JP2010249723A - Medical bed device, and radiation tomographic apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation tomographic apparatus capable of obtaining a tomographic image which is proper for diagnosis by suppressing surely incidence of a radiation generated out of a visual field range into a detection device ring. <P>SOLUTION: Since an externally generated radiation transmitted once through a top plate 10 toward the detection device ring 12 is absorbed into a first absorbing body 13, incidence of the externally generated radiation into the detection device ring 12 is suppressed. Hereby, a tomographic image which is proper for diagnosis is generated. In addition, the first absorbing body 13 does not enter a photographing field of the detection device ring 12, to thereby prevent an annihilation radiation generated in the photographing field from being absorbed into the first absorbing body 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiation imaging apparatus that images radiation emitted from a subject and a medical bed apparatus provided therein, and in particular, a radiation tomography apparatus including an absorber that shields excess radiation emitted from a subject, and the radiation tomography apparatus The present invention relates to a medical couch device provided.

  A medical institution is provided with a radiation tomography apparatus capable of imaging the distribution of a radiopharmaceutical. Such a radiation tomography apparatus detects annihilation radiation (for example, γ-rays) released from a radiopharmaceutical that is administered to the subject M and is localized at the site of interest, and detects the radiopharmaceutical distribution in the site of interest of the subject M. The tomographic image is obtained.

  The configuration of such a radiation tomography apparatus will be described. As shown in FIG. 9, the radiation tomography apparatus 51 according to the conventional configuration includes a top plate 52 on which a subject is placed and a detector ring 62 into which the top plate 52 is inserted. A portion of the subject M covered by the detector ring 62 has a visual field range in which a tomographic image can be obtained by the radiation tomography apparatus. If a tomographic image is taken while moving the top plate 52, the radiopharmaceutical distribution in the whole body of the subject M can also be known. Such a radiation tomography apparatus is described in Patent Document 1, for example.

  The detector ring 62 is configured to detect the distribution of the radiopharmaceutical by detecting both annihilation radiation pairs generated in the body of the subject and traveling in directions opposite to each other by 180 °. That is, when radiation is detected simultaneously at two locations where the positions of the detector ring 62 are different, they are paired to be an annihilation radiation pair. The radiation pair generated from the point P in FIG. 9 is an annihilation radiation pair that can be detected by the detector ring 62.

  However, since the radiopharmaceutical is distributed over the whole body of the subject, annihilation radiation pairs are generated even outside the field of view of the radiation tomography apparatus 51. For example, an annihilation radiation pair generated from point Q in FIG. Such an annihilation radiation pair cannot be detected by the detector ring 62 but also adversely affects tomographic image acquisition. That is, one of the annihilation radiation pairs generated from the point Q may go to the detector ring 62. The detector ring 62 detects one of the annihilation radiation pairs generated outside the field of view. For convenience, radiation generated outside this field of view is referred to as externally generated radiation.

  Such externally generated radiation is an obstacle to pairing radiation generated within the field of view. This is because the calculation of pairing is complicated, and externally generated radiation is erroneously used for pairing.

  Therefore, in the radiation tomography apparatus of the conventional configuration, as shown in FIG. 10, the top plate 52 of the detector ring 62 has a ring-shaped shielding plate 63 that absorbs radiation at both ends in the introduction direction. . The diameter of the inner hole of the shielding plate 63 is about 10 cm smaller than the inner diameter of the detector ring 62. As described above, the shielding plate 63 protrudes inside the detector ring 62. This prevents externally generated radiation from entering the detector ring 62.

JP 2004-194133 A

However, the radiation tomography apparatus according to the conventional configuration has the following problems.
That is, the radiation tomography apparatus according to the conventional configuration cannot completely shield externally generated radiation. According to the conventional configuration, in order to prevent the externally generated radiation from entering the detector ring 62, the inner hole of the shielding plate 63 must be further reduced. The detector ring 62 is configured to have an inner diameter as small as possible for the purpose of reducing costs. If the inner hole of the shielding plate 63 must be made smaller on that, the subject may interfere with the shielding plate.

  Although there is a purpose to suppress externally generated radiation, there is a limit to reducing the diameter of the inner hole of the shielding plate 63. Eventually, the externally generated radiation enters the detector ring 62 without being absorbed by the shielding plate 63.

  The present invention has been made in view of such circumstances, and an object thereof is tomographic images suitable for diagnosis by reliably suppressing radiation generated outside the visual field range from entering the detector ring. A radiation tomography apparatus capable of acquiring the same, and a medical bed apparatus provided therein.

The present invention has the following configuration in order to solve the above-described problems.
That is, the medical couch device according to claim 1 is a medical couch device deployed in a radiation tomography apparatus that detects an annihilation radiation pair, and (A) a top plate on which a subject is placed; A top plate moving means for moving the plate along the top plate longitudinal direction which is the longitudinal direction of the top plate, (C) a first absorber for absorbing radiation transmitted through the top plate, and (D) a first absorber. And an absorbent body moving means for moving along the longitudinal direction of the top plate.

  [Operation / Effect] According to the above-described configuration, it is possible to reliably absorb externally generated radiation generated outside the field of view of the radiation tomography apparatus. That is, according to the above-described configuration, the first absorber that absorbs radiation that can move in the longitudinal direction of the top plate is provided. This 1st absorber absorbs the radiation which permeate | transmitted the top plate. Since the externally generated radiation that passes through the top plate and travels toward the radiation tomography apparatus is absorbed by the first absorber, it is possible to prevent the externally generated radiation from entering the detector ring. The incidence of radiation generated outside the field of view of the detector ring on the detector ring is an obstacle in generating a tomographic image. However, according to the present invention, since the externally generated radiation is absorbed by the first absorber, the radiation tomography apparatus can generate a tomographic image suitable for diagnosis.

  The first absorber is movable along the top plate longitudinal direction. Thereby, since the position of the 1st absorber can be changed according to the position of a top plate, when the subject gets on and off the top plate, the 1st absorber does not become an obstacle. Furthermore, when the first absorber is always adjacent to the detector ring, the operator cannot approach the detector ring. According to the above configuration, since the position of the first absorber can be changed along the top plate longitudinal direction, a medical bed apparatus that can operate the radiation tomography apparatus more safely and easily can be provided. .

  The invention according to claim 2 is the medical bed apparatus according to claim 1, wherein (E) the first absorber covers the lower surface of the top plate opposite to the placement surface on which the subject is placed. Is provided.

  [Operation / Effect] The above-described configuration more specifically shows the relationship between the first absorber and the top plate. The 1st absorber absorbs the radiation which permeate | transmitted the top plate, and becomes a structure which moves independently with a top plate. In order to realize such a configuration, it is sufficient that the first absorber is provided so as to cover the lower surface of the top plate opposite to the placement surface on which the subject is placed. The radiation that passes through the top plate and travels toward the detector ring is incident on the first absorber and absorbed there before traveling to the radiation tomography apparatus. Thus, according to the above-described configuration, it is possible to reliably prevent externally generated radiation from entering the radiation tomography apparatus.

  The invention according to claim 3 is the medical couch device according to claim 1 or 2, further comprising (F) a synchronizing means for synchronizing the top board moving means and the first absorber moving means, (G ) The top plate and the first absorber move synchronously in the same direction in the longitudinal direction of the top plate.

  [Operation and Effect] According to the above-described configuration, the movement of the top plate and the movement of the first absorber can be synchronized. Therefore, since the position of the first absorber can be determined in accordance with the state of the top board, it is possible to provide a medical bed apparatus in which the first absorber does not get in the way when the subject gets on and off the top board. That is, the top plate and the first absorber are moved synchronously in the same direction in the top plate longitudinal direction. By doing in this way, a top plate and a 1st absorber will protrude in the same direction. In general, since the radiation tomography apparatus is positioned in the direction in which the top plate protrudes, the first absorber can reliably approach the radiation tomography apparatus and absorb externally generated radiation incident thereon as the top plate protrudes. .

  The radiation tomography apparatus according to claim 4 includes: (A) a top plate for placing a subject; and (B) a top plate for moving the top plate along a top plate longitudinal direction which is a longitudinal direction of the top plate. A medical bed apparatus comprising: moving means; (C) a first absorber that absorbs radiation that has passed through the top board; and (D) absorber moving means that moves the first absorber along the longitudinal direction of the top board. And a detector ring having an opening penetrating in the longitudinal direction of the top plate for introducing the top plate and a radiation detector configured to detect radiation and arranged in a ring shape. Is extended in the longitudinal direction of the top plate, the absorber moving means is provided so as to penetrate the opening of the detector ring, and the absorber moving means has a first tip which is a tip on the detector ring side in the first absorber. Limit on the first absorber side in the field of view of the detector ring It is characterized in that to move to the first limit position a position.

  [Operation / Effect] According to the above-described configuration, it is possible to prevent externally generated radiation generated outside the field of view of the detector ring from entering the detector ring. That is, according to the above-described configuration, the first absorber that absorbs radiation that can move in the longitudinal direction of the top plate is provided. This 1st absorber absorbs the radiation which permeate | transmitted the top plate. Since the externally generated radiation that passes through the top plate and travels toward the detector ring is absorbed by the first absorber, it is possible to prevent the externally generated radiation from entering the detector ring. The incidence of radiation generated outside the field of view of the detector ring on the detector ring is an obstacle in generating a tomographic image. However, according to the present invention, since the externally generated radiation is absorbed by the first absorber, a tomographic image suitable for diagnosis can be generated.

  Further, the tip of the first absorber on the detector ring side is configured not to approach the detector ring beyond a certain position. The position is a first limit position that is a limit position on the first absorber side in the imaging field of view of the detector ring. Thereby, since the first absorber does not enter the imaging field of the detector ring, the annihilation radiation generated in the imaging field is not absorbed by the first absorber.

  The first absorber is movable along the top plate longitudinal direction. Thereby, since the position of the 1st absorber can be changed according to the position of a top plate, when the subject gets on and off the top plate, the 1st absorber does not become an obstacle. Furthermore, if the first absorber is always adjacent to the detector ring, the operator cannot approach the detector ring. According to the above-described configuration, since the position of the first absorber can be changed along the longitudinal direction of the top plate, a radiation tomography apparatus that is safer and easy to maintain can be provided.

  The invention according to claim 5 is the radiation tomography apparatus according to claim 4, wherein (E) the first absorber covers the lower surface of the top plate opposite to the placement surface on which the subject is placed. It is characterized by being provided as follows.

  [Operation / Effect] The above-described configuration more specifically shows the relationship between the first absorber and the top plate. The 1st absorber absorbs the radiation which permeate | transmitted the top plate, and becomes a structure which moves independently with a top plate. In order to realize such a configuration, it is sufficient that the first absorber is provided so as to cover the lower surface of the top plate opposite to the placement surface on which the subject is placed. Since the first absorber is provided at a position closer to the inner wall of the detector ring when viewed from the center of the opening of the detector ring (the first absorber is temporarily extended in the longitudinal direction of the top plate). If so, the radiation passing through the top plate and traveling toward the detector ring is always directed to the first absorber. As described above, according to the above-described configuration, it is possible to reliably prevent externally generated radiation from entering the detector ring.

  The invention according to claim 6 is the radiation tomography apparatus according to claim 4 or claim 5, further comprising (F) a synchronizing means for synchronizing the top board moving means and the absorber moving means, and (G) The top plate and the first absorber move synchronously in the same direction in the longitudinal direction of the top plate, and the absorber moving means moves the first tip of the first absorber to the first limit position regardless of the movement of the top plate. It is characterized by stopping at.

  [Operation and Effect] According to the above-described configuration, the movement of the top plate and the movement of the first absorber can be synchronized. Therefore, since the position of the first absorber can be determined in accordance with the state of the top board, it is possible to provide a radiation tomography apparatus in which the first absorber does not get in the way when the subject gets on and off the top board. That is, the top plate and the first absorber are moved synchronously in the same direction in the top plate longitudinal direction. By doing in this way, a top plate and a 1st absorber will protrude in the same direction. Since the detector ring is generally positioned in the direction in which the top plate protrudes, the first absorber can reliably approach the detector ring and absorb the externally generated radiation incident thereon as the top plate protrudes.

  The invention according to claim 7 is the radiation tomography apparatus according to claim 6, further comprising a second absorber that is disposed so as to cover a lower surface of the top plate and absorbs radiation transmitted through the top plate, Assuming that the second absorber is extended in the longitudinal direction of the top plate, the second absorber is provided so as to penetrate the opening of the detector ring, and the detector ring is attached to the first absorber and the second absorber. The position of the second tip, which is disposed at the sandwiched position and is the tip of the second absorber on the detector ring side, is the second limit that is the limit position on the second absorber side in the field of view of the detector ring. It corresponds to the position.

  [Operation / Effect] According to the above-described configuration, the second absorber is provided on the opposite side of the first absorber as viewed from the detector ring. That is, the first absorber, the detector ring, and the second absorber are arranged in this order along the top plate longitudinal direction. This second absorber also absorbs radiation that has passed through the top plate, and its configuration is similar to that of the first absorber. However, the second absorber need not be configured to move. That is, the second absorber is sufficiently separated from the subject and does not hinder the getting on and off of the subject. With this configuration, the dose of externally generated radiation that is absorbed by the absorber increases, so that it is possible to provide a radiation tomography apparatus that can acquire a tomographic image more suitable for diagnosis.

  The invention according to claim 8 is the radiation tomography apparatus according to any one of claims 4 to 7, wherein (α) is rotatable about a central axis extending in a longitudinal direction of the top plate with respect to the top plate. A radiation source, (β) a radiation detection means rotatable around the central axis with respect to the top plate, (γ) a support means for supporting the radiation source and the radiation detection means, and (δ) a rotation means for rotating the support means. And (ε) an image generation apparatus including a rotation control means for controlling the rotation means is provided adjacent to the detector ring from the longitudinal direction of the top plate.

  [Operation / Effect] With the above-described configuration, it is possible to provide a radiation tomography apparatus capable of acquiring both the internal structure of the subject and the drug distribution. A PET device can generally obtain information relating to drug distribution. However, it may be necessary to make a diagnosis while referring to a tomographic image in which an organ or tissue of the subject is captured. According to the above-described configuration, since both the internal structure of the subject and the drug distribution can be acquired, for example, by superimposing both images, a composite image suitable for diagnosis can be generated.

  According to the configuration of the present invention, it is possible to prevent externally generated radiation generated outside the field of view of the detector ring from entering the detector ring. Since the externally generated radiation that passes through the top plate and travels toward the detector ring is absorbed by the first absorber, it is possible to prevent the externally generated radiation from entering the detector ring. Thereby, a tomographic image suitable for diagnosis can be generated. In addition, since the first absorber does not enter the imaging field of the detector ring, the annihilation radiation generated in the imaging field is not absorbed by the first absorber.

  The first absorber is movable along the top plate longitudinal direction. Thereby, since the position of the 1st absorber can be changed according to the position of a top plate, when the subject gets on and off the top plate, the 1st absorber does not become an obstacle.

1 is a functional block diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 1. FIG. 1 is a perspective view illustrating a radiation detector according to Embodiment 1. FIG. It is a perspective view explaining the structure of the absorber which concerns on Example 1. FIG. 3 is a cross-sectional view illustrating movement of an absorber according to Example 1. FIG. 3 is a cross-sectional view illustrating movement of an absorber according to Example 1. FIG. It is sectional drawing explaining the effect of the absorber which concerns on Example 1. FIG. 6 is a functional block diagram illustrating a configuration of a radiation tomography apparatus according to Embodiment 2. FIG. It is sectional drawing of the absorber which concerns on 1 modification of this invention. It is sectional drawing explaining the radiation tomography apparatus of a conventional structure. It is sectional drawing explaining the radiation tomography apparatus of a conventional structure.

  Embodiments of the radiation tomography apparatus according to the present invention will be described below with reference to the drawings. The gamma rays in Example 1 are an example of the radiation of the present invention. FIG. 1 is a functional block diagram illustrating the configuration of the radiation tomography apparatus according to the first embodiment. The radiation tomography apparatus 9 according to the first embodiment includes a top plate 10 on which the subject M is placed, a gantry 11 having an opening for introducing the top plate 10 from the longitudinal direction (top plate longitudinal direction: z direction), A ring-shaped detector ring 12 for introducing the top plate 10 provided in the gantry 11 from the z direction is provided. The opening provided in the detector ring 12 has a cylindrical shape extending in the z direction. The detector ring 12 also extends in the z direction.

  The top plate 10 is provided so as to penetrate the opening of the gantry 11 (detector ring 12) from the z direction, and is movable back and forth along the z direction. Such sliding of the top plate 10 is realized by the top plate moving mechanism 15. The top plate moving mechanism 15 is controlled by the top plate movement control unit 16. The top plate moving mechanism 15 corresponds to the top plate moving means of the present invention. The top board movement control unit 16 is a top board movement control means for controlling the top board movement mechanism 15. The top plate 10 slides from a position where the entire region is located outside the detector ring 12 and is introduced from one side into the opening of the detector ring 12 and penetrates the inside of the detector ring 12. Thus, it can protrude from the other side of the opening of the detector ring 12. The z direction corresponds to the longitudinal direction of the top plate of the present invention. Note that the surface of the top 10 on which the subject is placed is called a placement surface. The mounting surface of the top 10 is a plate shape extending in the body axis direction and the body side direction of the subject to be supine.

  Inside the gantry 11 is provided a detector ring 12 for detecting an annihilation gamma ray pair emitted from the subject M. The detector ring 12 has a cylindrical shape extending in the body axis direction of the subject M, and the length in the z direction is about 30 cm. The clock 19 sends time information as a serial number to the detector ring 12. The detection data output from the detector ring 12 is given time information indicating when the γ-rays were acquired, and is input to the filter unit 20 described later.

  The configuration of the detector ring 12 will be described. According to the first embodiment, one unit ring is formed by arranging around 100 radiation detectors 1 in a virtual circle on a plane perpendicular to the z direction. The unit rings are arranged in the z direction to form the detector ring 12.

  The configuration of the radiation detector 1 will be briefly described. FIG. 2 is a perspective view illustrating the configuration of the radiation detector according to the first embodiment. As shown in FIG. 2, the radiation detector 1 includes a scintillator 2 that converts radiation into fluorescence, and a photodetector 3 that detects fluorescence. A light guide 4 for transmitting and receiving fluorescence is provided at a position where the scintillator 2 and the photodetector 3 are interposed.

The scintillator 2 is configured by arranging scintillator crystals two-dimensionally. The scintillator crystal is composed of Lu _{2 (1-X)} Y _2X SiO ₅ (hereinafter referred to as LYSO ₎ in which Ce is diffused. The photodetector 3 can specify the fluorescence generation position indicating which scintillator crystal emits fluorescence, and can also specify the intensity of fluorescence and the time when the fluorescence is generated. it can. The scintillator 2 having the configuration of the first embodiment is merely an example of an aspect that can be adopted. Therefore, the configuration of the present invention is not limited to this.

  Detection data output from the detector ring 12 is sent to the coincidence counting unit 21 (see FIG. 1) via the filter unit 20. The two gamma rays incident on the detector ring 12 at the same time are an annihilation radiation pair caused by the radiopharmaceutical in the subject. The coincidence counting unit 21 counts the number of times the annihilation radiation pair is detected for every two combinations of scintillator crystals constituting the detector ring 12 and stores the result in the position information correcting unit 22. The positional relationship of the scintillator crystal in the coincidence count indicates the position where the annihilation radiation pair is incident on the detector ring 12 and the direction in which it is incident, and is information necessary for mapping of the radiopharmaceutical. The number of annihilation radiation pairs detected and the energy intensity of the annihilation radiation memorized for each combination of scintillator crystals indicates the variation in the occurrence of annihilation radiation pairs in the subject and is necessary information for mapping radiopharmaceuticals. . The coincidence of the detected data by the coincidence counting unit 21 uses time information given to the detected data by the clock 19.

  The filter unit 20 is provided for the purpose of preventing unnecessary data in the detector ring 12 from being sent to the coincidence unit 21. Since the coincidence counting unit 21 has to handle a large amount of data, it is likely to be loaded. The filter unit 20 can thin out the detection data so as to reduce the load on the coincidence counting unit 21. For example, all the detection data when the subject M is not inserted into the detector ring 12 is discarded by the filter unit 20 and is not input to the coincidence counting unit 21.

  By the way, since the top plate 10 moves in the z direction with respect to the detector ring 12, the positional relationship between the subject M and the detector ring 12 is shifted. The position information correction unit 22 corrects this deviation. The position information correction unit 22 receives a signal indicating the movement status of the top plate 10 from the top plate movement control unit 16. The position information correction unit 22 corrects the position information component of the coincidence count data sent from the coincidence unit 21 based on this signal. Specifically, the position information correction unit 22 shifts the position information component of the coincidence data in the z direction so as to follow the movement of the top 10 in the z direction. The corrected coincidence count data is stored in the data storage unit 23.

  The coincidence data is sent to the tomographic image acquisition unit 24. Therefore, the coincidence data is three-dimensionally mapped, and a plurality of axial images (slice images in a plane perpendicular to the z direction) of the subject M are acquired. In the tomographic image generated at this time, the distribution of the radiopharmaceutical in the subject is reflected.

  The synchronization unit 26 is provided for the purpose of controlling the top plate movement mechanism 15 and the absorber movement mechanism 17 described later in synchronization with the top plate movement control unit 16 and the absorber movement control unit 18. This will be described later. The synchronization unit 26 corresponds to the synchronization means of the present invention, and the absorber moving mechanism 17 corresponds to the absorber moving means of the present invention.

  The radiation tomography apparatus 9 includes a main control unit 41 that controls each unit in an integrated manner, and a display unit 36 that displays a radiation tomographic image. The main control unit 41 is constituted by a CPU, and realizes the respective units 16, 18, 20, 21, 22, 23, 24, and 26 by executing various programs. In addition, each above-mentioned part may be divided | segmented and implement | achieved by the control apparatus which takes charge of them.

  The set value storage unit 37 stores various parameters relating to the moving speed of the top board 10 and the first absorber 13. The console 35 is an input unit for inputting various instructions of the surgeon.

  The medical couch device according to the present invention includes a couchtop 10, a couchtop abutment 10p that supports the couchtop 10, a couchtop moving mechanism 15, a couchtop movement control unit 16, a first absorber 13, and an absorber. A moving mechanism 17 and an absorber movement control unit 18 are provided. The top board abutment 10p also supports the first absorber 13. Thus, the radiation tomography apparatus 9 has a mode in which the medical bed apparatus of the present invention is incorporated.

  In the present invention, the most characteristic first absorber 13 and second absorber 14 will be described. The first absorber 13 is a plate that is provided on the top plate 10 and extends in the z direction, and is made of lead or the like that shields γ rays. The first absorber 13 is provided on the top plate 10 side (the top plate abutment 10 p side that supports the top plate 10) when viewed from the detector ring 12. Further, the first absorber 13 is movable back and forth in the z direction, and such sliding of the first absorber 13 is realized by the absorber moving mechanism 17. The absorber moving mechanism 17 is controlled by the absorber moving control unit 18. The first absorber 13 and the top plate 10 are supported by a top plate support 10p that is grounded to the floor surface. The absorber movement control unit 18 is an absorber movement control unit that controls the movement of the first absorber 13. Moreover, the first absorber 13 is provided on the lower side of the top plate 10. Specifically, the 1st absorber 13 is provided so that the lower surface on the opposite side to the mounting surface in the top plate 10 may be covered.

  The second absorber 14 is provided on the side opposite to the top plate 10 side (the top plate abutment 10p side that supports the top plate 10) when viewed from the detector ring 12. That is, the detector ring 12 is disposed so as to be sandwiched between the first absorber 13 and the second absorber 14 from the z direction. The second absorber 14 also has a plate shape extending in the z direction, and is made of lead or the like that shields γ rays. The second absorber 14 is fixedly supported by a second absorber abutment 14p that is grounded to the floor surface. In addition, the second absorber 14 is provided below the top plate 10. Specifically, the 2nd absorber 14 is provided so that the lower surface on the opposite side to the mounting surface in the top plate 10 may be covered. However, since the top 10 slides in the z direction, when the second absorber 14 and a part of the top 10 are in the same position in the z direction, the bottom surface of the top 10 is the second absorber. 14 will be covered.

  The first absorber 13 and the second absorber 14 are provided on the inner side of the inner wall of the detector ring 12 when viewed from the center of the opening of the detector ring 12. Similarly, the first absorber 13 and the second absorber 14 are provided on the inner side of the inner wall of the gantry 11 when viewed from the center of the opening of the gantry 11. That is, when the detector ring 12 is extended in the front-back direction in the z direction, the first absorber 13 and the second absorber 14 are configured to exist inside the opening of the virtual detector ring 12. Thereby, the 1st absorber 13 and the 2nd absorber 14 can be located so that it may protrude toward the inner side of the opening of the gantry 11 from az direction.

  The shape of the 1st absorber 13 and the 2nd absorber 14 is demonstrated. As shown in FIG. 3, the absorbers 13 and 14 have a bowl shape that is bent downward along the shape of the opening of the gantry 11 (detector ring 12). Since the absorbers 13 and 14 have such a shape, they can be introduced into the gantry 11 without interfering with the gantry 11.

  FIG. 4 is a diagram for explaining the positional relationship between the detector ring 12, the first absorber 13, and the second absorber 14. As shown in FIG. 4, the first absorber 13 is provided so as to penetrate the opening of the detector ring 12 if it is extended in the z direction. In other words, the shape of the bowl-shaped plate extending from the inside of the detector ring 12 toward the top plate abutment 10p is such that the portion located inside the opening of the detector ring 12 is cut off. The first absorber 13 can slide away from the detector ring 12 by sliding in the z direction from the position closest to the detector ring 12. Similarly, as shown in FIG. 4, the second absorber 14 is provided so as to penetrate the opening of the detector ring 12 if it is extended in the z direction. In other words, of the bowl-shaped plate extending from the inside of the detector ring 12 toward the side opposite to the top plate abutment 10p, the portion located inside the opening of the detector ring 12 is cut off. ing.

  When the width in the direction A (the body side direction of the subject) that is the short direction of the top board 10 is the body side width, the width in the direction A of the absorbers 13 and 14 is the body side direction of the top board 10. It is the same.

  The positional relationship between the first absorber 13 and the second absorber 14 will be described in more detail. When the first tip 13 s, which is the tip of the first absorber 13 on the detector ring 12 side, is located closest to the detector ring 12, the first absorber 13 side of the imaging field of the detector ring 12 has It is located at the first limit position P1, which is the limit position (see FIG. 4). The first absorber 13 does not enter the detector ring 12 any more.

  The detector ring 12 can detect annihilation radiation inside the ring. That is, the detector ring 12 has an imaging field that can detect annihilation radiation, and the width in the z direction is equal to or smaller than the width of the detector ring 12. The position of the first absorber 13 is determined with reference to this field of view. The first absorber 13 slides along the z direction so as to move away from the detector ring 12 by the absorber moving mechanism 17 from the position closest to the detector ring 12 shown in FIG. 4 (see FIG. 5). In other words, the absorber moving mechanism 17 moves the first tip 13s of the first absorber 13 from the starting point away from the detector ring 12 in the z direction to the end point of the first limit position P1.

  Similarly, the position of the second absorber 14 is determined based on the above-described imaging field of view. That is, the second tip 14s, which is the tip of the second absorber 14 on the detector ring 12 side, is located at the second limit position P2, which is the limit position on the second absorber 14 side in the imaging field of the detector ring 12. positioned.

<Operation of radiation tomography system>
Next, the operation of the radiation tomography apparatus 9 will be described. In order to know the distribution of the radiopharmaceutical in the subject M with the radiation tomography apparatus 9, first, the radiopharmaceutical is injected into the subject M. At a time when a predetermined time has elapsed from this time, the subject M is placed on the top 10. As shown in FIG. 5, the entire top plate 10 at this time is located outside the detector ring 12. At this time, the first absorber 13 does not protrude from the top 10 so that the subject M does not get in the way of being positioned on the top 10. In other words, the first tip 13s of the first absorber 13 is located farther than the detector ring 12 than the tip of the top plate 10 on the detector ring 12 side.

  When the surgeon instructs the radiation tomography apparatus 9 to start the examination through the console 35, the top 10 is controlled by the top movement control unit 16 with the subject M placed thereon and slides in the z direction. That is, the top plate 10 and the first absorber 13 move synchronously in the same direction in z. Such synchronous movement is realized by the synchronization unit 26 simultaneously sending a movement start trigger signal to the top plate movement control unit 16 and the absorber movement control unit 18. Thus, the subject M is moved to a position where the region of interest falls within the field of view of the detector ring 12. During this time, the first tip 13s of the first absorber 13 does not overtake the tip of the top plate 10 on the detector ring 12 side, and the first tip 13s of the first absorber 13 moves to the above-mentioned end point position. And stop there. Regardless of the stop of the first absorber 13, the top 10 continues to move in the z direction so that the region of interest of the subject M falls within the field of view of the detector ring 12.

  At this point, the detector ring 12 detects an annihilation radiation pair in the region of interest of the subject M. In this way, a tomographic image of the region of interest of the subject M is acquired. The acquired tomographic image is displayed on the display unit 36, and the examination ends.

  Next, the manner in which the radiation that obstructs simultaneous counting is removed by the first absorber 13 and the second absorber 14 in the present invention will be described. FIG. 6 shows a state where radiopharmaceutical imaging is performed on the trunk of the subject M. An annihilation radiation pair generated at a site g in the field of view of the detector ring 12 is incident on two locations of the detector ring 12 as indicated by arrows. The annihilation radiation pair detected by the detector ring 12 is counted by the coincidence counting unit 21 and used for obtaining a tomographic image. On the other hand, it is desirable that the annihilation radiation pair (externally generated radiation) generated at the portion h outside the imaging field of the detector ring 12 does not go to the detector ring 12. However, as shown in FIG. 6, one of the annihilation radiation pairs generated outside the field of view may be directed to the detector ring 12. Such radiation is absorbed by the first absorber 13 and the second absorber 14 provided outside the field of view before moving toward the detector ring 12. For example, in the case of FIG. 6, the radiation generated at the part h is absorbed by the first absorber 13 and does not enter the detector ring 12 after all.

  Moreover, since the first absorber 13 and the second absorber 14 are provided to avoid the imaging field of the detector ring 12, the annihilation radiation pair generated in the imaging field to be used for acquiring the tomographic image is The first absorber 13 and the second absorber 14 are not reliably absorbed. The first absorber 13 and the second absorber 14 do not interfere with detection of the annihilation radiation pair generated at the site g.

  As described above, according to the configuration of the first embodiment, externally generated radiation generated outside the visual field range of the detector ring 12 can be prevented from entering the detector ring 12. That is, according to the configuration of the first embodiment, the medical bed apparatus includes the first absorber 13 that absorbs radiation that can move in the z direction. The first absorber 13 absorbs radiation transmitted through the top plate 10. Since the externally generated radiation that passes through the top plate 10 and travels toward the detector ring 12 is absorbed by the first absorber 13, it is possible to prevent the externally generated radiation from entering the detector ring 12. The incidence of radiation generated outside the field of view of the detector ring 12 on the detector ring 12 is an obstacle to generating a tomographic image. However, according to the present invention, since the externally generated radiation is absorbed by the first absorber 13, a tomographic image suitable for diagnosis can be generated.

  In addition, the first tip 13s, which is the tip of the first absorber 13 on the detector ring 12 side, is configured not to approach the detector ring 12 beyond the first limit position P1 in the field of view. Thereby, since the 1st absorber 13 does not enter into the imaging | photography visual field of the detector ring 12, the annihilation radiation produced in an imaging | photography visual field is not absorbed by the 1st absorber 13. FIG.

  The first absorber 13 is movable along the z direction. Thereby, since the position of the 1st absorber 13 can be changed according to the position of the top plate 10, when the subject M gets on and off the top plate 10, the 1st absorber 13 does not become obstructive. Furthermore, if the first absorber 13 is always adjacent to the detector ring 12, the operator cannot approach the detector ring 12. According to the configuration of the first embodiment, since the position of the first absorber 13 can be changed along the z direction, the radiation tomography apparatus 9 that is safer and easy to maintain can be provided.

  The first absorber 13 absorbs radiation that has passed through the top plate 10 and is configured to move independently of the top plate 10. In order to realize such a configuration, it is only necessary that the first absorber 13 is provided so as to cover the lower surface of the top plate 10 opposite to the placement surface on which the subject M is placed. Since the first absorber 13 is provided at a position closer to the inner wall of the detector ring 12 when viewed from the center of the opening of the detector ring 12, (the first absorber 13 is temporarily arranged in the z direction). If it is stretched, it is provided so as to penetrate through the opening of the detector ring 12), so that the radiation that passes through the top plate 10 and travels toward the detector ring 12 always goes to the first absorber 13. As described above, according to the configuration of the first embodiment, it is possible to reliably prevent the externally generated radiation from entering the detector ring 12.

  Moreover, according to the structure of Example 1, the movement of the top plate 10 and the movement of the 1st absorber 13 can be synchronized now. Therefore, since the position of the first absorber 13 can be determined in accordance with the state of the top board 10, the radiation tomography in which the first absorber 13 does not get in the way when the subject M gets on and off the top board 10 more. A device 9 can be provided. That is, the top plate 10 and the first absorber 13 are moved synchronously in the same direction in the z direction. By doing in this way, the top plate 10 and the 1st absorber 13 protrude in the same direction. Since the detector ring 12 is generally positioned in the direction in which the top plate 10 protrudes, the first absorber 13 reliably approaches the detector ring 12 and absorbs externally generated radiation incident thereon as the top plate 10 protrudes. be able to.

  Further, according to the configuration of the first embodiment, the second absorber 14 is provided on the opposite side of the first absorber 13 as viewed from the detector ring 12. That is, the detector ring 12 is disposed so as to be sandwiched between the first absorber 13 and the second absorber 14 from the z direction. The second absorber 14 also absorbs radiation that has passed through the top plate 10, and its configuration conforms to that of the first absorber 13. However, the second absorber 14 need not be configured to move. This is because the second absorber 14 is sufficiently separated from the subject M and does not hinder the getting on and off of the subject M. If configured in this manner, the dose of externally generated radiation absorbed by the absorbers 13 and 14 increases, so that it is possible to provide a radiation tomography apparatus 9 that can acquire a tomographic image more suitable for diagnosis.

  Next, a PET / CT apparatus according to the second embodiment will be described. The PET / CT apparatus has a configuration including the radiation tomography apparatus (PET apparatus) 9 described in the first embodiment and a CT apparatus 8 that generates a tomographic image using X-rays. It is a medical device which can produce | generate the synthesized image which overlap | superposed.

  A configuration of the PET / CT apparatus according to the second embodiment will be described. In the PET apparatus in the PET / CT apparatus according to the second embodiment, the radiation tomography apparatus (PET apparatus) 9 described in the first embodiment can be used. Therefore, a CT apparatus which is a characteristic part in the second embodiment will be described. As shown in FIG. 7, the CT apparatus 8 has a gantry 45. The gantry 45 is provided with an opening extending in the z direction, and the top plate 10 and the first absorber 13 are inserted into the opening. The CT apparatus 8 is adjacent to the radiation tomography apparatus 9 from the z direction side.

  An gantry 45 supports an X-ray tube 43 that irradiates the subject with X-rays, an FPD (flat panel detector) 44 that has passed through the subject, and the X-ray tube 43 and the FPD 44. A support 47 is provided. The support 47 has a ring shape and is rotatable around a central axis extending in the z direction. The rotation of the support 47 is performed by a rotation mechanism 39 including a power generation unit such as a motor and a power transmission unit such as a gear. The rotation control unit 40 controls the rotation mechanism 39. The X-ray tube 43 corresponds to the radiation source of the present invention. The FPD 44 corresponds to the radiation detection means of the present invention, and the support 47 corresponds to the support means of the present invention. The rotation mechanism 39 corresponds to the rotation means of the present invention, and the rotation control unit 40 corresponds to the rotation control means of the present invention.

  The CT image generation unit 48 generates an X-ray tomographic image of the subject M based on the X-ray detection data output from the FPD 44. The superimposing unit 49 generates a superposition image by superimposing the PET image indicating the drug distribution in the subject output from the radiation tomography apparatus (PET apparatus) 9 and the above-described X-ray tomographic image. It has a configuration.

  The first absorber 13 is provided inside the inner wall of the support 47 as viewed from the center of the opening of the support 47. Similarly, the first absorber 13 is provided on the inner side of the inner wall of the gantry 45 when viewed from the center of the opening of the gantry 45 of the CT apparatus 8. Accordingly, the first absorber 13 can be provided at a position protruding inside the opening of the gantry 45.

  The main control unit 41 realizes a rotation control unit 40, a CT image generation unit 48, a superposition unit 49, and an X-ray tube control unit 46 in addition to the respective units according to the first embodiment by executing various programs. is doing. In addition, each above-mentioned part may be divided | segmented and implement | achieved by the control apparatus which takes charge of them.

  A method for acquiring a fluoroscopic image will be described. The X-ray tube 43 and the FPD 44 rotate around the central axis extending in the z direction while maintaining the relative position of each other. At this time, the X-ray tube 43 intermittently irradiates the subject M with X-rays, and each time the CT image generation unit 48 generates an X-ray fluoroscopic image. The plurality of fluoroscopic images are assembled into a single tomographic image by the CT image generation unit 48 using, for example, an existing back projection method.

  Next, a method for generating a composite image will be described. In order to acquire a composite image with the PET / CT apparatus, a region of interest of the subject M is introduced into the CT apparatus, and an X-ray tomographic image is acquired while changing the positions of the subject M and the gantry 45. At this time, the first absorber 13 has not entered the gantry 45. Thereby, the X-rays irradiated from the X-ray tube 43 are not absorbed by the first absorber 13. Then, the region of interest of the subject M is introduced into a radiation tomography apparatus (PET apparatus) 9 to acquire a PET image. At this time, the first absorber 13 enters the opening of the gantry 45 and is adjacent to the detector ring 12 as shown in FIG. Both images are superimposed by the superimposing unit 49, and the completed composite image is displayed on the display unit 36. Thereby, since the drug distribution and the internal structure of the subject can be recognized simultaneously, a tomographic image suitable for diagnosis can be provided.

  According to the configuration of the second embodiment, the radiation tomography apparatus 9 that can acquire both the internal structure of the subject M and the drug distribution can be provided. A PET device can generally obtain information relating to drug distribution. However, it may be necessary to make a diagnosis while referring to a tomographic image in which an organ or tissue of the subject M is captured. According to the above configuration, since both the internal structure of the subject M and the drug distribution can be acquired, for example, a composite image suitable for diagnosis can be generated by superimposing both images.

  The present invention is not limited to the above-described configuration, and can be modified as follows.

  (1) According to each above-mentioned example, although the 1st absorber 13 was provided so that the lower surface of top plate 10 might be covered, the present invention is not restricted to this composition. As shown in FIG. 8, the present invention can also be implemented as a configuration in which the first absorber 13 is provided inside the top plate 10.

(2) The scintillator crystal referred to in each of the above examples is composed of LYSO. However, in the present invention, the scintillator crystal is composed of other materials such as GSO (Gd ₂ SiO ₅ ) instead. Also good. According to this modification, it is possible to provide a method of manufacturing a radiation detector that can provide a cheaper radiation detector.

  (3) In each of the embodiments described above, the photodetector is composed of a photomultiplier tube, but the present invention is not limited to this. Instead of the photomultiplier tube, a photodiode, an avalanche photodiode, a semiconductor detector, or the like may be used.

  (4) The shape of the top plate 10 may be a bowl shape bent along the opening of the gantry, or may be a planar shape. The shapes of the first absorber 13 and the second absorber 14 can be freely changed in accordance with the shape of the top plate 10.

P1 first limit position P2 second limit position 1 radiation detector 9 radiation tomography apparatus 10 top plate 12 detector ring 15 top plate moving mechanism (top plate moving means)
13 First absorber 13a First tip 14 Second absorber 14a Second tip 17 Absorber moving mechanism (absorber moving means)
26 Synchronizing part (synchronizing means)

Claims (8)

A medical couch device deployed in a radiation tomography device that detects annihilation radiation pairs,
(A) a top plate on which the subject is placed;
(B) a top plate moving means for moving the top plate along a top plate longitudinal direction which is a longitudinal direction of the top plate;
(C) a first absorber that absorbs radiation transmitted through the top plate;
(D) A medical bed apparatus comprising: an absorbent body moving means for moving the first absorbent body along the top plate longitudinal direction. The medical couch device according to claim 1,
(E) The medical bed apparatus, wherein the first absorber is provided so as to cover a lower surface of the top plate opposite to a placement surface on which the subject is placed. In the medical couch device according to claim 1 or 2,
(F) comprising synchronization means for synchronizing the top plate moving means and the first absorber moving means;
(G) The medical couch device, wherein the top plate and the first absorber move synchronously in the same direction in the top plate longitudinal direction. (A) a top plate on which the subject is placed;
(B) a top plate moving means for moving the top plate along a top plate longitudinal direction which is a longitudinal direction of the top plate;
(C) a first absorber that absorbs radiation transmitted through the top plate;
(D) a medical bed apparatus provided with an absorbent body moving means for moving the first absorbent body along the longitudinal direction of the top plate;
A detector ring having an opening penetrating in the longitudinal direction of the top plate for introducing the top plate and a radiation detector configured to detect radiation and arranged in a ring shape;
The first absorber is provided so as to pass through the opening of the detector ring, assuming that the first absorber is extended in the longitudinal direction of the top plate,
The absorber moving means is a first limit position that is a limit position on the first absorber side in a field of view in which the detector ring has a first tip that is a tip on the detector ring side of the first absorber. A radiation tomography apparatus characterized by being moved to a distance. The radiation tomography apparatus according to claim 4,
(E) The radiation tomography apparatus according to claim 1, wherein the first absorber is provided so as to cover a lower surface of the top plate opposite to a placement surface on which the subject is placed. The radiation tomography apparatus according to claim 4 or 5,
(F) provided with a synchronizing means for synchronizing the top board moving means and the absorber moving means,
(G) The top plate and the first absorber move synchronously in the same direction in the top plate longitudinal direction,
The radiation tomography apparatus according to claim 1, wherein the absorber moving means stops the first tip of the first absorber at the first limit position regardless of the movement of the top plate. The radiation tomography apparatus according to claim 6,
A second absorber that is disposed so as to cover the lower surface of the top plate and absorbs radiation transmitted through the top plate;
The second absorber is provided so as to penetrate through the opening of the detector ring, if it is extended in the top plate longitudinal direction,
The detector ring is disposed at a position sandwiched between the first absorber and the second absorber, and the position of the second tip that is the tip of the second absorber on the detector ring side is A radiation tomography apparatus characterized by being coincident with a second limit position which is a limit position on the second absorber side in an imaging field of view of a detector ring. The radiation tomography apparatus according to any one of claims 4 to 7,
(Α) a radiation source rotatable about a central axis extending in a longitudinal direction of the top plate with respect to the top plate;
(Β) a radiation detection means rotatable around the central axis with respect to the top plate;
(Γ) a support means for supporting the radiation source and the radiation detection means;
(Δ) rotating means for rotating the support means;
(Ε) A radiation tomography apparatus characterized in that an image generation apparatus comprising a rotation control means for controlling the rotation means is provided adjacent to the detector ring from the longitudinal direction of the top plate.

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