JP2005172477A - Nuclear-medical imaging device, gamma camera, and single photon discharge type tomographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nuclear-medical imaging device allowing conversions into both an inspection mode for enhancing spatial resolution and an inspection mode for enhancing sensitivity, without replacing a collimator. <P>SOLUTION: This gamma camera 1 is provided with the collimator 100 having a fixed collimator 10 and a movable collimator 20. A plurality of collimator elements 16 having a large number of holes (gamma-ray passage) 15 is attached to an inside of a rectangular shape body 11, in the fixed collimator 10. A plurality of collimator elements 17 having a large number of holes (gamma-ray passage) 25 is attached to an inside of a rectangular shape body 21, in the movable collimator 20. The collimator elements 17 are arranged between the collimator elements 16. The movable collimator 20 is movable along a direction orthogonal to an axial direction of the collimator 100. The collimator elements 16 are thereby movable along the orthogonal direction. A cross-sectional area of the gamma-ray passage is substantially regulated in the collimator 100, with an overlapping degree of the holes 15 and the holes 25 accompanying the moving of the movable collimator 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a nuclear medicine imaging apparatus, a gamma camera, and a single photon emission tomographic imaging apparatus for measuring a radioisotope distribution, and more particularly to a nuclear medicine imaging apparatus having a collimator, a gamma camera, and a single photon emission tomographic imaging apparatus. It is.

  Gamma rays are emitted in all directions from radioisotopes contained in a radiopharmaceutical accumulated in a site (for example, an affected area of a malignant tumor) administered to a subject (subject) that is an imaging target. For this reason, for example, a gamma camera or a SPECT apparatus, which is a nuclear medicine imaging apparatus, enters the radiation detector straight or only in a specific direction in order to correctly know the position where the radioisotope is accumulated (position of the affected part). A gamma ray is selected (emitted from the affected area) and other gamma rays are shielded from reaching the radiation detector. A typical collimator is a so-called parallel porous type in which gamma rays are incident on a radiation detector of a gamma camera or SPECT apparatus only from a direction perpendicular to the radiation detector. In addition, there are various types in which the direction of the hole (gamma ray passage) is changed. When the diameter of the hole is reduced and many holes are formed, the incident position of the gamma ray can be identified more finely. This type is called a high resolution collimator. On the other hand, when the diameter of the hole is increased, the number of gamma rays incident on the nuclear medicine imaging apparatus increases because the gamma rays blocked by the collimator decrease. Such a type is called a high sensitivity collimator. The intermediate type is called a general-purpose collimator. These need to be replaced depending on the purpose of the inspection.

  Since the collimator is made of lead, tungsten, or the like that has high radiation shielding ability for gamma ray photons, it is very heavy and replacing the collimator is a heavy labor. In addition, since a time of several minutes or more is required, preparation takes time, so that the patient throughput is lowered. In addition, there is a problem that it is necessary to secure a storage place in the nuclear medicine laboratory for holding a plurality of such heavy collimators. Furthermore, even in a handy-type gamma camera used in the operating field, it takes time and effort to attach and detach the collimator, which causes a demerit of extending the operation time.

  In order to solve the problem of such collimator, the collimator partition wall is configured to be layered with thin wire-like rods, and by thinning out this rod, the spatial resolution and the number of transmitted gamma rays are the same as the conventional collimator. A collimator that reduces the weight while maintaining it has been proposed (see Non-Patent Document 1, for example).

Further, in Patent Document 1, it is possible to adjust the spatial resolution and sensitivity without moving the collimator by moving the radiation detector in the gamma ray path of the collimator and changing the collimator, thereby supporting a plurality of examinations. A gamma camera device is described.
JP-A-9-236666 (paragraph 0013, FIG. 1) Medical Video Information (2002.12) Vol.34, No.15, page 1417

  By the way, although the collimator described in Non-Patent Document 1 is lightweight, the sensitivity and resolution cannot be changed, and the collimator needs to be replaced depending on the type of inspection. There is a problem that cannot be omitted. Moreover, in the gamma camera that moves the radiation detector in the gamma ray passage of the collimator as described in Patent Document 1, it is possible to omit the replacement of the collimator, but the collimator itself is integrated with the camera itself, It becomes a camera. In other words, various collimators such as a diverging collimator, a converging collimator, and a fan beam collimator cannot be replaced and mounted, and there is a problem that versatility is lacking.

  An object of the present invention is to provide a nuclear medicine imaging apparatus, a gamma camera, and a single-photon emission tomographic imaging apparatus that can be converted into an inspection mode that increases spatial resolution and an inspection mode that increases sensitivity without exchanging collimators. .

  A feature of the present invention that achieves the above object is that the collimator apparatus includes a fixed collimator having a first collimator element having a plurality of radiation paths and a second collimator element having a plurality of radiation paths. The movable collimator is movable in a direction crossing the axial direction, and the first and second collimator elements are arranged along the axial direction of the collimator device.

  Since the movable collimator can be moved in a direction crossing the axial direction of the collimator device (for example, a direction orthogonal thereto), the radiation path formed in the first collimator element of the fixed collimator and the radiation formed in the second collimator element of the movable collimator The state of overlap with the passage can be changed, and the cross-sectional area of the substantial radiation passage of the collimator device formed by the fixed collimator and the movable collimator (cross-sectional area in the direction intersecting the axial direction of the collimator device) is changed. Can do. Therefore, the angle of the radiation detector that faces the radiation source (for example, the position where the radiopharmaceutical is accumulated in the subject) can be adjusted via the collimator device. When the cross-sectional area of the substantial radiation path of the collimator device is large (for example, when the position of the radiation path of the first collimator element coincides with the position of the radiation path of the second collimator element), it is incident on the radiation detector. Radiation (for example, gamma rays) increases, and the detection sensitivity of the radiation increases. When the cross-sectional area of the substantial radiation path of the collimator device is reduced (for example, the position of the radiation path of the second collimator element is shifted in the direction intersecting the position of the radiation path of the first collimator element), the radiation detection As a result, radiation in a specific direction is incident on the vessel, and the spatial resolution is increased. For this reason, it is possible to cope with inspections for high resolution applications and high sensitivity applications without replacing the collimator.

  Preferably, a collimator moving device is provided in the movable collimator. Thereby, the movable collimator can be easily moved without using labor.

  Preferably, the number of collimator elements in the collimator device may be increased, or the thickness of a part of the plurality of collimator elements may be different from the thickness of the remaining collimator elements. As a result, a spatial resolution substantially equivalent to that of the high resolution collimator can be realized, and the weight can be reduced by about ½ compared to the high resolution collimator. For example, the use of a collimator other than a parallel collimator can be handled by removing the collimator device and replacing it.

  According to the present invention, in a nuclear medicine imaging apparatus, it is possible to easily change between an inspection mode that increases spatial resolution and an inspection mode that can increase radiation detection sensitivity without exchanging a collimator.

  Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings of FIGS.

(First embodiment)
A gamma camera which is a nuclear medicine imaging apparatus according to the first embodiment of the present invention will be described below. As shown in FIG. 16, the gamma camera 1 of the present embodiment mainly includes a plurality of radiation detectors 2 installed on a detector substrate 104, and a collimator (collimator device) disposed in front of each radiation detector 2. 100, a signal processing circuit (signal processing device) 105 for processing the radiation detection signal output from the radiation detector 2 is provided. The radiation detector 2 and the signal processing device 105 are stored in a housing (holding member) 3 having a light shielding / electromagnetic shielding function. The housing 3 is made of a material capable of light shielding and electromagnetic shielding.

  Gamma rays flying from the left direction in the figure enter the radiation detector 2 via the collimator 100. This incident gamma ray is only a component perpendicular to the gamma ray incident surface of the radiation detector 2. As a result, the shape of a radiopharmaceutical accumulation site that generates gamma rays of a subject (subject) (not shown) is projected onto the radiation detector 2. The radiation detector 2 detects an incident gamma ray and outputs a gamma ray detection signal. The gamma ray detection signal is input to the signal processing circuit 105 via the detector substrate 104. The signal processing circuit 105 processes the gamma ray detection signal to generate data such as detection position information, a peak value indicating energy, and a detection time. These data are transmitted to an image information creation device (not shown) via the connector 106. The image information creation device creates image information of the affected area of the subject using those data. This image information is displayed on a display device (not shown).

  The detailed structure of the collimator 100 will be described with reference to FIGS. The collimator 100 is disposed in front of a plurality of radiation detectors (semiconductor radiation detectors) 2 and includes a fixed collimator 10 and a movable collimator 20. The fixed collimator 10 is attached to the housing 3 of the gamma camera 1 (FIG. 3B). The radiation detector 2 has a size corresponding to the size of one hole (the size when the holes 15 and 25 are viewed from the front) in the high resolution mode described later. The radiation detector 2 may be a divided scintillation detector or a crystal plate that is not divided.

  As shown in FIG. 1, the fixed collimator 10 is arranged in a square cylinder 11 having a square cross section made of steel and the like, and inside the square cylinder 11, and arranged at intervals in the traveling direction of gamma rays. Five collimator elements 16. Each collimator element 16 is arranged at substantially equal intervals in the axial direction of the rectangular tube 11, and is made of a plurality of steel materials or the like provided on the four side surfaces inside the rectangular tube 11 as shown in FIG. Are attached to the support arm 12. Each collimator element 16 is a radiation shielding material that is attached to a plurality of support arms 12 and is held by a rectangular tube body 11 and has a square cross section and is arranged in a lattice shape within the frame body 13. A collimator plate 14 made of lead or the like is included. A square hole (gamma ray passage) 15 is formed between the collimator plates 14.

  In FIG. 1, each collimator plate 14 is schematically written roughly. However, a square hole 15 formed between actually used collimator plates 14 has a side length d (see FIG. 1A) of 3 mm. Degree. The collimator plate 14 has a wall thickness (septal thickness) of about 0.2 mm. Further, the frame-like body 13 is formed to be approximately 200 mm square. Further, as shown in FIGS. 1B and 1C, the four side walls 11 </ b> A of the rectangular tube body 11 are long at positions corresponding to the spaces formed between the adjacent frame bodies 13. A circular guide hole 11B is opened.

  As shown in FIG. 2, the movable collimator 20 is arranged in a square cylinder 21 having a square cross section made of steel and the like, and the square cylinder 21, and is arranged at intervals in the traveling direction of gamma rays. And four collimator elements 17. The collimator elements 17 are arranged at substantially equal intervals in the axial direction of the rectangular tube 21 and are made of a steel material or the like provided on the four side surfaces inside the rectangular tube 21 as shown in FIG. It is attached to the arm 22. Each collimator element 17 is attached to a plurality of support arms 22 and is held by a rectangular tube body 21. The collimator is composed of a frame body 23 having a square cross section and lead or the like arranged in a grid in the frame body 23. A plate 24 is included. A plurality of square holes (gamma ray passages) 25 are formed between the collimator plates 24. However, in each collimator element 17, as shown in FIG. 2A, all the holes adjacent to the left and upper side surfaces are rectangular holes (gamma ray passages) 26 of 1.5 mm × 3 mm.

  The number of holes 25 in the collimator element 17 is the same as the number of holes 15 in the collimator element 16, and the size of the portion of the collimator element 17 where the holes 25 are arranged is the size of the portion of the collimator element 16 where the holes 15 are arranged. Is the same. The cross-sectional area of the collimator element 17 is larger than the cross-sectional area of the collimator element 16 by the amount where the holes 26 are arranged. For this reason, the length of one side of the frame-like body 23 is longer than that of one side of the frame-like body 13. Further, one side of the rectangular tube 11 is longer than one side of the frame-like body 23, and one side of the square tube 21 is longer than one side of the square tube 11.

  In the collimator 100, as shown in FIG. 3B, the collimator elements 16 of the collimator 10 and the collimator elements 17 of the movable collimator 20 are alternately arranged in the axial direction of the collimator 100. In this state, each support arm 22 attached to each collimator element 17 is inserted into a guide hole 11 </ b> B formed in the rectangular tube 11 of the fixed collimator 10. For this reason, the movable collimator 20 is held by the fixed collimator 10.

  The movable collimator 20 is movable in a direction orthogonal to the axial direction of the collimator 100. That is, each collimator element 17 can move in that direction between the collimator elements 16. For this reason, the operator slides each collimator element 17 of the movable collimator 20 through the guide hole 11B so that the movable collimator 20 has the size of the hole 15 in the direction orthogonal to the incident direction of the gamma rays. It is moved within a range of about half, that is, within a range of about 0 to 1.5 mm. The total thickness of all the collimator elements 16 of the fixed collimator 10 and all the collimator elements 17 of the movable collimator 20 is about 60 mm.

  The detection of gamma rays using the gamma camera 1 will be described. The gamma camera 1 can perform gamma rays in either the high sensitivity mode or the high resolution mode depending on the position of the movable collimator 20. First, gamma ray detection in the high sensitivity mode will be described. In the high sensitivity mode, as shown in FIG. 3A, the movable collimator 20 is moved in the direction of the arrow A, and the two adjacent side walls 21 </ b> A of the rectangular cylinder 21 are changed to the two adjacent side walls 11 </ b> A of the rectangular cylinder 11. The positions of the hole 15 and the hole 25 coincide with each other. For this reason, in the high sensitivity mode, a plurality of gamma ray passages 27 whose cross section in the direction orthogonal to the axial direction of the collimator 100 is about 3 mm square are formed in the collimator 100. The radiation detector 2 comes to the outside through the gamma ray passage 27 having a large sectional area. Gamma rays emitted from the body of the subject enter the radiation detector 2 through the gamma ray passage 27. Since the gamma ray passage 27 has a large cross-sectional area in a direction orthogonal to the axial direction of the collimator 100, the gamma ray detection sensitivity is increased. That is, the mode is a high sensitivity mode in which sensitivity is prioritized over spatial resolution.

  Next, gamma ray detection in the high resolution mode will be described. In the high resolution mode, as shown in FIG. 4A, the movable collimator 20 is moved in the direction of arrow B, and the other two side walls 21A adjacent to the rectangular tube 21 are moved to other adjacent ones of the rectangular tube 11. By contacting the two side walls 11A, the positions of the holes 15 and the holes 25 are staggered. For this reason, in the high resolution mode, the collimator plate 14 of the fixed collimator 10 and the collimator plate 24 of the movable collimator 20 have a plurality of gamma rays whose cross section in the direction orthogonal to the axial direction of the collimator 100 is about 1.5 mm square. A passage 28 (FIG. 4A) is formed in the collimator 100. The cross-sectional area of the gamma ray passage 28 in the direction orthogonal to the axial direction of the collimator 100 is about a quarter of the cross-sectional area of the gamma ray passage 27. However, the number of gamma ray passages 28 is about four times that of the gamma ray passages 27. Gamma rays emitted from the body of the subject enter the radiation detector 2 through the gamma ray passage 28. In such a high resolution mode, the sensitivity to gamma rays is slightly reduced, but the spatial resolution is improved because the gamma ray passage 28 having a small cross-sectional area is used. That is, the high resolution mode is given priority to the spatial resolution. In this example, the total number of layers of the fixed collimator 10 and the movable collimator 20 is nine. However, as the number of layers increases, the closer to the ideal collimator, as will be described later.

Next, a simulation result of imaging in the high resolution mode of FIG. 4 is shown.
FIG. 5 shows a result of realizing a high resolution mode by dividing the collimator 100 having a thickness of 60 mm into 50 layers and alternately shifting the fixed collimator 10 and the movable collimator 20. As shown in FIG. 5A, a gamma ray source (140 keV: point source) is placed only directly above the hole 15 at the center of the fixed collimator 10, and FIG. 5 (b) is a gamma ray count distribution of the radiation detector 2 on the central axis of the fixed collimator. In an ideal collimator 100 having a hole with a side of 1.5 mm, gamma rays are counted only in the central radiation detector 2.

In the results of FIGS. 5A and 5B, gamma rays are detected at several points away from the center. However, the count is concentrated on the radiation detector 2 of one element at the center, and high resolution is achieved. Has been achieved. In this case, the reason why the gamma rays are counted in the portion other than the center is that the intervals between the fixed collimators 10 and the movable collimators 20 are equal intervals, as shown in FIGS. 5 (a) and 5 (b). As shown in the example, when the fixed collimators 10 and the movable collimators 20 are equidistant from each other, the gamma rays are not only in the arrow a direction shown in FIG. 6 but also in the arrow b direction, for example, the fixed collimator 10 and the movable collimator. It passes through the inside without hitting 20. In this direction, if the collimator hole width is d, the thickness t of the collimator, and the length h per division of the collimator (see FIG. 6), the direction θ is
θ = Tan ⁻¹ {(d + t) / h} (Formula 1)
It becomes. In this simulation result, gamma rays are counted at a plurality of locations away from the radiation source. This is presumably because the collimator 100 has 50 layers, so that the plurality of layers (for example, 5 layers) pass through the gap between the collimators 100 and move to the adjacent portion. For this reason, as the number divisible by the number of layers of the collimator 100 increases, the number of these paths may increase.

  From (Equation 1), as the number of layers is increased and h is reduced, θ increases and the transmission area in the b direction decreases. Therefore, the erroneous count in the imaging field of view decreases, and almost only the source position. Count distribution is obtained.

  In this embodiment configured as described above, the fixed collimator 10 and the movable collimator 20 are alternately arranged in a plurality of layers. Therefore, in the high sensitivity mode, the lower right side of the rectangular tube 11 and the rectangular tube 21 are used. By aligning the lower right side of the aperture (FIG. 3 (a)), the positions of the larger holes 15 and 25 can be matched, and the high sensitivity mode gives priority to sensitivity over spatial resolution. Can be realized. Further, in the high resolution mode, by aligning the upper left side of the rectangular tube 11 and the upper left side of the rectangular tube 21 (FIG. 4A), the positions of the holes 15 and the holes 25 are alternated, and the collimator The size of the holes 15 and 25 when the member 100 is viewed from the front can be formed as small as about a quarter of the size in the high sensitivity mode, and although the sensitivity to gamma rays is slightly reduced, the spatial resolution can be improved. Therefore, it is possible to realize a high resolution mode in which spatial resolution is prioritized over sensitivity.

  Therefore, in the present embodiment, the spatial resolution and the detection sensitivity can be changed in a short time and without requiring labor without exchanging the fixed collimator 10 and the movable collimator 20.

(Second Embodiment)
Next, a gamma camera according to a second embodiment of the present invention will be described with reference to the accompanying drawings of FIGS. The gamma camera of this embodiment has a configuration in which the collimator 100 of the gamma camera 1 of the first embodiment is replaced with a collimator (collimator device) 100 ′ having a fixed collimator 10 ′ and a movable collimator 20 ′. The other configuration of the gamma camera is the same as that of the gamma camera 1. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  A fixed collimator 10 ′ shown in FIG. 7 includes a rectangular tube 11, a support arm 12, and a plurality of collimator elements 16, similarly to the fixed collimator 10 in the first embodiment. The fixed collimator 10 'further includes a plurality of collimator elements 16A. The fixed collimator 10 ′ has four collimator elements 16 </ b> A at the top and two collimator elements 16 at the bottom. The thickness of the collimator element 16 </ b> A is thinner than the thickness of the collimator element 16. The collimator element 16A is configured by attaching a collimator plate 14 'arranged in a grid pattern to a frame 13' having a square cross section. A frame-like body 13 ′ of the collimator element 16 A is attached to the rectangular tube body 11 by a plurality of support arms 12. The collimator element 16 </ b> A has the same number of square holes 15 formed by the frame 13 ′ as the collimator element 16.

  Further, the movable collimator 20 ′ shown in FIG. 8 includes a rectangular tube body 21, a support arm 22, and a plurality of collimator elements 17 like the movable collimator 20 in the first embodiment. Further, a plurality of collimator elements 17A are provided on the movable collimator 20. The movable collimator 20 ′ has three collimator elements 17 </ b> A at the top and two collimator elements 17 at the bottom. The thickness of the collimator element 17A is thinner than the thickness of the collimator element 17. The collimator element 17A is configured by attaching a collimator plate 24 'arranged in a grid pattern to a frame body 23' having a square cross section. A frame-like body 23 ′ of the collimator element 17 A is attached to the rectangular tube body 21 by a plurality of support arms 22. The collimator element 17 </ b> A has the same number of square holes 25 formed by the frame-like body 23 ′ as the collimator element 16. The collimator element 17 </ b> A also has a rectangular hole 26 like the collimator element 17.

  The collimator elements 16 </ b> A and the collimator elements 17 </ b> A are alternately arranged in the axial direction of the collimator 100 ′ similarly to the collimator elements 16 and 17. A support arm 22 attached to the frame body 23 'of the collimator element 17A is also inserted into the guide hole 11B of the fixed collimator 10'. And an operator moves movable collimator 20 'to the direction orthogonal to the axial direction of collimator 100' like the movable collimator 20 in 1st Embodiment.

  As described above, the fixed collimator 10 'having the collimator elements 16 and 16A having different thicknesses and the movable collimator 20' having the collimator elements 17 and 17A having different thicknesses are provided as shown in FIG. The gamma rays penetrating obliquely through the collimator 100 'can be blocked, and the detection of gamma rays other than the source position can be reduced. The simulation results with such a fixed collimator 10 'and the movable collimator 20' are shown in FIGS. In this simulation, the collimator element 16A of the fixed collimator 10 ′ and the collimator element 17A of the movable collimator 20 ′ are combined into 25 layers, and the thickness of the collimator elements 16A and 17A is 1.0 mm. Further, the collimator element 16 of the fixed collimator 10 ′ and the collimator element 17 of the movable collimator 20 ′ are combined into 25 layers, and the thickness of the collimator elements 16 and 17 is 1.4 mm. As described in the first embodiment (see FIGS. 5 (a) and 5 (b)), detection of gamma rays other than the center is hardly observed, and a 1.5 mm square is obtained using a collimator having a 3 mm square hole. High-resolution imaging equivalent to a collimator having a plurality of holes is realized.

  Furthermore, with the number of collimators (frames) in a practical range, the collimator element thickness of the collimator is randomly set within a range of 1.5 mm to 4.5 mm as shown in the simulation results of FIG. It has been found that the same can be realized even when 20 collimator elements are arranged so that the total thickness of all the layers is 60 mm (including the collimator elements of the fixed collimator and the movable collimator).

(Third embodiment)
A single photon emission tomography apparatus (SPECT (Single Photon Emission Computed Tomography) apparatus) that is a nuclear medicine imaging apparatus according to a third embodiment of the present invention will be described with reference to FIGS. The SPECT apparatus 201 of this embodiment is demonstrated using FIG. The SPECT device 201 includes a pair of radiation detection devices 208, a rotation support base 210, an image information creation device 212, and a display device 213. These radiation detection devices 208 are arranged on the rotation support base 210 at positions shifted by 180 ° in the circumferential direction. The radiation detection device 208 includes a large number of radiation detectors 2 and has almost the same configuration as the gamma camera 1 of the first embodiment. Each of these radiation detection devices 208 can rotate independently and change the radiation incident angle, and can be used as a gamma camera for arranging two units side by side to increase the imaging area or for planar imaging. . The radiation detection device 208 further includes a signal processing circuit 205 provided for each radiation detector 2, one detector substrate 204 on which the radiation detector 2 and the signal processing circuit 205 are installed, and each of the radiation detectors 2. It has a collimator (collimator device) 100 arranged on the front surface, and itself constitutes one camera unit.

  Each radiation detector 2 faces the bed 214 side and is installed on the detector substrate 204. The detector substrate 204 is disposed in a light shielding / electromagnetic shield 207 installed on the rotation support base 210. The collimator 100 is detachably attached to a housing 207 having a light shielding / electromagnetic shielding function. The housing 207 blocks electromagnetic waves other than gamma rays and avoids adverse effects of electromagnetic waves on the radiation detector 2 and the signal processing circuit 205 and the like.

  The bed 214 on which the subject to whom the radiopharmaceutical is administered is moved, and the subject is moved between the pair of radiation detection devices 208. As the rotation support 210 is rotated, each radiation detection device 208 turns around the subject. Gamma rays emitted from an accumulation part (for example, an affected part) in the subject on which the radiopharmaceutical is accumulated enter a corresponding radiation detector 2 through a gamma ray passage formed in the collimator 100. The radiation detector 2 outputs a gamma ray detection signal. This gamma ray detection signal is processed by the signal processing circuit 205. The signal processing circuit 105 processes the gamma ray detection signal to generate data such as detection position information, a peak value indicating energy, and a detection time. These data are transmitted to the image information creation device 212 via the connector 106. The image information creation device 212 creates image information of the affected area of the subject using those data. This image information is displayed on the display device 213.

  The structure of the collimator moving devices 62 and 63 used in the SPECT device 201 will be described in detail with reference to FIGS. Since the collimator 100 is the same as the collimator 100 used in the first embodiment, the description thereof is omitted. In this embodiment, the collimator element 16 of the fixed collimator 10 used for the collimator 100 has a square frame 13 having a side of about 400 mm. The fixed collimator 10 is installed in the housing 207.

  The collimator moving device 62 includes two ball screw rotating screws 47, a belt 48, and a stepping motor 49 arranged along two opposing side walls 21 </ b> A of the rectangular cylinder 21 of the movable collimator 20. One rotary screw 47 is connected to the stepping motor 49. The two rotary screws 47 are connected by a belt 48. Two ball screw nuts 45 mesh with each rotary screw 47. A slide bearing 44 is attached to each nut 45. Guide shafts 46 supported by the respective slide bearings 44 so as to be movable in the respective axial directions are attached to the outer surface of the side wall 21A of the rectangular tube body 21.

  The collimator moving device 63 includes two ball screw rotary screws 57, a belt 58 and a stepping motor 59, which are arranged along the other two opposite side walls 21 </ b> A of the rectangular tube 21 of the movable collimator 20. Prepare. One rotary screw 57 is connected to the stepping motor 59. The two rotating screws 57 are connected by a belt 58. Two ball screw nuts 55 are engaged with the respective rotating screws 57. A slide bearing 54 is attached to each nut 55. A guide shaft 56 that is supported by each sliding bearing 54 so as to be movable in each axial direction is attached to the outer surface of the side wall 21 </ b> A of the rectangular tube body 21. Stepping motors 49 and 59 are installed on a support member (not shown) provided on the inner surface of the housing 207.

  By operating the stepping motors 49 and 59, each of the two rotation screws 47 and 57 rotates, and the movable collimator 20 can be moved back and forth, and left and right with respect to the fixed collimator 10, as in the first embodiment. Almost the same effect can be obtained. When the nut 45 moves straight along the rotation screw 47 by the rotation of the stepping motor 49, the guide shaft 56 moves in one direction in the slide bearing 54. Further, when the nut 55 moves straight along the rotary screw 57 by the rotation of the stepping motor 59, the guide shaft 46 moves in one direction in the slide bearing 44. Therefore, by operating the stepping motors 49 and 59, the movable collimator 20 can be moved in the direction of arrow A in FIG. 3A (or arrow B in FIG. 4A). The stepping motors 49 and 59 start and stop rotation based on the start command and stop command of the control device (not shown) in response to the start and stop operation signals from the operator panel (not shown). Made. The collimator moving device 62 moves the movable collimator 20 in a first direction in a plane orthogonal to the axial direction of the collimator 100. The collimator moving device 63 moves the movable collimator 20 in a second direction orthogonal to the first direction in the plane. Even in a large collimator 100 applied to a large apparatus such as a SPECT apparatus, the movable collimator 20 can be easily moved by using a stepping motor. In addition, since the movable collimator 20 is moved in this way to easily switch between the high sensitivity mode and the high resolution mode, the affected area is identified by rough scanning in the high sensitivity mode, and detailed imaging is immediately performed in the high resolution mode. It is also possible to do this. Further, the high sensitivity mode can be applied to a first pass examination in myocardial imaging, and the high resolution mode can be applied to myocardial SPECT performed immediately thereafter. That is, since there is no need to replace the movable collimator 40, it is possible to perform a continuous inspection quickly.

  In the third embodiment, the collimator moving devices 62 and 63 may be attached to the movable collimator 20 ′ of the collimator 100 ′ instead of the collimator 100 ′ used in the second embodiment. The collimator moving devices 62 and 63 are attached to the movable collimator 20 in the first embodiment and to the movable collimator 20 ′ in the second embodiment, so that the movable collimator is moved by the collimator moving devices 62 and 63 in the respective gamma cameras. Can be moved.

  In the first embodiment, as shown in FIG. 10A, the gamma ray detection positions other than the radiation source position appear asymmetrically on the left and right, and appear symmetrically with respect to a line drawn at 45 degrees. This is a two-dimensional asymmetry caused by sliding the collimator only in the 45-degree direction. In order to avoid this, the collimator (collimator device) is as shown in the first modification shown in FIG. Alternatively, the fixed collimator 50 may be provided in one stage, and the movable collimators 51, 52, and 53 may be provided in three stages.

  In this case, first, as shown in FIG. 13B, the movable collimator 51 is shifted upward with respect to the fixed collimator 50, and then the movable collimator 52 is shifted rightward with respect to the movable collimator 51. 13 (c), the movable collimator 53 is shifted downward with respect to the movable collimator 52. As shown in FIG. 13 (d), the holes formed by the fixed collimator 50 and the movable collimators 51-53 are formed. It may be made smaller to avoid two-dimensional asymmetry. In this operation mode, the above-described control of the three-stage movable collimators 51 to 53 can be realized only by increasing the number of stages of the threaded shaft and the number of stepping motors.

  In the first and second embodiments described above, a collimator 100 having a square hole is used as the collimator 100. However, the collimator 100 is replaced with a hexagonal hole fixed collimator 70 and a collimator 100 as in the second modification shown in FIG. Two movable collimators 71 and 72 can be stacked. The fixed collimator 70 and the movable collimator 71 are shifted as shown in FIG. 14B, and the movable collimator 71 and the movable collimator 72 are shifted as shown in FIG. 14C. You may make it become a fine hole.

  In the first embodiment, the case where the movable collimator 20 is moved with respect to the fixed collimator by providing the guide hole 11B as the movable means on the side wall 11A of the fixed collimator 10 has been described as an example. However, the collimator (collimator device) is not limited to this, and the movable collimator 20 is arranged in the directions of arrows A and B on the back side of the movable collimator 20 as in the third modification of the present invention shown in FIG. Alternatively, a plurality of guide walls 60 and a plurality of guide walls 61 which are movable means for guiding may be provided.

It is a block diagram of the fixed collimator used for the collimator shown in FIG. 3, (a) is a front view of a fixed collimator, (b) is sectional drawing of (a), (c) is a side view of a fixed collimator. It is a block diagram of the movable collimator used for the collimator shown in FIG. 3, (a) is a front view of a movable collimator, (b) is II-II sectional drawing of (a), (c) is a side view of a movable collimator. is there. It is a block diagram of the collimator of the gamma camera shown in FIG. 16, (a) is a front view of the collimator in the state at the time of a high sensitivity mode, (b) is III-III sectional drawing of (a). (A) is a front view of the collimator in the state in the high resolution mode, and (b) is a sectional view taken along line IV-IV in (a). It is a figure which shows the simulation result of the high-resolution mode by a 1.2-mm-thick 50-layer equidistant collimator, (a) is explanatory drawing which shows detected gamma-ray distribution, (b) shows gamma-ray count distribution on a central axis. It is explanatory drawing. It is explanatory drawing for demonstrating the mechanism of the gamma ray detected except a radiation source position. It is sectional drawing of the fixed collimator of the collimator used for the gamma camera of 2nd Embodiment of this invention. It is sectional drawing of the movable collimator of the collimator used for the gamma camera of 2nd Embodiment of this invention. It is a figure which shows the simulation result of the high-resolution mode by the non-uniform spacing collimator of 25 layers by thickness 1.0mm, and 25 layers by thickness 1.4mm, (a) is explanatory drawing of detected gamma ray distribution, (b) is a center. It is explanatory drawing which shows gamma ray count distribution on an axis | shaft. It is a figure which shows the simulation result of the gamma ray stopping ability by a 20-layer random thickness collimator. It is a front view of the collimator shown in FIG. It is a side view of the collimator shown in FIG. It is a figure which shows the 1st modification of a collimator, (a) is sectional drawing of the collimator of the 1st modification containing a fixed collimator and a movable collimator, (b) is a 1st layer movable collimator above a fixed collimator The front view which shows the state which shifted to (2), (c) shows the state which shifted the 2nd layer movable collimator rightward with respect to the fixed collimator, and shifted the 3rd layer movable collimator below with respect to the fixed collimator. Front view, (d) is a front view showing a state in which the front view of (b) and the front view of (c) are superimposed. It is a figure which shows the 2nd modification of a collimator, (a) is each front view of one fixed collimator and two movable collimators which comprise the collimator of a 2nd modification, (b)-(d) is two It is explanatory drawing which shows the movement of a movable collimator. It is a front view of the 3rd modification of a collimator. 1 is a longitudinal sectional view of a gamma camera according to a first embodiment which is a preferred embodiment of the present invention. It is a block diagram of the SPECT apparatus concerning 3rd Embodiment which is other embodiment of this invention.

Explanation of symbols

1 Gamma camera (nuclear medicine imaging device)
2 Radiation detector 10, 10 ', 30, 50, 70 Fixed collimator 20, 40, 51, 52, 53, 71, 72 Movable collimator 15, 25, 26 Hole 11B Guide hole 44, 54 Sliding bearing 45, 55 Nut ( Nut for ball screw)
46, 56 Guide shaft 47, 57 Rotating screw (Rotating screw for ball screw)
48, 58 Belt 49, 59 Stepping motor 100, 100 ', 200 Collimator (collimator device)
60, 61 Guide groove (movable means)
62, 63 Collimator moving device 104, 204 Detector board 105, 205 Signal processing circuit 106 Connector 107, 207 Housing 201 SPECT device (Single photon emission tomographic imaging device)
208 Camera head 210 Rotation support base 212 Image information creation device 214 Bed

Claims (8)

A plurality of radiation detectors, a collimator device that is arranged in front of the radiation detectors and is made of a radiation shielding material, and a holding member that holds the radiation detectors and the collimator device,
The collimator apparatus includes a fixed collimator having a first collimator element in which a plurality of radiation paths are formed, and a second collimator element in which a plurality of radiation paths are formed, in a direction intersecting the axial direction of the collimator apparatus. A movable collimator that is movable;
A nuclear medicine imaging apparatus, wherein the first and second collimator elements are arranged along an axial direction of the collimator apparatus.   A plurality of the first collimator elements and a plurality of the second collimator elements are arranged side by side in the axial direction, at least a part of the second collimator elements is arranged between the first collimator elements, and the second collimator The nuclear medicine imaging apparatus according to claim 1, wherein the element is movable in a direction orthogonal to the axial direction.   The nuclear medicine imaging apparatus according to claim 1, further comprising a collimator moving device that moves the movable collimator in a direction intersecting the axial direction.   The collimator moving device includes a first collimator moving device that moves the movable collimator in a first direction in a plane that intersects the axial direction, and a second direction that intersects the first direction in the plane. The nuclear medicine imaging apparatus according to claim 3, further comprising a second collimator moving device that moves the movable collimator.   5. A part of the plurality of first collimator elements of the fixed collimator is different in thickness in the axial direction of the collimator from that of other first collimator elements. The nuclear medicine imaging device according to any one of the above.   2. The apparatus according to claim 1, further comprising: a plurality of signal processing devices connected to each of the radiation detectors; and an image information creation device that inputs each information output from the plurality of signal processing devices. The nuclear medicine imaging apparatus of any one of Claim 5. A plurality of radiation detectors, a collimator device that is arranged in front of the radiation detectors and is made of a radiation shielding material, and a holding member that holds the radiation detectors and the collimator device,
The collimator apparatus includes a fixed collimator having a first collimator element in which a plurality of radiation paths are formed, and a second collimator element in which a plurality of radiation paths are formed, in a direction intersecting the axial direction of the collimator apparatus. A movable collimator that is movable;
The gamma camera characterized in that the first and second collimator elements are arranged along the axial direction of the collimator device. A plurality of radiation detectors, a collimator device that is arranged in front of the radiation detectors and is made of a radiation shielding material, and a holding member that holds the radiation detectors and the collimator device,
The collimator apparatus includes a fixed collimator having a first collimator element in which a plurality of radiation paths are formed, and a second collimator element in which a plurality of radiation paths are formed, in a direction intersecting the axial direction of the collimator apparatus. A movable collimator that is movable;
A single-photon emission tomography apparatus characterized in that the first and second collimator elements are arranged along the axial direction of the collimator apparatus.

Images