JP2006212173A - X-ray apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compensate the slowness of the output response speed of an FPD at the time of detecting a conical X-ray beam transmitted through a subject. <P>SOLUTION: A beam width XL to a direction along the moving route of the conical X-ray beam XA at the time of scanning for gathering X-ray detection data is made shorter than the width XD of the X-ray detection surface Xa of the FPD 2, a beam transverse direction RX is added to the conical X-ray beam XA, the constitution of relatively sliding the conical X-ray beam XA in the beam transverse direction RX to the X-ray detection surface Xa in synchronism with the scanning for gathering data is provided further, the detection area of the X-ray beam on the X-ray detection surface Xa of the FPD 2 is changed every moment accompanying the progress of the scanning for gathering the X-ray detection data, and thus the storage of the read residual of the X-ray detection data which can not be read all from the FPD 2 is suppressed. As a result, the afterimage of the FPD due to the slowness of the output response speed of the FPD 2 is weakened and the slowness of the output response speed of the FPD is compensated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is for obtaining an X-ray tomographic image by detecting a cone-shaped X-ray beam that is disposed opposite to an X-ray irradiation unit that irradiates a subject with a cone-shaped X-ray beam and sandwiches the subject. The two-dimensional X-ray detection means for outputting the X-ray detection data is moved along with the X-ray detection data collection scan by the X-ray imaging system scanning means, and the irradiation of the cone-shaped X-ray beam and the X-ray detection data The present invention relates to an X-ray imaging apparatus that performs output, and more particularly, to a technique for compensating for a slow output response speed of a two-dimensional X-ray detection means when detecting a cone-shaped X-ray beam that has passed through a subject to be imaged.

  As one of X-ray imaging apparatuses capable of capturing an X-ray tomographic image of a subject, there is an X-ray CT apparatus already used in a hospital or the like. In the case of a conventional X-ray CT apparatus, as shown in FIG. 10, the X-ray tube 61A and the X-ray diaphragm 61B are provided, and an X-ray that irradiates a subject M on the top BD with a cone-shaped X-ray beam XB. An X-ray CT image (X-ray tomographic image) is detected by detecting a cone-shaped X-ray beam XB that is placed opposite to the X-ray irradiation unit 61 with the irradiation unit 61 and the subject M sandwiched between the top plate BD and transmitted through the subject M. ) A flat panel X-ray detector (two-dimensional X-ray detector) 62 that outputs X-ray detection data for acquisition, and an X-ray irradiation unit 61 and a flat panel X-ray detector (hereinafter referred to as “FPD” as appropriate). The X-ray detection data collection scan is performed in which the object 62 is moved in a reciprocal orbit around the object M over an angle of 180 ° or more with the object M interposed therebetween in the state of being opposed to each other. It is supposed to be configured.

In the case of X-ray imaging by a conventional X-ray CT apparatus, the X-ray irradiation unit 61 and the FPD 62 are kept facing each other as the X-ray detection data collection scan is performed. As shown in a) to (c), irradiation of the cone-shaped X-ray beam XB and output of X-ray detection data for X-ray CT image acquisition are performed while circulating around the subject M over 180 °.
In the subsequent stage of the FPD 62, X-ray detection data output from the FPD 62 is collected, and the collected X-ray detection data is reconstructed by a computer calculation method according to a reconstruction algorithm, and the subject M is virtually processed. CT image data is obtained for the pixel signal of the X-ray CT image with respect to the three-dimensional lattice point matrix set to.
Then, according to the CT image data obtained for the three-dimensional lattice point matrix, an X-ray CT image for the cross section of the subject M to be imaged is acquired.

The X-ray CT image acquired in this way is displayed on a screen of an image display monitor (not shown) or printed by a printer (not shown) to be used for diagnosis by an operator or a doctor (for example, Patent Document 1). See).
In the case of a conventional X-ray CT apparatus, since a cone-shaped X-ray beam XB equivalent to a bundle of a large number of fan-shaped X-ray beams is irradiated, a large number of subjects M can be obtained by a single X-ray detection data collection scan. X-ray detection data for the cross section (slice plane) can be collected.

In addition, as an X-ray imaging apparatus that captures an X-ray tomographic image of the subject M that is irradiated with the cone-shaped X-ray beam XB, an X-ray tube and an FPD are each one of the subject M during X-ray detection data collection scanning. X-ray detection is performed after the FPD by irradiating a cone-shaped X-ray beam and outputting X-ray detection data for X-ray tomographic image acquisition while moving along a non-circular orbit set on the other side There is also an apparatus that acquires an X-ray tomographic image by performing an integration process on data for each pixel (see, for example, Patent Document 2).
In the case of this X-ray imaging apparatus, X-ray detection data collection scanning can be performed without moving the X-ray tube and FPD around the subject over 180 ° or more.

JP-A-9-298687 (pages 5-6, FIGS. 1-3) JP 2000-79119 A (page 4, FIGS. 5 to 8)

  However, the conventional X-ray imaging apparatus has a problem that the output response speed of the FPD 62 that detects the cone-shaped X-ray beam XB is slow. Specifically, in the case of the conventional apparatus, X-ray detection data for X-ray tomographic image acquisition is repeatedly read out from the FPD 62 every predetermined time and collected, but X-ray detection data is acquired at a high speed (fast speed rate). Are collected one after another because of the slow output response speed of the FPD 62 (the time lag is large), and the remainder of the X-ray detection data that cannot be read out appears as an afterimage (burn-in) on the FPD 62. The afterimage of the FPD 62 causes inconveniences such as an artifact (false image) that causes image quality degradation in the finally acquired X-ray tomographic image.

  The present invention has been made in view of such circumstances, and the output response speed of the two-dimensional X-ray detection means when detecting the cone-shaped X-ray beam transmitted through the subject to be imaged is slow. An object of the present invention is to provide an X-ray imaging apparatus capable of supplementing.

In order to achieve such an object, the present invention has the following configuration.
That is, the X-ray imaging apparatus according to the first aspect of the present invention is a cone-shaped device that is disposed opposite to an X-ray irradiating unit that irradiates a subject with a cone-shaped X-ray beam and sandwiches the subject and transmits the subject. A subject in which the two-dimensional X-ray detection means for detecting the X-ray beam and outputting X-ray detection data for acquiring an X-ray tomographic image, the X-ray irradiation means, and the two-dimensional X-ray detection means remain in an opposing arrangement state. X-ray imaging system scanning means for performing scanning for collecting X-ray detection data by moving the X-ray detection data, and the X-ray irradiation means and the two-dimensional X-ray detection means collect X-ray detection data by the X-ray imaging system scanning means. In an X-ray imaging apparatus that irradiates a cone-shaped X-ray beam and outputs X-ray detection data while moving synchronously by scanning for scanning, along the moving path of the cone-shaped X-ray beam at the time of scanning for collecting X-ray detection data Of cone-shaped X-ray beam with respect to different directions X-ray beam width limiting means for making the cone width shorter than the width of the X-ray detection surface of the two-dimensional X-ray detection means so that the cone-shaped X-ray beam has a shorter direction, and synchronization with X-ray detection data collection scanning The X-ray beam synchronizing slide means for sliding the cone-shaped X-ray beam relative to the X-ray detection surface in the beam short direction is provided.

  [Operation / Effect] When performing X-ray imaging by the X-ray imaging apparatus according to the first aspect of the present invention, an X-ray irradiating means for irradiating a subject with a cone-shaped X-ray beam by an X-ray imaging system scanning means; The two-dimensional X-ray detection means that detects the cone-shaped X-ray beam that has passed through and outputs the X-ray detection data for acquiring the X-ray tomographic image is moved in the state of being opposed to the X-ray detection means. A scan for collecting line detection data is performed. The X-ray irradiation means and the two-dimensional X-ray detection means perform irradiation with a cone-shaped X-ray beam and output of X-ray detection data while moving synchronously by scanning for X-ray detection data collection by the X-ray imaging system scanning means.

In the case of the X-ray imaging apparatus according to the first aspect of the present invention, the cone-shaped X-ray in the direction along the moving path of the cone-shaped X-ray beam during the X-ray detection data collection scan is obtained by the X-ray beam width limiting means. In addition to the beam width of the beam being made shorter than the width of the X-ray detection surface of the two-dimensional X-ray detection means, the cone-shaped X-ray beam has a beam short direction, and the X-ray beam synchronization slide means The cone-shaped X-ray beam is slid relative to the X-ray detection surface in the beam short direction in synchronization with the line detection data acquisition scan.
As a result, the detection area of the X-ray beam on the X-ray detection surface of the two-dimensional X-ray detection means changes with the progress of the X-ray detection data acquisition scan, so that the reading from the two-dimensional X-ray detection means is not completed. Accumulation of the read residue of the X-ray detection data generated is suppressed, and the output response speed of the two-dimensional X-ray detection means when detecting the cone-shaped X-ray beam transmitted through the subject to be imaged is slow. The degree of afterimage generated in the two-dimensional X-ray detection means is weaker than before.

Further, since the beam width of the cone-shaped X-ray beam only needs to be shortened with respect to the direction along the moving path of the cone-shaped X-ray beam associated with the X-ray detection data acquisition scan, the moving path of the cone-shaped X-ray beam. It is not necessary to shorten the direction not along the line, and the scanning area by the X-ray detection data collection scan is not narrowed.
Therefore, according to the X-ray imaging apparatus of the first aspect of the invention, it is compensated that the output response speed of the two-dimensional X-ray detection means when detecting the cone-shaped X-ray beam transmitted through the subject to be imaged is slow. Can do.

  An X-ray imaging apparatus according to a second aspect of the present invention is the X-ray imaging apparatus according to the first aspect, wherein the X-ray beam synchronization slide means synchronizes the two-dimensional X-ray detector with the X-ray detection data collection scan and The cone X-ray beam is slid relative to the X-ray detection surface relative to the X-ray detection surface by moving the X-ray beam in the beam short direction.

  [Operation / Effect] In the case of the apparatus of the invention of claim 2, the cone-shaped X-ray beam is slid relative to the X-ray detection surface relative to the X-ray detection surface by moving the two-dimensional X-ray detector. . As a result, since the X-ray irradiation optical system can maintain the same configuration during the X-ray detection data acquisition scan, X-ray detection data for X-ray tomographic image acquisition can be acquired without any change in the X-ray irradiation optical system.

  According to a third aspect of the present invention, there is provided the X-ray imaging apparatus according to the first aspect, wherein the X-ray beam synchronizing slide means synchronizes the X-ray beam width limiting means with the X-ray detection data collection scan and the cone. The cone X-ray beam is slid relative to the X-ray detection surface relative to the X-ray detection surface by moving the X-ray beam in the beam short direction.

  [Operation and Effect] In the case of the apparatus of the invention of claim 3, the cone-shaped X-ray beam is moved with respect to the X-ray detection surface by moving the X-ray beam width limiting means which is smaller and lighter than the two-dimensional X-ray detector. Is relatively slid in the beam transverse direction, and the cone-shaped X-ray beam can be easily slid relative to the X-ray detection surface.

  An X-ray imaging apparatus according to a fourth aspect of the present invention is the X-ray imaging apparatus according to any one of the first to third aspects, wherein the X-ray beam width limiting means sets the beam width of the cone-shaped X-ray beam in the beam short direction. The two-dimensional X-ray detection means is shortened in the range of ½ or less to ¼ or more of the width of the X-ray detection surface of the two-dimensional X-ray detection means. The line beam is slid from one edge to the other edge of the X-ray detection surface.

[Operation / Effect] In the case of the apparatus of the invention of claim 4, the beam width of the cone-shaped X-ray beam is the X-ray of the two-dimensional X-ray detection means in the beam short direction along the moving path of the cone-shaped X-ray beam. The range of the detection surface is ½ or less to ¼ or more of the width of the detection surface, and the cone-shaped X-ray beam is slid from one edge of the X-ray detection surface to the other edge along with the X-ray detection data collection scan. In addition, there is no area where the cone-shaped X-ray beam is constantly irradiated during the X-ray detection data acquisition scan, and as a result, the accumulation of X-ray detection data read residue over the entire X-ray detection surface is suppressed.
It should be noted that the beam width of the cone-shaped X-ray beam is set to 1/2 or less of the width of the X-ray detection surface when the beam width exceeds 1/2 of the width of the X-ray detection surface. This is because the area where the cone-shaped X-ray beam is constantly irradiated during scanning cannot be completely eliminated. The cone width of the X-ray beam is set to 1/4 or more of the width of the X-ray detection surface when the beam width is less than 1/4 of the width of the X-ray detection surface. This is because the merit of the cone-shaped X-ray beam that can collect a large amount of X-ray detection data by the acquisition scan is not sufficient.

  An X-ray imaging apparatus according to a fifth aspect of the present invention is the X-ray imaging apparatus according to any one of the first to fourth aspects, wherein the X-ray imaging system scanning means performs X-ray irradiation during the X-ray detection data collection scan. The X-ray irradiating means and the two-dimensional X-ray detecting means are moved along a circular orbit around the subject over an angle of 180 ° or more.

  [Operation / Effect] In the case of the apparatus of the invention of claim 5, the X-ray irradiation means and the two-dimensional X-ray detection means travel around the subject over 180 ° or more in accordance with the X-ray detection data acquisition scan. Since X-ray beam irradiation and X-ray detection data output are performed, X-ray detection data for X-ray tomographic image acquisition can be sufficiently collected.

  In the case of the X-ray imaging apparatus according to the first aspect of the present invention, the beam width of the cone-shaped X-ray beam with respect to the direction along the moving path of the cone-shaped X-ray beam at the time of scanning for collecting X-ray detection data is detected two-dimensionally. The cone-shaped X-ray beam is made shorter than the width of the X-ray detection surface of the means so that the short side direction of the cone-shaped X-ray beam is in addition to the X-ray detection surface. The X-ray beam is configured to be relatively slid in the beam short direction. As a result, the detection area of the X-ray beam on the X-ray detection surface of the two-dimensional X-ray detection means changes with the progress of the X-ray detection data acquisition scan, so that the reading from the two-dimensional X-ray detection means is not completed. Accumulation of the readout residue of the X-ray detection data generated is suppressed, and the output response speed of the two-dimensional X-ray detection means is slow when detecting the cone-shaped X-ray beam transmitted through the subject to be imaged. The afterimage generated in the two-dimensional X-ray detection means is weaker than before.

Further, since the beam width of the cone-shaped X-ray beam only needs to be shortened with respect to the direction along the moving path of the cone-shaped X-ray beam associated with the X-ray detection data acquisition scan, the moving path of the cone-shaped X-ray beam. It is not necessary to shorten the direction not along the line, and the scanning area by the X-ray detection data collection scan is not narrowed.
Therefore, according to the X-ray imaging apparatus of the first aspect of the invention, it is compensated that the output response speed of the two-dimensional X-ray detection means when detecting the cone-shaped X-ray beam transmitted through the subject to be imaged is slow. Can do.

A first embodiment of the X-ray imaging apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating the overall configuration of the X-ray imaging apparatus according to the first embodiment.
As shown in FIG. 1, the X-ray fluoroscopic apparatus according to the first embodiment includes an X-ray tube 1A and an X-ray diaphragm 1B, and irradiates a subject M on a top BD with a cone-shaped X-ray beam XA. An X-ray CT image (X-ray) is detected by detecting a cone-shaped X-ray beam XA that is disposed opposite to the X-ray irradiation unit 1 with the X-ray irradiation unit 1 and the subject M sandwiched between the top plate BD and transmitted through the subject M. An X-ray imaging system comprising a flat panel X-ray detector (hereinafter abbreviated as “FPD” where appropriate) 2 which is a two-dimensional X-ray detector for outputting X-ray detection data for acquisition. As the scan for collecting the line detection data is performed, the X-ray tube 1 and the FPD 2 are kept facing each other and the subject M is interposed therebetween so that the circumference of the subject M is 180 ° or more (for example, 180 ° or 360 °). It is configured to be moved along a circular orbit traversing over an angle.

As described above, in the apparatus of the first embodiment, the X-ray irradiation unit 1 and the FPD 2 travel around the subject M over 180 ° or more along the X-ray detection data collection scan, and the irradiation with the cone-shaped X-ray beam XA and the X Since X-ray detection data is output, X-ray detection data for X-ray tomographic image acquisition can be collected sufficiently.
In the following, for convenience of explanation, the case where the X-ray irradiation unit 1 and the FPD 2 travel around the subject M at an angle of 180 ° during the X-ray detection data collection scan will be described.

  In the case of the apparatus according to the first embodiment, the X-ray irradiation unit 1 and the FPD 2 are disposed opposite to the rotating ring 3 having an inner diameter that allows the subject M to enter the inside together with the top BD. During scanning for X-ray detection data collection, the ring rotation mechanism unit 4 rotates the rotating ring 3 in the circumferential direction of the rotating ring 3 indicated by the arrow RA in accordance with the control of the imaging system scanning control unit 5. The X-ray irradiation unit 1 irradiates the cone-shaped X-ray beam XA according to the control of the X-ray irradiation control unit 6 while the X-ray irradiation unit 1 and the FPD 2 go around the subject M as the rotating ring 3 rotates. At the same time, the FPD 2 detects the cone-shaped X-ray beam XA transmitted through the subject M and outputs X-ray detection data for acquiring an X-ray CT image. That is, in the apparatus according to the first embodiment, the ring rotation mechanism unit 4 and the imaging system scanning control unit 5 are provided as X-ray imaging system scanning means for performing X-ray detection data collection scanning.

  In the subsequent stage of the FPD 2, a detection data memory 7 for storing X-ray detection data collected in association with scanning for collecting X-ray detection data, and an algorithm for reconstructing the X-ray detection data collected and stored in the detection data memory 7 A reconstruction processing unit 8 for obtaining CT image data for pixel signals of an X-ray CT image for a three-dimensional lattice point matrix virtually set on the subject M by reconstruction processing by a computer processing calculation method according to An image data memory 9 for storing the CT image data obtained by the configuration processing unit 8 in association with a three-dimensional lattice point matrix virtually set in the subject M is provided.

  In addition, in the apparatus according to the first embodiment, a CT image acquisition unit 10 that acquires an X-ray CT image according to CT image data, an image memory 11 that stores the X-ray CT image, an X-ray CT image display monitor, and the like. 12 is provided with an operation unit 13 for inputting commands and data necessary for execution of X-ray imaging. Then, the CT image acquisition unit 10 stores the X-ray CT image at the image acquisition position designated by the operator or the like using the operation unit 13 on the screen of the display monitor 12. The X-ray CT image acquired by the CT image acquisition unit 10 is stored in the image memory 11 as necessary, and further displayed on the screen of the display monitor 12 for display. Or

In the case of the apparatus according to the first embodiment, as shown in FIGS. 2 and 3, the X-ray diaphragm 1 </ b> B is in the direction along the moving path of the cone-shaped X-ray beam XA during the X-ray detection data collection scan. The beam width XL of the cone-shaped X-ray beam XA is made shorter than the width XD of the X-ray detection surface Xa of the FPD 2 so that the cone-shaped X-ray beam XA is changed to the beam short direction RX (as indicated by the arrow in FIG. 2). It also serves as a means for limiting the X-ray beam width. Note that the beam width YL of the cone-shaped X-ray beam XA in the beam longitudinal direction RY is not particularly shortened and is substantially equal to the width YD of the X-ray detection surface Xa.
In the case of the FPD 2, as shown in FIG. 4, a large number of X-ray detection elements 2a are arranged in a matrix in the horizontal direction (X direction) and the vertical direction (Y direction) on the X-ray detection surface Xa. Therefore, X-ray detection data for the slice planes of the subject M as many as the number of X-ray detection element lines (rows) in the Y direction of the FPD 2 can be collected by one X-ray detection data collection scan.

As shown in FIG. 3, the X-ray stop 1B has two X-ray non-transparent leaves 1Ba and 1Bb that define the beam width XL in the beam short direction RX and 2 that defines the beam width YL in the beam longitudinal direction RY. It consists of a single X-ray non-transparent leaf 1Bc, 1Bd.
In the case of the X-ray stop 1B of the apparatus according to the first embodiment, the cone-shaped X-ray beam XA has a beam width XL in the beam transverse direction RX that is 1/2 or less to 1 / less than the width XD of the X-ray detection surface Xa of the FPD2. In addition to being configured to be shortened in a range of 4 or more, the X-ray non-transparent leaves 1Ba and 1Bb are moved in a direction parallel to the beam lateral direction RX, so that the beam width XL of the cone-shaped X-ray beam XA is increased. The beam width YL of the cone-shaped X-ray beam XA can be adjusted by adjusting the X-ray non-transparent leaves 1Bc and 1Bd in a direction parallel to the beam longitudinal direction RY.

  In addition, the apparatus according to the first embodiment includes an FPD slide mechanism unit that moves the FPD 2 in the beam transverse direction RX of the cone-shaped X-ray beam XA in synchronization with the X-ray detection data collection scan in accordance with the control of the FPD slide control unit 15. 16 is provided. That is, in the apparatus according to the first embodiment, the FPD slide control unit 15 and the FPD slide mechanism unit 16 emit the cone-shaped X-ray beam XA to the X-ray detection surface Xa in synchronization with the X-ray detection data collection scan. It is provided as an X-ray beam synchronous slide means for sliding relative to the direction RX.

  Further, the FPD slide control unit 15 and the FPD slide mechanism unit 16 are configured to slide the cone-shaped X-ray beam XA from one end edge to the other end edge of the X-ray detection surface Xa in accordance with the X-ray detection data collection scan. Has been. That is, as shown in FIG. 5A, when the X-ray detection data collection scan starts, the right edge of the cone-shaped X-ray beam XA is positioned at the right edge of the X-ray detection surface Xa. As shown in FIG. 5B, the FPD 2 is moved in a sliding manner in which the left end edge of the cone-shaped X-ray beam XA reaches the left end edge of the X-ray detection surface Xa only at the end of the X-ray detection data acquisition scan. is there.

The slide mode of the FPD 2 is not limited to the above. For example, the FPD 2 comes in the beam short direction RX during one X-ray detection data collection scan, and the cone-shaped X-ray beam XA is exposed at both edges of the X-ray detection surface Xa in one X-ray detection data collection scan. It may be a slide mode that reciprocates between the two.
Further, the main control unit 14 plays a role of a command tower that sends an appropriate command signal to each unit in a timely manner according to an instruction or data input by the operation unit 13 or progress of X-ray imaging, and operates the apparatus normally. Yes.

Next, a description will be given in accordance with a situation when the X-ray detection data collection scan over an angle of 180 ° is performed by the X-ray imaging apparatus according to the first embodiment having the above-described configuration.
At the start of the X-ray detection data collection scan, as shown in FIG. 6A, the X-ray irradiation unit 1 and the FPD 2 face each other horizontally, and as shown in FIG. The right edge of the line beam XA is located at the right edge of the X-ray detection surface Xa.

  After the X-ray detection data collection scan is started, as shown in FIG. 6B, the X-ray irradiation unit 1 and the FPB 2 rotate around the subject M while maintaining the facing state, The FPB 2 continues to move in the beam short direction RX of the cone-shaped X-ray beam XA in synchronization with the X-ray detection data acquisition scan. As the X-ray detection data collection scan progresses, the X-ray irradiation unit 1 irradiates the cone-shaped X-ray beam XA and collects X-ray detection data output from the FPD 2.

  Then, at the end of the X-ray detection data collection scan, as shown in FIG. 6C, the X-ray irradiation unit 1 and the FPD 2 face each other again in a state where the positions are opposite to those at the start of scanning. 5B, the left end edge of the cone-shaped X-ray beam XA is located at the left end edge of the X-ray detection surface Xa.

  As described in detail above, in the case of the apparatus of the first embodiment, the beam width XL of the cone-shaped X-ray beam XA with respect to the direction along the moving path of the cone-shaped X-ray beam XA at the time of scanning for collecting X-ray detection data is set. In addition to the width XD of the X-ray detection surface Xa of the FPD 2 being made shorter than the width XD of the cone-shaped X-ray beam XA, the X-ray detection surface is synchronized with the X-ray detection data acquisition scan. The X-ray beam detection area on the X-ray detection surface Xa of the FPD 2 collects X-ray detection data. Therefore, the accumulation of the remainder of the X-ray detection data read out without being completely read out from the FPD 2 is suppressed, and the cone-shaped X-ray beam XA transmitted through the subject M to be imaged is suppressed. Afterimage occurring FPD2 due to output response speed of FPD2 is slow when the output is weakened than before.

Further, the beam width of the cone-shaped X-ray beam XA only needs to be shortened with respect to the direction along the moving path of the cone-shaped X-ray beam XA accompanying the X-ray detection data acquisition scan. It is not necessary to shorten the direction that does not follow the movement path, and the scanning area by the X-ray detection data collection scan is not narrowed.
Therefore, according to the X-ray imaging apparatus of the first embodiment, it is possible to appropriately compensate for the slow output response speed of the FPD 2 when detecting the cone-shaped X-ray beam XA transmitted through the subject M to be imaged. .

  In the apparatus of the first embodiment, the FPD 2 is moved to slide the cone-shaped X-ray beam XA relative to the X-ray detection surface Xa in the beam lateral direction RX. Since the X-ray irradiation optical system can maintain the same configuration during the acquisition scan, X-ray detection data for acquiring an X-ray tomographic image can be acquired without any change in the X-ray irradiation optical system.

In addition, in the case of the apparatus of the first embodiment, the beam width XL of the cone-shaped X-ray beam XA is the width of the X-ray detection surface Xa of the FPD 2 in the beam short direction RX along the moving path of the cone-shaped X-ray beam XA. Since the X-ray detection data collection range is within a range of ½ or less to ¼ or more of XD, the cone-shaped X-ray beam XA is slid from one end edge to the other end edge of the X-ray detection surface Xa along with the X-ray detection data acquisition scan. In addition, there is no area where the cone-shaped X-ray beam XA is constantly irradiated during the X-ray detection data collection scan, and as a result, the accumulation of the read residue of the X-ray detection data can be suppressed over the entire X-ray detection surface Xa.
Note that the beam width XL of the cone-shaped X-ray beam XA is set to 1/2 or less of the width XD of the X-ray detection surface Xa when the beam width XL exceeds 1/2 of the width XD of the X-ray detection surface Xa. This is because the area where the cone-shaped X-ray beam XA is always irradiated during the X-ray detection data acquisition scan cannot be completely eliminated. The beam width XL of the cone-shaped X-ray beam XA is set to ¼ or more of the width XD of the X-ray detection surface Xa when the beam width XL is less than ¼ of the width XD of the X-ray detection surface Xa. This is because the merit of the cone-shaped X-ray beam XA that can collect a large amount of X-ray detection data by the X-ray detection data acquisition scan becomes insufficient.

An X-ray imaging apparatus according to Embodiment 2 will be described. FIG. 7 is a block diagram illustrating the overall configuration of the X-ray imaging apparatus according to the second embodiment.
In the X-ray imaging apparatus according to the second embodiment, the X-ray diaphragm 1B is moved in the beam short direction RX of the cone-shaped X-ray beam XA in synchronization with the scan for collecting the X-ray detection data by the FPD 2 according to the control of the diaphragm slide control unit 17. A diaphragm slide mechanism 18 is provided. That is, in the apparatus according to the second embodiment, the aperture slide control unit 17 and the aperture slide mechanism unit 18 generate a cone-shaped X-ray beam XA on the X-ray detection surface Xa in synchronism with the X-ray detection data collection scan. Since it is substantially the same as the apparatus of the first embodiment except that it is provided as an X-ray beam synchronous slide means that slides relatively in the direction RX, only the differences from the apparatus of the first embodiment will be described. A description of the common points is omitted.

  The diaphragm slide control unit 17 and the diaphragm slide mechanism unit 18 are configured to slide the cone-shaped X-ray beam XA from one end edge to the other end edge of the X-ray detection surface Xa along with the X-ray detection data collection scan. Yes. That is, as shown in FIG. 8A, at the start of scanning for X-ray detection data collection, the right edge of the cone-shaped X-ray beam XA is positioned at the right edge of the X-ray detection surface Xa. As shown in FIG. 8 (b), the X-ray aperture stop 1B is slid in such a manner that the left edge of the cone-shaped X-ray beam XA reaches the left edge of the X-ray detection surface Xa only at the end of the X-ray detection data collection scan. move.

Note that the slide mode of the X-ray diaphragm 1B is not limited to the above. For example, the X-ray diaphragm 1B comes in the beam transverse direction RX during one X-ray detection data collection scan, and one X-ray A slide mode may be employed in which the cone-shaped X-ray beam XA reciprocates between both end edges of the X-ray detection surface Xa in the detection data collection scan.
In the case of the apparatus of the second embodiment, when the X-ray diaphragm 1B moves as the X-ray detection data acquisition scan progresses, the four X-ray non-transparent leaves 1Ba to 1Bd move all at once and the X-rays are moved. The non-transparent leaves 1Ba and 1Bb are configured such that the movement amount is adjusted so that the beam width XL of the cone-shaped X-ray beam XA is always maintained at a constant width. However, if the dimensions of the X-ray non-transparent leaves 1Bc and 1Bd are long, only the two X-ray non-transparent leaves 1Ba and 1Bb are present when the X-ray diaphragm 1B moves as the X-ray detection data acquisition scan proceeds. A configuration may be adopted in which the remaining two X-ray non-transparent leaves 1Bc and 1Bd do not move. That is, in the case of the apparatus according to the second embodiment, as the movement mode of the X-ray diaphragm 1B by the diaphragm slide mechanism 18, only the X-ray non-transparent leaves 1Ba and 1Bb move.

Next, a description will be given according to the situation when the X-ray detection data collection scan over the angle of 180 ° is performed by the X-ray imaging apparatus of the second embodiment having the above-described configuration.
At the start of the X-ray detection data collection scan, as shown in FIG. 9A, the X-ray irradiation unit 1 and the FPD 2 face each other horizontally, and as shown in FIG. The right edge of the line beam XA is located at the right edge of the X-ray detection surface Xa.

  After the scan for collecting X-ray detection data is started, as shown in FIG. 9B, the X-ray irradiation unit 1 and the FPB 2 rotate around the subject M while maintaining the facing state. Simultaneously in parallel, X-ray detection data is read from the FPD 2 and the X-ray aperture 1B continues to move in the beam short direction RX of the cone-shaped X-ray beam XA in synchronization with the X-ray detection data acquisition scan. . As the X-ray detection data collection scan progresses, the X-ray irradiation unit 1 irradiates the cone-shaped X-ray beam XA and collects X-ray detection data output from the FPD 2.

  Due to the movement of the X-ray stop 1B during the X-ray detection data collection scan, the X-ray beam detection area on the X-ray detection surface Xa of the FPD 2 is also moved along with the progress of the X-ray detection data collection scan. Therefore, the accumulation of the X-ray detection data read remaining without being completely read out from the FPD 2 is suppressed, and the output of the FPD 2 is detected when detecting the cone-shaped X-ray beam XA transmitted through the subject M to be imaged. The afterimage generated in the FPD 2 due to the slow response speed is also weakened.

  Then, at the end of the X-ray detection data collection scan, as shown in FIG. 9C, the X-ray irradiation unit 1 and the FPD 2 face each other again in a state where the positions are opposite to those at the start of scanning. 8B, the left end edge of the cone-shaped X-ray beam XA is located at the left end edge of the X-ray detection surface Xa.

  As described above, in the case of the apparatus according to the second embodiment, the cone-shaped X-ray beam XA is moved in the beam short direction RX with respect to the X-ray detection surface Xa by moving the X-ray stop 1B that is smaller and lighter than the FPD 2. Therefore, the cone-shaped X-ray beam XA can be easily slid relative to the X-ray detection surface Xa.

The present invention is not limited to the above embodiment, and can be modified as follows.
(1) In the case of the apparatus according to the first and second embodiments, the cone-shaped X-ray beam XA is relative to the X-ray detection surface Xa by moving either the FPD 2 or the X-ray diaphragm 1B. However, the cone-shaped X-ray beam XA is slid relative to the X-ray detection surface Xa by moving both the FPD 2 and the X-ray aperture 1B. An apparatus having the same configuration as the example can be given as a modification.

  (2) In the apparatuses of Examples 1 and 2, as the X-ray detection data collection scan is performed, the X-ray irradiation unit 1 and the FPD 2 are kept facing each other and the subject M is placed between them. In the present invention, the X-ray irradiating unit 1 and the FPD 2 are respectively connected to the subject M during the X-ray detection data collection scan. X-ray detection data for irradiating the cone-shaped X-ray beam XA and acquiring an X-ray tomographic image while moving along a non-circular orbit set on one side and the other side (for example, parallel movement in the opposite direction) Can be applied to an apparatus that acquires an X-ray tomographic image by integrating the X-ray detection data for each pixel in the subsequent stage of the FPD or reconstructing it according to a reconstruction algorithm.

  (3) Although the apparatus of Examples 1 and 2 is configured to detect the cone-shaped X-ray beam transmitted through the subject M by the FPD, the present invention uses the two-dimensional X-ray detector other than the FPD to detect the subject M. The present invention can also be applied to an apparatus that detects a cone-shaped X-ray beam that has passed through the beam.

  (4) In the apparatus of the first and second embodiments, the X-ray aperture 1B is a beam of the cone-shaped X-ray beam XA in the direction along the moving path of the cone-shaped X-ray beam XA at the time of scanning for collecting X-ray detection data. Although the width XL is made shorter than the width XD of the X-ray detection surface Xa of the FPD 2, the cone-shaped X-ray beam XA is also used as an X-ray beam width limiting means for providing the beam transverse direction RX. The X-ray beam width limiting means may be configured to be provided separately from the X-ray diaphragm 1B.

  (5) Although the apparatuses of Examples 1 and 2 are medical X-ray imaging apparatuses, the present invention can also be applied to industrial or nuclear X-ray imaging apparatuses.

1 is a block diagram illustrating an overall configuration of an X-ray imaging apparatus according to Embodiment 1. FIG. It is a perspective view which shows the irradiation state of the cone-shaped X-ray beam in the apparatus of Example 1. FIG. FIG. 3 is a schematic plan view showing a state of irradiation with a cone-shaped X-ray beam in the apparatus of Example 1. FIG. 3 is a plan view illustrating the arrangement of X-ray detection elements on the X-ray detection surface of the FPD of the apparatus according to the first embodiment. 3 is a schematic plan view showing a positional relationship between a cone-shaped X-ray beam and an X-ray detection surface at the start and end of an X-ray detection data collection scan in the apparatus of Embodiment 1. FIG. It is a schematic diagram which shows the movement state of the X-ray irradiation part and FPD at the time of the scan for X-ray detection data collection in the apparatus of Example 1. FIG. 3 is a block diagram illustrating an overall configuration of an X-ray imaging apparatus according to Embodiment 2. FIG. 6 is a schematic plan view showing a positional relationship between a cone-shaped X-ray beam and an X-ray detection surface at the start and end of an X-ray detection data collection scan in the apparatus of Embodiment 2. FIG. It is a schematic diagram which shows the X-ray irradiation part at the time of the scan for X-ray detection data collection in the apparatus of Example 2, and the movement state of FPD and an X-ray aperture. It is a schematic diagram which shows the movement state of the X-ray irradiation part and FPD at the time of the scan for X-ray detection data collection in the conventional X-ray imaging apparatus.

Explanation of symbols

1 ... X-ray irradiation part (X-ray irradiation means)
1A X-ray tube (part of X-ray irradiation means)
1B: X-ray aperture (a part of X-ray irradiation means and X-ray beam width limiting means)
2 ... FPD (two-dimensional X-ray detection means)
4 ... Ring rotation mechanism (part of X-ray imaging system scanning means)
5: Imaging system scanning control unit (part of X-ray imaging system scanning means)
15 ... FPD slide control part (a part of X-ray beam synchronous slide means)
16 ... FPD slide mechanism (part of X-ray beam synchronous slide means)
17 ... Aperture slide control unit (part of X-ray beam synchronized slide means)
18 ... Aperture slide mechanism (part of X-ray beam synchronized slide means)
M ... subject XA ... cone-shaped X-ray beam Xa ... X-ray detection surface XD ... width of X-ray detection surface XL ... beam width (in the beam transverse direction of cone-shaped X-ray beam) RX ... (cone-shaped X-ray beam ) Beam short direction

Claims (5)

  X-ray detection for acquiring an X-ray tomographic image by detecting an X-ray irradiation means for irradiating a subject with a cone-shaped X-ray beam and a cone-shaped X-ray beam that is disposed opposite to the subject and that passes through the subject. X-ray detection data collection scanning is performed by moving the subject between the two-dimensional X-ray detection means that outputs data, the X-ray irradiation means, and the two-dimensional X-ray detection means in an opposed arrangement. X-ray irradiation means and two-dimensional X-ray detection means are synchronously moved by X-ray detection data collection scanning by the X-ray imaging system scanning means, Two-dimensional X-ray detection of the beam width of a cone-shaped X-ray beam with respect to the direction along the moving path of the cone-shaped X-ray beam at the time of scanning for collecting X-ray detection data in an X-ray imaging apparatus that outputs line detection data Shorter than the width of the X-ray detection surface of the means X-ray beam width limiting means for causing the cone-shaped X-ray beam to have a beam short direction, and the cone-shaped X-ray beam relative to the X-ray detection surface relative to the X-ray detection surface in synchronization with the X-ray detection data acquisition scan. An X-ray imaging apparatus comprising an X-ray beam synchronizing slide means for sliding the X-ray beam.   2. The X-ray imaging apparatus according to claim 1, wherein the X-ray beam synchronization slide means moves the two-dimensional X-ray detector in the beam lateral direction of the cone-shaped X-ray beam in synchronization with the X-ray detection data acquisition scan. Accordingly, an X-ray imaging apparatus that slides a cone-shaped X-ray beam relative to the X-ray detection surface relative to the lateral direction of the beam.   2. The X-ray imaging apparatus according to claim 1, wherein the X-ray beam synchronization slide means moves the X-ray beam width limiting means in the beam short direction of the cone-shaped X-ray beam in synchronization with the X-ray detection data collection scan. Accordingly, an X-ray imaging apparatus that slides the cone-shaped X-ray beam relative to the X-ray detection surface in the beam lateral direction.   4. The X-ray imaging apparatus according to claim 1, wherein the X-ray beam width restricting unit is configured to set a beam width of the cone-shaped X-ray beam in a short direction of the X-ray detection surface of the two-dimensional X-ray detection unit. The X-ray beam synchronous slide means reduces the cone-shaped X-ray beam from one end edge of the X-ray detection surface along with the X-ray detection data collection scan. X-ray imaging device that slides across the edge. 5. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging system scanning unit irradiates the X-ray irradiation unit and the two-dimensional X-ray detection unit during X-ray detection data collection scanning. An X-ray imaging apparatus in which the means and the two-dimensional X-ray detection means are moved along a circular orbit around the subject over an angle of 180 ° or more.

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