriminating device 21 includes the first filter described above, and is a device that generates a pulse signal when an imaging signal (γ-ray imaging signal) having energy equal to or higher than a first energy set value is input. When the imaging signal having an energy lower than the first energy set value (X-ray imaging signal) output from the waveform shaping device 20 is input, the pulse height analyzer 38 measures the count value of the imaging signal. In this embodiment, since the energy of the X-ray irradiated to the examinee 35 is 80 keV, the wave height analyzer 38 has a second energy set value of 70 keV or more and a third energy set value of 90 keV or less. An imaging signal (X-ray imaging signal) having energy is counted and a count value of the imaging signal is output. By performing such processing of the imaging signal of specific energy, the load on the wave height analyzer 38 is significantly reduced.

  As described above, in order to process an imaging signal having specific energy in the pulse height analyzer 38, a filter that passes the imaging signal in the set energy range is provided in the wave height analyzer 38 (or in the front stage of the wave height analyzer 38). A pulse height analyzer is provided with a second filter that allows an imaging signal having energy in a range greater than or equal to a second energy set value and less than or equal to a third energy set value to pass, and blocks an imaging signal having energy outside the range. 38. The pulse height analyzer 38 counts the imaging signal (X-ray imaging signal) that has passed through the second filter.

  In the present embodiment, by using the signal discriminating device 19A, the γ-ray imaging signal and the X-ray imaging signal having different energy with respect to the peak count value can be separated from the imaging signal that is the output of the radiation detector 4 separately. . The coincidence counting device 26 performs coincidence using a pulse signal that is an output from each γ ray discriminating device 21 of each signal discriminating device 19A, and obtains a count value for the γ ray imaging signal.

  The computer 27 executes processing based on the processing procedures of steps 21A, 22A, 39, 23A, and 24-28 shown in FIG. The computer 27 that executes such processing is also a tomogram data creation device. The count value of the γ-ray imaging signal counted by the coincidence counting device 26, the position information of the detection point output from the coincidence counting device 26, and the count value of the X-ray imaging signal output from the wave height analyzing device 38 are input. (Step 21A). The input count value of the γ-ray imaging signal, position information of the detection point, and count value of the X-ray imaging signal are stored in the storage device 28 (step 22A).

  Next, in step 39, the count value of the X-ray imaging signal is corrected. This correction will be described in detail below. The X-ray energy of 80 keV is lower than the gamma rays emitted from the examinee 35 due to the radiopharmaceutical. The count value of the X-ray imaging signal output from the wave height analyzer 38 includes the count value of the γ-ray imaging signal whose energy is attenuated to about 80 keV in the semiconductor element section. For this reason, correction for removing the count value of the γ-ray imaging signal from the count value of the X-ray imaging signal is performed to obtain the count value of the true X-ray imaging signal. An example of a method for correcting the count value of the X-ray imaging signal will be described. For example, a detection spectrum of 511 keV γ rays is measured in advance, and the intensity of γ rays around 80 keV is estimated using the measurement results of the detection spectra. It is assumed that a spectrum obtained when 511 keV γ rays are applied to the semiconductor element portion of the radiation detector 4 is obtained as shown in FIG. For example, it is assumed that 100 gamma rays emitted from the examinee 35 are detected in the semiconductor element unit. In that case, after multiplying the count value of the whole spectrum shown in FIG. 10 so that the count value (count number) in the peak portion of FIG. 10 is 100, it was multiplied by the count value of the X-ray imaging signal. By subtracting the count value, an accurate count value (count number) of the single X-ray imaging signal shown in FIG. 11 is obtained. The corrected count value is stored in the storage device 28.

  Thereafter, similarly to the first embodiment, the processing of steps 24 to 28 is executed, and the data of the composite tomogram created by combining the data of the first tomogram and the data of the second tomogram can be obtained. The combined tomographic image data can be displayed on the display device 29.

  In this embodiment, the effects (1) to (5), (7) and (8) produced in the first embodiment can be obtained. Furthermore, the present embodiment can obtain the following effects (9) and (10).

  (9) The X-ray imaging signal and the γ-ray imaging signal included in the output signal output from the radiation detector 4 can be separated. For this reason, it is possible to easily create the first tomogram data using the separated X-ray imaging signal and the second tomogram data using the separated γ-ray imaging signal. As in the first embodiment, the first tomogram data and the second tomogram data can be easily combined.

  (10) The semiconductor radiation detector used as the radiation detector 4 has high energy resolution. For this reason, in this embodiment, the X-ray imaging signal and the γ-ray imaging signal output from the radiation detector 4 can be easily separated by the signal discriminating device 19A.

(Example 3)
A radiation inspection apparatus 1B according to a third embodiment of the present invention will be described with reference to FIG. In the radiation inspection apparatus 1B, the configuration of the imaging apparatus 2B is slightly changed from the configuration of the imaging apparatus 2 of the first embodiment. That is, the imaging apparatus 2B is obtained by replacing the X-ray source circumferential direction moving device 7 with the X-ray source circumferential direction moving apparatus 7A in the configuration of the radiation inspection apparatus 1 in the imaging apparatus 2. The other configuration of the radiation inspection apparatus 1B is the same as that of the radiation inspection apparatus 1. The X-ray source circumferential direction moving device 7 </ b> A includes an X-ray source device 8 </ b> A and an annular X-ray source device holding unit 13. The X-ray source device holding unit 13 of the present embodiment has the same configuration as that of the first embodiment. The X-ray source device 8 </ b> A includes the X-ray source 9 and the X-ray source driving device 10, and does not include the axial movement arm 8. In the present embodiment, the X-ray source 9 is disposed so as to face one end face of the radiation detector annular body 3, that is, beside the one end face. The X-ray source 9 arranged as described above has an X-ray emission port of the radiation detector 4 of the radiation detector annular body 3 and the radiation detector 4 positioned 180 ° opposite to the X-ray source 9. It is attached to the casing of the X-ray source driving apparatus 10 while being inclined with respect to the axial direction of the hole 30 so as to face the direction. The length of the casing of the X-ray source driving apparatus 10 in the present embodiment is shorter than that of the casing of the X-ray source driving apparatus 10 in the first embodiment.

  In the present embodiment, similarly to the first embodiment, the PET inspection and the X-ray CT inspection are performed using one imaging apparatus. As in the first embodiment, the PET examination in the present embodiment is performed by detecting γ rays emitted from the examinee 35 due to the radiopharmaceutical with the second radiation detector 4. Further, the X-ray CT examination is performed by rotating the X-ray source device 8A along the scan rail 12 in the same manner as in the case of rotating the X-ray source device 8 in the first embodiment. In the PET examination and the X-ray CT examination, the examinee 35 is moved in the axial direction by the bed 16. In the present embodiment, X-rays emitted from the tilted X-ray source 9 are irradiated in an oblique direction with respect to the examinee 35 and are transmitted obliquely through the body of the examinee 35. The transmitted X-ray is detected by the first radiation detector 4. In the present embodiment, the first radiation detector 4 is located at one end of the radiation detector annular body 3 facing the X-ray source device 8. The process of obtaining composite tomographic image data using the X-ray imaging signal output from the first radiation detector 4 and the γ-ray imaging signal output from the second radiation detector 4 is performed in the same manner as in the first embodiment. Is called. In the present embodiment, an X-ray CT image is obtained by using an X-ray imaging signal for X-rays obliquely transmitted through the body of the examinee 35, so that the X-ray CT image has an angle that does not reduce the accuracy of the X-ray CT image. It is necessary to tilt the source 9.

  In the present embodiment, the effects (1) to (6) produced in the first embodiment can be obtained. Furthermore, the present embodiment can obtain the following effects (11) to (13).

  (11) In this embodiment, since the X-ray source 9 circulates beside the radiation detector annular body 3 in which the radiation detector 4 is installed in an annular shape, the diameter of the annular holding portion 5 is reduced. For this reason, the distance between the two radiation detectors 4 positioned opposite to each other by 180 ° is shortened, and the image quality of the PET image can be improved. A pair of γ rays generated in the body of the examinee 35 is not completely emitted in the direction of 180 ° ± 0.6 °, but 180 °. As the distance between the radiation detectors 4 increases, the influence of ± 0.6 ° increases, and the two detection points for the pair of γ rays specified by the coincidence counting device 26 are slightly shifted. When the distance between the radiation detectors 4 is short, the influence of ± 0.6 ° is reduced, and the two detection points for the pair of γ rays specified by the coincidence counting device 26 are also close to the true position. . For this reason, in this embodiment, the image quality of the PET image is improved.

  (12) In this embodiment, since the X-ray source 9 circulates beside the radiation detector annular body 3 in which the radiation detector 4 is installed in an annular shape, the X-ray source 9 and the axial movement arm 11 in Embodiment 1 Thus, there is no object on the front surface of the radiation detector 4 that blocks the γ rays emitted from the examinee 35. For this reason, in this embodiment, there is no problem that the detection data is lost as in the first embodiment.

  (13) In the present embodiment, the radiation inspection apparatus can be further reduced in size compared to the first embodiment because the diameter of the radiation detector annular body 3 is reduced.

  In this embodiment, the X-ray helical is obtained by continuously moving the examinee 35 in the hole 30 using the bed 16 of the examinee holding apparatus 14 as the X-ray source 9 rotates in the circumferential direction. It is also possible to scan.

Example 4
A radiation inspection apparatus according to embodiment 4, which is another embodiment of the present invention, will be described below with reference to FIG. The radiation inspection apparatus 1C of the present embodiment has a configuration in which the imaging apparatus 2 in the radiation inspection apparatus 1 is changed to an imaging apparatus 2C. Other configurations of the radiation inspection apparatus 1C are the same as those of the radiation inspection apparatus 1. The imaging device 2C includes a pair of radiation detector annular bodies 3A and 3B. The radiation detector annular body 3A includes an annular holder 5A and a large number of radiation detectors 4 arranged in an annular manner inside the annular holder 5A in the same manner as in the first embodiment. The radiation detector annular body 3B includes an annular holder 5B and a large number of radiation detectors 4 arranged in an annular manner inside the annular holder 5B in the same manner as in the first embodiment. Each radiation detector 4 provided on the radiation detector annular bodies 3A and 3B is the same as the radiation detector 4 used in the first embodiment. Each of the radiation detectors 4 provided in the radiation detector annular bodies 3A and 3B is connected to the corresponding signal discriminating device 19, specifically, the changeover switch 31 of the signal discriminating device 19 by the wiring 23 as in the first embodiment. Each is connected. Through holes 30 through which the bed 16 is inserted are respectively formed inside the respective radiation detectors 4 in the radiation detector annular bodies 3A and 3B. The radiation detector annular body 3A and the radiation detector annular body 3B are arranged adjacent to each other so that a slit (gap) 36 is formed therebetween. The slit 36 is formed over the entire circumference of the radiation detector annular body. The radiation detector annular body 3A is attached to a support member 6A that fixes the annular holding portion 5A to the floor surface. The radiation detector annular body 3B is attached to a support member 6B that fixes the annular holding portion 5B to the floor surface. The axis of the radiation detector annular body 3A coincides with the axis of the radiation detector annular body 3B, and the inner and outer diameters of the annular holding portions 5A and 5B are the same.

  Further, the imaging apparatus 2C includes an X-ray source circumferential direction moving device 7B having an X-ray source device 8B and an annular X-ray source device holding unit 13. The X-ray source device holding portion 13 of the X-ray source circumferential direction moving device 7B has the same configuration as that of the first embodiment and is attached to the outer surface of the annular holding portion 5A. The X-ray source device 8B includes an X-ray source 9 and an X-ray source driving device 10, and does not include the axial movement arm 11. In this embodiment, the X-ray source 9 is located outside the annular holding portions 5A and 5B and faces the slit 36. The X-ray source 9 has a hole so that the X-ray emission port faces the direction of the radiation detector 4 positioned 180 ° opposite to the X-ray source 9 in the radiation detector 4 of the radiation detector annular body 3B. It is attached to the casing of the X-ray source driving device 10 while being inclined with respect to the axial direction of the portion 30.

In the present embodiment, similarly to the first embodiment, the PET inspection and the X-ray CT inspection are performed using one imaging apparatus. As in the first embodiment, the PET examination in the present embodiment is performed by detecting γ rays emitted from the examinee 35 due to the radiopharmaceutical with the second radiation detector 4. Further, the X-ray CT examination is performed by rotating the X-ray source device 8B around the examinee 35 along the scan rail 12 in the same manner as in the case where the X-ray source device 8 is rotated in the first embodiment. Is called. In the case of the PET examination and the X-ray CT examination, similarly to the third embodiment, the examinee 35 is moved in the axial direction. In this embodiment, in order to smoothly circulate the X-ray source device 8B, a space 37 is formed between the support member 6B and the X-ray source device holding portion 13 outside the annular holding portion 5A. The X-ray source device 8B passes through the space 37 when it goes around. In this embodiment, the X-rays emitted from the tilted X-ray source 9 and passed through the slit 36 are irradiated in an oblique direction to the examinee 35 lying on the bed 16, and the inside of the examinee 35 Is transmitted obliquely. The transmitted X-ray is detected by the first radiation detector 4. In the present embodiment, the first radiation detector 4 is located at one end of the radiation detector annular body 3 </ b> B facing the X-ray source 9. Since the X-rays emitted from the X-ray source 9 have a spread, the first radiation detector 4 also exists on the one end surface side of the radiation detector annular body 3A facing the radiation detector annular body 3B. As the X-ray source 9 circulates, the first radiation detector 4 moves in the circumferential direction of the radiation detector annular body as in the first embodiment.

  The process of obtaining composite tomographic image data using the X-ray imaging signal output from the first radiation detector 4 and the γ-ray imaging signal output from the second radiation detector 4 is performed in the same manner as in the first embodiment. Is called. In the present embodiment, an X-ray CT image is obtained by using an X-ray imaging signal for X-rays obliquely transmitted through the body of the examinee 35, so that the X-ray CT image has an angle that does not reduce the accuracy of the X-ray CT image. It is necessary to tilt the source 9.

  In the present embodiment, the effects (1) to (6) generated in the first embodiment and the effects (11) to (13) generated in the third embodiment can be obtained.

In this embodiment, the X-ray source driving device 10 is extended to the radiation detector annular body 3B side, and the X-ray emission port in the X-ray source 9 is the radiation detector 4 of the radiation detector annular body 3A. It may be attached to the casing of the X-ray source driving device 10 so as to be inclined with respect to the axial direction of the hole 30 so as to face the direction of the radiation detector 4 located on the opposite side of 180 degrees. Further, the X-ray source device holding unit 13 may be attached to the annular holding unit 5B and tilted so that the X-ray emission port of the X-ray source 9 faces the radiation detector 4 of the radiation detector annular body 3A as described above. .

(Example 5)
A radiation inspection apparatus 1D according to embodiment 5 which is another embodiment of the present invention will be described below with reference to FIGS. The radiation inspection apparatus 1D of the present embodiment includes an imaging apparatus 2D, and the configuration other than the imaging apparatus 2D is the same as that of the radiation inspection apparatus 1. The imaging device 2D includes a radiation detector annular body 3C and an X-ray source circumferential direction moving device 7C. In the radiation detector annular body 3 </ b> C, a large number of radiation detectors 4 are installed on the inner surface of the annular holder 5 </ b> C installed on the holding member 6 in the same manner as in the first embodiment. The annular holding portion 5C has a slit 36A that is a through hole formed by being cut through 180 °. The slit 36A is located in the upper half of the annular holding portion 5C. The radiation detector 4 is not installed in the slit 36A. A collimator 39 is installed in the slit 36A inside the annular holding portion 5C. The collimator 39 is made of lead. The radiation detector 4 is disposed outside the collimator 39.

  Similarly to the X-ray source circumferential direction moving device 7B of the fourth embodiment, the X-ray source circumferential direction moving device 7C is arranged outside the annular holding member and holds the substantially semicircular X-ray source device holding portion 13A in an annular shape. It is installed on the outer surface of the upper part of the part 5C. A semicircular scan rail 12A is attached to the X-ray source device holding portion 13A. The X-ray source circumferential direction moving device 7 </ b> C includes an X-ray source device 8 </ b> C having an X-ray source 9 and an X-ray source driving device 10. The X-ray source device 8 </ b> C is such that the X-ray source 9 is attached to the X-ray source driving device 10 so that the X-ray emission port of the X-ray source 9 faces in a direction perpendicular to the axial center of the hole 30. Is different from the X-ray source device 8B only.

  Also in this embodiment, a PET examination and an X-ray CT examination are performed on the examinee 35 lying on the bed 16 by administering a PET radiopharmaceutical using one imaging device 2D. In the case of the PET examination and the X-ray CT examination, similarly to the third embodiment, the examinee 35 is moved in the axial direction. The X-ray CT examination is performed by irradiating the examinee 35 with X-rays emitted from the X-ray source 9 and passing through the slit 36 </ b> A and the collimator 39. The irradiation of the examinee 35 with the X-rays that have passed through the slit is the same as in the fourth embodiment. In the present embodiment, as in the first embodiment, the PET examination is performed by detecting the γ-rays emitted from the examinee 35 with the second radiation detector 4, and the X-ray CT examination is performed on the examinee 35. This is done by detecting the transmitted X-rays with the first radiation detector 4.

In the X-ray CT examination in this embodiment, the X-ray source 9 moves around the examinee 35 within a range of 180 ° by moving the X-ray source driving device 10 along the scan rail A, and the first An X-ray imaging signal is obtained by the radiation detector 4. Two-dimensional cross-sectional data of an X-ray CT image is obtained by processing of the computer 27 using this X-ray imaging signal. The other two-dimensional cross-sectional data is created using X-ray imaging signals obtained by the movement of the examinee 35 in the axial direction of the hole 30 and the movement of the X-ray source 9 along the scan rail 12A. it can. These two-dimensional cross-sectional data can be stacked to obtain three-dimensional cross-sectional data of an X-ray CT image. Further, a simulated helical scan of X-rays can be performed by continuously moving the examinee 35 as the X-ray source 9 moves in the circumferential direction. However, in the present embodiment in which the X-ray source 9 can move only within a range of 180 degrees, a simulated helical scan can be realized by continuously reciprocating the X-ray source 9.

  According to the present embodiment, the effects (1) to (6) generated in the first embodiment and the effects (11) to (13) generated in the third embodiment can be obtained. Furthermore, the present embodiment can obtain the following effects (14) and (15).

  (14) The radiation shielding function of the collimator 39 prevents X-rays from entering the radiation detector 4 adjacent to the slit 36A. Further, the collimator 39 collimates the X-rays emitted from the X-ray source 9 into a fan beam shape.

  (15) Since the weight of the X-ray source 9 is reduced as compared with the case where a collimator is installed in the X-ray source 9 described below, when the X-ray source 9 is moved by the X-ray source driving device 10, The load applied to the source driving device 10 is reduced. For this reason, the power consumption by the 1st motor of the X-ray source drive device 10 reduces.

  A collimator may be attached to the X-ray source 9 instead of the collimator 39 provided in the annular holding portion 5C. With this collimator, the width of the slit 36A can be reduced in order to suppress the spread of X-rays in the axial direction of the hole 30. Therefore, X-rays are not incident on the radiation detector 4 in the vicinity of the slit 36A.

  In the annular holding portion 5C, a plurality of slits 36A may be formed close to the axial direction of the annular holding portion 5C. In this case, the X-ray source 9 is arranged outward from the annular holding portion 5C so that X-rays emitted from the X-ray source 9 can pass through the slits 36A. The respective X-rays that have passed through the plurality of slits 36A can be detected by the respective first radiation detectors 4 that exist at different positions in the axial direction of the annular holding portion 5C. In such a configuration, by scanning the X-ray source 9 once in the circumferential direction, an X-ray imaging signal capable of creating a plurality of two-dimensional cross-sectional data of the X-ray CT image can be obtained simultaneously. For this reason, the efficiency of X-ray CT inspection can be improved.

(Example 6)
A radiation inspection apparatus 1E according to embodiment 6 which is another embodiment of the present invention will be described below with reference to FIGS. While the first to fifth embodiments fixed the radiation detector annular body, this embodiment has a configuration in which the radiation detector annular body is circulated together with the X-ray source. The radiation inspection apparatus 1E has a configuration in which the imaging apparatus 2 of the radiation inspection apparatus 1A illustrated in FIG. 7 is replaced with an imaging apparatus 2E. The other configuration of the radiation inspection apparatus 1E is the same as that of the radiation inspection apparatus 1. The imaging device 2E includes an annular rotator 40, a circumferential drive device 41, a drive device control device 17A, and an X-ray source control device 18A.

The annular rotating body 40 includes a radiation detector annular body 3D, an X-ray source device 8C, and an X-ray source device holding unit 48. The radiation detector annular body 3D includes a radiation detector 4 and an annular holding portion 5D. Similarly to the second embodiment, the radiation detector 4 is attached to the inner surface of the annular holding portion 5D. The annular holding portion 5D forms a slit 36B extending in the axial direction and having a rectangular cross section at one place in the circumferential direction. The radioactive detector 4 is not installed in the slit 36B. The X-ray source device holding part 48 extends in the axial direction and is installed on the outer surface of the annular holding part 5D. The X-ray source device 8C of the present embodiment has a configuration similar to that of the fifth embodiment. The X-ray source driving device 10 of the X-ray source device 8 </ b> C moves along the scan rail 12 </ b> B provided in the X-ray source device holding unit 48. For this reason, the X-ray source 9 moves in the axial direction of the radiation detector annular body 3D.

  The circumferential drive device 41 includes a substantially annular rotating body holding portion 42 and a drive device 44. As shown in FIG. 18, the rotating body holding part 42 is installed on a holding member 6C fixed to the floor surface. As shown in FIG. 18, the rotating body holding portion 42 is partly cut into a portion in contact with the holding member 6 </ b> C to form a space 43. The driving device 44 is disposed in the space 43. The drive device 44 includes a motor 45, a speed reduction device 46 connected to the rotation shaft of the motor 45, and a pinion 47 connected to the speed reduction device 46. The motor 45 and the speed reducer 46 are installed on the support member 6C. The rotating body holding part 42 has a guide groove 49 that is substantially annular on one end face facing the annular rotating body 40. The support member 15 also has a guide groove 50 that draws an arc on one end surface facing the annular rotator 40. One end portion of the annular holding portion 5D is inserted into the guide groove 49, and the multi-end portion thereof is inserted into the guide groove 50. Although not shown, a rack is provided on the outer surface of the end of the annular holding part 5D on the rotating body holding part 42 side. This rack meshes with the pinion 47. The annular rotating body 40 in which the end of the annular holding portion 5D is inserted into the guide grooves 49 and 50 is supported by the support member 15 and the rotating body holding portion.

  In this embodiment, the annular rotator 40 is rotated to perform X-ray CT inspection and PET inspection. When both inspections are performed, the radiation detector 4 and the X-ray source 9 both turn in the circumferential direction. At the start of inspection, the motor 45 is driven, and the rotational force is transmitted to the pinion 47 via the speed reducer 46. As the pinion 47 rotates, the annular holding portion 5 </ b> D rotates while being guided by the guide grooves 49 and 50. In this way, the annular rotator 40 is rotated. X-rays are emitted from the X-ray source 9 while the annular rotator 40 is rotating. A collimator (not shown) installed in the X-ray source 9 suppresses the spread of X-rays in the axial direction of the hole 30 and forms fan-shaped X-rays in the circumferential direction.

  In this embodiment, since both the radiation detector 4 and the X-ray source 9 rotate in the circumferential direction, the position of the radiation detector 4 that detects X-rays does not change as in the first to fifth embodiments. That is, when the X-ray source 9 is turned, a plurality of radiation detectors 4 (referred to as radiation detectors 4A, see FIG. 17) existing at specific positions in the radiation detector annular body 3D are always examined 35. X-rays transmitted through are detected. These radiation detectors 4A also detect γ rays emitted from the examinee 35 and output both X-ray imaging signals and γ-ray imaging signals. The signal discriminating device 19A connected to the radiation detector 4A performs processing of the X-ray imaging signal and the γ-ray imaging signal as in the second embodiment. A radiation detector 4 other than the radiation detector 4A (referred to as a radiation detector 4B, see FIG. 17) detects γ-rays but does not detect X-rays. The radiation detector 4B does not output an X-ray imaging signal but outputs a γ-ray imaging signal. For this reason, the signal discriminating apparatus 19A connected to the radiation detector 4B is not provided with the wave height analyzer 38 for processing the X-ray imaging signal, and the structure is simplified. The signal discriminating device 19A connected to the radiation detector 4B processes the γ-ray imaging signal. The computer 27 of the present embodiment executes the processing shown in FIG. 9 and creates composite tomographic image data.

  In this example, effects (2) to (4) obtained in Example 1, effects (9) and (10) obtained in Example 2, and effects (11) and (13) obtained in Example 3 were obtained. Produce. In the present embodiment, the following effect (16) can be further obtained. Also in the present embodiment, the collimator used in the fifth embodiment may be installed on the outlet side of the slit 36B. The installation of this collimator produces the effect (14) obtained in the fifth embodiment.

  (16) In this embodiment, a plurality of radiation detectors 4 provided in the rotating radiation detector annular body 3 are arranged in an annular shape. In the present embodiment, a plurality of pairs of γ rays emitted from the examinee 35 as a subject can be detected by the radiation detectors 4 arranged in an annular shape, and those radiation detectors arranged in an annular shape. X-rays emitted from the X-ray source 9 moving in the circumferential direction by a part of 4 and transmitted through the examinee 35 can also be detected. For this reason, in the present embodiment, similarly to the first embodiment, only one imaging apparatus is required, and the configuration of the radiation inspection apparatus capable of performing both the X-ray CT inspection and the PET inspection can be simplified.

  In the present embodiment, the cross-sectional shape of the slit 36B is an elongated rectangle in the axial direction of the radiation detector annular body, and the X-ray source 9 can be moved in the axial direction. However, the present invention is not limited to this. A minimum number of slits may be formed to match the beam shape. With such a configuration, an X-ray source axial movement mechanism (such as the X-ray source device holding unit 48 having the scan rail 12B) becomes unnecessary. In this case, the examinee 35 may be moved in the axial direction by the bed 16.

  In Examples 1 to 6, X-ray irradiation is performed in a fan beam shape, but 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 to sixth embodiments, 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 to sixth embodiments, the X-ray source or the X-ray source and the radiation detector are rotated around the subject. However, the subject is rotated by fixing the X-ray source and the radiation detector. Also good.

  In Examples 1 to 6, 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. Moreover, in Examples 1-6, although the radiation detector is arrange | positioned at cylindrical shape, the arrangement | positioning is not limited to it. For example, the shape can be variously configured such that six flat panels on which radiation detectors are installed are combined and arranged in a hexahedral shape.

It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 1 which is one suitable Example of this invention. It is II-II sectional drawing of FIG. It is a detailed block diagram of the signal discrimination apparatus in Example 1 shown in FIG. It is explanatory drawing which shows the waveform of the (gamma) ray imaging signal input into the waveform shaping apparatus of FIG. It is explanatory drawing which shows the waveform of the (gamma) ray imaging 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 longitudinal cross-sectional view of the radiation inspection apparatus of Example 2 which is another Example of this invention. It is a detailed block diagram of the signal discrimination apparatus in Example 2 shown in FIG. It is a flowchart of the process sequence performed with the computer of FIG. It is explanatory drawing which shows the energy spectrum of the gamma ray imaging signal detected with the radiation detector of FIG. It is explanatory drawing which shows the energy spectrum of the X-ray imaging signal which removed the gamma-ray imaging signal. It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 3 which is another Example of this invention. It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 4 which is another Example of this invention. It is a longitudinal cross-sectional view of the radiation inspection apparatus of Example 5 which is another Example of this invention. It is XV-XV 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 XVII-XVII sectional drawing of FIG. It is XVIII-XVIII sectional drawing of FIG.

Explanation of symbols

  1, 1A, 1B, 1C, 1D, 1E ... Radiation inspection apparatus, 2, 2A, 2B, 2C, 2D, 2E ... Imaging apparatus, 3, 3A, 3B, 3C, 3D ... Radiation detector annular body, 4 ... Radiation Detector: 6 ... Supporting member, 7 ... X-ray source circumferential movement device, 8, 8A, 8B, 8C ... X-ray source device, 9 ... X-ray source, 10 ... X-ray source driving device, 11 ... Examinee Holding device, 12, 12A, 12B ... scan rail, 13, 13A ... X-ray source device holding unit, 16 ... bed, 17, 17A ... drive device controller, 18, 18A ... X-ray source controller, 19, 19A ... Signal discriminating device, 20 ... waveform shaping device, 21 ... gamma ray discriminating device, 22 ... signal processing device, 26 ... coincidence counting device, 31 ... changeover switch, 36, 36A, 36B ... slit, 39 ... collimator.

Claims (6)

A bed on which the subject is placed and an imaging device;
The imaging device includes a radiation detector annular body having a plurality of radiation detectors arranged in an annular shape, and is disposed outside the radiation detector annular body in a radial direction of the radiation detector annular body, and emits X-rays. And an X-ray source moving means for moving the X-ray source in the circumferential direction of the radiation detector annular body,
The radiation detector outputs a first detection signal that is a detection signal of the X-ray that has passed through the subject and a second detection signal that is a detection signal of a γ-ray emitted from the subject;
A positron characterized in that a slit for passing X-rays emitted from the X-ray source toward the inside of the radiation detector annular body is formed between the radiation detectors of the radiation detector annular body. Emission CT device. A bed on which the subject is placed and an imaging device;
The imaging device includes a radiation detector annular body having a plurality of radiation detectors arranged in an annular shape, and is disposed outside the radiation detector annular body in a radial direction of the radiation detector annular body, and emits X-rays. And an X-ray source moving means for moving the X-ray source in the circumferential direction of the radiation detector annular body,
The radiation detector outputs an output signal including a first detection signal that is a detection signal of the X-ray that has passed through the subject and a second detection signal that is a detection signal of a γ-ray emitted from the subject. And
A positron characterized in that a slit for passing X-rays emitted from the X-ray source toward the inside of the radiation detector annular body is formed between the radiation detectors of the radiation detector annular body. Emission CT device.   The positron emission CT apparatus according to claim 1, wherein a collimator through which the X-ray passes is disposed between the slit and the radiation detector, and the radiation detector is disposed around the collimator. .   The positron emission CT according to claim 2, further comprising a signal separation device that separates the first detection signal and the second detection signal from the input output signal and is connected to each of the plurality of radiation detectors. apparatus.   The positron emission CT apparatus according to claim 1, wherein the radiation detector is a semiconductor radiation detector. Data of a first tomogram of the subject is created based on the first detection signal, data of a second tomogram of the subject is created based on the second detection signal, and the first tomogram The positron emission CT apparatus according to claim 1, further comprising a tomogram data creation device that creates data of a composite tomogram obtained by synthesizing the data of the second tomogram and the data of the second tomogram.

Images