JP2008104704A - Radiographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiographic apparatus which can ensure a uniformly irradiated visual field. <P>SOLUTION: The radiographic apparatus includes predetermining an X-ray intensity distribution (a relationship between position and X-ray intensity within an irradiated visual field), calculating the operation amount d corresponding to a position according to an X-ray intensity in the visual field to be irradiated from the uniformity of the set visual field to be irradiated and the above distribution, and operating with the operation amount d to control the radiated visual field. The uniformity can be set as an object to calculate the operation amount d in the visual field to irradiate, and the operation amount d can executed to control the irradiated visual field, allowing the X-ray tube 2 to irradiate the irradiated visual field with uniformity as an object to ensure the uniformly irradiated visual field suitable for photographic intention. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radiation imaging apparatus that performs radiation imaging, and more particularly to a technique for controlling an irradiation field of radiation emitted from radiation irradiating means.

  An explanation will be given by taking an X-ray fluoroscopic imaging apparatus as an example of the radiation imaging apparatus. In recent years, in X-ray imaging using an X-ray fluoroscopic apparatus, cases of bone mineral quantification in which the amount of Ca (calcium) contained in bone is measured based on the degree of X-ray absorption by the bone have been increasing. In order to perform bone mineral quantification, X-rays irradiated from an X-ray tube (radiation irradiation means) and transmitted through the subject M are converted into X-rays represented by an X-ray film, a flat panel X-ray detector (FPD) or the like. Detection is performed by a line detector, and an image showing bones is obtained based on the detected X-rays. Such bone mineral quantification requires uniformity of the film density of the X-ray film detected in the irradiation field (uniformity of the irradiation field).

  In general, in an X-ray tube, the X-ray intensity on the anode (also referred to as “target”) A side is weaker than the center O of the irradiation field, as shown in FIG. In addition, the code | symbol C in FIG. 8 is a cathode (cathode). This is a characteristic unique to the X-ray tube, also called “heel effect” (see, for example, Patent Documents 1 and 2). The standard that defines the uniformity of the X-ray intensity in the illumination field is the center of the illumination field (field center), both in the International Electrotechnical Commission (IEC) and the Japanese Industrial Standard (JIS). It is stipulated that 30% or more is required. However, when bone mineral content is determined, about 30% is insufficient, and uniformity of 80% or 90% is required.

  Therefore, in order to ensure sufficient uniformity, the heel effect is corrected by a filter as in Patent Document 1 described above, or the X-ray dose is measured in advance as in Patent Document 2 described above, and A uniform X-ray intensity distribution is obtained by providing a metallic filter, which is formed thicker at stronger sites, at the irradiation port of the X-ray tube. In addition, as shown in FIG. 9, when an electron beam emitted from the cathode C or an axis parallel to the axis connecting the cathode C and the anode A is defined as the tube axis Ax, it is perpendicular to the tube axis Ax. The direction of the axis Bx is used, as shown in FIG. 10, an X-ray tube with a larger target angle θ of the cathode C is used, or the focus-film distance (FFD) as shown in FIG. ) Larger than FIG. 11A, a uniform X-ray intensity distribution is obtained.

As described above, since the X-ray intensity on the anode A side becomes weaker with respect to the center O of the irradiation field as described above, the X-ray intensity distribution changes greatly with respect to the direction of the tube axis Ax in FIG. The change in the X-ray intensity distribution is small with respect to the direction of the central axis Bx. Therefore, a photographing technique as shown in FIG. 9 is performed. In the heel effect, X-rays generated in the anode (target) A are attenuated while passing through the target, and in particular, the anode A side from the X-rays emitted toward the cathode C side and the center O side of the irradiation field. The X-rays emitted from the light source are attenuated by the longer transmission length, and the X-ray intensity on the anode A side becomes weaker than the center O of the irradiation field. Therefore, an X-ray tube having the structure shown in FIG. 10 is used. When the portion where the X-ray intensity is 90%, that is, the uniformity of the irradiation field is 90% or more is indicated by hatching in FIG. 11, if the FFD is small as shown in FIG. However, if the FFD is large as shown in FIG. 11 (b), the illumination field at 90% or more can be increased.
Japanese Patent Laying-Open No. 2005-169110 (page 1-7, FIG. 3-5) JP 2004-214130 A (page 1-3, FIG. 1-3)

  As described above, in X-ray imaging that performs bone mineral quantification, it is necessary to increase the FFD in order to ensure the uniformity of film density (uniformity of illumination field). On the other hand, in normal X-ray imaging, a film density uniformity of about 30% is sufficient as described above. However, when X-ray imaging for bone mineral content determination is mistaken for normal X-ray imaging and an operator (engineer) and imaging is performed with a short FFD, uniformity of film density of 80% or 90% cannot be ensured. As a result, the measurement result of bone mineral quantification becomes inaccurate. In this case, useless exposure is given to the subject.

  This invention is made in view of such a situation, and it aims at providing the radiation imaging device which can ensure the uniformity of an irradiation visual field.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention according to claim 1 includes radiation irradiating means for irradiating a subject with radiation, detects radiation transmitted through the subject, and obtains a radiation image based on the detected radiation. A radiation imaging apparatus that performs radiation imaging with an irradiation field operation unit that operates an irradiation field of radiation irradiated from the radiation irradiation unit, and a position in the irradiation field expressed as a radiation intensity distribution and the radiation intensity Based on the correlation storage means for storing the correlation in advance, the uniformity of the irradiation field set in advance and the correlation stored in the correlation storage means in advance, according to the radiation intensity corresponding to the set uniformity. An operation amount calculation means for calculating an operation amount of the illumination field corresponding to the position in the illumination field, and operating the illumination field operation means with the operation amount calculated by the operation amount calculation means. It is characterized in further comprising a irradiation field control means for controlling.

  [Operation / Effect] According to the first aspect of the present invention, the correlation between the position in the irradiation field expressed as the radiation intensity distribution and the radiation intensity is stored in the correlation storage means in advance. Based on the set uniformity of the irradiation field and the correlation stored in advance in the above-described correlation storage unit, the operation amount calculation unit is provided in the irradiation field according to the radiation intensity corresponding to the above-described set uniformity. The operation amount of the illumination field corresponding to the position is calculated. The illumination field control means controls the illumination field by operating with the operation amount calculated by the operation amount calculation means. As a result, if the target uniformity is set, the operation amount of the illumination field is calculated, and the illumination field control means controls the illumination field by operating the operation amount. The visual field can be irradiated from the radiation irradiation means. Therefore, the uniformity of the irradiation field can be ensured according to the purpose of imaging.

  In the above-described invention, an input means for inputting the set uniformity may be provided (the invention according to claim 2), or a transfer means for transferring to / from an external device outside the device is provided. The uniformity set by the means may be transferred (the invention according to claim 3). That is, in the case of the invention described in claim 2, the uniformity is input and set in the input unit, and in the case of the invention described in claim 3, the set uniformity data is transferred from the external device to the transfer unit. The input is set by transferring to the radiation imaging apparatus according to the present invention.

  In addition, in the examples of the inventions described above, when the radiation intensity is distributed symmetrically at the center of the irradiation field, the distance from the center to the position corresponding to the radiation intensity to be set is the manipulated variable. The calculating means calculates and calculates an operation amount based on a radiation intensity to be set corresponding to the set uniformity by calculating an operation amount corresponding to the calculated distance. Item 4).

  When the radiation intensity is distributed symmetrically at the center of the irradiation field, there are two distances from the center to the location corresponding to the radiation intensity to be set in one direction, including the reverse direction. Are the same distance from each other. The operation amount calculation means calculates the distance, and can calculate the operation amount corresponding to the calculated distance. By calculating the operation amount in this way, the operation amount is calculated based on the radiation intensity to be set corresponding to the set uniformity.

  In addition, in another example of these inventions described above, when the radiation intensity is distributed asymmetrically at the center of the irradiation field, the distance from the center to the location corresponding to the radiation intensity to be set is The operation amount calculation means calculates the operation amount corresponding to the calculated distance by selecting the shortest distance from the plurality of existing distances, and corresponds to the set uniformity. The operation amount is calculated based on the radiation intensity to be set (the invention according to claim 5).

  When the radiation intensity is distributed asymmetrically at the center of the irradiation field, there are two distances from the center to the location corresponding to the radiation intensity to be set in one direction, including the reverse direction. Are different distances from each other. Therefore, by selecting the shortest distance from among a plurality of existing distances, a radiation intensity smaller than the radiation intensity at the selected distance is not set. The operation amount calculation means calculates the distance, and can calculate the operation amount corresponding to the calculated distance. By calculating the operation amount in this way, the operation amount is calculated based on the radiation intensity to be set corresponding to the set uniformity.

  According to the radiation imaging apparatus according to the present invention, if the target uniformity is set, the operation amount of the illumination field is calculated, and the illumination field operation means is operated by the operation amount to control the illumination field. The irradiation field having the target uniformity can be irradiated from the radiation irradiation means, and the uniformity of the irradiation field can be ensured according to the purpose of imaging.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of an X-ray fluoroscopic apparatus according to an embodiment. In this embodiment, a radiographic imaging apparatus will be described as an example of a radiographic imaging apparatus.

  As shown in FIG. 1, the X-ray fluoroscopic imaging apparatus transmits a top plate 1 on which a subject M is placed, an X-ray tube 2 that emits X-rays toward the subject M, and the subject M. A flat panel X-ray detector (hereinafter abbreviated as “FPD”) 3 for detecting X-rays is provided. In addition to the FPD, the X-ray detector may be an image intensifier or an X-ray film. The X-ray tube 2 corresponds to the radiation irradiation means in this invention.

  In addition, the X-ray fluoroscopic apparatus includes a top panel control unit 4 that controls the elevation and horizontal movement of the top panel 1, an FPD control unit 5 that controls scanning of the FPD 3, and the tube voltage and tube current of the X-ray tube 2. Are output from an X-ray tube control unit 7 having a high voltage generation unit 6 that generates a signal, an A / D converter 8 that digitizes and extracts an X-ray detection signal that is a charge signal from the FPD 3, and an A / D converter 8. An image processing unit 9 that performs various processes based on the detected X-ray detection signal, a controller 10 that controls these components, a memory unit 11 that stores processed images, and an operator perform input settings. An input unit 12 and a monitor 13 for displaying processed images are provided.

  The top board control unit 4 horizontally moves the top board 1 to accommodate the subject M up to the imaging position, moves the top and bottom, rotates and horizontally moves the subject M to a desired position, or horizontally moves the subject M. Then, the image is picked up, or the image is moved horizontally after the image pickup is finished, and the control is performed to retract from the image pickup position. The FPD control unit 5 performs control related to scanning by moving the FPD 3 horizontally or rotating around the body axis of the subject M. The high voltage generation unit 6 generates a tube voltage and a tube current for irradiating X-rays and applies them to the X-ray tube 2. The X-ray tube control unit 7 moves the X-ray tube 2 horizontally, Control relating to scanning by rotating around the axis of the body axis of M, control of the setting of the irradiation field of the collimator 16 on the X-ray tube 2 side (see FIGS. 2 and 4), and the like are performed. When scanning the X-ray tube 2 or the FPD 3, the X-ray tube 2 and the FPD 3 move while facing each other so that the FPD 3 can detect the X-rays emitted from the X-ray tube 2.

  In this embodiment, the X-ray tube control unit 7 controls the irradiation field by operating the collimator 16 (see FIGS. 2 and 4) with the operation amount d of the irradiation field (see FIG. 4). Therefore, the X-ray tube control unit 7 corresponds to the irradiation field control means in the present invention. The operation amount of the illumination field is also referred to as the “opening amount” of the collimator 16.

  The controller 10 is configured by a central processing unit (CPU) and the like, and the memory unit 11 is configured by a storage medium represented by ROM (Read-only Memory), RAM (Random-Access Memory), and the like. Yes. The input unit 12 includes a pointing device represented by a mouse, a keyboard, a joystick, a trackball, a touch panel, and the like. In the fluoroscopic imaging apparatus, the FPD 3 detects X-rays transmitted through the subject M, and the image processing unit 9 performs image processing based on the detected X-rays, thereby imaging the subject M.

  In the present embodiment, the memory unit 11 stores in advance a correlation memory unit 11a in which a correlation between the position in the irradiation field expressed as an X-ray intensity distribution (see FIGS. 4 and 6) and the X-ray intensity is stored in advance. It has. Further, the ROM of the memory unit 11 corresponds to the X-ray intensity corresponding to the set uniformity based on the set uniformity of the irradiation field and the correlation previously stored in the correlation memory unit 11a. A program for calculating the operation amount of the illumination field corresponding to the position within the illumination field is stored in advance, and the controller 10 executes the program. Therefore, the controller 10 has the function of the operation amount calculation means in this invention. Therefore, the correlation memory unit 11a corresponds to the correlation storage means in this invention. The input unit 12 includes a touch panel 12a (see FIGS. 2 and 3) described later, and inputs the set uniformity. Therefore, the input unit 12 including the touch panel 12a corresponds to the input means in this invention.

  Next, the imaging system will be described with reference to FIGS. FIG. 2 is a schematic diagram illustrating a specific configuration of an imaging system of the fluoroscopic imaging apparatus, and FIG. 3 is a schematic diagram of a touch panel illustrating an example of an input unit.

  As shown in FIG. 2, a cage 14 for suspending and supporting the above-described X-ray tube 2 from the ceiling is provided. A lamp 15 is disposed on the X-ray tube 2 supported in a suspended manner, and a collimator 16 is disposed on the irradiation side. The collimator 16 operates the irradiation field of X-rays emitted from the X-ray tube 2. The light emitted from the lamp 15 is also operated by the collimator 16. Therefore, the operator can visually recognize the irradiation field of X-rays by the light emitted from the lamp 15. Note that the lamp 15 is not necessarily provided. Further, the X-ray tube 2 is not limited to a type that is suspended and supported by the cage 14, and may be a type that is supported together with the FPD 3, a type that can be transported in accordance with the round trip, and the like. The collimator 16 corresponds to the illumination field operation means in this invention.

  A touch panel 12a is disposed on the side of the suspended X-ray tube 2. As shown in FIG. 3, the touch panel 12a is provided with uniformity setting screens such as “30%”, “50%”, “80%”, and “90%”. Touch to set the uniformity corresponding to the touched screen. For example, touching “30%” inputs and sets the uniformity of “30%”. Similarly, touch “50%” to set “50%” uniformity, touch “80%” to set “80%” uniformity, and touch “90%”. Use to input “90%” uniformity.

  Next, a series of illumination field control based on the set uniformity will be described with reference to FIGS. 4 (a) to 4 (c) are schematic diagrams showing the irradiation field and the X-ray intensity distribution for each operation amount (opening amount) of each irradiation field, and FIG. 5 shows the X-ray intensity distribution. FIG. 6 is a graph showing the correlation between the position in the irradiation field represented and the X-ray intensity, and FIG. 6 is an X-ray intensity distribution different from FIG. 4 for each operation amount (opening amount) of each irradiation field. It is the schematic diagram which showed. 4 shows an X-ray intensity distribution when the X-ray intensity is asymmetrically distributed at the center O of the irradiation field, and FIG. 6 shows an X-ray intensity when the X-ray intensity is distributed symmetrically at the center O of the irradiation field. Intensity distribution.

  The X-ray intensity distribution represents the uniformity of the illuminated field, that is, the degree of uniformity of the illuminated field. As described in FIG. 8 of the prior art, as shown in FIGS. 4 and 6, when the X-ray intensity at the center O of the illumination field is 100%, the intensity decreases as the distance from the center decreases, and the uniformity is maintained. It ’s gone. The X-ray intensity distribution is represented by the correlation between the position in the irradiation field and the X-ray intensity, and is a distribution as shown in FIG. The graph of FIG. 5 shows the X-ray intensity distribution when the X-ray intensity is distributed asymmetrically at the center O of the irradiation field as in FIG. Such correlation is obtained in advance at the stage of the factory before shipment of the X-ray tube 2 or X-ray fluoroscopic apparatus. Thereafter, the X-ray tube 2 or the X-ray fluoroscopic apparatus is shipped.

  Imaging is performed using a phantom such as water or a copper plate as the subject in a state where the operation amount (opening amount) d of the irradiation field is maximized. Then, the X-ray intensity is measured according to the position of the irradiation field, and the distribution as shown in FIG. 5 is measured. In addition, when there are a plurality of types of X-ray tubes 2 (see FIGS. 1 and 2) (for example, X-ray tubes having different target angles, X-ray tubes having different anode and cathode structures and materials, etc.) X-ray intensity distribution is measured according to each kind. It is not always necessary to measure the X-ray intensity distribution with the irradiation field manipulated variable d maximized, but in actual imaging after shipment, the irradiation field manipulated variable d may be maximized. Considering this, it is preferable to measure the X-ray intensity distribution with the maximum manipulated variable d of the irradiation field. The X-ray intensity distribution measured in this way is stored in advance in the correlation memory unit 11a (see FIG. 1) as a correlation between the position in the irradiation field and the X-ray intensity, and then shipped. Further, photographing may be performed in a state where the operation amount (opening amount) d of the illumination field is maximized without the phantom being inserted.

  The case where the X-ray intensity is distributed asymmetrically at the center O of the illumination field will be described. FIG. 4A shows a state where the operation amount (opening amount) d is maximized. At this time, it exceeds 50% on the cathode C side, but is less than 30% on the anode A side. When 30% is input and set from the touch panel 12a (see FIGS. 2 and 3), the X-ray intensity corresponding to 30% is as shown in FIG. 4B. The position in the illumination field corresponding to the X-ray intensity is a portion where the X-ray intensity distribution changes from a solid line to a two-dot chain line in the figure. The operation amount d of the illumination field corresponding to this position is as shown in FIG. Knowing this position makes it possible to calculate the manipulated variable d. When 90% is input from the touch panel 12a, the X-ray intensity corresponding to 90% is as shown in FIG. The position in the illumination field corresponding to the X-ray intensity is a portion where the X-ray intensity distribution changes from a solid line to a two-dot chain line in the figure. The operation amount d of the illumination field corresponding to this position is as shown in FIG.

  Here, the X-ray intensity is asymmetrically distributed at the center O of the illumination field (in this embodiment, the anode A side has a smaller intensity distribution than the cathode C side), and in one direction including the reverse direction. There are two distances from the center O to the portion corresponding to the X-ray intensity to be set, but they are different from each other. When 90% is input and set, the X-ray intensity to be set corresponding to 90% on the anode A side is a portion indicated by a solid line in the figure, and therefore corresponds to the X-ray intensity to be set from the center O. The distance to the location is up to the portion corresponding to the solid line. However, on the opposite cathode C side, the X-ray intensity corresponding to 90% extends not only to the part indicated by the solid line in the figure but also to the two-dot chain line part, so the distance from the center O to the part corresponding to the X-ray intensity. Is up to the portion corresponding to the solid line and the two-dot chain line, and the distances are different from each other. Therefore, by selecting the shortest distance from a plurality of existing distances, an X-ray intensity smaller than the X-ray intensity at the selected distance is not set. When 90% is input and set, the distance on the anode A side is the shortest distance, and by selecting this distance, the X-ray intensity at the selected distance is as shown in FIG. The cathode C side also exceeds 100% and 90%, and an X-ray intensity smaller than the X-ray intensity at the selected distance is not set.

  It is possible to calculate the operation amount d corresponding to the calculated distance while calculating the distance. By calculating the operation amount d in this way, the operation amount d is calculated based on the X-ray intensity to be set corresponding to the set uniformity.

  When the X-ray intensity is distributed symmetrically at the center O of the irradiation field, the operation amount d is changed as shown in FIGS. 6 (a) to 6 (c). Since the X-ray intensity is symmetrically distributed at the center O of the irradiation field, there are two distances from the center O to the position corresponding to the X-ray intensity to be set in one direction including the reverse direction. Although they exist, they are the same distance from each other. When 90% is input and set, the X-ray intensity to be set corresponding to 90% on the anode A side is a portion indicated by a solid line in the figure, and therefore corresponds to the X-ray intensity to be set from the center O. The distance to the location is up to the portion corresponding to the solid line. The X-ray intensity to be set corresponding to 90% on the reverse cathode C side is the portion indicated by the solid line in the figure, so the distance from the center O to the location corresponding to the X-ray intensity to be set corresponds to the solid line. The distance is the same.

  Similar to the case where the X-ray intensity is distributed asymmetrically at the center O of the irradiation field, it is possible to calculate the distance and to calculate the operation amount d corresponding to the calculated distance. By calculating the operation amount d in this way, the operation amount d is calculated based on the X-ray intensity to be set corresponding to the set uniformity.

  According to the X-ray fluoroscopic apparatus according to the present embodiment, the correlation between the position in the irradiation field expressed as the X-ray intensity distribution and the X-ray intensity is stored in the correlation memory unit 11a in advance. Based on the set uniformity of the irradiation field and the correlation stored in the correlation memory unit 11a in advance, the controller 10 can adjust the irradiation field in the irradiation field according to the X-ray intensity corresponding to the set uniformity. The operation amount d of the illumination field corresponding to the position is calculated. The irradiation field of view is controlled by the X-ray tube controller 7 operating with the operation amount d calculated by the controller 10. As a result, if the target uniformity is set, the operation amount d of the irradiation field is calculated, and the irradiation field is controlled by operating the X-ray tube control unit 7 with the operation amount d. It is possible to irradiate an irradiation field having Therefore, the uniformity of the irradiation field can be ensured according to the purpose of imaging.

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

  (1) In the above-described embodiments, the X-ray fluoroscopic imaging apparatus has been described as an example of the radiation imaging apparatus. However, an ECT (typically represented by a PET (Positron Emission Tomography) apparatus, a SPECT (Single Photon Emission CT) apparatus, or the like). A radiation imaging apparatus that performs radiation imaging by detecting radiation other than X-rays (gamma rays in the case of a PET apparatus) and obtaining a radiation image based on the detected radiation, such as an Emission Computed Tomography apparatus You may apply.

  (2) In the above-described embodiment, the X-ray fluoroscopic apparatus as shown in FIG. 1 has been described as an example. However, the present invention is also applied to, for example, an X-ray imaging apparatus disposed on a C-arm. May be. The present invention may also be applied to an X-ray CT apparatus.

  (3) In the embodiment described above, X-ray imaging was performed with the subject M in a horizontal posture as shown in FIG. 1, but X-ray imaging may be performed with the subject in a standing posture, or obliquely. X-ray imaging may be performed in the direction.

  (4) In the above-described embodiment, the touch panel 12a has been described as an example of input means for inputting the set uniformity, but it is represented by a mouse, keyboard, joystick, trackball, touch panel, or the like other than the touch panel 12a. You may apply to a pointing device.

  (5) In the above-described embodiment, the uniformity is input and set to the input means represented by the touch panel 12a or the like. However, as shown in FIG. 7, the cable 17 for transferring between the external device outside the device is connected. The uniformity set from the cable 17 may be transferred. That is, the set uniformity data is input and set by transferring it from the external device to the device via the cable 17. Such a configuration is useful, for example, in the case of a system in which procedure information ordered by a doctor (data of set uniformity) is sent from a hospital network (network consisting of devices, cables 17 and external devices). It is possible to automatically set the uniformity according to the information. The cable 17 corresponds to the transfer means in this invention. In addition to the cable 17, there is no particular limitation as long as it is a transfer means that is normally used as exemplified by a wireless local area network (LAN).

1 is a block diagram of an X-ray fluoroscopic apparatus according to an embodiment. It is the schematic which shows the specific structure of the imaging system of a X-ray fluoroscopic apparatus. It is the schematic of the touch panel which shows an example of an input part. (A)-(c) is the schematic diagram which showed the irradiation visual field and X-ray intensity distribution for every operation amount (opening amount) of each irradiation visual field. It is the graph which showed the correlation with the position in the irradiation visual field represented as X-ray intensity distribution, and X-ray intensity. FIG. 5 is a schematic diagram showing an X-ray intensity distribution different from that in FIG. 4 for each operation amount (opening amount) of each irradiation field. It is a block diagram of the X-ray fluoroscopic apparatus which concerns on a modification. It is the schematic diagram which showed X-ray intensity distribution. It is the schematic diagram which showed the imaging form at the time of using a direction perpendicular | vertical with respect to a pipe axis. It is the schematic which shows the structure of the X-ray tube which enlarged the target angle. (A), (b) is the schematic diagram which showed the imaging form for every focus / film distance (FFD).

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... X-ray tube 7 ... X-ray tube control part 10 ... Controller 11a ... Correlation memory part 12 ... Input part 12a ... Touch panel 16 ... Collimator d ... Operation amount (opening amount) of an illumination field
O… Center of illumination field M… Subject

Claims (5)

  A radiation imaging apparatus that includes radiation irradiating means for irradiating radiation toward a subject, detects radiation transmitted through the subject, and obtains a radiation image based on the detected radiation to perform radiation imaging. Irradiating field operation means for manipulating the irradiation field of the radiation irradiated from the radiation irradiating means; correlation storage means for storing in advance the correlation between the position in the irradiation field expressed as a radiation intensity distribution and the radiation intensity; Based on the set uniformity of the irradiation field and the correlation stored in advance in the correlation storage means, the irradiation field corresponding to the position in the irradiation field corresponding to the radiation intensity corresponding to the set uniformity The operation amount calculation means for calculating the operation amount of the camera and the illumination field control means for controlling the illumination field by operating the illumination field operation means with the operation amount calculated by the operation amount calculation means. The radiation imaging apparatus according to claim and.   The radiation imaging apparatus according to claim 1, further comprising an input unit that inputs the set uniformity.   The radiation imaging apparatus according to claim 1, further comprising a transfer unit that transfers data to / from an external device outside the device, wherein the set uniformity is transferred from the transfer unit. apparatus.   4. The radiation imaging apparatus according to claim 1, wherein when the radiation intensity distribution is symmetrically distributed at the center of the irradiation field, the radiation intensity distribution corresponds to a radiation intensity to be set from the center. Based on the radiation intensity to be set corresponding to the set uniformity by calculating the operation amount corresponding to the calculated distance while the operation amount calculating means calculates the distance to the place to be A radiation imaging apparatus characterized by calculating an operation amount.   4. The radiation imaging apparatus according to claim 1, wherein when the radiation intensity is asymmetrically distributed at the center of the irradiation field, the radiation intensity distribution corresponds to the radiation intensity to be set from the center. There are a plurality of distances to the location to be selected, and the operation amount calculation means calculates the operation distance corresponding to the calculated distance by selecting the shortest distance from the plurality of distances. An operation amount is calculated based on the radiation intensity to be set corresponding to the set uniformity.

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