JP2012192031A - Registration apparatus - Google Patents

Abstract

Provided is an alignment device capable of preventing an image from being disturbed by the influence of a shadow of a radiation grid when photographing with the radiation detector by precisely adjusting a relative position between the radiation detector and the radiation grid. To do.
An alignment apparatus 10 according to the present invention adjusts a relative position between an FPD 4 and an X-ray grid 5. That is, by actually irradiating the radiation, a map m in which the position of the FPD 4 and the incident amount of the radiation are related is generated, and the width of the shadow of the absorbing foil projected on the detection surface of the FPD 4 is reduced based on the map m. Thus, the inclination angle of the X-ray grid 5 with respect to the FPD 4 is adjusted. As a result, the relative position between the FPD 4 and the X-ray grid 5 is adjusted accurately, and it is possible to prevent the image from being disturbed by the influence of the shadow of the X-ray grid 5 when photographing using the FPD 4.
[Selection] Figure 1

Description

  The present invention relates to a configuration for imaging a fluoroscopic image of a subject using radiation, and more particularly to an alignment apparatus for a radiation grid that removes scattered radiation components of radiation.

  A medical institution is equipped with a radiation imaging apparatus that acquires an image of the subject M with radiation (see, for example, Patent Document 1). As shown in FIG. 18, the radiation imaging apparatus 51 includes a top plate 52 on which the subject M is placed, a radiation source 53 that radiates radiation, and a radiation detector 54 that detects radiation. Based on the detection signal output from the radiation detector 54, an image in which a fluoroscopic image of the subject M is reflected is acquired.

  A radiation grid 55 for removing scattered radiation generated in the subject M is provided on an incident surface (detection surface) on which radiation of the radiation detector 54 is incident. The radiation grid 55 is configured by arranging elongated absorbing foils like a blind. When scattered radiation strikes this absorbing foil, most of the radiation is absorbed by the absorbing foil and does not enter the radiation detector 54.

  Incidentally, the radiation detector 54 is configured by arranging a plurality of detection elements in a matrix. When the shadow of the absorption foil of the radiation grid 55 is projected onto the radiation detector 54 having such a configuration, the interference fringes appear on the image due to interference between the pitch of the detection element and the shadow of the absorption foil in the radiation detector 54. May appear.

  In order to suppress this, in recent years, a synchronous radiation grid 55 in which the shadow pitch of the absorbing foil is an integral multiple of the pitch of the detection element has been developed. According to the radiation imaging apparatus equipped with the synchronous radiation grid 55, no interference fringes appear in the acquired image.

Japanese Patent Laid-Open No. 2001-346795

However, the conventional configuration has the following problems.
That is, it is difficult to accurately adjust the relative position between the radiation detector 54 and the radiation grid 55. That is, when photographing is performed with the radiation grid 55 arranged so as to cover the detection surface for detecting radiation in the radiation detector 54, the arrangement of the detection elements and the shadow arrangement of the absorbing foil projected on the radiation detector 54 Since the positional relationship is not ideal, a false image resulting from the shadow of the radiation grid 55 appears in the acquired image.

  In order to suppress the occurrence of such false images, it is necessary to strictly adjust the relative position between the radiation detector 54 and the radiation grid 55. However, this operation cannot be completed easily. That is, the false image that appears in the image changes greatly only when the relative position is shifted by about 0.1 mm.

  Further, the absorption foil of the radiation grid 55 is slightly distorted or bent. That is, even if the radiation grids 55 are manufactured in the same manner, there is a slight difference that may be an individual difference. Therefore, the relative positions of the two 54 and 55 that are suitable for imaging differ for each radiation grid 55. Therefore, each time the radiation grid 55 is placed on the radiation detector 54, the relative positions of the two 54 and 55 must be manually adjusted.

  Further, since the radiation grid 55 has to be attached / detached / replaced according to the purpose of imaging, the number of times of adjusting the positions of the both 54 and 55 is large.

  The present invention has been made in view of such circumstances, and its purpose is to precisely adjust the relative position between the radiation detector and the radiation grid, so that radiation can be obtained during imaging using the radiation detector. An object of the present invention is to provide an alignment apparatus capable of preventing an image from being disturbed by the influence of a grid shadow.

The present invention has the following configuration in order to solve the above-described problems.
That is, the alignment apparatus according to the present invention is formed by arranging radiation detecting means for detecting radiation and an absorbing foil extending in the first direction in a second direction orthogonal to the first direction and detecting radiation. In a positioning apparatus for adjusting the relative position of a radiation grid arranged so as to cover a surface to detect radiation in the means, a radiation source for irradiating the radiation to the radiation detection means, and a radiation detection means to which the radiation has entered A map generating means for generating a map in which the position of the radiation detecting means and the incident amount of radiation are related based on the detection signal output from the position, a position adjusting means for adjusting an inclination angle of the radiation grid with respect to the radiation detecting means, and a position A position adjustment control means for controlling the adjustment means, and the position adjustment control means is a suction unit projected on the detection surface of the radiation detection means based on the map. It is characterized in that the width of the shadow of the foil to control the position adjustment means so as to decrease.

  [Operation and Effect] The alignment apparatus according to the present invention adjusts the relative position between the radiation detection means and the radiation grid. That is, by actually irradiating the radiation, a map in which the position of the radiation detecting means and the incident amount of the radiation are related is generated, and the width of the shadow of the absorbing foil projected on the detection surface of the radiation detecting means is based on the map. The inclination angle of the radiation grid with respect to the radiation detection means is adjusted to be smaller. As a result, the relative position between the radiation detection means and the radiation grid is precisely adjusted so that the radiation grid does not block the radiation as much as possible, and the image is distorted due to the influence of the shadow of the radiation grid when photographing using the radiation detection means. Can be prevented.

  Further, in the above alignment apparatus, the position adjustment control unit controls the radiation detection unit to incline the radiation grid with the axis parallel to the first direction as the rotation axis, and controls the radiation shown in the map. It is more desirable to reduce the shadow width of the absorbing foil by controlling the position adjusting means so that the amount of radiation incident on the radiation detecting means increases based on the amount of incident.

  [Operation / Effect] The above-described configuration shows a specific configuration of the alignment apparatus of the present invention. That is, if the inclination angle is adjusted with the axis parallel to the first direction in which the absorption foil of the radiation grid extends as the rotation axis, the thickness of the shadow of the absorption foil appearing on the detection surface of the radiation detection means depends on the inclination angle. Therefore, it is possible to control the position adjusting means so that the amount of radiation incident on the radiation detecting means is surely increased.

  In the above alignment apparatus, the position adjustment control unit controls the radiation detection unit to incline the radiation grid with the axis parallel to the second direction as the rotation axis, and positions the grids at the peripheral portions of the map. More preferably, the radiation incident amounts at a plurality of different reference points are acquired and the position adjusting means is controlled so that the radiation incident amounts at the respective reference points coincide.

  [Operation / Effect] The above-described configuration shows a specific configuration of the alignment apparatus of the present invention. That is, if the inclination angle is adjusted with the axis parallel to the second direction in which the absorption foils of the radiation grid are arranged as the rotation axis, the difference in the thickness of the absorption foil varies depending on the part of the radiation detection means depending on the inclination angle. Expands or narrows. If the position adjusting means is controlled so that the amount of radiation incident on each part of the radiation detecting means matches, the shadows of the absorbing foil are arranged more regularly in the radiation detecting means, so that the amount of radiation incident on the radiation detecting means is surely large. Thus, the position adjusting means can be controlled.

  Moreover, in the above-described alignment apparatus, the position adjusting means can rotate the radiation grid relative to the radiation detection means as a rotation axis orthogonal to the first direction and the second direction as well as the inclination of the radiation grid. The position adjustment control means controls the radiation detection means to rotate the radiation grid, acquires the radiation incident amounts at a plurality of reference points having different positions at the peripheral edge of the map, It is more desirable to control the position adjusting means so that the amount of radiation incident on the reference point matches.

  [Operation / Effect] The above-described configuration shows a specific configuration of the alignment apparatus of the present invention. That is, if the radiation grid is rotated with respect to the radiation detection means about the rotation axis orthogonal to the first direction and the second direction, the direction of the absorption foil of the radiation grid can be set as set, so that the image The false image derived from the radiation grid that appears can be suppressed.

  Further, in the above alignment apparatus, the position adjustment means can move the radiation grid in the second direction with respect to the radiation detection means as well as the inclination of the radiation grid. , Control the radiation detection means to move the radiation grid, and acquire the radiation incident amounts at multiple reference points at different positions on the periphery of the map, and the radiation incident amounts at each reference point match It is more desirable to control the position adjusting means.

  [Operation / Effect] The above-described configuration shows a specific configuration of the alignment apparatus of the present invention. That is, if the radiation grid is moved in the second direction with respect to the radiation detection means, the direction of the absorption foil of the radiation grid can be set as set, so that false images derived from the radiation grid appearing in the image are suppressed. can do.

  In the above alignment apparatus, the position adjustment control means includes four reference points located at four corners away from the rotation axis of the rectangular map corresponding to the rectangular radiation detection means. It is more desirable to operate on the target.

  [Operation / Effect] The above-described configuration shows a specific configuration of the alignment apparatus of the present invention. That is, if the operation is performed on four reference points located at the four corners of the rectangular map corresponding to the shape of the rectangular radiation detection unit, the reference point is a radiation grid for the radiation detection unit. Therefore, the reference point at which the incident amount of radiation changes most sensitively to the movement of the position is operated. This is because this portion has the largest amount of movement by rotation. Therefore, according to this configuration, the radiation grid can be more reliably aligned with the radiation detection means.

  Further, in the above-described alignment apparatus, it is more preferable that the position adjustment control means aligns the radiation grid with respect to the radiation detection means by feedback control in which the control of the position adjustment means and the map reference are alternately performed.

  [Operation / Effect] The above-described configuration shows a specific configuration of the alignment apparatus of the present invention. That is, if the operation of the position adjustment control means is feedback control, the radiation grid can be automatically aligned with the radiation detection means.

  Further, in the above-described alignment apparatus, a reading unit that reads identification information for individual identification stored in the radiation grid, and a control mode of the position adjustment unit that is output after the position adjustment control unit completes the alignment of the radiation grid. And storage means for storing preset data related to the identification information, and when the alignment is performed again for the radiation grid of the same individual, the reading means reads the identification information for the current radiation grid, and the position adjustment control means More preferably, the preset data corresponding to the identification information acquired by the reading means this time is acquired from the storage means, and the position adjusting means is controlled based on the acquired preset data.

  [Operation / Effect] The above-described configuration shows a specific configuration of the alignment apparatus of the present invention. That is, if the preset data corresponding to the identification information acquired by the reading means is acquired from the storage means, and the position adjusting means is controlled based on the acquired preset data, the radiation grid that has been aligned once before With respect to the above, even if the alignment is not performed by irradiating radiation again, the alignment is completed only by controlling the position adjusting means according to the preset data. Therefore, according to this configuration, a highly secure alignment device can be provided.

  The alignment apparatus according to the present invention adjusts the relative position between the radiation detection means and the radiation grid. That is, by actually irradiating the radiation, a map in which the position of the radiation detecting means and the incident amount of the radiation are related is generated, and the width of the shadow of the absorbing foil projected on the detection surface of the radiation detecting means is based on the map. The inclination angle of the radiation grid with respect to the radiation detection means is adjusted to be smaller. As a result, the relative position between the radiation detection means and the radiation grid is precisely adjusted so that the radiation grid does not block the radiation as much as possible, and the image is distorted due to the influence of the shadow of the radiation grid when photographing using the radiation detection means. Can be prevented.

FIG. 3 is a functional block diagram illustrating the configuration of the alignment apparatus according to the first embodiment. 1 is a perspective view illustrating a housing according to Embodiment 1. FIG. 3 is a plan view illustrating a configuration of a detection surface of the FPD according to Embodiment 1. FIG. 3 is a plan view illustrating the configuration of an X-ray grid according to Embodiment 1. FIG. 3 is a schematic diagram illustrating the configuration of an X-ray grid according to Embodiment 1. FIG. It is a perspective view explaining the position adjustment mechanism which concerns on Example 1. FIG. It is a perspective view explaining the position adjustment mechanism which concerns on Example 1. FIG. It is sectional drawing explaining the relationship between the shadow of the absorption foil which concerns on Example 1, and FPD. It is sectional drawing explaining the relationship between the shadow of the absorption foil which concerns on Example 1, and FPD. 3 is a flowchart for explaining the operation of the alignment apparatus according to the first embodiment. FIG. 6 is a perspective view for explaining the operation of the alignment apparatus according to the first embodiment. FIG. 6 is a perspective view for explaining the operation of the alignment apparatus according to the first embodiment. FIG. 6 is a perspective view for explaining the operation of the alignment apparatus according to the first embodiment. FIG. 6 is a perspective view for explaining the operation of the alignment apparatus according to the first embodiment. FIG. 6 is a plan view for explaining the operation of the alignment apparatus according to the first embodiment. FIG. 6 is a schematic diagram for explaining the operation of the alignment apparatus according to the first embodiment. It is a schematic diagram explaining a mode that the housing | casing which concerns on Example 1 is mounted | worn with an X-ray imaging apparatus. It is a schematic diagram explaining the subject of a conventional structure.

  Hereinafter, examples of the present invention will be described. X-rays in the examples correspond to the radiation of the present invention. FPD is an abbreviation for flat panel detector.

<Overall configuration of alignment device>
First, the overall configuration of the alignment apparatus 10 according to the present invention will be described. As shown in FIG. 1, the alignment apparatus 10 according to the first embodiment adjusts the relative position between the FPD 4 and the X-ray grid 5. Therefore, the FPD 4 and the X-ray grid 5 do not constitute the alignment device 10. Note that the FPD 4 detects X-rays, and the X-ray grid 5 is arranged so as to cover a surface to be detected on the FPD 4 for detecting X-rays. The FPD 4 corresponds to the radiation detection means of the present invention, and the X-ray grid 5 corresponds to the radiation grid of the present invention.

  As shown in FIG. 1, the alignment apparatus 10 includes a housing 1 that introduces an FPD 4 and an X-ray grid 5, an X-ray tube 3 that irradiates the FPD 4 with X-rays, and an X-ray tube 3 that controls the X-ray tube 3. A map generation unit 11 that generates a map m in which the position of the FPD 4 and the amount of incident X-rays are related to each other based on the detection signal output from the FPD 4 on which the X-rays are incident, and the X-rays for the FPD 4 A position adjustment mechanism 7 that adjusts the positional relationship of the grid 5 and a position adjustment control unit 8 that controls the position adjustment mechanism 7 are provided. The X-ray tube 3 corresponds to the radiation source of the present invention, and the position adjusting mechanism 7 corresponds to the position adjusting means of the present invention. The position adjustment control unit 8 corresponds to the position adjustment control unit of the present invention, and the map generation unit 11 corresponds to the map generation unit of the present invention.

  In addition to the above-described configuration, the alignment apparatus 10 includes a reading unit 12 that reads identification information for individual identification stored in the X-ray grid 5 and a storage unit 15 that stores a table T described later. . The reading unit 12 corresponds to the reading unit of the present invention, and the storage unit 15 corresponds to the storage unit of the present invention.

  The housing 1 is a rectangular parallelepiped shaped like a rectangular FPD 4 and X-ray grid 5 as shown in FIG. In the alignment operation, the FPD 4 and the X-ray grid 5 are introduced into the housing 1. The housing 1 is provided with a slit 1a into which the FPD 4 is inserted. By providing this housing 1, the operator's safety is achieved. The FPD 4 is fixed to the bottom of the housing 1. One X-ray grid 5 is detachable from the housing 1.

  As shown in FIG. 3, the FPD 4 is a rectangular device that detects incident X-rays, and is configured by two-dimensionally arranging detection elements 4a that detect X-rays. For convenience of explanation, it is assumed that the detection elements 4a are arranged vertically and horizontally. The detection elements 4a are arranged vertically and horizontally at a pitch of 150 μm, for example.

  As shown in FIG. 4, the X-ray grid 5 is a sheet-like rectangular member provided so as to cover the incident surface on which the X-rays of the FPD 4 are incident so that scattered rays generated from the subject do not enter the FPD 4. Thus, the strip-shaped absorbent foil s extending in the a direction is arranged in a blind shape in the b direction orthogonal to the a direction. The absorbing foil s is made of a material such as a molybdenum alloy that absorbs X-rays, and absorbs X-rays. The strip-shaped absorbent foil s is provided such that the short side direction coincides with the X-ray traveling direction. The a direction corresponds to the first direction of the present invention, and the b direction corresponds to the second direction of the present invention.

  The role of the X-ray grid 5 will be described. Most of the X-rays traveling from the X-ray tube 3 to the FPD 4 do not enter the absorbing foil s but enter the FPD 4. However, some of the X-rays are scattered while passing through the subject. The traveling direction of the scattered radiation generated in this manner has been changed due to scattering, which is a factor that deteriorates the visibility of an image obtained by X-ray imaging. When the X-ray grid 5 is provided, such scattered rays whose traveling direction has changed are not incident on the absorption foil s and reach the FPD 4. Thus, if the X-ray grid 5 is provided so as to cover the incident surface of the FPD 4, an image with high visibility can be acquired.

  FIG. 5 explains the inclination of the absorbing foil s of the X-ray grid 5. The X-ray tube 3 emits X-rays radially from the focal point toward the FPD 4. Therefore, the X-ray incident direction differs depending on the position of the FPD 4. The absorbing foils s are arranged in consideration of this. More specifically, the absorption foil s of the X-ray grid 5 is set so that its short direction is along a straight line connecting the absorption foil s from the focal point of the X-ray tube 3. As a result, the shadow of the absorbing foil s appears on the incident surface of the FPD 4 only in the longitudinal direction of the absorbing foil s and the width in the thickness direction orthogonal to the lateral direction. As a result, the direct X-rays directly traveling to the FPD 4 without being scattered from the X-ray tube 3 are not absorbed by the X-ray grid 5 as much as possible.

  The X-ray grid 5 in the first embodiment is a synchronous grid, which will be described. When the X-ray grid 5 is placed on the FPD 4, the vertical direction in which the detection elements 4a of the FPD 4 are arranged and the direction in which the absorption foil s extends are made to coincide. At this time, in the X-ray grid 5, the arrangement pitch in the b direction of the strip-shaped absorbent foil s is set based on the arrangement pitch of the detection elements 4a in the horizontal direction. Hereinafter, this point will be specifically described.

  During X-ray imaging, X-rays emitted from the X-ray tube 3 pass through the X-ray grid 5 and enter the FPD 4. At this time, the shadow of the absorbing foil s of the X-ray grid appears on the detection surface of the FPD 4. The arrangement pitch in the b direction of the strip-shaped absorption foil s is set so that the arrangement pitch of the shadow of the absorption foil s appearing on the detection surface of the FPD 4 is an integral multiple of the arrangement pitch in the horizontal direction of the detection element 4a. As a result, the arrangement of the detection elements 4a and the arrangement of the shadow of the absorbing foil s do not interfere with each other, and interference fringes do not appear on the image at the time of X-ray photography, so that an image with excellent visibility can be generated. is there.

  A chip for storing a production number is embedded in the X-ray grid 5, and this production number is identification information for individual identification of the X-ray grid 5. Therefore, the serial number is different for each X-ray grid 5.

  The position adjustment mechanism 7 that adjusts the relative position between the FPD 4 and the X-ray grid 5 by adjusting the position of the X-ray grid 5 inside the housing will be described. The position adjustment mechanism 7 includes six drive units 7 a whose tips are in contact with the X-ray grid 5 and springs for applying stress. The drive unit 7a has an elongated shape that can be expanded and contracted, and is driven by a stepping motor that can control the amount of rotation. The positional relationship between the FPD 4 and the X-ray grid 5 can be adjusted by expanding and contracting the drive unit 7a.

  FIG. 6 illustrates three of the drive units 7a constituting the position adjustment mechanism 7. FIG. The base end portions of these drive units 7 a are fixed to the frame portion that supports the sensor on the detection surface of the FPD 4. As shown by the arrows in FIG. 6, the X-ray grid 5 is stressed so as to approach the three drive units 7 a fixed to the FPD 4 by springs. If the drive unit 7a is driven, the X-ray grid 5 can be moved away from the FPD 4 against this stress. Furthermore, the X-ray grid 5 can be inclined with respect to the FPD 4 by driving the three drive units 7a in cooperation.

  FIG. 7 explains the other three of the drive units 7 a constituting the position adjusting mechanism 7. The base end portions of these drive units 7 a are fixed to the inner surface of the housing 1. One of the drive units 7a can move the X-ray grid 5a in the extending direction (direction a) of the absorption foil s, and the remaining two move the X-ray grid 5a in the arrangement direction (b) of the absorption foil s. Direction).

  As shown by the arrows in FIG. 7, the X-ray grid 5 is stressed from two directions so as to approach the drive unit 7 a fixed to the housing 1 by a spring. If the drive unit 7a is driven, the X-ray grid 5 can be moved relative to the FPD 4 against this stress. Furthermore, if the three drive units 7a are driven in cooperation, the X-ray grid 5 can be rotated with respect to the FPD 4.

  As shown in FIG. 1, the alignment apparatus 10 includes a main control unit 18 that comprehensively controls the units 6, 8, 11, and 12. The main control unit 18 is configured by a CPU, and realizes each unit by executing various programs. Further, each of the above-described units may be divided and executed by an arithmetic device that takes charge of them. The console 16 is provided for the purpose of causing the operator to input an instruction to start alignment to the alignment apparatus 10, and the display unit 17 is provided for the purpose of displaying the alignment status to the operator. .

<Need for X-ray grid alignment>
Next, the necessity of alignment of the X-ray grid 5 with respect to the FPD 4 will be described with reference to FIG. The relationship between FPD4 and the shadow of absorption foil s in X-ray imaging is shown. Since the X-rays irradiated from the X-ray tube 3 pass through the X-ray grid 5 before entering the FPD 4, a shadow of the X-ray grid 5 is generated on the incident surface of the FPD 4. As shown in FIG. 8, this shadow has only the width of the absorbing foil s, and the shadow of the X-ray grid 5 reflected in the FPD 4 is the minimum. This state is a state where the positional relationship between the FPD 4 and the X-ray grid 5 is ideal.

  FIG. 9 shows a state where the positional relationship between the FPD 4 and the X-ray grid 5 is not ideal. That is, when the X-ray grid 5 is inclined with respect to the FPD 4, the short direction of the absorbing foil s does not coincide with the direction from the focal point of the X-ray tube 3 toward the absorbing foil s. Then, when the absorption foil s is viewed from the focal point of the X-ray tube 3, the surface formed by the short direction and the long direction of the absorption foil s that could not be seen until now is directed to the focal point. Accordingly, the absorbing foil s blocks X-rays directly from the focal point of the X-ray tube 3 toward the FPD 4, and the shadow of the absorbing foil s reflected on the FPD 4 becomes thicker than ideal. When photographing is performed in this state, the shadow of the absorbing foil s appears more clearly on the image, which is not desirable from the viewpoint of image visibility.

  The ideal position of the X-ray grid 5 cannot be predicted in advance. This is because the X-ray grid 5 has individual differences. That is, it is difficult to secure the position of the absorbing foil s with a precise accuracy of about 50 μm with respect to the outer frame that supports the grid structure of the X-ray grid 5 and arrange the absorbing foil s in an orderly manner. Further, the absorbing foil s constituting the X-ray grid 5 is distorted or bent with respect to the outer frame, and the distortion pattern is different for each X-ray grid 5. That is, it is necessary to acquire the ideal positional relationship with respect to the FPD 4 for each X-ray grid 5 by actually irradiating X-rays.

<Operation of alignment device>
Next, the operation of the alignment apparatus 10 will be described. In this description of the operation, it is assumed that the X-ray grid 5 has already been introduced into the housing 1 through the slit 1a, and the X-ray grid 5 has already been attached to the position adjustment mechanism 7 therein. In order to adjust the relative position between the FPD 4 and the X-ray grid 5 using the alignment apparatus 10 according to the first embodiment, first, identification information of the X-ray grid 5 is read (identification information) as shown in FIG. Reading step S1), various positions are aligned (rotation adjustment step S2 to second inclination adjustment step S5). Finally, the mode of position adjustment of the X-ray grid 5 that differs depending on the individual X-ray grid 5 is acquired as preset data (preset data generation step S6). Hereinafter, these steps will be described in order.

<Identification information reading step S1>
When the operator instructs the alignment apparatus 10 to start adjustment of the relative position between the FPD 4 and the X-ray grid 5 through the console 16, first, the reading unit 12 indicates the serial number from the chip embedded in the X-ray grid 5. Get information (identification information). Thereby, the alignment apparatus 10 can discriminate which individual the X-ray grid 5 inserted into the housing 1 is. The reading unit 12 sends the identification information to the position adjustment control unit 8.

<Rotation adjustment step S2>
Next, position adjustment of both 4 and 5 is performed about the movement style regarding rotation. That is, in the rotation adjustment step S2, as shown in FIG. 11, the X-ray grid 5 is orthogonal to the FPD 4 in the a direction and the b direction, and the axis passing through the center point of the X-ray grid 5 is used as the rotation axis. Rotate. The actual rotation is performed by the position adjustment mechanism 7 and the position adjustment control unit 8 controls the position adjustment mechanism 7.

  The map m is acquired every time the position adjustment control unit 8 moves the X-ray grid 5 by a certain amount, and the position adjustment control unit 8 uses the evaluation value acquired from the map m to determine the movement policy of the X-ray grid 5. This situation will be described. When the position adjustment control unit 8 moves (rotates) the X-ray grid 5 in a certain direction by a certain amount, the position adjustment control unit 8 then instructs the X-ray tube control unit 6 to irradiate X-rays, and creates a new map m. To get. The position adjustment control unit 8 compares the previously acquired map m with the currently acquired map m, and determines how to move (rotate) the X-ray grid 5 with respect to the FPD 4 next. In other words, the position adjustment control unit 8 compares the data indicating the X-ray intensity of the reference point located at the peripheral edge (four corners) of the rectangular map m, and shows the degree of coincidence of the four data. Get evaluation value. As a method for calculating the evaluation value, an existing statistical test method can be used. If the evaluation value of the map m acquired this time is larger than the evaluation value of the map m acquired this time, the position adjustment control unit 8 recognizes that the positions of both 4 and 5 are close to ideal. The FPD 4 is controlled to move (rotate) the X-ray grid 5 in the same direction as before.

  In this step, when the position adjustment control unit 8 adjusts the positions of both 4 and 5, the arrangement direction of the detection elements 4a of the FPD 4 and the a direction of the absorbing foil s of the X-ray grid 5 coincide with each other. The positional relationship becomes even more ideal.

<Translation adjustment step S3>
Next, the position adjustment of both 4 and 5 is performed for another motion mode. That is, in the parallel movement adjustment step S3, the X-ray grid 5 is moved in the b direction with respect to the FPD 4 as shown in FIG. The actual movement is performed by the position adjustment mechanism 7 and the position adjustment control unit 8 controls the position adjustment mechanism 7. When the position adjustment control unit 8 moves the X-ray grid 5 by a certain amount, the map m is acquired, and the position adjustment control unit 8 moves the X-ray grid 5 using the evaluation value acquired from the map m. The manner in which the policy is determined is the same as that in the rotation adjustment step S2 described above, and a description thereof will be omitted.

<First inclination adjusting step S4>
Next, the alignment apparatus 10 gives an instruction to the X-ray tube control unit 6 to irradiate the X-ray tube 3 with X-rays. Since the control mode of the X-ray tube 3 at this time is stored in the storage unit 15, the X-ray tube control unit 6 reads it from the storage unit 15 and uses it. X-rays irradiated from the X-ray tube 3 pass through the X-ray grid 5 and reach the FPD 4. The FPD 4 detects X-rays and sends a detection signal to the map generation unit 11.

  The map generation unit 11 generates a rectangular map m following the shape of the detection surface of the rectangular FPD 4. In this map m, data representing the intensity of the X-rays generated based on the detection signal output from each detection element 4a on the FPD 4 is arranged in a matrix form following the arrangement of the detection elements 4a. This map m serves as an index indicating how ideal the relative position between the current FPD 4 and the X-ray grid 5 is.

  The position adjustment mechanism 7 can change the positional relationship between the FPD 4 and the X-ray grid 5 with a high degree of freedom. Therefore, the position adjustment of both 4 and 5 is configured to be sequentially performed for various motion modes. In the first tilt adjustment step S4, as shown in FIG. 13, the X-ray grid 5 is tilted with respect to the FPD 4 as an axis of rotation that is parallel to the a direction and passes through the center point of the X-ray grid 5. The actual inclination is performed by the position adjustment mechanism 7 and the position adjustment control unit 8 controls the position adjustment mechanism 7.

  When the position adjustment control unit 8 moves the X-ray grid 5 in a certain direction by a certain amount, the position adjustment control unit 8 then gives a control instruction to irradiate the X-ray tube control unit 6 with X-rays and acquires a new map m. . The position adjustment control unit 8 compares the previously acquired map m with the currently acquired map m and determines how to move the X-ray grid 5 with respect to the FPD 4 next. That is, the position adjustment control unit 8 averages data representing the intensity of the X-rays arranged in the map m, and acquires an average value indicating how much X-rays are incident on the entire FPD 4. If the average value of the map m acquired this time is larger than the average value of the map m acquired this time, the position adjustment control unit 8 recognizes that the positions of both 4 and 5 are close to ideal. The FPD 4 is controlled to move the X-ray grid 5 in the same direction as before.

  In addition, if the average value of the map m acquired this time is smaller than the average value of the map m acquired last time, the position adjustment control unit 8 recognizes that the positions of both 4 and 5 are far from ideal. The FPD 4 is controlled to move the X-ray grid 5 in the opposite direction. As described above, the position adjustment control unit 8 controls the position adjustment mechanism 7 so that the X-ray incident amount in the FPD 4 is increased based on the X-ray incident amount shown in the map m. That is, the position adjustment control unit 8 aligns the X-ray grid 5 with respect to the FPD 4 by feedback control that alternately performs control of the position adjustment mechanism 7 and reference to the map m.

  When the position adjustment control unit 8 adjusts the positions of both 4 and 5 in this way, the positions of both 4 and 5 are shown in FIG. 8 from the state in which the shadow of the absorbent foil s shown in FIG. The absorption foil s is changed so that the shadow of the absorbing foil s is reflected to a minimum. As described above, the position adjustment control unit 8 controls the position adjustment mechanism 7 so that the width of the shadow of the absorbing foil s projected on the detection surface of the FPD 4 is reduced based on the map m. Thereby, 1st inclination adjustment step S4 is complete | finished.

<Second inclination adjustment step S5>
Next, the position adjustment of both 4 and 5 is performed for another motion mode. That is, in the second inclination adjustment step S5, as shown in FIG. 14, the X-ray grid 5 is inclined with respect to the axis that is parallel to the FPD 4 in the b direction and passes through the center point of the X-ray grid 5. Let The actual inclination is performed by the position adjustment mechanism 7 and the position adjustment control unit 8 controls the position adjustment mechanism 7. Since the state of the operation of the position adjustment control unit 8 at this time is the same as that of the rotation adjustment step S2, description thereof will be omitted.

  If the evaluation value of the map m acquired this time is smaller than the evaluation value of the map m acquired last time, the position adjustment control unit 8 recognizes that the positions of both 4 and 5 are far from ideal. The FPD 4 is controlled to move the X-ray grid 5 in the opposite direction. As described above, the position adjustment control unit 8 controls the position adjustment mechanism 7 so that the incident amounts of X-rays at the respective reference points coincide. That is, the position adjustment control unit 8 aligns the X-ray grid 5 with respect to the FPD 4 by feedback control that alternately performs control of the position adjustment mechanism 7 and reference to the map m.

  By the way, since X-rays spread radially from the X-ray tube 3, when the absorbing foil s approaches or separates from the FPD 4, the thickness of the shadow of the absorbing foil s reflected on the FPD 4 changes. In the second inclination adjustment step S5, the thickness of the shadow can be adjusted. That is, when the position adjustment control unit 8 adjusts the positions of both 4 and 5, the shadow of the absorbing foil s greatly expands on the FPD 4 because the X-ray grid 5 is too far away from the FPD 4 at one end in the a direction of the FPD 4. The state that has been excessively eliminated is eliminated, and the positions of both 4 and 5 are adjusted so that the thickness of the shadow of the absorbent foil s reflected in the FPD 4 is the same at the four corners.

  In this step, when the position adjustment control unit 8 adjusts the positions of both 4 and 5, as shown in FIG. 15, one absorbent foil is arranged in a row of detection elements 4a whose width is one detection element. The shadow of s is reflected, and the position where the shadow appears is the center in the width direction in the row of detection elements 4a. In this way, the positional relationship between the two 4 and 5 becomes more ideal.

  Here, the reason why the reference points located at the four corners of the map m are the comparison targets of the position adjustment control unit 8 in the rotation adjustment step S2, the parallel movement adjustment step S3, and the second inclination adjustment step S5 will be described. . In the rotation adjustment step S <b> 2 and the second inclination adjustment step S <b> 5, the amount of movement differs depending on the portion of the X-ray grid 5 when inclination or rotation is applied. Specifically, the amount of movement of the X-ray grid 5 increases as the distance from the center axis of inclination or rotation increases. Since the central axis of the inclination or rotation passes through the center point of the X-ray grid 5, the peripheral part (four corners) away from the center point of the X-ray grid 5 is moved most greatly by the inclination or rotation. Therefore, if the four corners of the X-ray grid 5 are observed in accordance with the inclination and rotation, the change of the shadow on the FPD 4 according to the inclination and rotation can be most sensitively detected. On the other hand, in the parallel movement adjustment step S3, since the positional relationship between the four and the fifth can be recognized by the same method as the rotation adjustment step S2 and the second inclination adjustment step S5, the control becomes simple.

<Preset data generation step S6>
The position adjustment control unit 8 associates the control mode of the X-ray grid 5 with respect to the FPD 4 performed in steps S <b> 2 to S <b> 5 and the identification information output from the reading unit 12, and sends them to the storage unit 15. As shown in FIG. 16, the storage unit 15 stores a table T in which the identification information of the X-ray grid 5 that has been subjected to position adjustment and the control mode are associated with each other. A set of identification information and control mode associated with each other is called preset data. The preset data is output to the storage unit 15 after the position adjustment control unit 8 completes the alignment of the X-ray grid 5. In this state, the display unit 17 displays that the adjustment of the positions of both 4 and 5 has been completed, and the operation of the alignment apparatus 10 according to the first embodiment is completed.

  After the operation of the alignment apparatus 10, the FPD 4 and the X-ray grid 5 are removed from the alignment apparatus 10 together with the housing 1 in a state where the positional relationship is maintained. Then, as shown in FIG. 17, the entire housing 1 is placed on the X-ray imaging apparatus, and the subject M is imaged in this state. In this X-ray imaging apparatus, an X-ray tube 3 and an FPD 4 to which an X-ray grid 5 is attached are placed with a top 2 on which a subject is placed. The X-ray imaging apparatus performs imaging in this state.

  By the way, the relative position of the X-ray tube 3 with respect to the FPD 4 in the alignment apparatus 10 is set to coincide with the relative position at the time of imaging of the X-ray imaging apparatus. Therefore, when imaging is performed with the X-ray imaging apparatus, the state of the shadow of the absorbing foil s appearing in the image matches the state of the shadow of the absorbing foil s appearing on the FPD 4 in the position adjusted state in the alignment apparatus 10.

  In the X-ray imaging apparatus, the position of the X-ray tube 3 with respect to the FPD 4 can be changed. Therefore, the relative position of the X-ray tube 3 with respect to the FPD 4 in the alignment apparatus 10 is made to coincide with the standard position of the X-ray tube 3 with respect to the FPD 4 at the time of imaging with the X-ray imaging apparatus. This standard position is a position of the X-ray tube 3 that is normally used in imaging, and a position corresponding to the middle of the movement range of the X-ray tube 3 relative to the FPD 4. Therefore, even if the X-ray tube 3 is moved from the standard position to the limit of the movable range, the deviation from the ideal shadow of the absorbing foil s appearing on the FPD 4 is minimal.

<Use of preset data>
Finally, the use of preset data will be described. When changing the X-ray grid 5 used in the X-ray imaging apparatus, the casing 1 is removed from the X-ray imaging apparatus, the X-ray grid 5 inside the casing 1 is replaced, and the positions of both 4, 5 are adjusted again. Will be done. At this time, the initial positions of the housing 1 and the X-ray grid 5 when the X-ray grid 5 is set in the housing 1 are the same every time the X-ray grid 5 is inserted. Therefore, regarding the X-ray grid 5 that has been aligned once, if the X-ray grid 5 is moved with respect to the FPD 4 as in the previous alignment, the positional relationship between the two 4 and 5 is ideal. Should be. Further, it is desirable to complete the alignment in this way, since it is not necessary to perform X-ray irradiation and the safety of the apparatus is improved. The preset data is provided for the purpose of aligning the X-ray grid 5 that has been aligned once without X-ray irradiation.

  That is, in the above-described identification information reading step S1, until the reading unit 12 reads the identification information stored in the chip by the X-ray grid 5 inserted in the housing 1 and sends it to the position adjustment control unit 8. Although only described above, actually, the position adjustment control unit 8 inquires of the storage unit 15 about the identification information. When the identification information of the X-ray grid 5 currently inserted in the housing 1 is not stored in the table T, the position adjustment control unit 8 performs the operations after the rotation adjustment step S2 described above.

  When the identification information of the X-ray grid 5 inserted in the casing 1 this time matches the preset data stored in the table T, the X-ray grid 5 is an X-ray that has been aligned once. It is the same individual as the grid 5. Therefore, the position adjustment control unit 8 acquires preset data corresponding to the identification information acquired by the current reading unit 12 from the storage unit 15 and controls the position adjustment mechanism 7 based on the acquired preset data. At this time, X-rays are not irradiated from the X-ray tube 3. After the movement of the X-ray grid 5 is completed, the display unit 17 displays that the adjustment of the positions of both 4 and 5 has been completed, and the operation of the alignment apparatus 10 according to the first embodiment is completed.

  As described above, the alignment apparatus 10 according to the first embodiment adjusts the relative position between the FPD 4 and the X-ray grid 5. That is, a map m in which the position of the FPD 4 and the amount of incident X-rays are related by actually irradiating X-rays is generated, and the width of the shadow of the absorbing foil s projected on the detection surface of the FPD 4 based on the map m The inclination angle of the X-ray grid 5 with respect to the FPD 4 is adjusted so as to decrease. As a result, the relative position between the FPD 4 and the X-ray grid 5 is precisely adjusted so that the radiation grid does not block the radiation as much as possible. Can be prevented.

  Further, as described above, if the inclination angle is adjusted with the axis parallel to the a direction in which the absorption foil s of the X-ray grid 5 extends as the rotation axis, the absorption foil appearing on the detection surface of the FPD 4 depending on the inclination angle. Since the thickness of the shadow of s changes, the position adjustment mechanism 7 can be controlled so that the incident amount of X-rays in the FPD 4 is surely increased.

  As described above, if the inclination angle is adjusted with the axis parallel to the b direction in which the absorption foil s of the X-ray grid 5 is arranged as the rotation axis, the absorption foils s that differ depending on the FPD 4 portion depending on the inclination angle. The difference in thickness widens or narrows. If the position adjustment mechanism 7 is controlled so that the amount of X-ray incident on each part of the FPD 4 matches, the shadows of the absorbing foils s are arranged more orderly on the FPD 4 so that the amount of X-ray incident on the FPD 4 is surely increased. Thus, the position adjusting mechanism 7 can be controlled.

  Further, when the alignment is performed, if the X-ray grid 5 is rotated with respect to the FPD 4 about the rotation axis orthogonal to the a direction and the b direction, the direction of the absorbent foil s of the X-ray grid 5 is set as set. Therefore, the false image derived from the X-ray grid appearing in the image can be suppressed.

  Further, when the X-ray grid 5 is moved in the b direction with respect to the FPD 4 at the time of alignment, the direction of the absorbing foil s of the X-ray grid 5 can be set as set, so that X appearing in the image The false image derived from the line grid can be suppressed.

  As described above, if the position adjustment control unit 8 operates on the four reference points located at the four corners of the map m that is rectangular corresponding to the shape of the rectangular FPD 4, this reference point Operates on a reference point at which the amount of X-ray incidence changes most sensitively to the position movement of the X-ray grid 5 with respect to the FPD 4. This is because this portion has the largest amount of movement by rotation. Therefore, according to this configuration, the X-ray grid 5 can be more reliably aligned with the FPD 4.

  If the operation of the position adjustment control unit 8 is feedback control, the X-ray grid 5 can be automatically aligned with the FPD 4.

  As described above, if preset data corresponding to the identification information acquired by the reading unit 12 is acquired from the storage unit 15 and the position adjustment mechanism 7 is controlled based on the acquired preset data, the alignment is performed once before. Even if the X-ray grid 5 that has been used is not aligned again by irradiating X-rays, the alignment is completed only by controlling the position adjusting mechanism 7 in accordance with the preset data. Therefore, according to this structure, the highly safe alignment apparatus 10 can be provided.

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

  (1) You may change and implement the order of each step of the alignment in the above-mentioned Example. Even in this case, the first inclination adjustment step S4 and the second inclination adjustment step S5 are preferably performed before the rotation adjustment step S2 and the parallel movement adjustment step S3.

  (2) Although the drive unit 7a has a stepping motor in the above-described embodiment, the present invention may be configured by using a hydraulic cylinder or the like instead of the drive unit 7a.

  (3) Although the embodiment described above is a medical device, the present invention can also be applied to industrial and nuclear devices.

  (4) X-rays referred to in the above-described embodiments are an example of radiation in the present invention. Therefore, the present invention can be applied to radiation other than X-rays.

m Maps Absorbing foil 3 X-ray tube (radiation source)
4 FPD (radiation detection means)
5 X-ray grid (radiation grid)
7 Position adjustment mechanism (position adjustment means)
8 Position adjustment control unit (position adjustment control means)
11 Map generator (map generator)
12 Reading unit (reading means)
15 Storage unit (storage means)

Claims (8)

A radiation detecting means for detecting radiation and an inspection surface for detecting radiation in the radiation detecting means are formed by arranging absorption foils extending in the first direction in a second direction orthogonal to the first direction. In the alignment device that adjusts the relative position with the radiation grid arranged to cover,
A radiation source for irradiating the radiation detection means with radiation;
Map generating means for generating a map in which the position of the radiation detecting means and the incident amount of radiation are related based on a detection signal output from the radiation detecting means on which the radiation has entered;
Position adjusting means for adjusting an inclination angle of the radiation grid with respect to the radiation detecting means;
A position adjustment control means for controlling the position adjustment means,
The position adjustment control means controls the position adjustment means so that the width of the shadow of the absorbing foil projected on the detection surface of the radiation detection means is reduced based on the map. . The alignment apparatus according to claim 1,
The position adjustment control unit controls the radiation detection unit to incline the radiation grid with an axis parallel to the first direction as a rotation axis, and based on an incident amount of radiation indicated in the map. Further, the position adjustment device is controlled so that the amount of radiation incident on the radiation detection device is increased, thereby reducing the width of the shadow of the absorbing foil. The alignment apparatus according to claim 1 or 2,
The position adjustment control unit controls the radiation detection unit to incline the radiation grid with an axis parallel to the second direction as a rotation axis, and a plurality of positions different from each other in a peripheral portion of the map. An alignment apparatus characterized by acquiring an amount of incident radiation at a reference point and controlling the position adjusting means so that the amount of incident radiation at each reference point coincides. The alignment apparatus according to any one of claims 1 to 3,
The position adjustment means can rotate the radiation grid relative to the radiation detection means as a rotation axis orthogonal to the first direction and the second direction as well as the inclination of the radiation grid. ,
The position adjustment control unit controls the radiation detection unit to rotate the radiation grid, and acquires radiation incident amounts at a plurality of reference points at positions different from each other at a peripheral portion of the map, An alignment apparatus that controls the position adjusting means so that the amount of incident radiation at a reference point matches. The alignment apparatus according to any one of claims 1 to 4,
The position adjusting means is capable of moving not only the inclination of the radiation grid but also the radiation grid in the second direction with respect to the radiation detection means,
The position adjustment control unit controls the radiation detection unit to move the radiation grid, and acquires radiation incident amounts at a plurality of reference points that are different from each other in a peripheral portion of the map, An alignment apparatus that controls the position adjusting means so that the amount of incident radiation at a reference point matches. The alignment apparatus according to claim 3 or 4,
The position adjustment control means operates on four reference points located at four corners away from the rotation axis of the map that is rectangular corresponding to the shape of the radiation detecting means that is rectangular. An alignment apparatus characterized by that. The alignment apparatus according to any one of claims 1 to 6,
The position adjustment control means performs position adjustment of the radiation grid with respect to the radiation detection means by feedback control in which control of the position adjustment means and reference of the map are alternately performed. The alignment apparatus according to any one of claims 1 to 7,
Reading means for reading identification information for individual identification stored in the radiation grid;
Storage means for storing preset data related to the control mode and identification information of the position adjustment means to be output after the position adjustment control means completes the alignment of the radiation grid;
Again, when performing alignment for the radiation grid of the same individual, the reading means also reads identification information for the current radiation grid, and the position adjustment control means corresponds to the identification information acquired by the current reading means. An alignment apparatus, wherein preset data is acquired from the storage means, and the position adjusting means is controlled based on the acquired preset data.

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