JP2008173233A - Tomography apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tomography apparatus capable of easily and accurately removing scattered rays among X-rays which have transmitted through an object. <P>SOLUTION: The tomography apparatus includes two shielding plates 31a and 31b separately provided above the detection surface 13a of an FPD 13 and a shielding plate moving part 33 for moving the respective shielding plates 31a and 31b to the FPD 13, and an imaging control part 3 emits the X-rays while moving the shielding plates 31a and 31b so as to form an interval between them. An irradiation visual field is narrowed by a collimator 21 and the object M is irradiated with the X-rays. Of the X-rays that have transmitted through the object M, the scattered rays are shielded by the shielding plates 31a and 31b, and only the X-rays that have moved straight without being scattered are made to reach the detection surface 13a through a gap between the shielding plates 31a and 31b. Thus, the scattered rays of the X-rays that have transmitted through the object M are easily and accurately removed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tomographic apparatus that captures a subject and generates at least one of a tomographic image and tomographic volume data, and more particularly to a technique for easily removing scattered X-rays.

Conventionally, an imaging system of this type of apparatus includes an X-ray tube, a flat panel X-ray detector (hereinafter simply referred to as FPD as appropriate), a scattered radiation removal grid provided above the detection surface of the FPD, A C-shaped arm that supports the tube and the FPD so as to face each other and a rotation drive mechanism that rotates the arm are configured. In the scattered radiation removal grid, a foil such as lead that absorbs X-rays and an intermediate substance such as aluminum having high X-ray permeability are alternately arranged in parallel. By providing the scattered radiation removal grid configured as described above, among the X-rays transmitted through the subject, the X-rays scattered by the subject or the like are absorbed (removed) by the scattered radiation removal grid, and go straight without scattering. Only reaches the FPD. As a result, it is possible to prevent occurrence of artifacts due to scattered rays in the tomographic plane image or tomographic volume data generated based on the FPD detection result (see, for example, Patent Document 1).
JP 2006-280517 A

However, the conventional example having such a configuration has the following problems.
The conventional scattered radiation removal grid has the disadvantage that it is not easy to manufacture. In addition, in a tomographic apparatus that generates a tomographic image or the like, the distance in the direction in which X-rays are selectively transmitted through the scattered radiation removal grid, that is, the performance of removing scattered radiation improves as the height increases. However, there is an inconvenience that the higher the height of the scattered radiation removal grid, the more difficult it is to manufacture the scattered radiation removal grid.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a tomographic apparatus capable of easily and accurately removing scattered rays from X-rays transmitted through a subject. And

In order to achieve such an object, the present invention has the following configuration.
That is, according to the first aspect of the present invention, in the tomography apparatus for photographing a subject to generate at least one of a tomographic image and tomographic volume data, an irradiation unit for irradiating the subject with X-rays and the subject are transmitted X-rays which are provided separately from the detection means for detecting X-rays, the rotation means for rotating the irradiation means and the detection means in a state of being opposed to each other, and the detection surface of the detection means, and transmitted through the subject A moving means for moving each shielding plate relative to the detecting means in a moving direction intersecting a tomographic plane created by rotation of the irradiating means and the detecting means, the rotating means, The moving means and the irradiating means are controlled to rotate the irradiating means and the detecting means to move the shielding plate so that there is a gap at one or more places between the shielding plates. And an X-ray irradiation control unit that shoots the subject by causing the X-rays to enter an imaging region that is a part of the detection surface according to an interval formed between the shielding plates. And reconstruction means for performing reconstruction calculation processing based on detection data corresponding to the imaging area obtained from the detection means in each imaging, and generating at least one of a tomographic plane image and tomographic volume data. It is characterized by this.

  [Operation / Effect] According to the first aspect of the present invention, a plurality of shielding plates are provided above the detection surface of the detecting means, and the shielding plates are moved so that there is an interval at one or more places between the shielding plates. The scattered radiation can be easily removed from the X-rays that have passed through the subject M with a simple configuration that includes the moving means to be moved. In addition, literally a plate-shaped shielding plate is provided above the detection surface, so that when the detection surface is viewed from the front, the X-ray shielding area can be taken large and continuously, so that scattered radiation can be reliably and accurately detected. Can be removed. Further, since the moving means moves the shielding plate in the moving direction intersecting the tomographic plane, the imaging region moves in the direction intersecting with the rotation direction of the detecting means, and the detection data for generating the tomographic volume data is preferably used. Can be acquired.

  In the above-described invention, it is preferable that the imaging control unit controls the moving unit so that the imaging region moves over the entire detection surface for each imaging. The detection surface can be used effectively.

  In the above-described invention, it is preferable that the number of the shielding plates is two. Scattered rays can be removed with a simple structure.

  In the above-described invention, it is preferable that the space between the shield plates spaced apart is a space. Scattered rays can be removed with a simple structure.

  According to a fifth aspect of the present invention, in a tomography apparatus for photographing a subject and generating at least one of a tomographic plane image and tomographic volume data, an irradiating means for irradiating the subject with X-rays and the subject are transmitted. X-ray, which is provided with detection means for detecting X-rays, rotation means for rotating the irradiation means and the detection means in a state of being opposed to each other, and an elongated opening provided above the detection surface of the detection means A moving plate that moves the shielding plate relative to the detecting unit in a moving direction that intersects a tomographic plane formed by rotation of the irradiating unit and the detecting unit, the rotating unit, and the moving unit The irradiation means and the detection means are rotated, the shielding plate is moved, and the X-ray is irradiated to control the detection according to the opening. A tomographic plane that performs X-ray incidence on an imaging region that is a part of the plane, and performs reconstruction calculation processing based on detection data obtained from the detection means in each imaging, Reconstructing means for generating at least one of an image and tomographic volume data.

  [Operation / Effect] According to the invention described in claim 5, with a simple configuration including a shielding plate having an opening formed above the detection surface of the detection means and a moving means for moving the shielding plate. The scattered radiation can be easily removed from the X-rays transmitted through the subject M. In addition, literally a plate-shaped shielding plate is provided above the detection surface, so that when the detection surface is viewed from the front, the X-ray shielding area can be taken large and continuously, so that scattered radiation can be reliably and accurately detected. Can be removed. Further, since the moving means moves the shielding plate in the moving direction intersecting the tomographic plane, the imaging region moves in the direction intersecting with the rotation direction of the detecting means, and the detection data for generating the tomographic volume data is preferably used. Can be acquired.

  In the above-described invention, a collimator that is attached to the irradiation unit and changes the irradiation field of the X-ray irradiated to the subject, and the imaging control unit is further configured to irradiate the imaging region with X-rays. It is preferable to control the collimator. Irradiating an object with unnecessary X-rays can be avoided.

  In the above-described invention, it is preferable that the imaging control unit controls the moving unit so that the imaging region repeatedly moves on the detection surface in one direction of the moving direction (Claim 7). The amount by which the detection means is displaced every time an arbitrary position on the detection surface becomes the imaging region is the same regardless of the position of the detection surface. Therefore, there is no bias in the obtained detection data.

  In the above-described invention, it is preferable that the imaging control unit controls the moving unit so that each of a plurality of divided areas dividing the detection surface becomes the imaging area. Since the shooting areas do not overlap and move while touching, the subject can be shot efficiently.

  In the above-described invention, the imaging control unit performs the movement of the detection unit and the movement of the imaging region in parallel, and the apparatus performs interpolation for correcting each detection data according to the displacement of the detection unit for each imaging. Interpolating and synthesizing to obtain frame data corresponding to a projection image for one frame obtained from the entire detection surface when the detection means is stopped at an arbitrary position by performing processing and connecting the corrected detection data It is preferable that the reconstruction means performs the reconstruction calculation process based on the frame data obtained from the interpolation synthesis means. By providing the interpolating and synthesizing means, a plurality of detection data can be collected as frame data even when the movement of the detecting means and the movement of the photographing area are performed in parallel. As a result, the number of data to be reconstructed by the reconstruction means can be reduced, and the processing load on the reconstruction means can be reduced.

  In the above-described invention, it is preferable that the moving means is capable of moving the shielding plate to a position deviated from above the detection surface. It is possible to easily switch to imaging that detects X-rays over the entire detection surface.

  The present specification also discloses an invention relating to the following tomographic apparatus.

  (1) The tomographic apparatus according to any one of claims 1 to 10, wherein the moving direction is a direction substantially orthogonal to a tomographic plane.

  According to the invention described in (1) above, it is possible to more suitably acquire detection data for generating tomographic plane volume data.

  (2) The tomography apparatus according to any one of claims 1 to 10, wherein the detection means includes a plurality of detection elements arranged on the detection surface and configured to detect X-rays. Further, the tomography apparatus further comprises: a collection unit that collects detection results obtained from the detection elements in the imaging region as detection data for each imaging in cooperation with the imaging control unit.

  According to the invention as described in said (2), detection data can be suitably obtained from a detection means.

  (3) In the tomography apparatus according to any one of claims 1 to 4, an interval between the shielding plates is set so that the imaging region extends to both ends of the detection surface in parallel with the tomographic surface. A tomography apparatus characterized by forming.

  According to the invention described in (3) above, the detection surface can be used effectively.

  (4) In the tomography apparatus according to any one of claims 1 to 4, the apparatus includes a transmission allowing member that allows X-ray transmission between the shield plates spaced apart from each other. A tomographic apparatus characterized by comprising:

  According to the invention as described in said (4), an imaging | photography area | region can be formed suitably.

  (5) The tomographic apparatus according to claim 5, wherein the shielding plate is provided with openings so that the imaging region extends to both ends of the detection surface in parallel with the tomographic surface. Shooting device.

  According to the invention as described in said (5), a detection surface can be utilized effectively.

  (6) The tomography apparatus according to claim 5, wherein the opening provided in the shielding plate is single.

  According to the invention as described in said (6), it can be set as a simple structure.

  (7) The tomographic apparatus according to claim 5, wherein an opening provided in the shielding plate is a space.

  According to the invention as described in said (7), it can be set as a simple structure.

  (8) The tomography apparatus according to claim 5, wherein the apparatus includes a transmission allowing member that is disposed in an opening provided in the shielding plate and allows X-ray transmission. Tomography equipment.

  According to the invention as described in said (8), an imaging | photography area | region can be formed suitably.

  (9) In the tomography apparatus according to any one of claims 1 to 6, the imaging control unit includes the moving unit so that the imaging region reciprocates on the detection surface in the moving direction for each imaging. A tomographic apparatus characterized by controlling the tomography apparatus.

  According to the invention as described in said (9), the distance which a shielding board moves between each imaging | photography can be made constant, and imaging | photography can be performed efficiently.

  (10) In the tomography apparatus according to any one of claims 1 to 8, the imaging control unit changes the position of the detection unit each time the imaging region moves once over the entire detection surface, The apparatus includes combining means for joining detection data obtained when the detection means are at the same position and combining them into combined data, and the reconstruction means is the combining means obtained from the combining means. A tomography apparatus that performs the reconstruction calculation processing based on data.

  According to the invention described in the above (10), the synthesizing unit can combine a plurality of detection data as synthesized data by simply connecting the detection data obtained when the detection unit is at the same position. As a result, the number of data to be reconstructed by the reconstruction means can be reduced, and the processing load on the reconstruction means can be reduced.

  The tomographic apparatus according to the present invention includes a plurality of shielding plates above the detection surface of the detection means, and a moving means for moving the shielding plates so that there is a gap at one or more locations between the shielding plates. With a simple configuration, scattered rays can be easily removed from the X-rays transmitted through the subject. In addition, literally a plate-shaped shielding plate is provided above the detection surface, so that when the detection surface is viewed from the front, the X-ray shielding area can be taken large and continuously, so that scattered radiation can be reliably and accurately detected. Can be removed. In addition, since the moving means moves the shielding plate in the moving direction intersecting the tomographic plane, the detection area for moving the imaging area in the direction intersecting the rotation direction of the detecting means and generating tomographic plane volume data is preferable. Can be obtained.

Embodiment 1 of the present invention will be described below with reference to the drawings.
1 is an overall configuration diagram illustrating a tomography apparatus according to a first embodiment, FIG. 2 is a plan view schematically illustrating a detection surface of an FPD, and FIG. 3 is a configuration of a shielding plate and a shielding plate moving unit. FIG.

  The tomography apparatus according to this embodiment is divided into an imaging system 1, an imaging control unit 3, an image processing unit 5, and a monitor 7. The imaging system 1 includes an X-ray tube 11 that irradiates a subject M with X-rays, a flat panel X-ray detector (hereinafter abbreviated as “FPD”) 13 that detects X-rays transmitted through the subject M, a subject, A substantially C-shaped arm 15 that supports the X-ray tube 11 and the FPD 13 so as to face each other with M interposed therebetween, and a rotation drive mechanism 17 that rotates the arm 15 are provided. The rotation drive mechanism 17 is held in a base 19 that is fixedly installed on the floor. The rotation drive mechanism 17 rotates the arm 15 around one axis A so that the X-ray tube 11 and the FPD 13 rotate in the tomographic plane B. Therefore, one axis A is orthogonal to the tomographic plane B. Here, the X-ray tube 11 and the FPD 13 correspond to the irradiation means and the detection means in the present invention, respectively. The arm 15 and the rotation drive mechanism 17 correspond to the rotation means in this invention.

  The X-ray tube 11 is provided with a collimator 21 for adjusting the irradiation field of irradiated X-rays. The collimator 21 includes an aperture leaf 23 in which an opening that allows passage of X-rays is formed, and a leaf moving unit 25 that moves the aperture leaf 23 relative to the X-ray tube 11. The aperture provided in the aperture leaf 23 is single and has an elongated strip shape. As a material of the diaphragm leaf 23, a material having a high X-ray absorption rate is preferable. Specifically, lead etc. are illustrated.

  As shown in FIG. 2, the FPD 13 is held by the arm 15 so that its detection surface (front surface of the light receiving unit) 13 a is orthogonal to the tomographic plane B. The shape of the detection surface 13a is a rectangle, and one side thereof is always parallel to one axis A. As shown in FIG. 2, a plurality of detection elements d are arranged on the detection surface 13a in the direction of the one axis A and in the direction orthogonal thereto.

  Above the detection surface 13 a of the FPD 13, two shielding plates 31 a and 31 b that shield X-rays transmitted through the subject M are provided. The shielding plate moving unit 33 separates and holds the shielding plates 31a and 31b, and relatively moves the shielding plates 31a and 31b integrally with the FPD 13.

  As shown in FIG. 3, the size of each shielding plate 31a, 31b is slightly smaller than the detection surface 13a. However, the length L of each shielding plate 31a, 31b in the direction along the tomographic plane B (direction orthogonal to the one axis A) is the length L in the direction along the tomographic plane B of the detection surface 13a (direction orthogonal to the one axis A). Longer than length l. Such shielding plates 31a and 31b are arranged side by side in the uniaxial A direction. Therefore, a region C (hereinafter simply referred to as an imaging region) C on which the X-ray incidence is allowed according to the distance between the shielding plates 31a and 31b is parallel to the tomographic plane B. Extending to both ends of the detection surface 13a in a straight direction (a direction perpendicular to the one axis A). In addition, as a material of shielding board 31a, 31b, a substance with a high X-ray absorption rate is preferable, for example, lead etc. are illustrated. A space is provided between the shielding plates 31a and 31b.

  The shielding plate moving unit 33 includes a motor 35 and a screw shaft 37 that is connected to the motor 35 and disposed on one side of the shielding plates 31a and 31b. The screw shaft 37 is rotatably held by a bearing 45 so that its axis is parallel to one axis A and is rotatable. The bearing 45 is fixedly installed on the FPD 13. A first holding portion 39 is engaged with a screw portion of the screw shaft 37, and the first holding portion 39 is configured to be movable back and forth in the direction of the one axis A by the rotation of the screw shaft 37. The first holding part 39 holds one side part of the shielding plates 31a and 31b. One side portion on the opposite side of each of the shielding plates 31 a and 31 b is held by the second holding portion 41. In addition, these 1st, 2nd holding | maintenance parts 39 and 41 hold | maintain each shielding board 31a, 31b at intervals in the 1-axis A direction so that it may show in figure. The second holding portion 41 is slidably supported by a guide shaft 43 that is disposed opposite to and parallel to the screw shaft 37. The guide shaft 43 is also supported by the bearing 45. The shielding plate moving unit 33 configured as described above moves the shielding plates 31a and 31b back and forth in the direction of the one axis A while maintaining a constant distance from each other. Here, the shielding plate moving part 33 corresponds to the moving means in the present invention.

  Note that the opening provided in the diaphragm leaf 23 described above is formed in such a size that an irradiation field corresponding to the size and shape of the imaging region C can be obtained. Although a specific configuration of the leaf moving unit 25 is not illustrated, the leaf moving unit 25 is configured by a uniaxial drive mechanism similar to the shielding plate moving unit 33, and moves the diaphragm leaf 23 back and forth in the direction of the single axis A.

  The shooting control unit 3 comprehensively controls shooting of the subject M. Specifically, X-ray irradiation from the X-ray tube 11 is controlled via a high voltage generator (not shown). Further, the rotation drive mechanism 17 is controlled to rotate the X-ray tube 11 and the FPD 13. Further, the shielding plate moving unit 33 is controlled to move the two shielding plates 31a and 31b, and the leaf moving unit 25 is controlled so that the imaging region C is irradiated with X-rays.

  Please refer to FIG. FIG. 4 is a cross-sectional view schematically illustrating an example of movement control of the shielding plate and the diaphragm leaf. In the present embodiment, one side of the detection surface 13a parallel to one axis A is divided into three equal parts and divided into three regions (hereinafter simply referred to as divided regions) D1, D2, and D3. D3 is sequentially set as an imaging region C. For example, when the divided area D2 is the imaging area C, the shielding plates 31a and 31b and the aperture leaf 23 are positioned at the positions shown in FIG. Further, when moving the photographing area C from the divided area D2 to the divided area D3, the shielding plates 31a and 31b and the aperture leaf 23 are moved in synchronization with the positions shown in FIG. 4B.

  The image processing unit 5 includes a collection unit 51, an interpolation / synthesis unit 53, and a reconstruction unit 55. The collection unit 51 collects detection data corresponding to the imaging region C from the FPD 13 for each imaging. The interpolation synthesis unit 53 performs a predetermined interpolation process according to the displacement of the FPD 13 for each photographing for each detection data, and connects the detection data corrected by the interpolation process to obtain frame data. The reconstruction unit 55 performs reconstruction calculation processing based on the frame data, and generates at least one of a tomographic plane image and tomographic volume data of the subject M. The monitor 7 displays the tomographic plane image and the tomographic volume data tomographic image generated by the reconstruction unit 55.

  The image processing unit 5 is realized by a central processing unit (CPU) that reads and executes a predetermined program, a RAM (Random-Access Memory) that stores various information, a storage medium such as a fixed disk, and the like. The collection unit 51, the interpolation / synthesis unit 53, and the reconstruction unit 55 correspond to the storage unit, complementing unit, and reconstruction unit in the present invention, respectively.

  Next, the operation of the tomography apparatus according to Embodiment 1 will be described with reference to FIG. FIG. 5 is a flowchart showing a procedure of photographing by the imaging system and processing by the image processing unit.

<Step S <b>1> Shooting a Subject The shooting control unit 3 controls the rotation drive mechanism 17 to rotate the arm 15 around one axis A. As a result, the X-ray tube 11 and the FPD 13 rotate within the tomographic plane B. In addition, the imaging control unit 3 controls the leaf moving unit 25 and the shielding plate moving unit 33 to move the imaging region C to each of the divided regions D1 to D3. Further, every time the imaging region C is moved to each of the divided regions D1 to D3, X-rays are intermittently emitted from the X-ray tube 11.

  A part of cone beam-shaped X-rays irradiated from the X-ray tube 11 is shielded by the diaphragm leaf 23. Thereby, the irradiation field of the cone beam-shaped X-ray is narrowed down to the imaging region C, and the subject M is irradiated. Of the X-rays that have entered the subject M, X-rays that travel straight without scattering (hereinafter, referred to as direct X-rays as appropriate) pass between the shielding plate 31a and the shielding plate 31b and enter the detection surface 13a. . However, X-rays scattered by the subject M and changed in direction (hereinafter referred to as scattered rays as appropriate) are absorbed by the shielding plates 31a and 31b and do not reach the detection surface 13a. As a result, the FPD 13 detects only the X-rays directly in the imaging region C defined by the interval between the shielding plates 31a and 31b, and does not detect the X-rays on the detection surface 13a outside the imaging region C. .

  Please refer to FIG. FIG. 6 is a diagram schematically illustrating an example of the relationship between the X-ray tube and FPD positions and the imaging region in each imaging. 6A to 6D are front views when the tomographic plane B is viewed from the front, and the lower stage is a diagram illustrating the position of the shielding plate with respect to the detection surface of the FPD. Here, a case will be described in which the imaging region C is controlled so as to repeatedly move the divided regions D1 to D3 sequentially in one direction.

  As shown in FIG. 6, the FPD 13 is rotated and the shielding plates 31 a and 31 b are moved for each photographing. As a result, the position of the FPD 13 is displaced every time photographing is performed, and the range of the photographing region C on the detection surface 13a is also moved. Therefore, while the imaging region C moves once over the entire detection surface 13a, that is, when imaging for one frame is performed (for example, the period for performing imaging illustrated in FIGS. 6A to 6C). The position of the FPD 13 is also displaced. Then, when the imaging area C moves from one end side to the other end side of the detection surface 13a (see FIGS. 6A to 6C), the imaging area C returns to one end side (FIG. 6D). And the operation of moving from one end side to the other end side is repeated again.

<Step S2> Collecting Detection Data The collection unit 51 collects detection results from the FPD 13 for each photographing. At this time, the collection unit 51 handles only the detection result obtained from the detection element d in the shooting region C in each shooting as detection data in cooperation with the shooting control unit 3. Whether or not to collect the detection result from the detection element d that is out of the imaging region C in each imaging may be any, and is an item selected as appropriate. For example, when collecting uniformly from all the detection elements d, the collection unit 51 is configured to extract the detection data from the detection results of all the detection elements d with reference to the position information of the shielding plates 31a and 31b. Is done.

  Here, since the shooting area C in each shooting is a part of the detection surface 13a cut out at different positions, even if a group of detection data obtained by shooting for one frame is connected together. The projection image does not have a rectangular shape corresponding to the contour of the detection surface 13a.

  Please refer to FIG. FIG. 7A is a diagram schematically showing a positional deviation of detection data in each photographing. The vertical axis in the figure is the distance in the direction of one axis A, and the horizontal axis in the figure is the angle of the imaging area viewed from the one axis A (for example, in FIG. 4A, the imaging area is in the range of angle α to angle β. Equivalent). In FIG. 7A, the detection data obtained by each photographing is schematically shown with reference numerals e1 to e12. In addition, a group of detection data obtained by imaging for one frame is schematically shown with reference numerals f1 to f4. As is apparent from the figure, even between the detection data included in the group of detection data, the angular regions are shifted from each other in accordance with the displacement of the FPD 13 between the photographings.

<Step S3> Interpolation processing The interpolating / combining unit 53 detects, for each group of detection data obtained by photographing for one frame, another group obtained by photographing at an angle (position) adjacent thereto. Perform linear interpolation using the data. Then, the detection data corrected by this interpolation processing is connected to obtain frame data. This frame data would be obtained for one frame that would have been obtained if the FPD 13 was stationary at approximately the middle of each position of the FPD 13 when a group of detection data was obtained and the entire detection surface 13a was used for imaging. It corresponds to the projected image.

  FIG. 7B is a schematic diagram of frame data obtained from the detection data shown in FIG. In the figure, the frame data is schematically shown with reference numerals g1 to g3. For example, a group of detection data f1 and a group of detection data f2 obtained at an angle (position) adjacent thereto are interpolated and joined together to obtain frame data g1 at an angle (position) substantially between the two. Is calculated. Note that the outline of the frame data g1 has a rectangular shape like the detection surface 13a.

<Step S <b>4> Performing reconstruction processing The reconstruction unit 55 appropriately receives an image required by the operator, performs reconstruction calculation processing based on the frame data obtained from the interpolation synthesis unit 53, and produces a tomographic plane. Image or tomographic volume data or both are generated. Examples of the reconstruction calculation process include a process of performing convolution integration using an appropriate reconstruction function and backprojecting the result of convolution integration. The generated tomographic plane image or tomographic volume data is appropriately displayed on the monitor 7 based on an operator instruction or the like.

  As described above, according to the tomography apparatus according to the first embodiment, the scattered radiation among the X-rays transmitted through the subject M can be easily removed with a simple configuration using the two shielding plates 31a and 31b. Moreover, since the literally plate-shaped shielding plates 31a and 31b are provided above the detection surface 13a, the area for shielding X-rays can be increased continuously when the detection surface 13a is viewed from the front. It is not small and chopped like the foil of lead etc. provided in the scattered radiation removal grid. Therefore, scattered radiation can be reliably removed with high accuracy.

  The scattered radiation removal performance is determined by the ratio (grid ratio) between the opening width of the slit and the height of the shield. In the case of a conventional scattered radiation removing grid, an intermediate material is sandwiched between foils, and the direct material is attenuated by this intermediate material. Therefore, if the grid ratio is increased too much, direct X-ray attenuation by the intermediate substance becomes a problem. Therefore, the grid ratio cannot be increased. There are also air grids that do not sandwich intermediate materials. However, since the mechanical strength of the foil itself is limited, an air grid with a high grid ratio cannot be manufactured. On the other hand, in the case of the present invention, even if the shielding plates 31a and 31b are made high, the above-mentioned problem of direct X-ray attenuation and mechanical strength does not occur. Can be removed systematically.

  In addition, in the conventional tomography apparatus, since the removal of scattered radiation is insufficient with only the scattered radiation removal grid, there is a case where improvement is sometimes made by using the scattered radiation removal processing on software together. Then, it is not necessary to use the scattered radiation removal processing on such software together.

  In addition, since there is no space between the shielding plates 31a and 31b, compared to the case where the region that transmits X-rays is an intermediate material such as aluminum as in the conventional scattered radiation removal grid. Furthermore, it can be set as a simple structure.

  Further, by providing the shielding plate moving unit 33, the shielding plates 31a and 31b can be moved so that the imaging region C moves in the direction of the one axis A orthogonal to the tomographic plane B, and three-dimensional volume data is generated. It is possible to effectively acquire detection data for the purpose.

  In addition, the single shielding plate moving unit 33 is configured to move the shielding plates 31a and 31b in common, thereby moving the shielding plates 31a and 31b with a certain distance therebetween. Can do.

  Further, since the shielding plates 31a and 31b are spaced so that the imaging region C extends to both ends of the detection surface 13a in parallel with the tomographic plane B, the shielding plate moving unit 33 moves the imaging region C for each imaging. In this case, the distance to be moved to a position that does not overlap with the immediately preceding photographing area C is short, and the efficiency is high.

  In addition, by providing the shooting control unit 3, each of the divided areas D1 to D3 sequentially becomes the shooting area C. Therefore, the shooting areas C do not overlap each other and are in contact with each other, so that the subject M can be shot efficiently. can do.

  In addition, by providing the imaging control unit 3, the imaging area C repeats moving each of the divided areas D1 to D3 sequentially in one direction, so the displacement amount of the FPD 13 for each imaging in which the divided area D1 becomes the imaging area C is The divided areas D2 and D3 are the same as the displacement amount of the FPD 13 for each photographing in which the photographing area C is obtained. Therefore, the amount by which the angle area of the imaging area C changes during each imaging to obtain the detection data e1, e4,... From the divided area D1 is detected data e2, e5,. -It is equal to the amount of change in the angular area of the imaging area C between each imaging to obtain (e3, e6, ...). That is, there is no bias in the detection data obtained depending on the position of the imaging region C with respect to the detection surface 13a.

  In addition, by providing the interpolation / synthesis unit 53, a group of detection data obtained by photographing for one frame can be collected as frame data. As a result, the number of data to be subjected to reconstruction calculation processing such as back projection by the reconstruction unit 55 can be reduced, and the processing load on the reconstruction unit 55 can be reduced.

  Further, by providing the collimator 21 (the aperture leaf 23 and the leaf moving unit 25 that moves the collimator leaf 21), the irradiation field can be set as the imaging region C, and unnecessary X that cannot reach the imaging region C directly as X-rays. Irradiating the subject M with a line can be avoided. Thereby, the exposure amount of the subject M can be reduced. Further, there is no possibility that X-rays that cannot reach the imaging region C are scattered and reach the imaging region C.

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

  (1) In the above-described embodiment, the configuration includes the two shielding plates 31a and 31b, but is not limited thereto. For example, you may comprise so that the shielding board in which the elongate opening which accept | permits transmission of X-rays was formed was provided.

  This will be described with reference to FIG. FIG. 8 is a plan view of the shielding plate and the shielding plate moving part provided in the tomography apparatus according to the modification. As shown in FIG. 8A, the shielding plate 32 has an elongated opening H that allows X-ray transmission. According to such a shielding plate 32, the imaging region C can be formed on a part of the detection surface 13 a of the FPD 13 with one shielding plate 32.

  Moreover, you may comprise so that three or more shielding plates may be provided. In this case, there are a plurality (two or more) between the shielding plates, but a gap may be provided at one place, or a gap may be provided at a plurality of places.

  When three or more shielding plates are provided, three or more shielding plates may be moved one by one, and locations between the shielding plates provided with a gap may be sequentially shifted. .

  (2) In the above-described embodiment, the interval provided between the two shielding plates 31a and 31b is a space, but is not limited thereto. For example, a transmission allowing member made of a substance with little X-ray absorption may be provided between the two shielding plates 31a and 31b. Examples of the material of the permeation allowing member include aluminum. By comprising in this way, a permeation | transmission permissible member can be functioned as a spacer for keeping the space | interval between shielding board 31a, 31b constant.

  (3) In the above-described embodiment, the shielding plate moving unit 31 is moved while keeping the distance between the two shielding plates 31a and 31b constant, but is not limited thereto. For example, this interval may be appropriately expanded and contracted. Specifically, the imaging region C may be widened by configuring the shielding plate moving unit so as to include a plurality of uniaxial drive mechanisms that individually move the two shielding plates 31a and 31b.

  Correspondingly, the collimator 21 is configured so that the opening width and the like provided in the diaphragm leaf 23 can be expanded and contracted so that the size and shape of the X-ray illumination field can be changed according to the imaging region C. It may be changed.

  (4) In the above-described embodiment, the shielding plate moving unit 33 moves the shielding plates 31a and 31b so that the projection area C moves on the detection surface 13a. However, the invention is not limited to this. For example, the shielding plate moving unit may be configured to be retractable to a position where the shielding plate is removed from above the detection surface 13a. Specifically, as shown in FIG. 8B, a shielding plate moving unit 34 configured to be able to move the shielding plate 32 to a position off the detection surface 13a is configured. Thereby, it can be easily switched to detect X-rays on the entire detection surface 13a. Note that the conventional scattered radiation removal grid is fixedly attached above the detection surface 13a, and the operation of removing this from the FPD 13 is manually performed by the operator himself. Therefore, the imaging conditions are easily switched as described above. I can't.

  (5) In the above-described embodiment, the imaging control unit 3 performs control so that the divided areas D1 to D3 sequentially become the imaging area C, but is not limited thereto. For example, the imaging area C may be controlled to move for each imaging so that a plurality of different imaging areas C overlap each other.

  (6) In the above-described embodiment, the imaging control unit 3 controls the imaging area C to repeat the operation of sequentially moving the divided areas D1 to D3 in one direction, but the present invention is not limited to this. For example, the imaging area C may be controlled so as to sequentially reciprocate in the divided directions D1 to D3 in both directions.

  (7) In the above-described embodiment, the FPD 13 is rotated in parallel when the photographing region C is moved and one frame is photographed. However, the present invention is not limited to this. For example, when the photographing area C is moved and one frame is photographed, the FPD 13 may be controlled to be stationary, and the FPD 13 may be rotated every time one frame is photographed. According to this, since the angle range of the imaging region C corresponding to each detection data included in the group of detection data is equal, the interpolation processing described in the embodiment is not required, and the interpolation / synthesis unit 53 can be omitted. . In this case, the detection data obtained when the FPD 13 is at the same position is connected as it is, and a synthesis unit for combining the detection data is provided, so that the reconstruction unit 55 performs the reconstruction calculation process based on the synthesis data. It may be changed.

  (8) In the above-described embodiment, the interpolation / synthesis unit 53 is provided, but the present invention is not limited to this. In other words, the interpolation / synthesis unit 53 may be omitted, and the reconstruction unit 55 may be configured to directly perform the reconstruction calculation process based on the detection data.

  (9) In the above-described embodiment, the collimator 21 moves the irradiation field irradiated from the X-ray tube 11, but this is not restrictive. For example, the X-ray tube 11 may be provided on the arm 15 so as to be able to swing, and the X-ray irradiation field of view may be moved. Further, the X-ray tube 11 may be provided on the arm 15 so as to be movable in the direction of the single axis A so as to move the X-ray irradiation field. According to each of such modifications, it is possible to prevent the detection data at the end portion from being distorted as compared to the central portion of the detection surface 13a.

  (10) In the above-described embodiment, the imaging control unit 3 controls the X-ray tube 11 to intermittently irradiate X-rays for each imaging, but this is not restrictive. For example, the X-ray tube 11 may be controlled so as to continuously irradiate X-rays.

  (11) In the above-described embodiment, the description has been made so that the shielding plates 31a and 31b are spaced apart so that the imaging region C has an elongated shape in a direction parallel to the tomographic plane B. However, the present invention is not limited to this. For example, the imaging region C is a matter that can be appropriately selected as long as it is not a shape that extends in a direction parallel to the axis A. Moreover, although the shielding-plate moving part 33 was moved to the 1-axis A direction orthogonal to the tomographic plane B, it is not restricted to this. For example, as long as the direction intersects the tomographic plane B, the shielding plate moving unit 33 may be changed so that the shielding plates 31a and 31b are moved in an appropriate movement direction. In response to this, the leaf moving unit 25 may be changed to move the diaphragm leaf 23 in an appropriate direction intersecting the tomographic plane B.

  (12) Although the FPD 13 is used in the above-described embodiment, an image intensifier, a multi-row detector, or the like may be used as the present invention.

  (13) In the above-described embodiments, the tomography apparatus is for medical use, but is not limited thereto. For example, the present invention can also be applied to tomography apparatuses used in industrial fields such as non-destructive inspection, RI (Radio Isotope) inspection, and optical inspection, and in the nuclear field. In each embodiment, the subject M is described, but the subject M is not limited to the human body.

  (14) You may combine each modification mentioned above suitably.

1 is an overall configuration diagram illustrating a tomography apparatus according to Embodiment 1. FIG. It is a top view which shows typically the detection surface of FPD. It is a top view which shows the structure of a shielding board and a shielding board moving part. It is sectional drawing which shows typically an example of the movement control of a shielding board and an aperture leaf. It is a flowchart which shows the procedure of imaging | photography by an imaging system, and the process by an image process part. It is a figure which shows typically an example of the relationship between the position of X-ray tube and FPD and imaging | photography area | region in each imaging | photography, The upper stage of FIG. 6 (a)-(d) is a front view when the tomographic plane is seen in front The lower row shows the position of the shielding plate with respect to the detection surface of the FPD. FIG. 7A is a diagram schematically showing a positional deviation of detection data in each photographing, and FIG. 7B is a schematic diagram of frame data obtained from the detection data shown in FIG. is there. It is a top view of the shielding board and shielding board moving part with which the tomography apparatus which concerns on a modification is provided.

Explanation of symbols

3 ... Imaging control unit 11 ... X-ray tube 13 ... Flat panel X-ray detector (FPD)
13a ... Detection surface 15 ... Arm 17 ... Rotation drive mechanism 21 ... Collimator 31a, 31b, 32 ... Shield plate 33, 34 ... Shield plate moving part 51 ... Collection part 53 ... Interpolation composition part 55 ... Reconstruction part A ... Single axis B ... Tomographic plane C ... Imaging region D1, D2, D3 ... Divided region d ... Detection element

Claims (10)

  In a tomography apparatus for photographing a subject and generating at least one of a tomographic plane image and tomographic volume data, an irradiating unit for irradiating the subject with X-rays, a detecting unit for detecting X-rays transmitted through the subject, and the irradiation A rotating means for rotating the means and the detecting means facing each other, a plurality of shielding plates provided separately above the detection surface of the detecting means for shielding X-rays transmitted through the subject, and the irradiation A moving means for moving each shielding plate relative to the detecting means in a moving direction intersecting a tomographic plane created by rotation of the detecting means and the detecting means, and controlling the rotating means, the moving means and the irradiating means. The irradiation means and the detection means are rotated, the shielding plate is moved so that there is a gap at one or more places between the shielding plates, and X-rays are irradiated, An imaging control means for imaging an object by making an X-ray incident on an imaging area that is a part of the detection surface according to an interval provided between shielding plates, and the detection means obtained from the detection means in each imaging A tomography apparatus comprising: a reconstruction unit that performs reconstruction calculation processing based on detection data corresponding to an imaging region and generates at least one of a tomographic plane image and tomographic volume data. The tomography apparatus according to claim 1,
The tomography apparatus, wherein the imaging control unit controls the moving unit so that the imaging region moves over the entire detection surface for each imaging.   The tomography apparatus according to claim 1 or 2, wherein the number of the shielding plates is two.   4. The tomography apparatus according to claim 1, wherein a space is provided between the shield plates spaced apart from each other.   In a tomography apparatus for photographing a subject and generating at least one of a tomographic plane image and tomographic volume data, an irradiating unit for irradiating the subject with X-rays, a detecting unit for detecting X-rays transmitted through the subject, and the irradiation A rotating means for rotating the means and the detecting means facing each other, a shielding plate provided above the detection surface of the detecting means and formed with an elongated opening for shielding X-rays, the irradiation means, and A moving means for moving the shielding plate relative to the detecting means in a moving direction intersecting a tomographic plane created by the rotation of the detecting means; and the rotating means, the moving means and the irradiation means, The irradiation means and the detection means are rotated, the shielding plate is moved, and X-rays are irradiated so that X is applied to an imaging region that is a part of the detection surface corresponding to the opening. Is input, and a reconstruction control process is performed on the basis of detection data obtained from the detection unit in each imaging to generate at least one of a tomographic plane image and tomographic volume data A tomography apparatus comprising: a reconstruction unit.   The tomography apparatus according to any one of claims 1 to 5, further comprising: a collimator attached to the irradiation unit and configured to change an irradiation field of an X-ray irradiated to a subject, the imaging control unit comprising: Furthermore, the tomography apparatus is characterized in that the collimator is controlled so that the imaging region is irradiated with X-rays.   7. The tomography apparatus according to claim 1, wherein the imaging control unit controls the moving unit so that the imaging region repeatedly moves on the detection surface in one direction of the moving direction. A tomography apparatus characterized by controlling.   8. The tomography apparatus according to claim 1, wherein the imaging control unit controls the moving unit such that each of a plurality of divided areas dividing the detection surface becomes the imaging area. 9. A tomographic apparatus characterized by that.   9. The tomography apparatus according to claim 1, wherein the imaging control unit performs movement of the detection unit and movement of the imaging region in parallel, and the apparatus detects the detection for each imaging. One frame obtained from the entire detection surface when interpolation processing is performed to correct each detection data according to the displacement of the means, and the corrected detection data is joined and the detection means is stopped at an arbitrary position. Interpolating and synthesizing means for obtaining frame data corresponding to a projected image of minutes, and the reconstructing means performs the reconstruction calculation processing based on the frame data obtained from the interpolating and synthesizing means. Tomography equipment.   10. The tomography apparatus according to claim 1, wherein the moving unit is capable of moving the shielding plate to a position deviated from above the detection surface. 11.

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