JP2014025768A - Radiation detector and radiographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform detection characteristics of each detection cell in a radiation detector in which a radiation detector and a collimator device are configured by arraying a plurality of modules.SOLUTION: A plurality of detector modules and collimator modules are disposed with the joints thereof shifted to a channel direction so that the detection elements adjacent to the joint between the detector modules, and sectioned regions adjacent to the joint between the collimator modules may not overlap one another in the channel direction. Detection characteristics of detection cells corresponding to the detection elements and sectioned regions adjacent to the joint are easy to deteriorate, but can be dispersed avoiding the overlapping of the deterioration.

Description

  The present invention relates to a radiation detection apparatus and a radiation imaging apparatus.

  An X-ray CT (Computed Tomography) apparatus includes an X-ray detector for detecting transmitted X-rays to be imaged. On the X-ray incident surface side of the X-ray detector, a collimator device for removing scattered X-ray radiation is provided.

  Usually, the X-ray detection apparatus is required to have uniform detection characteristics in all detection cells from the viewpoint of suppressing artifacts in the reconstructed image. In order to meet such a demand, it is necessary to increase the processing accuracy of the X-ray detector and the collimator device and the alignment accuracy of each other.

  However, since the X-ray detector and the collimator device are relatively large devices, it is very difficult to increase the processing accuracy and alignment accuracy when they are formed integrally.

  Therefore, a method of configuring the X-ray detector and the collimator device with a plurality of modules has been proposed, and there are many X-ray detection devices that actually employ this method.

  Typically, the X-ray detector is formed by arranging a plurality of detector modules in which a plurality of detection elements are two-dimensionally arranged in the channel direction. In addition, the collimator device is formed by arranging a plurality of collimator modules arranged in a channel direction so that a plurality of collimator plates separate the detection elements (see, for example, Patent Document 1, Abstract, etc.).

JP2012-013421A

  Generally, the collimator module is made to cover an integer number of detector modules. The seam in the channel direction of the detector module and the seam in the channel direction of the collimator module are usually coincident or close to each other. Since the collimator plate must be correctly positioned at the position where the detector module should be, that is, the boundary between the detection elements, the design, processing and alignment of the detector module and the collimator module have very high accuracy. Done.

  However, at the joint between the detector module and the collimator module, it is most difficult to increase the accuracy of processing and alignment, and the detection characteristic of the detection cell tends to deteriorate at this joint. Moreover, as described above, the joint of the detector module and the joint of the collimator module are usually coincident with each other or close to each other, so that the detection characteristics of the detection cell at such a joint are significantly deteriorated due to the overlap. There is a fear.

  Under such circumstances, a technique for making the detection characteristics of each detection cell uniform is desired in a radiation detection apparatus in which the radiation detector and the collimator apparatus are configured by an array of a plurality of modules.

The invention of the first aspect
A radiation detector comprising a plurality of detector modules arranged in the channel direction and a plurality of detector modules arranged in the channel direction;
A radiation detection apparatus comprising: a collimator device in which a plurality of collimator plates arranged in the channel direction so as to partition the detection elements are arranged in the channel direction on the radiation incident surface side of the radiation detector. Because
The plurality of detector modules and the plurality of collimator modules are arranged such that a segmented region adjacent to a seam between the collimator modules separates a detection element different from a detection element adjacent to the seam between the detector modules. A radiation detection apparatus is provided.

The invention of the second aspect is
The number of detection elements in the channel direction of the plurality of detector modules constituting the main part of the radiation detector and the number of segmented regions in the channel direction of the plurality of collimator modules constituting the main part of the collimator device, respectively Constant,
The radiation detection apparatus according to the first aspect, wherein a detection element adjacent to the joint between the detector modules and a segmented region adjacent to the joint between the collimator modules are positioned at regular intervals in the channel direction. I will provide a.

The invention of the third aspect is
The number of division regions in the channel direction of the collimator module constituting the main part of the collimator device is an integral multiple of the number of detection elements in the channel direction of the detector module constituting the main part of the radiation detector. The radiation detection apparatus of the viewpoint is provided.

The invention of the fourth aspect is
At least one of the number of detection elements in the channel direction of the plurality of detector modules constituting the main part of the radiation detector and the number of section regions in the channel direction of the plurality of collimator modules constituting the main part of the collimator device Is irregular,
In the first aspect, at least one of the detection element adjacent to the joint between the detector modules and the segmented region adjacent to the joint between the collimator modules is positioned at irregular intervals in the channel direction. A radiation detection apparatus is provided.

The invention of the fifth aspect is
The number of detection elements in the channel direction of the detector module and the number of segmented regions in the channel direction of the collimator module are 8 or more and 128 or less, respectively. A radiation detection apparatus according to any one of the aspects is provided.

The invention of the sixth aspect is
The radiation detection apparatus according to any one of the first to fifth aspects, wherein the detector module includes a scintillator array tip.

The invention of the seventh aspect
Provided is a radiation imaging apparatus including the radiation detection apparatus according to any one of the first to sixth aspects.

The invention of the eighth aspect
A radiation imaging apparatus according to the seventh aspect for performing radiation tomography is provided.

  According to the invention of the above aspect, the detection element adjacent to the seam between the detector modules and the section area adjacent to the seam between the collimator modules do not overlap in the channel direction. Degradation of the detection characteristics of adjacent detection cells can be distributed in the channel direction, and the detection characteristics of each detection cell are made uniform in the radiation detection apparatus in which the radiation detector and collimator device are composed of multiple modules. can do.

It is an external view of an X-ray CT apparatus. It is a figure which shows the structure of the X-ray detection apparatus which concerns on 1st Embodiment. It is a table | surface which shows the correspondence of the detection cell located in a CH direction in the conventional X-ray detection apparatus, the detection element which a detection characteristic tends to deteriorate, and a division area. 4 is a table showing a correspondence relationship between detection cells arranged in the CH direction, detection elements and detection regions whose detection characteristics are likely to deteriorate, in the X-ray detection apparatus according to the first embodiment. It is a figure which shows the structure of the X-ray detection apparatus which concerns on 2nd Embodiment. It is a figure which shows the structure of the X-ray detection apparatus which concerns on 3rd Embodiment. It is a table | surface which shows the correspondence of the detection cell located in a CH direction in the X-ray detection apparatus which concerns on 3rd Embodiment, and the detection element and division area which a detection characteristic tends to deteriorate.

  Embodiments of the invention will be described below.

(First embodiment)
FIG. 1 is a diagram schematically showing the configuration of the X-ray CT apparatus 1. As shown in FIG. 1, the X-ray CT apparatus 1 includes a scanning gantry 2, an imaging table 3, and an operation console 4.

  The scanning gantry 2 scans the subject 10 under the control of the operation console 4 and collects projection data (data). The imaging table 3 mounts the subject 10 and conveys it to the bore of the scanning gantry 2 that is an imaging space. In response to an operation from the operator, the operation console 4 controls the scanning gantry 2 and the imaging table 3 or reconstructs and displays an image based on projection data collected by scanning.

  The scanning gantry 2 includes an X-ray tube 5 and an X-ray detection device 6. The X-ray tube 5 and the X-ray detection device 6 are disposed to face each other with the subject 10 interposed therebetween, and are supported rotatably around the subject 10 while maintaining this positional relationship. The X-ray tube 5 emits X-rays 52 from the X-ray focal point 51 toward the subject 10, and the X-ray detection device 6 detects the transmitted X-rays.

  Here, as shown in FIG. 1, the direction in which the X-ray 52 is irradiated from the focal point 51 of the X-ray tube 5 is the X-ray irradiation direction (I direction), and the rotation axis direction of the scanning gantry 2 (the subject 10). Is the slice direction (SL direction), and the fan angle direction of the X-ray 52 is the channel direction (CH direction).

  The configuration of the X-ray detection apparatus 6 will be described.

  FIG. 2 is a diagram illustrating a configuration of the X-ray detection apparatus according to the first embodiment.

  FIG. 2A is a side view of the X-ray detection device 6 as viewed in the SL direction. As shown in FIG. 2A, the X-ray detection device 6 includes an X-ray detector 7 and a collimator device 8. The collimator device 8 is disposed on the X-ray incident surface side of the X-ray detector 7. The X-ray detector 7 and the collimator device 8 are supported by a support member (not shown). FIG. 2B is a top view when the X-ray detector 7 is viewed in the I direction. FIG. 2C is a top view when the collimator device 8 is viewed in the I direction.

  As shown in FIGS. 2A and 2B, the X-ray detector 7 is configured by arranging a plurality of detector modules 71 in the CH direction. The detector module 71 is configured by two-dimensionally arranging a plurality of detection elements 71i in the CH direction and the SL direction. The number of detection elements 7i in the CH direction in the detector module 71 is, for example, about 8 to 128. The number of detection elements 7i in the SL direction in the detector module 71 is, for example, about 1 to 1256. The detection element 7i has a size of about 1 mm square, for example. The X-ray detector 7 is configured by arranging about ten to several tens of such detector modules 71 in the CH direction. Here, for the sake of simplicity, the detector module 71 is configured by arranging 6 (CH) × 8 (SL) detection elements 7i, and the X-ray detector 7 has the detector module 71 arranged in the CH direction. It is assumed that four are arranged in a row.

  The detector module 71 includes a scintillator array chip in which scintillators that receive X-rays to emit light are formed in an array, and a photodiode array chip (photodiode chip in which photodiodes that convert light into electrical signals are formed in an array. array tip) are stacked. The detection element 7i includes a scintillator and a photodiode that correspond to each other.

  As shown in FIGS. 2A and 2C, the collimator apparatus 8 is configured by arranging a plurality of types of collimator modules, that is, a first collimator module 81 and a second collimator module 82 in the CH direction. ing. The first and second collimator modules 81 and 82 are configured by combining a plurality of collimator plates in a lattice shape so as to divide the detection element 7i into the CH direction and the SL direction. The collimator plate is made of a heavy metal such as tungsten or molybdenum.

  The first collimator module 81 includes three first channel collimator plates 81CH whose plate surfaces are parallel to the SL direction in the CH direction, and nine first slice collimator plates 81SL whose plate surfaces are parallel to the CH direction in the SL direction. It is composed of sheets. As a result, the first collimator module 81 forms 3 (CH) × 8 (SL) segment regions 8i of the detection elements 7i.

  Similarly, the second collimator module 82 includes six second channel collimator plates 82CH whose plate surfaces are parallel to the SL direction in the CH direction and SL second collimator plates 82SL whose plate surfaces are parallel to the CH direction. Nine sheets are arranged in the direction. As a result, the second collimator module 82 forms 6 (CH) × 8 (SL) segmented regions 8i of the detection elements 7i.

  Here, the collimator apparatus 8 is configured by disposing one first collimator module 81 at each of both ends in the CH direction and three second collimator modules 82 at the main portion near the center in the CH direction. Shall.

  Similar to the detector module 71, the number of the divided areas 8i in the CH direction in the collimator module is, for example, about 8 or more and 128 or less. Here, for the sake of simplicity, the number of segmented areas is set to be smaller than the actual number.

  In the X-ray detection apparatus 6 configured as described above, a detection cell (cell) is configured by the detection element 7i and the segmented region 8i corresponding to the I direction 1: 1.

  The operation and effect of the X-ray detection apparatus according to the first embodiment will now be described.

  FIG. 3 is a table showing a correspondence relationship between detection cells arranged in the CH direction, detection elements and detection regions whose detection characteristics are likely to deteriorate, in an X-ray detection apparatus according to a conventional example. FIG. 4 is a table showing the correspondence between the detection cells arranged in the CH direction, the detection elements whose detection characteristics are likely to deteriorate, and the segmented areas in the X-ray detection apparatus according to the first embodiment. In FIG. 3 and FIG. 4, the first row represents the detected cell number. The second row represents the collimator module number, and the third row represents the position of the segmented area where the detection characteristics of the corresponding detection cell are likely to deteriorate in gray. The fourth row indicates the detector module number, and the fifth row indicates the position of the detection element in which the detection characteristics of the corresponding detection cell easily deteriorate in gray.

  Conventionally, as can be seen from FIG. 3, the collimator module is made to cover an integral multiple of the number of detector modules. Further, the seam in the CH direction of the detector module and the seam in the CH direction of the collimator module are usually coincident with or close to each other. In general, the detection characteristics of the detection cells corresponding to the detection element group adjacent to the joint of the detector module and the segmented area group adjacent to the joint of the collimator module are likely to deteriorate. Therefore, the detection characteristics of the detection cell at such a joint may deteriorate significantly due to overlapping.

  On the other hand, in the first embodiment, as can be seen from FIG. 4, the joint of the detector module and the joint of the collimator module are shifted. That is, the group of divided regions 8i adjacent to the CH direction joint in the plurality of collimator modules including the first and second collimator modules 81 and 82 is the detection element 7i group adjacent to the CH direction joint in the detector module 71. Are arranged so as to separate different detection element 7i groups in the CH direction. Therefore, as shown in FIG. 4, the detection element in which the detection characteristic of the corresponding detection cell is likely to deteriorate does not overlap in the CH direction with the segmented region in which the detection characteristic of the corresponding detection cell is likely to deteriorate. Therefore, in the case of the present embodiment, the deterioration of the detection characteristics does not overlap with the same detection cell but is distributed in the CH direction, so that the detection characteristics of each detection cell can be made uniform.

  Further, in the present embodiment, the number of detection elements 7 i in the CH direction of the detector module 71 constituting the main part of the X-ray detector 7 is constant at six, and the number of detection elements 7 i constituting the main part of the collimator device 8 is the first. The number of the divided areas 8i in the CH direction of the second collimator module 82 is also constant at six. Therefore, in this embodiment, the detection element 7i group adjacent to the CH-direction joint in the plurality of detector modules 71, and the divided region adjacent to the CH-direction joint in the plurality of first and second collimator modules 81 and 82 The 8i group is regularly arranged alternately. Therefore, the detection cells whose detection characteristics are likely to deteriorate can be reliably dispersed by simply arranging the same type of collimator modules continuously in the main part excluding both ends in the CH direction. This makes it possible to reduce the number of assembly steps and mistakes.

(Second Embodiment)
In the second embodiment, the number of detection elements 7 i in the CH direction of a plurality of detector modules 71 constituting the main part of the X-ray detector 7 and the number of collimator modules 81 constituting the main part of the collimator device 8 are described. The number of segmented regions 8i in the CH direction is constant, and the detection element 7i adjacent to the joint between the detector modules and the segmented region 8i adjacent to the joint between the collimator modules are regular in the CH direction. It is another example which is located at intervals. Further, the number of segmented regions 8 i in the CH direction of the collimator module 81 constituting the main part of the collimator device 8 is the number of detection elements 7 i in the CH direction of the detector module 71 constituting the main part of the X-ray detector 7. It is an example that is an integer multiple.

  FIG. 5 is a diagram showing a configuration of an X-ray detection apparatus 6 ′ according to the second embodiment. FIG. 5A is a side view of the X-ray detection device 6 ′ when viewed in the SL direction. As shown in FIG. 5A, the X-ray detection device 6 'includes an X-ray detector 7 and a collimator device 8'. FIG. 5B is a top view when the X-ray detector 7 is viewed in the I direction. FIG. 5C is a top view when the collimator device 8 ′ is viewed in the I direction.

  As shown in FIGS. 5A and 5B, the X-ray detector 7 is configured by arranging four detector modules 71 in the CH direction. The detector module 71 is configured by arranging 6 (CH) × 8 (SL) detection elements 7i.

  As shown in FIGS. 5A and 5C, the collimator device 8 ′ is configured by arranging a plurality of second collimator modules 82 in the CH direction. The second collimator modules 82 are arranged so that the joints between the detector modules 71 and the joints between the second collimator modules 82 are alternately arranged at a constant interval.

  Even in such a second embodiment, the same effect as in the first embodiment can be obtained. Further, in the second embodiment, since only one type of collimator module is used, manufacturing / assembly costs can be further reduced.

(Third embodiment)
In the third embodiment, the number of detection elements 7 i in the CH direction of a plurality of detector modules 71 constituting the main part of the X-ray detector 7 and the number of collimator modules 81 constituting the main part of the collimator device 8 are described. At least one of the number of segmented regions 8i in the CH direction is irregular, and at least one of the detection element 7i adjacent to the joint between the detector modules and the segmented region 8i adjacent to the joint between the collimator modules is This is an example of being positioned at irregular intervals in the CH direction.

  FIG. 6 is a diagram showing a configuration of an X-ray detection apparatus 6 ″ according to the third embodiment. FIG. 6A is a side view of the X-ray detection apparatus 6 ″ viewed in the SL direction. . As shown in FIG. 6A, the X-ray detector 6 ″ includes an X-ray detector 7 and a collimator device 8 ″. FIG. 6B is a top view when the X-ray detector 7 is viewed in the I direction. FIG. 6C is a top view when the collimator device 8 ″ is viewed in the I direction.

  The second collimator module 82 forms 6 (CH) × 8 (SL) segmented regions 8i of the detection elements 7i. The third collimator module 83 forms the divided area 8i corresponding to 4 (CH) × 8 (SL) detection elements 7i. The fourth collimator module 84 forms 5 (CH) × 8 (SL) segmented regions 8i of the detection elements 7i.

  Here, the collimator apparatus 8 ″ has one third collimator module 83, two fourth collimator modules 84, and one second collimator module 82 from one end to the other end in the CH direction. Assume that one third collimator module 83 is sequentially arranged.

  FIG. 7 is a table showing a correspondence relationship between the detection cells arranged in the CH direction, the detection element whose detection characteristics are likely to be deteriorated, and the segmented region in the X-ray detection apparatus according to the third embodiment. The meaning of this table is the same as in FIG. 3 and FIG.

  As can be seen from FIG. 7, in the third embodiment, between the detection element 7 i group adjacent to the CH-direction joint between the detector modules 71 and the collimator modules including the second to fourth collimator modules 82 to 84. The sectioned region 8i group adjacent to the joint in the CH direction does not match in the CH direction and is arranged at a different position. Therefore, in the present embodiment as well, as in the first embodiment, the deterioration in detection characteristics does not overlap with the same detection cell and is distributed in the CH direction, so that the detection characteristics of each detection cell are made uniform. It becomes possible.

  The number of detection elements 7i in the CH direction of the detector module 71 that constitutes the X-ray detector 7 is constant at six, but the second to fourth collimator modules 82 to 82 that constitute the collimator device 8 ″. The number of the divided regions 8i in the CH direction of 84 is not constant at 6, 4, and 5. Therefore, the detection element 7i group adjacent to the CH direction joint between the detector modules 71 and the second to second Accordingly, the divided regions 8i adjacent to the joint in the CH direction between the collimator modules including the four collimator modules 82 to 84 are irregularly arranged, and as a result, the detection characteristics of the detection cells are also more irregularly distributed. The influence on the reconstructed image due to the periodicity of the detection characteristics of the detection cells can be further reduced.

  As mentioned above, although embodiment of invention was described, embodiment of invention is not limited to said embodiment, A various addition and change are possible in the range which does not deviate from the meaning of invention.

  For example, in the above embodiment, by arranging a plurality of types of collimator modules having different numbers of section regions in the CH direction, the position of the detection element group adjacent to the joint of the detector module and the joint of the collimator module are adjacent to each other. The positions of the detection element groups adjacent to the joints of the detector modules are arranged by arranging a plurality of types of detector modules having different numbers of detection elements in the CH direction. And the position of the segmented area group adjacent to the joint of the collimator module may be shifted.

  Further, for example, in the above embodiment, the detector module and the collimator module are arranged only in the CH direction, but at least one of the modules is also arranged in the SL direction, and between the modules in the SL direction. The modules may be arranged so that the joints of the two are shifted.

  Further, for example, in the above embodiment, the collimator module is a two-dimensional collimator module in which collimator plates are arranged in a grid in the CH direction and SL direction, but the collimator plate may be arranged only in the CH direction. .

  Further, for example, in the first and second embodiments, the number of segment areas in the CH direction of the collimator module constituting the main part is the same as the number of detection elements in the CH direction of the detector module. The number of segment regions in the CH direction of the collimator module to be configured may be an integer multiple of 2 or more of the number of detection elements in the CH direction of the detector module.

  Further, for example, in the first and second embodiments, the number of segment areas in the CH direction of the collimator module constituting the main part and the number of detection elements in the CH direction of the detector module are respectively constant, and Although the number is the same, the number of segment areas in the CH direction of the collimator modules constituting the main part and the number of detection elements in the CH direction of the detector modules may be constant and different from each other.

  Examples of embodiments of the invention are not only X-ray detection apparatuses, but also X-ray CT apparatuses and general (simple) X-ray imaging apparatuses provided with such X-ray detection apparatuses are examples of embodiments of the invention. is there.

  The embodiments of the invention are not limited to X-rays but can be applied to other radiation, for example, γ (gamma) rays as handled by a SPECT apparatus.

DESCRIPTION OF SYMBOLS 1 X-ray CT apparatus 2 Scanning gantry 3 Imaging table 4 Operation console 5 X-ray tube 51 Focus 52 X-ray 6,6 ', 6 "X-ray detector 7 X-ray detector 7i Detection element 8,8', 8" Collimator Device 8i Division area 10 Subject 71 Detector module 81-84 First to fourth collimator module 81CH First channel collimator plate 81SL First slice collimator plate 82CH Second channel collimator plate 82SL Second slice collimator plate

Claims (8)

A radiation detector comprising a plurality of detector modules arranged in the channel direction and a plurality of detector modules arranged in the channel direction;
A radiation detection apparatus comprising: a collimator device in which a plurality of collimator plates arranged in the channel direction so as to partition the detection elements are arranged in the channel direction on the radiation incident surface side of the radiation detector. Because
The plurality of detector modules and the plurality of collimator modules are arranged so that a segmented region adjacent to a seam between the collimator modules separates a detection element different from a detection element adjacent to the seam between the detector modules. Radiation detector. The number of detection elements in the channel direction of the plurality of detector modules constituting the main part of the radiation detector and the number of segmented regions in the channel direction of the plurality of collimator modules constituting the main part of the collimator device are respectively Constant,
The radiation detection apparatus according to claim 1, wherein the detection element adjacent to the joint between the detector modules and the segmented region adjacent to the joint between the collimator modules are positioned at regular intervals in the channel direction. .   3. The number of segment areas in the channel direction of the collimator module constituting the main part of the collimator device is an integral multiple of the number of detection elements in the channel direction of the detector module constituting the main part of the radiation detector. The radiation detection apparatus according to 1. At least one of the number of detection elements in the channel direction of the plurality of detector modules constituting the main part of the radiation detector and the number of section regions in the channel direction of the plurality of collimator modules constituting the main part of the collimator device Is irregular,
The detection element adjacent to the joint between the detector modules and at least one of the segmented regions adjacent to the joint between the collimator modules are located at irregular intervals in the channel direction. Radiation detection device.   The number of detection elements in the channel direction of the detector module and the number of segmented regions in the channel direction of the collimator module are 8 or more and 128 or less, respectively. The radiation detection apparatus according to item.   The radiation detector according to any one of claims 1 to 5, wherein the detector module includes a scintillator array chip.   A radiation imaging apparatus comprising the radiation detection apparatus according to claim 1.   The radiation imaging apparatus according to claim 7, wherein radiation tomography is performed.

Images