JP2007333509A - Tomographic device using radiation, and tomographic method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tomographic device using radiation, and capable of providing a tomographic image of an excellent image quality by employing a collimator not only capable of reducing effect of scattered radiation, but also capable of reducing influence on radiation penetrating a measurement object and entering a detector. <P>SOLUTION: The tomographic device using radiation is constituted so that a radiation source, a radiation detector and a collimator arranged on the front surface of a detection surface of the radiation detector and forming a plurality of passages through which the radiation penetrated a measurement object passes can be moved at least one of a horizontal direction with respect to the radiation detector and a vertical line direction. An image reconstructing calculation device generating a tomographic image based on a detection signal of the radiation detector is constituted such that a plurality of tomographic images of the measurement object corresponding the movement position of the collimator is generated based on the respective detection signals obtained by detecting the radiation penetrated the measurement object at different positions with the collimator moved thereto; and a tomographic image of the whole measurement object is generated by combining the plurality of tomographic images with one another. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tomography apparatus and a tomography method using radiation in which an X-ray generator or a radioisotope is used as a radiation source, and radiation transmitted through an object to be measured mounted on a turntable is detected by a two-dimensional radiation detector. .

  Detection of a CT apparatus that irradiates an object to be measured such as a structure mounted on a turntable as a radiation source with an X-ray generator or a radioisotope, and captures radiation transmitted through the object as a detailed tomographic image A flat panel detector is used for the vessel.

  When Compton scattering occurs when the object is irradiated with radiation, the contrast of the tomographic image is lowered by the scattered radiation scattered in the object to be measured, and the image quality of the tomographic image of the object to be measured is deteriorated. It has been desired to reduce the influence of scattered radiation because deterioration in the image quality of tomographic images lowers the dimensional measurement accuracy and defect detection ability of the object to be measured.

  Japanese Patent Application Laid-Open No. 2003-139724 discloses a radiation source that irradiates the object to be measured, a collimator having a plurality of through holes that allow the radiation that has passed through the object to be measured, and radiation that has passed through the through holes of the collimator. Techniques relating to a detector to detect and a CT apparatus that generates a tomographic image of a measurement object from a detection signal of radiation detected by the detector are disclosed.

  The CT apparatus described in Japanese Patent Laid-Open No. 2003-139724 has a structure in which a collimator is provided with a plurality of through holes having different cross-sectional areas and is mounted on a vertical movement apparatus.

  The tomographic image of the object to be measured corresponding to the required spatial resolution is obtained by moving the collimator up and down with the vertical movement device and selecting a through hole with an appropriate cross-sectional area through which the radiation beam passes. To do.

JP 2003-139724 A

  By the way, a two-dimensional radiation detector that is a flat panel detector that detects a high-accuracy tomographic image of an object to be measured such as a structure with a CT apparatus has a fine radiation detection element of about 0.1 to 0.2 mm in the vertical direction. Therefore, a high-resolution tomographic image can be obtained by detecting radiation such as X-rays irradiated to the object to be measured using this flat panel detector. I can do it.

  However, in a CT apparatus in which a collimator having a conventional structure that reduces the influence of scattered radiation is arranged on the front surface of a detector that detects radiation such as X-rays, a flat panel detector in which a large number of radiation detection elements are densely arranged is used as a detector. When used, the large number of radiation detection elements that make up the flat panel detector are arranged in a small and dense manner, so the collimator itself becomes an obstacle that shields the entrance of radiation. There has been a problem that a sufficient amount of radiation that has passed through the object to be measured necessary for imaging can not be obtained.

  The object of the present invention is to not only reduce the influence of scattered radiation, but also to adopt a collimator that can reduce the influence on the radiation that passes through the object to be measured and enters the detector. It is an object of the present invention to provide a tomography apparatus and a tomography method using radiation that can be obtained.

  A tomography apparatus using radiation according to the present invention includes a radiation source that irradiates radiation, a radiation detector that includes a plurality of radiation detection elements arranged in a plate shape to form a detection surface, and a radiation source and a radiation detector. A turntable device having a table arranged in between and rotating the object to be measured; a collimator disposed in front of the detection surface of the radiation detector to form a plurality of passages through which the radiation transmitted through the object to be measured passes; and a collimator An image reconstruction calculation device that generates a tomographic image of the object to be measured based on a detection signal detected by the radiation detection element of the radiation detection apparatus through the object to be measured that has passed through the passage formed on the collimator The detector is configured to be movable in at least one of a horizontal direction and a vertical line direction parallel to the detection surface of the detector. A plurality of tomographic images of the object to be measured corresponding to the movement position of the collimator are generated based on each detection signal of the radiation detector that respectively detects the radiation transmitted through the object to be measured, and the plurality of tomograms of these objects to be measured The present invention is characterized in that the image is synthesized to generate a tomographic image of the entire object to be measured.

  Further, the tomography method using radiation according to the present invention irradiates the measurement object mounted on the turntable device for rotating the measurement object with radiation from the radiation source, and detects the radiation transmitted through the measurement object. The radiation that has passed through the object to be measured that has passed through the multiple passages formed in the collimator is guided to the radiation detector through a plurality of passages formed in the collimator placed in front of the detector's detection surface, and arranged in a flat plate on the radiation detector. In a tomography method for a measurement object that detects a plurality of radiation detection elements and generates a tomographic image of the measurement object based on detection signals detected by these radiation detection elements, a collimator is placed on the detection surface of the radiation detector. The collimator is moved in at least one of the horizontal direction and the vertical direction parallel to the collimator, and the object is measured from the radiation source to the object to be measured. The radiation that has passed through the object to be measured at a plurality of different positions where the collimator is moved is detected by the radiation detection element of the radiation detection device, and based on each detection signal detected by the radiation detection element. A configuration in which a plurality of tomographic images of the object to be measured corresponding to the movement position of the collimator is generated, and a plurality of tomographic images of these objects to be measured are combined to generate an entire tomographic image of the object to be measured. Features.

  According to the present invention, a collimator that can not only reduce the influence of scattered radiation but also reduce the influence of radiation that passes through the object to be measured and enters the detector can be used to produce a tomographic image with excellent image quality. A tomographic apparatus and a tomographic method using radiation thus obtained can be realized.

  A tomography apparatus using radiation having a flat panel detector according to an embodiment of the present invention will be described below with reference to the drawings.

  FIGS. 1 to 4 show a tomographic apparatus using radiation and equipped with a flat panel detector according to an embodiment of the present invention.

  FIG. 1 is a side view showing a main configuration of a tomography apparatus having a flat panel detector according to an embodiment of the present invention. In FIG. 1, the tomography apparatus is a radiation source that irradiates X-rays by operation of an X-ray controller 53 provided on a base 6, a support 11 installed on the base 6, and an upper part of the support 11. The X-ray source 1, the turntable device 2 mounted on the base 6 and mounted with the object 5 to be measured is rotated by the rotation of the turntable rotating shaft 22, and the support base on which the two-dimensional radiation detector 3 is mounted. 12 is provided.

  A collimator mounting guide 41 is attached to the support 12 provided on the base 6, and the collimator 4 for a flat plate-like two-dimensional radiation detector that forms a plurality of radiation paths made of radiation shielding material is a position controller. The collimator 4 is arranged so as to move up and down in the vertical direction with respect to the collimator mounting guide 41 by operating the driving device 48 by the operation 55.

  In addition, a two-dimensional radiation detector 3 in which a plurality of radiation detection elements are densely arranged in a flat plate shape is installed on the support base 12 of the base 6 at a position on the back side of the collimator 4.

  The X-ray source 1 is provided with necessary radiation shielding so as to irradiate X-rays, which are radiation, only in the direction of the measurement object 5 mounted on the turntable 21 provided on the upper part of the turntable device 2. Yes.

  The turntable device 2 has a turntable 21 on which the object to be measured 5 is mounted, a turntable rotating shaft 22 that is installed perpendicular to the base 6 and rotates the turntable 21 by operating the rotation / position controller 54, It is comprised from the support | pillar 23 which accommodates and supports the table rotating shaft 22 inside.

  The height of the turntable 21 from the base 6 can be adjusted by a position adjusting device (not shown) that is driven by the operation of the rotation / position controller 54.

  The two-dimensional radiation detector 3 has a planar detection surface in which a large number of fine 0.1 to 0.2 mm square radiation detection elements made of a semiconductor and a scintillator are arranged densely in a vertical direction and a horizontal direction in a flat plate shape. This is a flat panel detector, and is installed on the support base 12 so that its detection surface is vertical.

  The dimension of the detection surface of the two-dimensional radiation detector 3 is set to a size large enough to project X-rays irradiated from the X-ray source 1 and transmitted through the object to be measured 5 on the turntable 21.

  A collimator 4 provided to reduce the influence of scattered radiation scattered in the measurement object due to Compton scattering when the measurement object is irradiated with X-rays is a position in front of the two-dimensional radiation detector 3. It is installed on the support base 12 so as to be arranged close to each other so as to be parallel to the detection surface of the radiation detector 3.

  The collimator 4 is supported by a collimator mounting guide 41 and has a structure movable in parallel to the detection surface of the two-dimensional radiation detector 3. A detailed configuration of the collimator 4 of this embodiment will be described later with reference to FIG.

  The X-ray source 1, the object to be measured 5 mounted on the turntable 21, the collimator 4 for the two-dimensional radiation detector, and the central portions of the two-dimensional radiation detector 3 are shown by the one-dot chain line a and They are arranged so as to be sequentially located on the center line of the quadrangular pyramid of the X-ray bundle indicated by b (the chain line c in FIG. 1).

  X-rays irradiated from the X-ray source 1 toward the object to be measured 5 pass through the object to be measured 5 and travel to the radiation detector 3.

  X-rays traveling to the two-dimensional radiation detector 3 are partially scattered by the measured object 5 when passing through the measured object 5 and become X-rays with a component perpendicular to the traveling direction added. By passing the X-rays through a slit 44 formed in the collimator 4 in the horizontal direction, the progress of the X-rays that are scattered is prevented, and only the X-rays with little or no scattering are detected by the X-ray radiation detector 3. Proceed to.

  X-rays transmitted through the object to be measured 5 passing through the slit 44 of the collimator 4 travel in this way and are detected by the two-dimensional radiation detector 3 of the flat panel detector.

  The collimator 4 moves the opening position of the slit 44 along the vertical direction for each scan for irradiating the object to be measured 5 with X-rays, and detects the X-ray transmitted through the object to be measured 5 that has passed through the slit 44 by two-dimensional radiation detection. The X-ray transmitted through the two-dimensional radiation detector 3 is detected.

  The X-ray transmission data transmitted through the measurement object 5 detected by the two-dimensional radiation detector 3 for each scan for irradiating the X-rays is obtained from the two-dimensional radiation detector 3 and the image reconstruction calculator provided in the computer 50. 51, the image reconstruction calculator 51 synthesizes each transmission data to create complete transmission data of the object 5 to be measured.

  Transmission data of the object to be measured 5 created by combining processing by the image reconstruction calculator 51 can be displayed on the display device 52.

  FIG. 2 is a front view of the two-dimensional radiation detector 3 and the collimator 4 as viewed from the X-ray source 1 in the tomography apparatus using radiation having a collimator according to an embodiment of the present invention. It is disposed on the front surface of the radiation detector 3.

  2A shows a state before the position of the slit 44 opened in the horizontal direction formed in the collimator 4 is moved, and FIG. 2B shows the collimator 4 detected by the two-dimensional radiation detector 3. A situation is shown in which the opening position of the slit 44 is moved upward by being moved in parallel to the surface and along the vertical line direction.

  As shown in FIGS. 1 and 2, the collimator 4 includes a vertical member 42 provided at each of the left and right ends that move up and down in the collimator mounting guide 41, and the vertical member 42 from the top to the bottom. It is a ladder-like structure constituted by a plurality of cross-tree-like radiation shielding members 43 arranged so as to be held at equal intervals.

  Then, a slit 44 opened in the horizontal direction is formed by a gap between a plurality of cross-beam-like radiation shielding members 43 arranged adjacent to each other in the vertical direction, and only X-rays transmitted through the object to be measured 5 passing through the slit 44 are transmitted. It is configured so that it can proceed to the two-dimensional radiation detector 3 arranged on the back side of the collimator 4.

  By forming a plurality of horizontal tree-like radiation shielding members 43 of the collimator 4 with a radiation shielding material (tungsten, brass, etc.), X-rays scattered by Compton scattering by irradiation of the object to be measured 5 from the slit 44 are shielded from the horizontal tree radiation. The presence of the member 43 blocks the forward travel and prevents the X-rays scattered by the two-dimensional radiation detector 3 from traveling.

  The collimator 4 includes a vertical member 42 that is disposed inside a collimator mounting guide 41 and is held so as to be movable in a vertical direction indicated by an arrow.

  The slit 44 opened in the horizontal direction, which is a gap between the vertically adjacent horizontal tree-like radiation shielding members 43, becomes a passage through which X-rays transmitted through the object to be measured 5 travel. The width of the gap forming this slit 44 is The radiation detecting elements 43 are configured to have substantially the same width as the plate width along the vertical direction, and N pieces of radiation detecting elements constituting the two-dimensional radiation detector 3 installed on the back side of the collimator 4. It is designed to correspond to a distance of minutes (N ≧ 1; usually several).

  The vertical movement amount of the horizontal tree-shaped radiation shielding member 43 is a distance corresponding to N radiation detection elements constituting the two-dimensional radiation detector 3 (N ≧ 1; usually several).

  For easy understanding in the collimator 4 shown in FIG. 2, the vertical dimension of the slit 44 serving as the gap between the horizontal tree radiation shielding members 43 and the vertical plate width of the horizontal tree radiation shielding members 43 are exaggerated. However, it is actually a very small size.

  In other words, the collimator 4 has a structure in which thin plate-like radiation shielding members 43 having a small thickness are stacked in layers in the vertical direction while maintaining a narrow interval, and the object to be measured is placed in the gap between the adjacent plate-like radiation shielding members 43. The X-rays scattered by the object to be measured 5 and added with the component perpendicular to the traveling direction are collimated by the collimator 4 having the elongated slits 44 that pass through the X-rays that have passed through the plate-shaped radiation shielding member 43. The presence is prevented from proceeding, and the scattered X-rays are prevented or reduced from entering the two-dimensional radiation detector 3.

  Next, referring to FIG. 1 to FIG. 3 and FIG. 10, the to-be-measured object 5 is irradiated with X-rays using the tomography apparatus using radiation provided with the collimator of the present embodiment. A process for acquiring the transparent image data of will be described.

  FIG. 10 is a flowchart showing a tomographic imaging process of the object 5 to be measured using X-rays. First, in step 101 of collimator position setting, which is the first step, position control is performed based on a command from the computer 50. The driving device 48 is operated by operating the device 55, and the position of the collimator 4 is set to the position of the first scan shown in FIG. 2A with respect to the two-dimensional radiation detector 3.

  In the next radiation irradiation step 102, the X-ray source controller 53 is operated based on a command from the computer 50 to direct the measured object 5 mounted on the turntable 21 of the turntable device 2 from the X-ray source 1. X-rays are emitted.

  Step 103 of the next first scan is a process of detecting a X-ray that has passed through the DUT 5 and capturing a tomographic image, and includes the following Step 103a and Step 103b.

  That is, in the step 103a of rotating the turntable, the collimator 4 is set to the position of the first scan, and the X-ray source 1 rotates the X-ray to the object 5 to be measured based on a command from the computer 50. / The position controller 54 is operated to drive the turntable rotating shaft 22, and the turntable 21 on which the object 5 to be measured is mounted is rotated by 180 degrees or 360 degrees at a rotation angle.

  In the transmission image data acquisition step 103b, X-ray transmission image data transmitted through the measurement object 5 is acquired while the measurement object 5 is rotating 180 degrees or 360 degrees on the turntable 21. The transmission image data acquisition step 103b is performed simultaneously with the turntable rotation step 103a.

  In addition, the image data of the object to be measured 5 acquired at a specific rotation angle while the turntable 21 rotates 180 degrees or 360 degrees in the transmission image data acquisition step 103b is shown in FIG. As described above, among the transmission image data detected by the radiation detection element of the two-dimensional radiation detector 3, the transmission image data of the radiation detection element in the region where the cross-beam radiation shielding member 43 of the collimator 4 is located just in front is missing. Although the image data is one scan, the first scan step 103 is completed.

  When step 103 of the first scan is completed, collimator position resetting step 104 is then performed, and the position controller 55 is operated based on a command from the computer 50 to operate the drive unit 48 to configure the collimator 4. The vertical member 42 to be moved is moved upward in the vertical direction indicated by an arrow inside the collimator mounting guide 41.

  As a result of the moving operation, the positions of the plurality of cross-shaped radiation shielding members 43 are moved upward by N radiation detection elements as shown in FIG. 2B, and the position of the collimator 4 is moved with respect to the two-dimensional radiation detector 3. Thus, the second scan position shown in FIG.

  In step 105 of the next second scan, as in step 103 of the first scan, this is a process of detecting a X-ray that has passed through the object to be measured 5 and capturing a tomographic image, and comprises the following steps 105a and 105b. Has been.

  That is, in step 105a of the turntable rotation, the collimator 4 is set to the second scan position, and the command from the computer 50 is applied under the condition where the X-ray source 1 irradiates the object to be measured 5 with X-rays. Based on the above, the rotation / position controller 54 is operated to rotate the turntable 21 on which the object 5 to be measured is rotated by 180 degrees or 360 degrees at a rotation angle.

  In the transmission data acquisition step 105b, transmission data of X-rays transmitted through the measurement object 5 while the measurement object 5 is rotating 180 degrees or 360 degrees on the turntable 21 is acquired. The acquisition step 105b is performed simultaneously with the turntable rotation step 105a.

  In the transmission data acquisition step 105b, the transmission data of the DUT 5 acquired at a specific rotation angle while the turntable 21 rotates slightly 180 degrees or 360 degrees is as shown in FIG. In the transmission data detected by the radiation detection element of the two-dimensional radiation detector 3, the horizontal tree-shaped radiation shielding member 43 moved upward by the number N of radiation detection elements constituting the collimator 4 is located just in front of the region. The image data of the second scan in which the transmission data of the radiation detection element is lost, and this completes the step 105 of the second scan.

  Next, the transmission image data synthesis step 106 is performed. In this transmission image data synthesis step 106, each transmission obtained by the first scan and the second scan of the object 5 to be measured at the same specific rotation angle of the turntable 21. By combining the image data with the image reconstruction calculation device 51 installed in the computer 50, transmission image data of X-rays transmitted through the measurement object 5 that is not shielded by the transverse tree-like radiation shielding member 43 of the collimator 4 is obtained. Therefore, it is possible to obtain transmission image data that is a tomographic image of the entire object to be measured 5 shown in FIG.

  Finally, the tomographic image / three-dimensional stereoscopic image creation step 107 is performed. In the tomographic image / three-dimensional stereoscopic image step 107, the transmission image showing the entire object to be measured 5 obtained in the transmission image data synthesis step 106 is shown. Based on the set of data, the image reconstruction calculation device 51 performs an image reconstruction calculation to create a complete tomographic image and / or a three-dimensional stereoscopic image showing the entire object to be measured 5.

  Then, the tomographic image and / or the three-dimensional stereoscopic image of the measurement object 5 created by the image reconstruction calculation device 51 is output to the display device 52 and displayed.

  The calculation of the rotation angle of the turntable 21 described above, the acquisition of transmission image data from the two-dimensional radiation detector 3, the synthesis of the acquired transmission image data and the calculation of image reconstruction are performed by commands from the computer 50, In addition, it is executed by an image reconstruction calculation device 51 provided in the computer 50.

  In the present embodiment, only the collimator 4 is moved in the vertical direction, but the height direction position of the turntable 21 and the collimator 4 are fixed, and the X-ray source 1 and the radiation detector 3 are synchronized to move up and down. The same effect as that of the above embodiment can be obtained as a structure that moves in the direction.

  Further, the radiation detector 3 and the collimator 4 are fixed, and the X-ray source 1 and the turntable 21 are moved in the vertical direction in synchronization with each other, or the collimator 4 is fixed to the radiation detector 3. A similar effect can be obtained by moving both the collimator 4 and the radiation detector 3 in the vertical direction. In this case, transmission data is acquired from the same radiation detection element in the first scan and the second scan, but may be processed as height position data corresponding to the amount of movement in the vertical direction.

  The embodiment of the present invention employs a collimator that not only reduces the influence of scattered radiation but also reduces the influence on the radiation that passes through the object to be measured and enters the detector. A tomography apparatus and a tomography method using radiation having a flat panel detector capable of obtaining a tomogram can be realized.

  Next, a tomography apparatus using radiation having a flat panel detector according to another embodiment of the present invention will be described with reference to FIG.

  The tomography apparatus having a flat panel detector according to another embodiment shown in FIG. 4 has the same basic configuration as that of the first embodiment of the present invention shown in FIG. In addition, description of the imaging process of the tomographic image of the DUT 5 will be omitted, and only the different parts will be described below.

  In FIG. 4, the collimator 4 of this embodiment provided in the tomographic apparatus using radiation also moves left and right moving up and down in the collimator mounting guide 41 as in the first embodiment shown in FIG. A ladder member is formed by a vertical member 42 provided at each end, and a plurality of cross-shaped radiation shielding members 43c arranged to be held at equal intervals from the upper part to the lower part with respect to the vertical member 42. The structure is adopted.

  A slit 44 opened in the horizontal direction is formed by the gap between the plurality of horizontal tree-like radiation shielding members 43c arranged adjacent to each other. The X-ray transmitted through the object to be measured 5 passing through the slit 44 is transmitted. Of the plurality of horizontal tree-like radiation shielding members 43c along the traveling direction, the horizontal plane of the arrangement direction of the horizontal tree-like radiation shielding members 43c located in the upper region and the lower region approaches the upper and lower portions from the central portion of the collimator 4. The inclination angle is increased with respect to the measurement object 5 so as to coincide with the traveling direction of the X-rays transmitted through the DUT 5.

  That is, the path of the X-ray transmitted through the object to be measured 5 that passes through the slit 44 opened in the horizontal direction formed in the collimator 4 in the embodiment of FIG. 4 is a line segment a at the upper end of the radiation detector 3 in the vertical line direction. And the depression angle indicated by the line segment b at the lower part of the radiation detector 3 in the vertical line direction.

  Therefore, in order to reduce an error in the angle generated between the X-ray path passing through the line segment a and the line segment b and the opening shape of the slit 44, a plurality of horizontal tree radiations that define the slit 44 of the collimator 4 are used. The horizontal direction of the collimator 4 approaches the top and bottom from the center of the collimator 4 so that the arrangement direction of the shielding member 43c is along the traveling direction of the X-ray that passes through the DUT 5 and enters the two-dimensional radiation detector 3. The inclination angle is increased.

  The process for capturing a tomographic image of the object 5 to be measured by X-rays in this embodiment is the same as the flowchart of the first embodiment shown in FIG.

  According to the embodiment of the present invention, a collimator that can not only reduce the influence of scattered radiation but also reduce the influence of radiation that passes through the object to be measured and enters the detector can be used to achieve higher definition. A tomographic apparatus and a tomographic method using radiation having a flat panel detector capable of obtaining a tomographic image with excellent image quality can be realized.

  Next, a tomography apparatus using radiation having a flat panel detector according to still another embodiment of the present invention will be described with reference to FIGS.

  The tomography apparatus having a flat panel detector according to another embodiment shown in FIGS. 5 and 6 has the same basic configuration as that of the first embodiment of the present invention shown in FIG. And the description of the tomographic imaging process of the DUT 5 will be omitted, and only the differences will be described below.

  5 and 6, in the collimator 4 of this embodiment provided in the tomography apparatus using radiation, a plurality of horizontal tree-like radiations are provided on the left and right vertical members 42 as in the collimator of Embodiment 1 shown in FIG. A ladder-like structure in which the shielding members 43a are held at equal intervals is employed.

  The collimator 4 according to the present embodiment includes a plurality of horizontal tree-like radiation shielding members 43a constituting a movable collimator in the central region, and a plurality of horizontal tree-like radiation shielding members 43b constituting a fixed collimator above and below the central region. It has a structure.

  That is, when only a necessary part of the object to be measured 5 is imaged, there is no need to mount a movable collimator on the entire surface of the radiation detector 3, so a plurality of areas are provided in the central region corresponding to the necessary part of the object to be measured 5. Thus, the structure of the collimator 4 can be simplified by significantly reducing the number of manufacturing steps and costs.

  A plurality of cross-beam-like radiation shielding members 43a constituting the movable collimator of the collimator 4 of the present embodiment are disposed inside a collimator mounting guide 41 arranged vertically, and are held movably in a vertical line direction indicated by an arrow. A ladder-shaped movable collimator is configured by being arranged so as to be held at equal intervals from the upper part to the lower part with respect to the vertical members 42 provided at the left and right ends respectively.

  Further, the plurality of transverse tree radiation shielding members 43b constituting the fixed collimator of the collimator 4 are fixed in a ladder shape by the plurality of transverse tree radiation shielding members 43b arranged so as to be held with respect to the collimator mounting guide 41. It constitutes a collimator.

  The movable collimator forms a slit 44 opened in the horizontal direction by a gap between the plurality of cross-beam-like radiation shielding members 43a, and forms a passage through which X-rays transmitted through the DUT 5 passing through the slit 44 travel. .

  The vertical member 42 of the movable collimator is configured to move up and down in the collimator mounting guide 41 by the operation of the drive unit 48.

  FIG. 6A shows a state in which the positions of the slits 44 opened in the horizontal direction formed in the plurality of cross-shaped radiation shielding members 43a of the movable collimator are in the position at the time of the first scan. b) moves the plurality of cross-shaped radiation shielding members 43a from the position of the first scan in parallel to the detection surface of the two-dimensional radiation detector 3 and along the vertical line direction, thereby changing the opening position of the slit 44. It shows a state where it has been moved to the upper second scan position.

  The vertical movement amount of the horizontal tree-shaped radiation shielding member 43a is a distance corresponding to N radiation detection elements constituting the two-dimensional radiation detector 3 (N ≧ 1; usually several).

  The process for capturing a tomographic image of the object 5 to be measured by X-rays in the present embodiment is also the same as the flowchart of the first embodiment shown in FIG.

  The embodiment of the present invention employs a collimator that not only reduces the influence of scattered radiation but also reduces the influence on the radiation that passes through the object to be measured and enters the detector. A tomography apparatus and a tomography method using radiation having a flat panel detector capable of obtaining a tomogram can be realized.

  In addition, since the movable collimator provided with a plurality of horizontal tree-like radiation shielding members 43a that move in the vertical direction as the collimator 4 only needs to be configured in the central region of the collimator that covers the range of the central portion of the object to be measured. There is an advantage that the structure can be simplified.

  Next, a tomography apparatus using radiation having a flat panel detector according to another embodiment of the present invention will be described with reference to FIGS.

  The tomographic apparatus having a flat panel detector according to another embodiment shown in FIGS. 7 to 9 has the same basic configuration as that of the first embodiment of the present invention shown in FIG. And the description of the tomographic imaging process of the DUT 5 will be omitted, and only the differences will be described below.

7 to 9, the collimator 4 of this embodiment provided in the tomography apparatus using radiation is a movable collimator configured not only to move up and down in the vertical direction but also to the left and right in the horizontal direction. is there.
The movable collimator has a vertical member 42 provided at each of the left and right ends that move up and down in the collimator mounting guide 41 arranged vertically, and an equal interval from the upper part to the lower part of the vertical member 42. It is a ladder-like structure constituted by a plurality of cross-tree-like radiation shielding members 47a arranged so as to be held in the space.

  Then, a slit 44 opened in the horizontal direction is formed by a gap between a plurality of horizontal tree-like radiation shielding members 47 a arranged adjacent to each other in the vertical direction, and only X-rays transmitted through the object to be measured 5 traveling through the slit 44 are transmitted. It is configured so that it can proceed to the two-dimensional radiation detector 3 arranged on the back side of the collimator 4.

  The vertical member 42 of the movable collimator moves up and down in the vertical direction in the collimator mounting guide 41 by the operation of the driving device 48.

  Further, the movable collimator includes a horizontal member 46 provided at the lower end that moves left and right inside the collimator mounting guide 45 disposed in the horizontal direction, and a plurality of vertical tree-like radiation shielding members on the horizontal member 46. A ladder-like structure in which 47b is held at equal intervals is adopted.

  Then, a slit 44 opened in the vertical direction is formed by a gap between a plurality of vertical tree-like radiation shielding members 47b arranged adjacent to the left and right, and only X-rays transmitted through the object to be measured 5 passing through the slit 44 are transmitted. Is configured to proceed to the two-dimensional radiation detector 3 disposed on the back side of the collimator 4.

  Then, the horizontal member 46 of the movable collimator is moved left and right in the horizontal direction within the collimator mounting guide 45 by the operation of the driving device 49.

  The collimator of the present embodiment is composed of a flat plate-like movable collimator provided with a plurality of horizontal tree-like radiation shielding members 47a and a flat plate-like movable collimator provided with a plurality of vertical tree-like radiation shielding members 47b.

  The amount of vertical movement of the plurality of cross-shaped radiation shielding members 47a along the vertical line direction is N (N ≧ 1; usually several) of the radiation detection elements constituting the two-dimensional radiation detector 3. Distance.

  Similarly, the amount of movement in the left-right direction along the horizontal direction of the plurality of vertical tree-shaped radiation shielding members 47b is equal to N radiation detection elements constituting the two-dimensional radiation detector 3 (N ≧ 1; usually several). It becomes the distance.

  By the way, the collimator of the present embodiment is composed of two movable collimators including a movable collimator provided with a horizontal tree-like radiation shielding member 47a and a movable collimator provided with a vertical tree-like radiation shielding member 47b. You may comprise only one movable collimator provided with the several vertical tree-like radiation shielding member 47b which moves to the left-right direction along a direction.

  In the case of the configuration including only the movable collimator provided with the radiation shielding member 47b, the tomography apparatus is the same as that obtained by changing the arrangement direction of the collimator of the embodiment shown in FIG. An imaging process of the tomographic image of the DUT 5 is also an imaging process according to the flowchart of FIG.

  Next, referring to FIG. 7 to FIG. 9 and FIG. 11, using the tomography apparatus provided with the collimator of the present embodiment, X-rays are irradiated on the object to be measured 5 and transmission image data of the object to be measured 5 is obtained. The process of acquiring

  FIG. 11 is a flowchart showing a tomographic image capturing process of the object 5 to be measured by X-rays. First, in step 101 of collimator position setting, which is the first step, FIG. 7 is based on a command from the computer 50. The position controller 55 in the tomography apparatus is operated to operate the driving device 49, and the position of the vertical tree-like radiation shielding member 47b of the collimator 4 is set to N radiation detection elements constituting the two-dimensional radiation detector 3 ( The distance is moved rightward by a distance of N ≧ 1 (normally several) and set to the position of the first scan shown in FIG. 8A with respect to the two-dimensional radiation detector 3.

  In the next radiation irradiation step 102, the X-ray source controller 53 is operated based on a command from the computer 50 to direct the measured object 5 mounted on the turntable 21 of the turntable device 2 from the X-ray source 1. X-rays are emitted.

  Step 103 of the next first scan is a process of detecting a X-ray that has passed through the DUT 5 and capturing a tomographic image, and includes the following Step 103a and Step 103b.

  That is, in step 103a of rotating the turntable, the position of the vertical tree radiation shielding member 47b of the collimator 4 is set to the position of the first scan, and X-rays are irradiated from the X-ray source 1 to the object 5 to be measured. Based on the command from the computer 50, the rotation / position controller 54 is operated to drive the turntable rotating shaft 22, and the turntable 21 on which the object to be measured 5 is mounted is rotated by 180 degrees or 360 degrees at a rotation angle. .

  In the transmission image data acquisition step 103b, X-ray transmission image data transmitted through the measurement object 5 is acquired while the measurement object 5 is rotating 180 degrees or 360 degrees on the turntable 21. The transmission image data acquisition step 103b is performed simultaneously with the turntable rotation step 103a.

  In addition, the image data of the measured object 5 acquired at a specific rotation angle while the turntable 21 rotates 180 degrees or 360 degrees in the transmission image data acquisition step 103b is shown in FIG. As described above, in the transmission image data detected by the radiation detection element of the two-dimensional radiation detector 3, the radiation detection element in a region where the vertical tree-like radiation shielding member 47b and the transverse tree-like radiation shielding member 47a of the collimator 4 are located just in front. The first scan image data in which part of the vertical and horizontal directions of the transmitted image data to be detected is lost, and step 103 of the first scan is completed.

  When step 103 of the first scan is completed, the next step is step 104 for resetting the collimator position. The collimator 4 is configured by operating the position controller 55 based on the command from the computer 50 and operating the drive unit 48. The vertical member 42 is moved in the collimator mounting guide 41 by a distance of N radiation detection elements (N ≧ 1; usually several) upward in the vertical direction indicated by the arrow.

  As a result of the moving operation, the position of the plurality of cross-shaped radiation shielding members 47a is moved upward by a distance of N radiation detection elements (N ≧ 1; usually several) as shown in FIG. The position of the beam-like radiation shielding member 47a of the collimator 4 is set to the position of the second scan shown in FIG. 8B with respect to the two-dimensional radiation detector 3.

  In step 105 of the next second scan, as in step 103 of the first scan, this is a process of detecting a X-ray that has passed through the object to be measured 5 and capturing a tomographic image, and comprises the following steps 105a and 105b. Has been.

  That is, in step 105a of the turntable rotation, the collimator 4 is set to the second scan position, and the command from the computer 50 is applied under the condition where the X-ray source 1 irradiates the object to be measured 5 with X-rays. Based on the above, the rotation / position controller 54 is operated to rotate the turntable 21 on which the object 5 to be measured is rotated by 180 degrees or 360 degrees at a rotation angle.

  In the transmission data acquisition step 105b, transmission data of X-rays transmitted through the measurement object 5 while the measurement object 5 is rotating 180 degrees or 360 degrees on the turntable 21 is acquired. The acquisition step 105b is performed simultaneously with the turntable rotation step 105a.

  In the transmission data acquisition step 105b, the transmission data of the DUT 5 acquired at a specific rotation angle while the turntable 21 is rotated 180 degrees or 360 degrees is as shown in FIG. 9B. Of the transmission data detected by the radiation detection element of the two-dimensional radiation detector 3, the horizontal tree radiation shielding member 47a and the vertical tree radiation shielding member 47b of the collimator 4 are detected by the radiation detection element in the region located just in front. The image data of the second scan in which part of the vertical direction and the horizontal direction of the power transmission data is missing is obtained, and the step 105 of the second scan is completed.

  When the second scanning step 105 is completed, the collimator position resetting step 108 follows. The collimator 4 is configured by operating the position controller 55 based on a command from the computer 50 to operate the drive unit 49. The horizontal member 46 is moved in the collimator mounting guide 45 in the left direction indicated by the arrow by a distance of N radiation detection elements (N ≧ 1; usually several).

  The position of the plurality of vertical tree radiation shielding members 47b is moved to the left as shown in FIG. 8 (c) by the above moving operation, and the position of the collimator 4 with respect to the two-dimensional radiation detector 3 in FIG. Set to the third scan position shown in c).

  In the next radiation irradiation step 109, the X-ray source controller 53 is operated based on a command from the computer 50 to direct the measured object 5 mounted on the turntable 21 of the turntable device 2 from the X-ray source 1. X-rays are emitted.

  Step 111 of the next third scan is a process of detecting a X-ray that has passed through the DUT 5 and capturing a tomographic image, and includes the following steps 111a and 111b.

  That is, in step 111a of rotating the turntable, the position of the vertical tree radiation shielding member 47b of the collimator 4 is set to the position of the third scan, and the X-ray source 1 is irradiated with the X-ray from the X-ray source 1 Based on the command from the computer 50, the rotation / position controller 54 is operated to drive the turntable rotating shaft 22, and the turntable 21 on which the object to be measured 5 is mounted is rotated by 180 degrees or 360 degrees at a rotation angle. .

  In the transmission image data acquisition step 111b, X-ray transmission image data transmitted through the measurement object 5 while the measurement object 5 is rotating 180 degrees or 360 degrees on the turntable 21 is acquired. The transmission image data acquisition step 111b is performed simultaneously with the turntable rotation step 111a.

  Further, in step 111b of transmission image data acquisition, the image data of the DUT 5 acquired at a specific rotation angle while the turntable 21 rotates slightly 180 degrees or 360 degrees is shown in (c) of FIG. As described above, in the transmission image data detected by the radiation detection element of the two-dimensional radiation detector 3, the radiation detection element in a region where the vertical tree-like radiation shielding member 47b and the transverse tree-like radiation shielding member 47a of the collimator 4 are located just in front. The first scan image data in which part of the transmission image data in the vertical direction and the horizontal direction is missing is obtained, and step 111 of the third scan is completed.

  When the third scan step 111 is completed, the collimator position is subsequently reset to step 112. The collimator 4 is configured by operating the position controller 55 based on a command from the computer 50 to operate the drive unit 48. The vertical member 42 to be moved is moved in the collimator mounting guide 41 by a distance of N radiation detection elements (N ≧ 1; usually several) downward in the vertical direction indicated by an arrow.

  As a result of the moving operation, the positions of the plurality of cross-shaped radiation shielding members 47a are moved downward by a distance of N radiation detection elements (N ≧ 1; usually several) as shown in FIG. The position of the beam-like radiation shielding member 47a of the collimator 4 is set to the position of the fourth scan shown in FIG. 8D with respect to the two-dimensional radiation detector 3.

  Step 113 of the next fourth scan is a process for detecting a X-ray that has passed through the DUT 5 and picking up a tomographic image in the same manner as Step 111 of the third scan, and comprises the following Step 113a and Step 113b. Has been.

  That is, in step 113a of the turntable rotation, the collimator 4 is set to the position of the fourth scan, and the command from the computer 50 is applied under the state where the X-ray source 1 irradiates the measurement object 5 with X-rays. Based on the above, the rotation / position controller 54 is operated to rotate the turntable 21 on which the object 5 to be measured is rotated by 180 degrees or 360 degrees at a rotation angle.

  In the transmission data acquisition step 113b, transmission data of X-rays transmitted through the measurement object 5 while the measurement object 5 is rotating 180 degrees or 360 degrees on the turntable 21 is acquired. The acquisition step 113b is performed simultaneously with the turntable rotation step 113a.

  In the transmission data acquisition step 113b, the transmission data of the DUT 5 acquired at a specific rotation angle while the turntable 21 rotates slightly 180 degrees or 360 degrees is as shown in FIG. 9D. Of the transmission data detected by the radiation detection element of the two-dimensional radiation detector 3, the horizontal tree radiation shielding member 47a and the vertical tree radiation shielding member 47b of the collimator 4 are detected by the radiation detection element in the region located just in front. The image data of the fourth scan in which a part of the vertical direction and the horizontal direction of the power transmission data is missing is obtained, and the step 113 of the fourth scan is completed.

  Next, the transmission image data synthesis step 106 is performed. In this transmission image data synthesis step 106, each transmission obtained by the first scan to the fourth scan of the object 5 to be measured at the same specific rotation angle of the turntable 21 is performed. By combining the image data with the image reconstruction calculation device 51 installed in the computer 50, X that has passed through the object to be measured 5 that is not shielded by the horizontal tree radiation shielding member 47 a and the vertical tree radiation shielding member 47 b of the collimator 4. Since transmission image data of a line is obtained, transmission image data that is a tomographic image of the entire object to be measured 5 shown in FIG. 9E can be obtained.

  Finally, the tomographic image / three-dimensional stereoscopic image creation step 107 is performed. In the tomographic image / three-dimensional stereoscopic image step 107, the transmission image showing the entire object to be measured 5 obtained in the transmission image data synthesis step 106 is shown. Based on the set of data, the image reconstruction calculation device 51 performs an image reconstruction calculation to create a complete tomographic image and / or a three-dimensional stereoscopic image showing the entire object to be measured 5.

  Then, the tomographic image and / or the three-dimensional stereoscopic image of the measurement object 5 created by the image reconstruction calculation device 51 is output to the display device 52 and displayed.

  The calculation of the rotation angle of the turntable 21 described above, the acquisition of transmission image data from the two-dimensional radiation detector 3, the synthesis of the acquired transmission image data and the calculation of image reconstruction are performed by commands from the computer 50, In addition, it is executed by an image reconstruction calculation device 51 provided in the computer 50.

  According to the embodiment of the present invention, a collimator that can not only reduce the influence of scattered radiation but also reduce the influence of radiation that passes through the object to be measured and enters the detector can be used to achieve higher definition. A tomographic apparatus and a tomographic method using radiation having a flat panel detector capable of obtaining a tomographic image with excellent image quality can be realized.

  The present invention relates to a tomography apparatus and a tomography method using radiation that uses an X-ray generator or a radioisotope as a radiation source, and detects radiation transmitted through an object mounted on a turntable with a two-dimensional radiation detector. Applicable.

1 is a side view showing a main configuration of a tomography apparatus using radiation according to an embodiment of the present invention. It is a front view which shows the arrangement | positioning relationship between the radiation detector used for the tomography apparatus of the Example shown in FIG. 1, and a ladder-like collimator, Comprising: (a) is a figure which shows the collimator position at the time of a 1st scan, (b) ) Is a diagram showing a collimator position at the time of the second scan in which the collimator is moved upward. 1A and 1B are diagrams of transmission image data acquired by scanning the object to be measured in the tomography apparatus of the embodiment shown in FIG. 1, wherein FIG. The figure which shows the transmission image data at the time of a 2nd scan, (c) is a figure which shows the transmission image data which synthesize | combined the transmission image data of a 1st scan and a 2nd scan. The side view which shows the main structures of the tomography apparatus using the radiation which is the other Example of this invention. The side view which shows the main structures of the tomography apparatus using the radiation which is further another Example of this invention. It is a front view which shows the arrangement | positioning relationship between the radiation detector used for the tomography apparatus of another Example shown in FIG. 5, and a ladder-like collimator, Comprising: (a) is a figure which shows the collimator position at the time of a 1st scan. (B) is a figure which shows the collimator position at the time of the 2nd scan which moved the collimator upward. The side view which shows the main structures of the tomography apparatus using the radiation which is another Example of this invention. It is a front view which shows the arrangement | positioning relationship between the radiation detector used for the tomography apparatus of another Example shown in FIG. 7, and a ladder-like collimator, Comprising: (a) is the time of the 1st scan which moved the collimator to the right. The figure which shows the collimator position of this, (b) The figure which shows the collimator position at the time of the 2nd scan which moved the collimator upward, (c) The figure which shows the collimator position at the time of the 3rd scan which moved the collimator to the left (D) is a figure which shows the collimator position at the time of the 4th scan which moved the collimator below. FIG. 8 is a diagram of transmission image data obtained by scanning a measurement object in the tomography apparatus of another embodiment shown in FIG. 7, (a) is a diagram showing transmission image data at the time of the first scan; (b) is a diagram showing transmission image data at the second scan, (c) is a diagram showing transmission image data at the third scan, (d) is a diagram showing transmission image data at the fourth scan, (e) FIG. 4 is a diagram illustrating transmission image data obtained by combining transmission image data of the first scan to the fourth scan. 2 is a flowchart showing an imaging process of a tomographic image of an object to be measured by X-rays in the tomography apparatus of the embodiment shown in FIG. 1. The flowchart which shows the imaging process of the tomographic image of the to-be-measured object by the X-ray in the tomography apparatus of another Example shown in FIG.

Explanation of symbols

  1: X-ray source, 2: Turntable device, 3: Two-dimensional radiation detector, 4: Collimator, 5: Object to be measured, 6: Base, 11: Support, 12: Support base, 21: Turntable, 22: Turntable rotating shaft, 23: support, 41, 45: collimator mounting guide, 42: vertical member, 43: cross-beam radiation shielding member, 44: slit, 46: cross member, 47a: cross-tree radiation shield member, 47b: Vertical tree radiation shielding member, 48, 49: drive unit, 50: computer, 51: image reconstruction calculation device, 52: display device, 53: X-ray source controller, 54: rotation / position controller, 55: position Controller.

Claims (7)

  A radiation source that irradiates radiation; a radiation detector in which a plurality of radiation detection elements are arranged in a flat plate to form a detection surface; and a table that is disposed between the radiation source and the radiation detector and that rotates the object to be measured. A turntable device having a collimator that is disposed in front of the detection surface of the radiation detector and forms a plurality of passages through which the radiation transmitted through the object to be measured passes, and the object to be measured that has passed through the passage formed in the collimator. Equipped with an image reconstruction calculation device that generates a tomographic image of the object to be measured based on a detection signal detected by the radiation detection element of the radiation detection device, and the collimator is in a horizontal direction parallel to the detection surface of the radiation detector The image reconstruction calculation device detects radiation transmitted through the object to be measured at different positions where the collimator is moved. A plurality of tomographic images of the object to be measured corresponding to the moving position of the collimator are generated based on each detection signal of the radiation detector, and a plurality of tomographic images of these objects to be measured are combined to generate an entire tomographic image of the object to be measured. A tomography apparatus using radiation, characterized by being configured to generate an image.   2. The tomography apparatus using radiation according to claim 1, wherein the collimator is configured in a ladder shape by a vertical member and a plurality of cross members attached to the vertical member at a predetermined interval, and the cross member is formed by a radiation shielding material. A path through which the radiation transmitted through the object to be measured passes is defined by a gap between adjacent cross members, and the width of this gap is formed to be substantially the same as the vertical plate width of the cross member. A tomography apparatus using radiation, wherein a plurality of cross members are held movably up and down along a vertical line direction.   The tomography apparatus using radiation according to claim 1, wherein the collimator is configured in a ladder shape by a horizontal member and a plurality of vertical wooden members attached to the horizontal member at a predetermined interval, and the vertical wooden member is formed by a radiation shielding material. The passage through which the radiation transmitted through the object to be measured passes is defined by the gap between the adjacent vertical members, and the width of this gap is formed to be substantially the same as the horizontal plate width of the vertical members. A tomographic apparatus using radiation, wherein the plurality of vertical members of the collimator are held movably left and right along the horizontal direction.   2. The tomography apparatus using radiation according to claim 1, wherein the collimator is configured in a ladder shape by a vertical member and a plurality of cross members attached to the vertical member at a predetermined interval, and the cross member is formed by a radiation shielding material. A passage through which the radiation transmitted through the object to be measured passes through a gap between adjacent crosspiece members, and the width of the gap is formed to be substantially the same as the vertical plate width of the crosspiece member. The member is configured in a ladder shape by a first movable collimator that is movably held up and down along the vertical direction, and a plurality of vertical members attached to the horizontal member and the horizontal member at a predetermined interval. A passage formed by a radiation shielding material and passing through the object to be measured is defined by a gap between adjacent vertical tree members, and the width of the gap is substantially the same as the horizontal plate width of the vertical tree members. Multiple vertical section formed into dimensions Tomography apparatus using radiation, characterized in that it is composed of a second movable collimator held on the movable side to side along the horizontal direction.   5. The tomography apparatus using radiation according to claim 2 or 4, wherein the plurality of cross members constituting the collimator travels the radiation irradiated from the radiation source and transmitted through the object to be measured to the radiation detection apparatus. A tomography apparatus using radiation, wherein the tomography apparatus is disposed so as to be inclined with respect to a horizontal plane so as to follow a direction.   The tomography apparatus using radiation according to claim 2 or 4, wherein the plurality of cross members constituting the collimator are movable up and down along the vertical direction with respect to the cross members located in the central region of the collimator. A tomography apparatus using radiation, which is arranged to be held.   Radiation was irradiated from the radiation source to the measurement object mounted on the turntable device that rotates the measurement object, and the radiation that passed through the measurement object was formed on the collimator placed in front of the detection surface of the radiation detector The radiation that is guided to the radiation detector through a plurality of passages and passes through the object to be measured that has passed through the plurality of passages formed in the collimator is detected by a plurality of radiation detection elements arranged in a plate shape on the radiation detection device, and these radiation detections are performed. In a tomography method of an object to be measured for generating a tomographic image of the object to be measured based on a detection signal detected by an element, the collimator is at least one of a horizontal direction and a vertical line direction parallel to the detection surface of the radiation detector The collimator is moved by irradiating the object to be measured with radiation from the radiation source at different positions where the collimator is moved. The radiation that has passed through the measurement object at a plurality of positions is detected by the radiation detection element of the radiation detection device, and the measurement object corresponding to the movement position of the collimator is detected based on each detection signal detected by the radiation detection element. A tomography method using radiation, wherein a plurality of tomographic images are generated, and a plurality of tomographic images of these objects to be measured are combined to generate a whole tomographic image of the object to be measured.

Images