Radiation imaging device

Abstract

The present invention provides a radiation imaging device capable of aligning a detector and a collimator while keeping the position of a radiation source fixed. The radiation imaging device comprises: a radiation source that irradiates a subject with radiation; a plurality of detection elements that detect photons of the radiation; and a collimator that is arranged between the radiation source and the detection elements and has a plurality of walls that form a plurality of through holes through which the radiation passes, and is characterized in that the detection elements and the collimator are aligned in a direction orthogonal to the direction in which the radiation is irradiated so that the ratio or difference of the output signals between the adjacent detection elements separated by the wall is within a given range.

Description

Technical Field

[0001] The present invention relates to a radiation imaging device equipped with a photon counting detector, and relates to the alignment of a collimator used for removing scattered radiation and the photon counting detector. Background Art

[0002] Unlike conventional charge-integrating detectors, photon-counting detectors, which use a photon-counting method, can count the photons of radiation incident on each detection element formed on the semiconductor layer and measure the energy of each photon. Therefore, a photon-counting CT (Computed Tomography) device equipped with a photon-counting detector can obtain more information than a CT device equipped with a charge-integrating detector.

[0003] In radiation imaging devices such as CT devices, in order to suppress the incidence of scattered rays generated in the subject etc. on the detection element, a collimator formed of heavy metals such as tungsten, molybdenum, tantalum, etc., as a slit or grid, is arranged between the subject and the detection element. However, if the alignment accuracy of the collimator with respect to the detection element is insufficient, a false image called an artifact may be generated in the tomographic image generated by the CT device.

[0004] Patent document 1 discloses a radiation imaging device capable of aligning a collimator with respect to a detection element with high precision. Specifically, the device discloses that: outputs of a given number of detection elements from the wall of the collimator are obtained for different radiation source positions, the output of one is inverted with the middle of the two radiation source positions as an axis, and the detection element and the collimator are aligned based on the difference between the inverted output and the output of the other.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: JP Patent No. 5852540

[0008] However, in Patent Document 1, in order to align the detection element and the collimator, it is necessary to obtain the output of each detection element at two radiation source positions, which increases the man-hours required for the alignment. Summary of the invention

[0009] Therefore, an object of the present invention is to provide a radiation imaging device capable of performing positional alignment between a detection element and a collimator while keeping the position of a radiation source fixed.

[0010] In order to achieve the above-mentioned purpose, the present invention comprises: a radiation source, which irradiates radiation to a subject; a plurality of detection elements, which detect photons of the radiation; and a collimator, which is arranged between the radiation source and the detection elements and has a plurality of walls that form a plurality of through holes through which the radiation passes, and is characterized in that the detection elements and the collimator are aligned in a direction orthogonal to the direction of irradiating the radiation so that the ratio or difference of the output signals between adjacent detection elements separated by the wall is within a given range.

[0011] Effects of the Invention

[0012] According to the present invention, it is possible to provide a radiation imaging device capable of performing positional alignment between a detector and a collimator while keeping the position of a radiation source fixed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing the overall structure of an X-ray CT apparatus to which the present invention is applied.

[0014] Figure 2A This is a top view of an example of a detection element module, and is a diagram for explaining the correspondence between one semiconductor layer and one collimator.

[0015] Figure 2B yes Figure 2A AA cross-section diagram.

[0016] Figure 3A This is a top view of another example of the detection element module, and is a diagram for explaining the correspondence between two semiconductor layers and one collimator.

[0017] Figure 3B yes Figure 3A BB cross-section diagram.

[0018] Figure 4A This is a diagram for explaining detection elements that are adjacent to each other with a wall between them.

[0019] Figure 4B This is a diagram for explaining output signals between adjacent detection elements separated by a wall.

[0020] Figure 5A This is a diagram for explaining a situation where the position of the collimator is misaligned with respect to the semiconductor layer.

[0021] Figure 5B Yes Figure 5A A diagram illustrating output signals between detection elements in a situation where .

[0022] Fig. 6A This is a diagram for explaining a situation where one semiconductor layer is misaligned with respect to a collimator.

[0023] Figure 6B Yes Fig. 6A A diagram illustrating output signals between detection elements in a situation where .

[0024] Fig. 7A This is a diagram for explaining a case where a collimator is rotated and deviated relative to a semiconductor layer.

[0025] Figure 7B Yes Fig. 7A A diagram illustrating output signals between detection elements in a situation where .

[0026] Fig. 8A This is a diagram for explaining the detection elements that are not used for alignment when three detection elements are arranged through holes.

[0027] Figure 8B This is a diagram for explaining the detection elements that are not used for alignment when four detection elements are arranged through holes.

[0028] Description of Reference Numerals

[0029] 1: X-ray source,

[0030] 2: X-ray detector,

[0031] 3: Signal processing unit,

[0032] 4: Image generation unit,

[0033] 5: Rotating plate,

[0034] 6: bed platform,

[0035] 7: Subject,

[0036] 200: Detection element module,

[0037] 201: Collimator,

[0038] 202: High voltage wiring,

[0039] 203, 203A, 203B: semiconductor layer,

[0040] 204: Photon counting circuit,

[0041] 205: through the hole,

[0042] 206: pixel electrode,

[0043] 207: pixel boundary,

[0044] 208: wall,

[0045] 801: Excluded components DETAILED DESCRIPTION

[0046] Embodiments of the present invention are described below with reference to the accompanying drawings. In addition, the radiation imaging device of the present invention is used in a device having a radiation source and a radiation detector having a plurality of detection elements for detecting radiation photons. In the following description, an example is described in which the radiation is X-rays, the radiation detector is a photon counting type X-ray detector, and the radiation imaging device is an X-ray CT device.

[0047] <First Embodiment>

[0048] The X-ray CT apparatus of this embodiment is as follows Figure 1 As shown, the X-ray source 1 irradiates the subject 7 with X-rays; the X-ray detector 2 has a plurality of detection elements for detecting X-ray photons; the signal processing unit 3; and the image generating unit 4. The signal processing unit 3 performs correction and other processing on the detection signals of the detection elements, and controls each unit of the X-ray CT apparatus. The image generating unit 4 generates an image of the subject 7 using the signal that has been processed by the correction and other processing in the signal processing unit 3. The X-ray source 1 and the X-ray detector 2 are supported by a rotating plate 5 at positions facing each other, and are relatively rotated relative to the subject 7 around the subject 7 lying on the bed 6. The X-ray source 1, the X-ray detector 2, and the rotating plate 5 are also referred to as a scanner.

[0049] The X-ray detector 2 is composed of a plurality of detection element modules 200 arranged in an arc shape with the X-ray source 1 as the center. The detection element module 200 is a photon counting detector, and has a collimator 201, a high voltage wiring 202, a semiconductor layer 203, and a photon counting circuit 204. The semiconductor layer 203 is composed of, for example, cadmium zinc telluride (CZT), cadmium telluride (CdTe), etc., and generates charges equivalent to the photons of incident X-rays. The photon counting circuit 204 counts the charges generated by the semiconductor layer 203 and outputs the counting result as a counting signal. The collimator 201 is configured as a slit or a grid formed of a heavy metal such as tungsten or molybdenum, and suppresses scattered rays incident on the semiconductor layer 203. The high voltage wiring 202 supplies a high voltage to the semiconductor layer 203 in order to move the charges generated by the semiconductor layer 203 to the photon counting circuit 204. Regarding the structure of the detection element module 200, use Figure 2A as well as Figure 2B To be described later.

[0050] While the X-ray source 1 and the X-ray detector 2 arranged opposite to each other rotate around the object 7, the X-ray irradiation from the X-ray source 1 and the detection of the X-rays transmitted through the object 7 by the X-ray detector 2 are repeated. The count signal output by the photon counting circuit 204 of the X-ray detector 2 is processed by correction and the like in the signal processing unit 3, and then sent to the image generating unit 4. In the image generating unit 4, a tomographic image of the object 7, i.e., a so-called CT image, is generated based on the sent signal. Figure 1 In FIG. 1 , the Z axis is the direction of the rotation axis of the rotating plate 5 , the Y axis is the direction of irradiating X-rays, and the X axis is the direction orthogonal to the YZ plane. That is, the arc-shaped detection element modules 200 each have a different Y axis and X axis.

[0051] use Figure 2A as well as Figure 2B A detailed structure of an example of the detection element module 200 will be described. Figure 2A is a top view of the detection element module 200, Figure 2B yes Figure 2A The detection element module 200 is constructed by stacking a collimator 201 , a high voltage wiring 202 , a semiconductor layer 203 , and a photon counting circuit 204 in this order from the X-ray source 1 side.

[0052] The collimator 201 is a two-dimensional grid formed of heavy metal, and has a plurality of through holes 205 surrounded by a wall 208. Each through hole 205 is formed parallel to the direction of irradiation of X-rays, has an equal opening area, and is arranged at equal intervals. The collimator 201 can be formed by combining heavy metal plates in a tic-tac-toe shape, or can be manufactured using a three-dimensional printer. Since scattered rays, etc., incident obliquely with respect to the through holes 205, are absorbed by the wall 208, the scattered rays are suppressed in the post-stage of the collimator 201.

[0053] The semiconductor layer 203 is a semiconductor that generates electric charge when an X-ray photon is incident. High voltage wiring 202 is arranged at equal intervals in two dimensions on the entire surface of the side where the X-ray is incident, and a plurality of pixel electrodes 206 are arranged at equal intervals in two dimensions on the opposite side. By applying a high voltage relative to the pixel electrode 206, which is a ground voltage, to the high voltage wiring 202, an electric field is formed between the pixel electrode 206 and the high voltage wiring 202. The electric charge generated in the semiconductor layer 203 moves toward the nearest pixel electrode 206 through the formed electric field, and is read out as an output signal by the photon counting circuit 204 connected to the pixel electrode 206. That is, the region where the electric charge moves to the pixel electrode 206 is equivalent to the detection element of the semiconductor layer 203. In addition, in the semiconductor layer 203, although there is no physical boundary between the detection elements, Figure 2A as well as Figure 2B In FIG. 1 , the boundary between the detection elements, i.e., the pixel boundary 207, is virtually shown by a dotted line. Figure 2A , the position of the pixel electrode 206 in the ZX plane is virtually indicated.

[0054] exist Figure 2A as well as Figure 2BIn the embodiment, one semiconductor layer 203 corresponds to one collimator 201, and eight pixel electrodes 206 are provided in the X direction and sixteen pixel electrodes 206 are provided in the Z direction on the semiconductor layer 203. In addition, four through holes 205 are provided in the X direction and eight through holes 205 are provided in the Z direction on the collimator 201, and four pixel electrodes 206 correspond to one through hole 205.

[0055] use Figure 3A as well as Figure 3B Other examples of the detection element module 200 are described below. Figure 2A as well as Figure 2B The difference is that one collimator 201 corresponds to the semiconductor layer 203A and the semiconductor layer 203B arranged in the Z direction. Generally, the larger the semiconductor area, the lower the yield. Therefore, by Figure 2A as well as Figure 2B The semiconductor layer 203 is divided into Figure 3A as well as Figure 3B The semiconductor layer 203A and the semiconductor layer 203B can improve the productivity of the detection element module 200. Figure 2A as well as Figure 2B Similarly, that is, four pixel electrodes 206 are provided in the X direction and eight in the Z direction, four through holes 205 are provided in the X direction and eight in the Z direction, and four pixel electrodes 206 correspond to one through hole 205. By establishing a correspondence between a plurality of pixel electrodes 206 and one through hole 205, a higher count rate characteristic can be ensured.

[0056] exist Figure 2A , Figure 2B , Figure 3A , Figure 3B In the illustrated structure, for example, it is desired to align the center of the through hole 205 with the center of the four pixel electrodes 206 with an error of less than 10%. If the alignment accuracy of the two is insufficient, an artifact called an artifact will be generated in the tomographic image generated by the CT device. Therefore, in this embodiment, the semiconductor layer 203 having a plurality of detection elements and the collimator 201 are aligned based on the output signals of the adjacent detection elements separated by the wall 208 of the collimator 201. More specifically, the semiconductor layer 203 and the collimator 201 are aligned so that the ratio or difference of the output signals between the adjacent detection elements separated by the wall 208 is within a given range.

[0057] use Figure 4A as well as Figure 4B The output signals between the adjacent detection elements separated by the wall 208 of the collimator 201 are described. Figure 4AIt is a top view of the detection element module 200 in which both the semiconductor layer 203A and the semiconductor layer 203B are associated with one collimator 201 , and the coordinate units of the vertical axis, i.e., the X axis, and the horizontal axis, i.e., the Z axis, are the number of detection elements.

[0058] exist Figure 4A The following is an example of detection elements that are adjacent to each other across the wall 208 of the collimator 201. That is, the detection element (2, 1) and the detection element (3, 1) are examples of detection elements that are adjacent to each other across the wall 208 between Z = 2 and Z = 3. When the center of the through hole 205 is substantially consistent with the center of the four pixel electrodes 206, the output signal of the detection element (2, 1) and the output signal of the detection element (3, 1) are substantially equal.

[0059] Figure 4B 2 is an example of an output signal when the semiconductor layer 203 and the collimator 201 are correctly aligned, the vertical axis is the output signal of each detection element, and the horizontal axis is the Z axis. Figure 4B As shown in the example, when the semiconductor layer 203 and the collimator 201 are correctly aligned, the output signals of each detection element are equal. Therefore, in the present embodiment, the semiconductor layer 203 and the collimator 201 are aligned based on the group of output signals of the detection elements adjacent to each other separated by the partition wall 208. More specifically, the two are aligned so that the ratio or the relative value difference between the output signals of the detection elements adjacent to each other separated by the partition wall 208 is within a given range, for example, if it is a ratio, it is within a range of 0.9 to 1.1, and if it is a relative value difference, it is within a range of -0.1 to 0.1.

[0060] In addition, a plurality of detection elements arranged along the wall 208 may be gathered together. For example, at Z=6 and Z=7, the detection elements from X=1 to X=8 are gathered together and shown as adjacent detection elements separated by the wall 208 between Z=6 and Z=7. In addition, at Z=12 and Z=13, the detection elements from X=3 to X=6 are gathered together and shown as adjacent detection elements separated by the wall 208 between Z=12 and Z=i3.

[0061] Furthermore, the direction in which the plurality of detection elements arranged along the wall 208 are gathered is not limited to the X direction, but may also be the Z direction. For example, at X=2 and X=3, the detection elements of Z=15 and Z=16 are gathered and shown as adjacent detection elements separated by the wall 208 between X=2 and X=3. Also, at X=4 and X=5, the detection elements from Z=2 to Z=5 are gathered and shown as adjacent detection elements separated by the wall 208 between X=4 and X=5.

[0062] When a plurality of detection elements are brought together, the output signals of the detection elements are added together. By adding the output signals, the SNR (Signal to Noise Ratio) of the output signals is improved, and a more precise alignment can be performed. Here, the added output signal is marked using the coordinates of the plurality of detection elements that are brought together. For example, when the detection elements from Z=2 to Z=5 are brought together at X=4, the added output signal is marked as S(2~5,4). In addition, when the output signal of one of the adjacent detection elements separated by the wall 208 is an added value, the other side also uses the added output signal. For example, in the adjacent detection elements separated by the wall 208 between Z=6 and Z=7, the added value of the output signals of S(6, 1~8) and S(7, 1~8) is used in the alignment.

[0063] Furthermore, when using the added output signal, it is desirable to exclude the outermost detection elements, specifically, the detection elements with X=1, X=8, Z=1, and Z==16. Since the response characteristics of the output signals of the outermost detection elements are different from those of the detection elements other than the outermost detection elements, excluding the outermost detection elements enables more accurate alignment.

[0064] use Figure 5A as well as Figure 5B The following describes a case where the collimator 201 is misaligned in the Z direction relative to the semiconductor layer 203A and the semiconductor layer 203B, that is, a case where alignment in the Z direction is required. Figure 5A is a top view of the detection element module 200 including the collimator 201 and the semiconductor layer 203A and the semiconductor layer 203B. Figure 4A The same coordinate system, Figure 5B yes Figure 5A The distribution of the output signals of each detection element in the Z direction in the case of Figure 5B The output signal may be the output signal of a single detection element or the value obtained by adding the output signals of a plurality of detection elements. Regardless of whether the output signal is a single detection element or the output signals of a plurality of detection elements are the added value, the output signals of the detection elements with the same X coordinate are used.

[0065] exist Figure 5A In FIG. 1 , since the collimator 201 is offset in the z direction relative to the semiconductor layer 203A and the semiconductor layer 203B, Figure 5B As shown, a difference occurs in the output signals of the respective detection elements. In this embodiment, the position adjustment amount ΔAL in the direction perpendicular to the wall 208 is calculated based on the output signals S1 and S2 of two adjacent detection elements separated by the wall 208 using, for example, the following equation.

[0066] ΔAL=(PW / 2)·(S1-S2) / (S1+S2)...(1)

[0067] Here, P is the length of one side of the detection element, and W is the thickness of the wall 208 .

[0068] If the ΔAL calculated by equation (1) is a positive value, the collimator 201 is moved ΔAL toward the detection element that outputs S1. For example, when the output signal of the detection element with an even Z coordinate is set to S1 and the output signal of the detection element with an odd Z coordinate is set to S2, if Figure 5B The distribution of the output signal of , since ΔAL becomes a positive value, the collimator 201 is moved to the side of the detection element of the output S1, that is, in the -Z direction. In addition, the direction of alignment is not limited to Figure 5A as well as Figure 5B In the Z direction described in the figure, if the position is deviated in the X direction, the collimator 201 can be moved by using the position adjustment amount ΔAL in the X direction calculated by rewriting the Z coordinate into the X coordinate using the output signals S1 and S2 and equation (1). The calculated position adjustment amount ΔAL can also be displayed on a display unit such as a liquid crystal display.

[0069] use Fig. 6A as well as Figure 6B The following describes a case where the semiconductor layer 203A is correctly aligned with the collimator 201 but the semiconductor layer 203B is misaligned in the Z direction. Fig. 6A is a top view of the detection element module 200 including the collimator 201 and the semiconductor layer 203A and the semiconductor layer 203B. Figure 4A The same coordinate system, Figure 6B yes Fig. 6A The distribution of the output signals of each detection element in the Z direction in the case of Figure 6B The output signal is also Figure 5B Similarly to the case of , it may be the output signal of a single detection element or the value obtained by adding the output signals of a plurality of detection elements.

[0070] exist Fig. 6A In the embodiment, since the semiconductor layer 203B is offset in the Z direction relative to the collimator 201, Figure 6B As shown in FIG. 2 , a difference is generated in the output signals of the detection elements of the semiconductor layer 203B. In this case, the collimator 201 and the semiconductor layer 203B can be aligned using the position adjustment amount ΔAL in the direction perpendicular to the wall 208 calculated based on the output signals S1 and S2 of the two adjacent detection elements separated by the wall 208. In the calculation of ΔAL, for example, formula (1) is used. In addition, Fig. 6A as well as Figure 6BIn the example, since the object to be moved is the semiconductor layer 203B, if ΔAL is a positive value, the semiconductor layer 203B is moved to the side of the detection element that outputs S2. For example, when the output signal of the detection element with an odd Z coordinate is set to S1 and the output signal of the detection element with an even Z coordinate is set to S2, if Figure 6B The output signal distribution of the semiconductor layer 203A is ΔAL=0, and the semiconductor layer 203B is ΔAL>0. That is, the semiconductor layer 203A does not need to be adjusted in position, while the semiconductor layer 203B needs to be adjusted in the Z direction so that the semiconductor layer 203B moves toward the side of the detection element of the output S2, that is, in the -Z direction. Fig. 7A as well as Figure 7B The following describes a case where the collimator 201 is displaced relative to the semiconductor layer 203A and the semiconductor layer 203B in the rotation direction with the Y axis as the rotation axis. Fig. 7A is a top view of the detection element module 200 including the collimator 201 and the semiconductor layer 203A and the semiconductor layer 203B. Figure 4A The same coordinate system. In addition, Figure 7B yes Fig. 7A The distribution of the output signal of the detection element in the Z direction in the case of X=8, 6, 4, and 2 is shown.

[0071] exist Fig. 7A In FIG. 1 , since the collimator 201 is offset in the clockwise direction relative to the semiconductor layer 203A and the semiconductor layer 203B, Figure 7B As shown, differences occur in the output signals of the detection elements of the semiconductor layer 203B. In particular, the difference or ratio of the output signals between the detection elements adjacent to each other separated by the partition wall 208 is different according to the X coordinate and the Z coordinate. In such a case, the position adjustment amount is also calculated based on the output signals S1 and S2 of the two detection elements adjacent to each other separated by the partition wall 208. Among them, since it is a movement in the rotation direction with the Y axis as the rotation axis, the position adjustment amount in the X direction and the Z direction is different according to the coordinates of the detection element. In particular, since the distance from the rotation axis to any one of the through holes 205-11, 12, 21, and 22 at the four corners of the collimator 201 is the largest among all the through holes 205, the position adjustment amount is the largest in any one of the through holes 205-11, 12, 21, and 22.

[0072] Therefore, in Fig. 7A as well as Figure 7BIn the calculation, the position adjustment amount is calculated based on the output signals of the detection elements corresponding to two of the four corner through holes, namely, the first through hole and the second through hole, and the detection element corresponding to the through hole inside the first through hole and the second through hole. The position adjustment amount is calculated at the positions of the first through hole and the second through hole with respect to the first direction and the second direction which is a direction orthogonal to the first direction and the direction of irradiation of X-rays. For example, the following formula is used to calculate the position adjustment amount in each direction at each position.

[0073] ΔAL11=(PW / 2)·{S111-S112) / (S111+S112)...(2)

[0074] ΔAL21=(PW / 2)·{S211-S212) / (S211+S212)...(3)

[0075] ΔAL12=(PW / 2)·{S121-S122) / (S121+S122)...(4)

[0076] ΔAL22=(PW / 2)·{S221-S222) / (S221+S222)...(5)

[0077] Here, ΔAL11 is the position adjustment amount in the first through hole in the first direction, ΔAL21 is the position adjustment amount in the second through hole in the first direction, ΔAL12 is the position adjustment amount in the first through hole in the second direction, and ΔAL22 is the position adjustment amount in the second through hole in the second direction. In addition, P is the length of one side of the detection element, and W is the thickness of the wall 208. Furthermore, S111 and S112 are output signals of the detection elements adjacent to the wall 208 between the first through hole and the inner through hole of the first through hole in the first direction. In addition, S211 and S212 are output signals of the detection elements adjacent to the wall 208 between the first through hole and the inner through hole of the first through hole in the second direction. Furthermore, S121 and S122 are output signals of the detection elements adjacent to the wall 208 between the second through hole and the inner through hole of the second through hole in the first direction. In addition, S221 and S222 are output signals of detection elements adjacent to each other in the second direction with the wall 208 between one inner through hole and the second through hole being spaced apart.

[0078] More specifically, when the first through hole is the through hole 205-21, the through hole inside the first through hole is the through hole 205-21Z in the first direction, i.e., the Z direction, and the through hole 205-21X in the second direction, i.e., the X direction. In addition, the groups of the adjacent detection elements separated by the wall 208 are the groups of (2, 8) and (3, 8) in the Z direction, and the groups of (1, 7) and (1, 6) in the X direction. In addition, any one of the through holes 205-11, 12, and 22 is used as the second through hole.

[0079] By calculating the position adjustment amount using equations (2) to (5), the collimator 201 that is deviated in the rotation direction with the Y axis as the rotation axis can be aligned with the semiconductor layer 203. In particular, since the position adjustment amounts in the first direction and the second direction are calculated at two positions among the through holes at the four corners of the collimator 201 where the position adjustment amount becomes the largest, higher-precision alignment can be performed.

[0080] As described above, the collimator 201 and the semiconductor layer 203 are moved so that the ratio or difference of the output signals between the adjacent detection elements separated by the wall 208 of the collimator 201 is within a given range, and the two can be aligned. According to this embodiment, since the collimator 201 and the semiconductor layer 203 can be aligned while the position of the X-ray source 1 is fixed, the increase in the man-hours required for the alignment can be suppressed.

[0081] In addition, when it is necessary to perform position adjustment in the rotation direction with the Y axis as the rotation axis and position adjustment in the Z direction or the X direction, it is desirable to perform position adjustment in the Z direction or the X direction after performing position adjustment in the rotation direction. By first performing position adjustment in the rotation direction, the added value of a plurality of detection elements can be used when performing position adjustment in the Z direction or the X direction, so that higher-precision alignment can be performed.

[0082] <Second Embodiment>

[0083] In the first embodiment, the alignment of the semiconductor layer 203 having a plurality of detection elements and the collimator 201 is described in the case where two detection elements are arranged along the wall 208 in the through hole 205 of the collimator 201. The number of detection elements arranged along the wall 208 in the through hole 205 is not limited to two, and may be three or more. In this embodiment, the alignment in the case where three or more detection elements are arranged along the wall 208 in the through hole 205 is described. In addition, in this embodiment, since part of the structure and function described in the first embodiment can be applied, the same figure mark is used for the same structure and function, and the description is omitted.

[0084] use Fig. 8A as well as Figure 8BFIG. gA is a top view of the case where three detection elements are arranged along the wall 208 in the through hole 205. Figure 8B This is a top view of a case where four detection elements are arranged. As the number of detection elements arranged in the through hole 205 increases, the output signal of each detection element becomes smaller, so it is desirable to add the output signals of multiple detection elements to improve the SNR. Among them, it is better not to add output signals that do not change even if position deviation occurs. In addition, it is also better not to add output signals whose direction of position deviation is difficult to determine.

[0085] Therefore, in this embodiment, the output signals of the detection elements that do not overlap with the wall 208 of the collimator 201 and the detection elements arranged at the four corners of the through hole 205 are not included in the addition. Fig. 8A as well as Figure 8B The semiconductor layer 203 and the collimator 201 are aligned except for the output signal of the element 801 shown with diagonal lines. In addition, since the output signals of the detection elements arranged in a direction orthogonal to the alignment direction are added, the output signals of the detection elements other than the two ends among the detection elements arranged along the wall 208 in the through hole are added. Moreover, as in the first embodiment, the semiconductor layer 203 and the collimator 201 are aligned so that the ratio or difference of the output signals between the adjacent detection elements separated by the wall 208 is within a given range.

[0086] According to the present embodiment, even when the number of detection elements arranged in the through hole 205 increases and the output signal of each detection element decreases, the semiconductor layer 203 and the collimator 201 can be aligned with higher accuracy.

[0087] A plurality of embodiments of the radiographic imaging device of the present invention have been described above. The radiographic imaging device of the present invention is not limited to the above-described embodiments, and the constituent elements can be deformed and concretized within the scope of the gist of the invention. In addition, the plurality of constituent elements disclosed in the above-described embodiments can be appropriately combined. Furthermore, some constituent elements can be deleted from all the constituent elements shown in the above-described embodiments.

Claims

1. A radiation imaging device comprising: a radiation source that irradiates radiation to a subject; a plurality of detection elements that detect photons of said radiation; and a collimator disposed between the radiation source and the detection element and having a plurality of walls forming a plurality of passage holes through which the radiation passes; The radiation imaging device is characterized in that The detection element and the collimator are aligned in a direction orthogonal to the direction of irradiation of the radiation so that the ratio or difference of the output signals between the adjacent detection elements separated by the wall is within a given range, The ratio of the output signals between the adjacent detection elements separated by the wall is calculated based on a value obtained by adding the output signals of the plurality of detection elements arranged along the wall.

2. The radiation imaging device according to claim 1, wherein: When three or more detection elements are arranged along the wall in the through hole, output signals of the detection elements other than the two ends are added.

3. A radiation imaging device comprising: a radiation source that irradiates radiation to a subject; a plurality of detection elements that detect photons of said radiation; and a collimator disposed between the radiation source and the detection element and having a plurality of walls forming a plurality of passage holes through which the radiation passes; The radiation imaging device is characterized in that The detection element and the collimator are aligned in a direction orthogonal to the direction of irradiation of the radiation so that the ratio or difference of the output signals between the adjacent detection elements separated by the wall is within a given range, When the size of the detection element is set to P, the thickness of the wall is set to W, and the output signals of the adjacent detection elements separated by the wall are set to S1 and S2, the position adjustment amount ΔAL in the direction orthogonal to the wall when the detection element and the collimator are aligned is calculated as: ΔAL=(PW / 2)·(S1-S2) / (S1+S2) The collimator is moved by ΔAL to one side of the detection element of the output S1.

4. The radiation imaging device according to claim 3, wherein: The radiation imaging device further includes a display unit that displays the position adjustment amount ΔAL calculated based on the values ​​of the output signals S1 and S2.

5. A radiation imaging device comprising: a radiation source that irradiates radiation to a subject; a plurality of detection elements that detect photons of said radiation; and a collimator disposed between the radiation source and the detection element and having a plurality of walls forming a plurality of passage holes through which the radiation passes; The radiation imaging device is characterized in that The detection element and the collimator are aligned in a direction orthogonal to the direction of irradiation of the radiation so that the ratio or difference of the output signals between the adjacent detection elements separated by the wall is within a given range, When the detection element and the collimator are aligned in a direction rotated with the direction of irradiating the radiation as a rotation axis, a position adjustment amount is calculated based on output signals of detection elements adjacent to a wall between a first through hole that is one of the four corner through holes of the collimator and a through hole on the inner side of the first through hole, and output signals of detection elements adjacent to a wall between a second through hole that is one of the four corner through holes of the collimator and different from the first through hole and a through hole on the inner side of the second through hole.

6. The radiation imaging device according to claim 5, characterized in that When the size of the detection element is set to P and the thickness of the wall is set to W, In the first direction, if the output signals of the detection elements adjacent to the wall between the inner through hole and the first through hole are set as S111 and S112, the position adjustment amount ΔAL11 in the first through hole in the first direction is ΔAL1 1=(PW / 2)·(S111-S112) / (S111+S112), If the output signals of the detection elements adjacent to the wall between the inner through hole and the second through hole are defined as S211 and S212, the position adjustment amount ΔAL21 in the second through hole in the first direction is ΔAL21=(PW / 2)·(S211-S212) / (S211+S212), In the second direction, which is a direction orthogonal to the direction of irradiating the radiation and the first direction, if the output signals of the detection elements adjacent to the wall between an inner through hole and the first through hole are separated by S121 and S122, the position adjustment amount ΔAL12 in the first through hole in the second direction is ΔAL12=(PW / 2)·(S121-S122) / (S121+S122), If the output signals of the adjacent detection elements separated by the wall between the inner through hole and the second through hole are S221 and S222, the position adjustment amount ΔAL22 in the second through hole in the second direction is ΔAL22=(PW / 2)·(S221-S222) / (S221+S222).

7. The radiation imaging device according to any one of claims 1 to 6, characterized in that: The detection element is formed in the semiconductor layer, When a plurality of semiconductor layers are corresponding to the collimator, the collimator and each semiconductor layer are aligned in a direction orthogonal to the direction of irradiating the radiation so that the ratio or difference of the output signals between adjacent detection elements separated by the wall in each semiconductor layer is within a given range.

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