JP3193440U - Scattered X-ray removal grid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grid for removing scattered X-rays capable of removing scattered X-rays with a minimum amount of cutoff even when the SID changes. A scattered X-ray removing grid 4 includes a support member 40, a plurality of long thin plate-shaped absorbing members 43 composed of an X-ray absorbing substance, and a pair of supporting rollers 41. One side surface of each absorbing member 43 is inserted into the groove portion 44 formed in the support member 40, and the other side surface engages with a plurality of groove portions 42 formed in the pair of support rollers 41, respectively. There is. As the pair of support rollers 41 rotate synchronously, the inclination angle of the plurality of absorbing members 43 increases from the absorbing members 43 arranged at the center thereof to the absorbing members 43 arranged at both ends. In addition, the absorbing member 43 arranged at the center thereof is inclined in opposite directions to each other. [Selection diagram] Fig. 2

Description

  The present invention relates to a convergent scattered X-ray removal grid.

  For example, in a medical or industrial X-ray imaging apparatus, scattered X-rays are interposed between a subject and the X-ray detector in order to prevent X-rays scattered in the subject from entering the X-ray detector. A removal grid is provided.

  Such a scattered X-ray removal grid is a long thin plate-shaped absorbing member made of an X-ray absorbing material itself such as lead, or a long thin plate in which both ends of the X-ray absorbing material are supported by a thin plate member. The X-ray absorption mechanism having a large number of absorption members and an intermediate substance as a spacer interposed between the large number of absorption members. And a long thin plate-shaped absorption member is arrange | positioned so that it may become parallel to a primary X-ray. That is, in a normal X-ray imaging apparatus using an X-ray tube as a radiation source, the long thin plate-like absorbing members are arranged so that the extension of each surface is focused on one straight line at the focusing distance. A focusing grid is used.

  As the intermediate substance interposed between the absorbing members, for example, aluminum or paper fiber is used. However, X-rays are also absorbed by these intermediate materials. For this reason, a grid using air as an intermediate substance has also been proposed (Patent Document 1).

  The focusing grid is provided with driving means for transforming the convergence grid into a cylindrical shape having a predetermined curvature with the extending direction of the grid as a longitudinal axis, and the curvature of the cylindrical shape is converted into the SID (X-ray tube focal point / image receiving surface distance). : Scattered X-ray removal grids that determine the X-ray cut-off amount at both ends in the grid arrangement direction in accordance with the source image distance (Source Image Distance) have been proposed (see Patent Document 2).

JP 2008-168110 A JP 2004-313546 A

  FIG. 6 is an explanatory diagram showing a state in which a conventional scattered X-ray removal grid 102 is disposed between the X-ray tube 100 and the X-ray detector 101.

  As shown in FIG. 6 (a), when the surface of the absorbing member 103 in the scattered X-ray removal grid 102 is accurately directed to the focus of the X-ray tube 100, there is no problem in X-ray imaging. However, when the SID is changed, as shown in FIG. 6B, there is a problem that X-rays irradiated from the X-ray tube 100 are absorbed by the absorbing member 103 and a cutoff 104 is generated.

  As described in Patent Document 2, such a problem can be solved by adopting a configuration in which the grid is deformed so that the cut-off amount is minimized according to the SID. However, it is difficult to accurately change the curvature of the convergence grid, and it becomes difficult to uniformly reduce the cut-off amount over the entire X-ray irradiation field.

  The present invention has been made to solve the above-described problems, and provides a scattered X-ray removal grid that can remove scattered X-rays with a minimum cut-off amount even when the SID changes. For the purpose.

  The invention described in claim 1 is composed of an X-ray absorbing material, or a convergent type in which a plurality of long thin plate-like absorbing members provided with an X-ray absorbing material are arranged so as to be parallel to the primary X-ray. A scattered X-ray removal grid that defines a position of a side surface in the vicinity of an edge in each of the plurality of absorbing members by engaging with a side surface in the vicinity of an end edge in the longitudinal direction of the plurality of absorbing members. The groove portion is formed on the outer peripheral surface, and includes a support roller configured to be rotatable about its axis, and the groove portion is formed in a direction intersecting with a plane orthogonal to the axis of the support roller. When the SID is changed when the angle of the groove portion engaging with the absorbing member disposed near both ends is set larger than the groove portion engaging with the absorbing member disposed near the center among the plurality of absorbing members. And turn the support roller By, characterized by arranging the plurality of absorbent members to the primary X-ray and a direction parallel to.

  According to a second aspect of the present invention, in the first aspect of the present invention, the plurality of absorbing members are inserted into grooves formed on one side surface of the support member, and the other side surface is formed on the support roller. Engage with the groove.

  According to a third aspect of the present invention, in the device according to the second aspect, the plurality of absorbing members respectively engage with grooves formed in the pair of support rollers in the vicinity of both end edges in the longitudinal direction.

  According to a fourth aspect of the present invention, there is provided the device according to the first aspect, wherein each of the plurality of absorbing members has a configuration in which both ends of the X-ray absorbing material are supported by thin plate members. The pair of thin plate members that support both ends of the material are pulled in directions away from each other by the pulling member.

  According to a fifth aspect of the present invention, in the device of the fourth aspect, both side surfaces of the thin plate member are engaged with groove portions formed in support rollers arranged to face each other, and the thin plate member is Tilt about the contact portion with the traction member.

  According to the first aspect of the invention, by rotating the support roller, a plurality of absorbing members can be arranged in a direction parallel to the primary X-ray even when the SDI changes. For this reason, scattered X-rays can be efficiently removed with the cut-off amount being minimized.

  According to the second aspect of the invention, the plurality of absorbing members are parallel to the primary X-ray by rotating the support roller and tilting the plurality of absorbing members around the side surface inserted into the groove portion of the supporting member. Can be arranged in any direction.

  According to the third aspect of the present invention, the plurality of absorbing members are supported by the supporting rollers in the vicinity of both end edges in the longitudinal direction, so that each absorbing member is accurately arranged in a direction parallel to the primary X-ray. Is possible.

  According to the fourth aspect of the present invention, even when a foil-like X-ray absorbing material is used as a part of the absorbing member, the absorbing member can be disposed at a desired position.

  According to the invention described in claim 5, by rotating the support roller and tilting the plurality of absorbing members around the contact portion with the traction member, the plurality of absorbing members are arranged in a direction parallel to the primary X-ray. It becomes possible to arrange.

It is a schematic diagram which shows the X-ray imaging apparatus to which the grid 4 for scattered X-ray removal which concerns on this device is applied. It is a perspective view which shows the principal part of the grid 4 for scattered X-ray removal which concerns on 1st Embodiment of this invention. 4 is an explanatory diagram showing a relationship between the distance between the focal point of the X-ray tube 1 and the absorbing member 43 and the shape of the groove portion 42 formed in the support roller 41. It is a perspective view which shows the principal part of the grid for scattered X-ray removal which concerns on 2nd Embodiment of this invention. It is a front view of the absorption member 53 used for the grid for scattered X-ray removal which concerns on 2nd Embodiment. It is explanatory drawing which shows the state which has arrange | positioned the conventional grid 102 for scattered X-ray removal between the X-ray tube 100 and the X-ray detector 101. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an X-ray imaging apparatus to which a scattered X-ray removal grid 4 according to the present invention is applied.

  This X-ray imaging apparatus includes a table 3 on which a subject M is placed, an X-ray tube 1 that irradiates the subject M on the table 3 with X-rays, and a subject M that is irradiated from the X-ray tube 1. And an X-ray detector 2 such as a flat panel detector for detecting X-rays that have passed through, and a scattered X-ray removal grid 4 according to the present invention. The X-ray detector 2 and the scattered X-ray removal grid 4 are housed in the table 3.

  The scattered X-ray removal grid 4 has a converging type configuration that faces a direction corresponding to the SID by arranging a plurality of absorbing members 43 described later in parallel with the primary X-rays. Here, primary X-rays are X-rays irradiated to the subject M from the X-ray tube 1 and are compared with secondary X-rays (scattered rays) emitted from the subject. is there.

  FIG. 2 is a perspective view showing a main part of the scattered X-ray removal grid 4 according to the first embodiment of the present invention.

  The scattered X-ray removal grid 4 includes a support member 40 made of an X-ray transmitting material such as a carbon sheet, a plurality of long thin plate-like absorbing members 43 made of an X-ray absorbing material such as lead, A pair of support rollers 41 rotatably supported by a support mechanism (not shown). One side surface of each absorbing member 43 is inserted into a groove portion 44 formed in the support member 40, and the other side surface is engaged with a plurality of groove portions 42 formed in each of the pair of support rollers 41. Yes. In FIG. 2, seven absorbing members 43 are illustrated, but actually, a larger number of absorbing members 43 are provided.

  The groove portions 42 formed in the pair of support rollers 41 are formed in a direction intersecting with a plane orthogonal to the axis of the support roller 41. For this reason, when the pair of support rollers 41 rotate in synchronization, the plurality of absorbing members 43 tilt about the groove portion 44 formed in the support member 40, and the crossing angle with respect to the upper surface of the support member 40 is changed. The

  The crossing angle between each groove portion 42 and the plane orthogonal to the axis of the support roller 41 is arranged near both ends of the groove portion 42 that engages with the absorbing member 43 arranged near the center among the plurality of absorbing members 43. The groove portion 42 that engages with the absorbing member 43 is set to be larger, and the crossing direction of the groove portion 42 with respect to the groove portion 42 that engages with the absorbing member 43 disposed in the center among the plurality of absorbing members 43 is the absorbing member. 43 is opposite on both sides. For this reason, when a pair of support roller 41 rotates synchronously, the some absorption member 43 is inclined as the absorption member 43 arrange | positioned in the center part reaches the absorption member 43 arrange | positioned in both ends. And are inclined in directions opposite to each other centering on the absorbing member 43 disposed at the center thereof. And the shape of the groove part 42 formed in the support roller 41 is a direction parallel to a primary X-ray by rotating a pair of support roller 41 synchronously, when SID is changed. It is a shape that can be arranged in.

  FIG. 3 is an explanatory diagram showing the relationship between the distance between the focal point of the X-ray tube 1 and the absorbing member 43 and the shape of the groove 42 formed in the support roller 41. In this figure, only a pair of groove portions 42 arranged symmetrically with respect to the center portion of the support roller 41 is shown.

  In this figure, L1 indicates the maximum distance between the focal point of the X-ray tube 1 and the absorbing member 43 in the scattered X-ray removal grid 4, and L2 indicates the minimum distance between the focal point of the X-ray tube 1 and the absorbing member 43. Yes. P1 indicates the maximum pitch of the pair of grooves 42 arranged symmetrically, and P2 indicates the minimum pitch of the pair of grooves 42 arranged symmetrically. As shown in this figure, the groove portion 42 has a shape in which the pitch continuously changes from P1 to P2 in accordance with the change in the distance between the focal point of the X-ray tube 1 and the absorbing member 43. For convenience of explanation, FIG. 3 shows a case where the pitch of the groove 42 continuously changes from P1 to P2 in the front view of the support roller 41. For example, the support roller 41 is rotated by an angle of 180 degrees. In the case where the pitch of the groove portion 42 is changed from P1 to P2 during the process, the groove portion 42 in which the pitch continuously changes from P1 to P2 is formed in a region corresponding to an angle of 180 degrees on the outer peripheral surface of the support roller 41. That's fine.

  Then, the angle θ at which the support roller 41 should be rotated at the time of shooting can be obtained based on the following formula based on the SID at the time of shooting when the maximum rotation angle of the support roller is 180 degrees.

  θ = 180 × (SID at shooting−minimum SID) / (maximum SID−minimum SID)

  The groove 42 may have a shape having a certain depth from the outer peripheral surface of the support roller 41, or may be configured by forming a linear cut on the outer peripheral surface of the support roller 41. In the latter case, it is preferable to provide a guide member or the like so that the absorbing member 43 does not enter the groove portion 42 by a predetermined amount or more.

  In the scattered X-ray removal grid 4 having the above-described configuration, the plurality of absorbing members 43 are parallel to the primary X-rays by rotating the support roller 41 according to the SID and tilting the plurality of absorbing members 43. Can be arranged in any direction. For this reason, even when the SID changes, scattered X-rays can be efficiently removed with the cut-off amount being minimized.

  Next, another embodiment of the present invention will be described. FIG. 4 is a perspective view showing the main part of the scattered X-ray removal grid according to the second embodiment of the present invention. FIG. 5 is a front view of the absorbing member 53 used in the scattered X-ray removal grid according to the second embodiment.

  The absorbing member 53 used in the scattered X-ray removing grid according to the second embodiment has a configuration in which both end portions of the foil-like X-ray absorbing material 51 are supported by the thin plate member 52. A pair of thin plate members 52 that support both ends of each X-ray absorbing material 51 are provided with holes 54 (see FIG. 5). The outer diameter of the holes 54 is smaller than the inner diameter of the holes 54. A small pair of shafts 55 are inserted. The pair of shafts 55 are urged in directions away from each other by urging means such as a spring (not shown). For this reason, the pair of thin plate members 52 in each absorbing member 53 are pulled in directions away from each other by a pair of shafts 55 functioning as a pulling member, and the shape of the foil-shaped X-ray absorbing material 51 is kept constant. .

  A pair of support rollers 41 is disposed above the pair of thin plate members 52 in each absorbing member 53. The upper side surface of each thin plate member 52 is engaged with a groove portion 42 formed in the support roller 41 disposed above each thin plate member 52. A pair of support rollers 41 is also disposed below the pair of thin plate members 52 in each absorbing member 53. A lower side surface of each thin plate member 52 is engaged with a groove portion 42 formed in a support roller 41 disposed below each thin plate member 52.

  The groove portion 42 formed in the support roller 41 disposed above each thin plate member 52 has the same shape as that of the first embodiment described above. On the other hand, the groove portion 42 formed on the support roller 41 disposed below each thin plate member 52 is formed on the support roller 41 disposed above each thin plate member 52 with respect to a plane orthogonal to the support roller. The groove portion 42 has a shape inclined in the opposite direction.

  For this reason, when the four support rollers 41 are rotated in synchronization with each other, the upper side surface and the lower side surface of the pair of thin plate members 52 in each absorbing member 53 move in opposite directions. . Therefore, by rotating the four support rollers 41 in synchronization with each other, each absorbing member 53 can be tilted around the contact portion with the pair of shafts 55.

  As a result, similarly to the scattered X-ray removal grid 4 according to the first embodiment, the plurality of absorbing members 53 are tilted by rotating the support roller 41 in accordance with the SID, thereby tilting the plurality of absorbing members 53 to primary X-rays. It becomes possible to arrange | position in the direction parallel to. For this reason, even when the SID changes, scattered X-rays can be efficiently removed with the cut-off amount being minimized.

  In the first embodiment described above, the entire absorbing member 43 is made of an X-ray absorbing material, and in the second embodiment, the absorbing member 53 is made up of a foil-like X-ray absorbing material 51 and a thin plate member 52. Although configured, this may be reversed. When using a material that is relatively large and capable of being self-supporting, the entire absorbing member 43 can be composed of an X-ray absorbing member, and when using a material that is difficult to stand on, such as a foil shape, What is necessary is just to use the member which assists.

  Further, in the first embodiment described above, the pair of support rollers 41 is disposed near both ends of the absorbing member 43, but the support roller 41 may be single. However, it is possible to tilt the large number of absorbing members 43 with higher accuracy when the configuration in which the pair of support rollers 41 is disposed near both ends of the absorbing member 43 is employed.

  Furthermore, in the above-described embodiment, the scattered X-ray removal grid 4 according to the present invention is applied to a medical X-ray imaging apparatus that performs X-ray imaging of the subject M. The scattered X-ray removal grid 4 according to the present invention may be applied to an X-ray imaging apparatus or the like.

DESCRIPTION OF SYMBOLS 1 X-ray tube 2 X-ray detector 3 Table 4 Scattered X-ray removal grid 40 Support member 41 Support roller 42 Groove part 43 Absorbing member 44 Groove part 51 X-ray absorption material 52 Thin plate member 53 Absorbing member 54 Hole part 55 Shaft M Test Person

Claims (5)

A convergent scattered X-ray removal grid comprising a plurality of long thin plate-like absorbing members made of an X-ray absorbing material or arranged so as to be parallel to the primary X-ray. ,
By engaging with the side surface near the edge in the longitudinal direction of the plurality of absorbing members, a groove portion that defines the position of the side surface near the edge in each of the plurality of absorbing members is formed on the outer peripheral surface, A support roller configured to be rotatable around an axis,
The groove portion is formed in a direction intersecting with a plane orthogonal to the axis of the support roller, and the intersection angle is near the both ends from the groove portion engaged with the absorbing member arranged near the center among the plurality of absorbing members. The groove portion that engages with the absorbing member disposed in is set larger,
The scattered X-ray removal grid, wherein when the SID is changed, the plurality of absorbing members are arranged in a direction parallel to the primary X-rays by rotating the support roller. The scattered X-ray removal grid according to claim 1,
The plurality of absorbing members is a scattered X-ray removal grid in which one side surface is inserted into a groove portion formed in the support member and the other side surface engages with the groove portion formed in the support roller. The scattered X-ray removal grid according to claim 2,
The plurality of absorbing members are scattered X-ray removal grids respectively engaged with grooves formed in a pair of support rollers in the vicinity of both end edges in the longitudinal direction. The scattered X-ray removal grid according to claim 1,
Each of the plurality of absorbing members has a configuration in which both ends of the X-ray absorbing material are supported by a thin plate member,
A pair of thin plate members that support both ends of each X-ray absorbing material is a scattered X-ray removal grid that is pulled in a direction away from each other by a pulling member. The scattered X-ray removal grid according to claim 4,
Both side surfaces of the thin plate member are respectively engaged with grooves formed in support rollers arranged opposite to each other, and the thin plate member is tilted around a contact portion with the traction member, and the scattered X-ray removal grid .

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