JP5451099B2 - Radiation imaging system and method of detecting amount of displacement from focal position of radiation source - Google Patents

Description

  The present invention relates to a radiation imaging system for converting radiation emitted from a radiation source into a radiation image by a radiation detector, and a detection method for detecting a positional deviation amount from a focal position of the radiation source with respect to the radiation detector. About.

  A radiation imaging apparatus, such as a mammography apparatus, that constitutes a radiation imaging system acquires a radiation image by converting radiation emitted from a radiation source through a breast of a subject into a radiation image by a radiation detector.

  In this mammography apparatus, for example, when performing head-to-tail (CC) imaging in which radiation is emitted from the upper part of the breast, the correct focal position of the radiation source with respect to the radiation detector is a plan view and the radiation detection in the left-right direction of the subject. It is the position of the end of the subject on the chest wall side of the radiation detector in the center in the horizontal direction of the instrument and in the front-rear direction of the subject. That is, when performing CC imaging, the radiation source is adjusted to the focal position above the center of the radiation detector in the left-right direction and the chest wall side end of the radiation detector.

  Patent Document 1 proposes a mammography apparatus that performs tomosynthesis imaging by moving a radiation source in an arc shape with respect to a radiation detector.

JP 2003-305031 A

  In the mammography apparatus of Patent Document 1, a radiation source is movably attached to an arc-shaped track via a gantry, and the gantry is moved along the arc-shaped track so that the radiation source is moved with respect to a radiation detector. The radiation source is moved in an arc shape, or the radiation source is attached to one end of an arm (base) and rotated around the center of the arm, thereby moving the radiation source in an arc shape with respect to the radiation detector.

  In this case, when CC imaging (normal imaging) is performed after tomosynthesis imaging, it is necessary to return the radiation source to the above-described focal position. However, positioning of the focal position is performed by moving the radiation source to the focal position along the arc-shaped trajectory, or rotating the arm to move the radiation source to the focal position. Is done. Therefore, in such positioning based on the mechanical position accuracy, it is difficult to accurately position the radiation source at the focal position.

  Further, in the mammography apparatus, in the lateral direction (ML) imaging in which the radiation is irradiated from the side surface, the radiation source is rotated by 90 ° from the focal point position of the CC imaging with respect to the radiation detector, while from the oblique direction. In inside / outside oblique (MLO) imaging, in which imaging is performed by irradiating radiation, the radiation source needs to be rotated from the focal position of the CC imaging to the angle in the oblique direction with respect to the radiation detector. In this case, even if the focal position of the radiation source with respect to the radiation detector is accurately positioned based on the mechanical position accuracy, the gantry is deformed by the weight of the radiation source, and the position of the radiation source is the focus position. There is a risk of displacement.

  The present invention has been made in view of the above problems, and a detection method capable of accurately detecting a displacement amount from a correct focal position of a radiation source with respect to a radiation detector, and a detected displacement amount. It is an object of the present invention to provide a radiation imaging system capable of accurately adjusting the position of the radiation source to the focal position based on the above.

In the present invention,
The radiation source irradiates the radiation detector with radiation,
The radiation detector converts the radiation into a radiation image;
When the marker arranged in the radiation irradiation area is projected as a marker image on the radiation image by the radiation irradiation,
The calculation means calculates a positional deviation amount from the correct focal position of the radiation source with respect to the radiation detector based on the position of the marker image in the radiation image.

  According to the present invention, the positional deviation amount from the correct focal position of the radiation source with respect to the radiation detector is calculated based on the position of the marker image in the radiation image actually obtained by irradiating the radiation. It is possible to accurately detect the amount of deviation.

It is a perspective view of the mammography apparatus which comprises the radiography system which concerns on this embodiment. It is an internal block diagram of the imaging stand in the mammography apparatus of FIG. 1 is a configuration block diagram of a radiation imaging system according to the present embodiment. It is a flowchart of operation | movement of the radiography system of FIG. 5A to 5C are explanatory diagrams showing display contents on the display unit. 6A to 6C are explanatory diagrams illustrating display contents on the display unit. 7A to 7C are explanatory diagrams illustrating other display contents on the display unit. 8A to 8C are explanatory diagrams illustrating other display contents on the display unit. It is an internal block diagram of the imaging stand at the time of arrange | positioning a marker in a different height. 10A and 10B are explanatory diagrams showing display contents on the display unit.

  A preferred embodiment of a radiation imaging system according to the present invention will be described with reference to the drawings in connection with a method for detecting a positional deviation amount from a focal position of a radiation source.

  As shown in FIG. 1, a mammography apparatus (radiation imaging apparatus) 10 applied to the radiation imaging system 50 (see FIG. 3) according to the present embodiment includes a base 12 installed in a standing state and a base 12. An arm member 16 fixed to the pivot shaft 14 disposed at a substantially central portion of the body 18, and a radiation source 22 for irradiating radiation X to a breast 20 (see FIG. 2) that is an imaging region of the subject 18. A radiation source storage unit (stand) 24 fixed to one end of the arm member 16 and a radiation detector 26 that detects the radiation X transmitted through the breast 20 and converts it into a radiation image are stored. An imaging table 28 fixed to the body and a compression plate 30 that compresses and holds the breast 20 against the imaging table 28 are provided.

  The arm member 16 that connects the radiation source storage unit 24 and the imaging base 28 is configured to be adjustable in the imaging direction with respect to the breast 20 of the subject 18 by rotating in the arrow A direction about the rotation axis 14. In addition, by rotating the arm member 16 in the direction of arrow A about the pivot axis 14 by a radiation source moving means (not shown) (see, for example, Japanese Patent Application Laid-Open No. 2008-104673), radiation is performed independently of the imaging table 28. It is also possible to turn the source storage unit 24. The compression plate 30 is disposed between the radiation source storage unit 24 and the imaging table 28 in a state of being connected to the arm member 16 via the support member 34 and can be displaced in the direction of arrow B. It should be noted that the arm member 16, the radiation source storage unit 24, the imaging table 28, and the compression plate 30 connected to the distal end side of the turning shaft 14 are moved along the base 12 under the action of the driving means (not shown). By moving in the C direction, it can move integrally in the arrow C direction.

  In addition, the base 12 displays photographing information such as a photographing part and photographing direction of the subject 18, ID information of the subject 18, and the like, and a display operation unit 38 that can set the information as necessary. Is done.

  FIG. 2 shows a state in which the breast 20 that is the imaging region of the subject 18 is disposed between the imaging table 28 and the compression plate 30. Reference numeral 40 indicates the chest wall of the subject 18.

  The radiation detector 26 includes a grid 42 disposed on the radiation source 22 side and a solid state detector 44 disposed on the back surface (bottom surface) of the grid 42. The grid 42 removes scattered radiation of the radiation X generated in the breast 20 and, for example, a radiation transmissive body made of aluminum or the like through which the radiation X is transmitted and a radiation opaque body containing lead or the like are alternately arranged. Composed. The solid state detector 44 is an array of thin film transistors in which a photoelectric conversion layer made of a substance such as amorphous selenium (a-Se) that senses radiation X incident through the breast 20 and the grid 42 and generates a charge is formed, for example. After the generated charge is stored in the storage capacitor, the thin film transistor is sequentially turned on for each row, and the stored charge is read out as an image signal (radiation image).

  FIGS. 1 and 2 illustrate, as an example, a case of performing head-to-tail (CC) imaging in which radiation X is emitted from the upper part of the breast 20, and the radiation source 22 for the solid state detector 44 in CC imaging. The right focal position of the subject 18 is the center in the left-right direction of the solid detector 44 in the left-right direction of the subject 18 and the end of the subject 18 on the chest wall 40 side of the solid detector 44 in the front-rear direction of the subject 18 in plan view. Position. That is, when CC imaging is performed, the radiation source 22 is configured so that the focal position above the end of the solid detector 44 on the chest wall 40 side in the horizontal direction of the solid detector 44 (of the radiation source 22 shown in FIG. 2). Position). On the other hand, the convergence point of the grid 42 is set to the focal position of the radiation source 22 shown in FIG.

  Further, in FIGS. 1 and 2, the radiation X is not transmitted to the radiation X in the irradiation range of the radiation X on the upper surface of the compression plate 30 (in the irradiation region indicated by X in FIG. 2, the location on the upper surface of the compression plate 30). A cylindrical marker 46 made of a metal such as conductive or semi-permeable lead is disposed. Therefore, the marker 46 is projected on the radiation image as the marker image 116 by the irradiation of the radiation X.

  FIG. 3 is a block diagram of the radiation imaging system 50 having the mammography apparatus 10.

  The radiation imaging system 50 includes the mammography apparatus 10 described above, a medical information system (HIS) 56 that manages medical office processing in the hospital, and radiation that manages radiographic imaging processing in the radiology department under the management of the HIS 56. A department information system (RIS) 58, a viewer 54 for performing diagnostic interpretation by a doctor, and a console 51 that is installed in a processing room adjacent to a radiology room and that manages and controls the mammography apparatus 10 are provided. Are connected to the viewer 54, the HIS 56 and the RIS 58 via the hospital network 52. The in-hospital network 52 can be connected to other consoles, photographing devices, and the like as necessary.

  The mammography apparatus 10 includes, in addition to the components shown in FIGS. 1 and 2, a radiation source control unit 60 that controls the radiation source 22, and a compression plate drive control unit that displaces the compression plate 30 in the direction of arrow B (see FIG. 1). 62, controls the compression plate height detection unit 48 such as an encoder or potentiometer provided in the compression plate drive control unit 62 to detect the height of the compression plate 30 relative to the imaging table 28, and the radiation detector 26; It further includes a detector control unit 64 that transmits a radiation image detected by the radiation detector 26 to the console 51 and the display operation unit 38, and a transmission / reception unit 66 that transmits and receives signals to and from the console 51.

  The console 51 transmits / receives signals to / from the mammography apparatus 10, and transmits / receives signals to / from the viewer 54, HIS 56, and RIS 58 via the in-hospital network 52, and a necessary operation by a technician. An operation unit 72, a control unit 74 that controls the console 51 and the mammography apparatus 10, an imaging condition memory 80 that stores imaging conditions set by operation of the operation unit 72 by a technician, and a radiographic image acquired from the mammography apparatus 10 In the radiographic image corresponding to the correct focal position of the radiation source 22 with respect to the solid state detector 44, the information processing unit 76 that processes the radiographic image, the display unit 78 that displays the processed radiographic image, and the solid state detector 44. And a marker image memory 86 for storing the normal position of the marker image.

  The imaging conditions are conditions such as a tube voltage, a tube current, and an irradiation time that define the dose of the radiation X irradiated to the breast 20, and these imaging conditions are the radiation source of the mammography apparatus 10 at the time of imaging. It is set in the control unit 60.

  Further, the correct focal position of the radiation source 22 with respect to the solid detector 44 is, for example, in the case of CC imaging, as described above, the center in the left-right direction of the solid detector 44 and the chest wall 40 side of the solid detector 44. It refers to a predetermined position above the end (the focal position of the radiation source 22 in FIGS. 1 and 2). Furthermore, the normal position of the marker image 116 in the radiographic image corresponding to the correct focal position is the radiographic image when the radiation X is applied to the breast 20 from the radiation source 22 arranged at the correct focal position. This refers to the position information of the projected marker image 116.

  Note that the focal position in lateral direction (ML) imaging in which imaging is performed by irradiating with radiation X from the side surface and the focal position in inner / outer oblique position (MLO) imaging in which imaging is performed by irradiating with radiation X from an oblique direction are basic. Specifically, it is at a predetermined position on a vertical line from the center in the left-right direction of the solid state detector 44, like the focal position in CC imaging. The marker image memory 86 can also store the normal position of the marker image 116 according to these focal positions.

  The radiation imaging system 50 according to the present embodiment is basically configured as described above. Next, the operation (a method of detecting the amount of positional deviation from the focal position of the radiation source 22) will be described. 4 and the explanatory diagrams of FIGS. 5A to 6C. Here, a case where CC imaging is performed will be described.

  First, the engineer operates the operation unit 72 (see FIG. 3) of the console 51 to set the ID information of the subject 18, the imaging method for the breast 20, and the imaging conditions (step S1). The ID information is information for specifying the subject 18 such as the name and age of the subject 18. The photographing methods include CC photographing, ML photographing, and MLO photographing. In this case, the engineer designates CC photographing as the photographing method.

  The control unit 74 causes the display unit 78 to display the set ID information, shooting method, and shooting conditions, and temporarily stores the shooting conditions in the shooting condition memory 80. The engineer can confirm the information displayed on the display unit 78, and can add or change information using the operation unit 72 as necessary. The determined imaging conditions are transmitted from the console 51 to the mammography apparatus 10 and set in the radiation source control unit 60.

  After the shooting conditions are set, shooting using the mammography apparatus 10 is started. In this case, the engineer turns the arm member 16 of the mammography apparatus 10 around the turning shaft 14 in accordance with the designated photographing method (CC photographing) to set a desired photographing posture (step S2). Note that by transmitting information related to the imaging method from the console 51 to the display operation unit 38 of the mammography apparatus 10 for display, the engineer can adjust the mammography apparatus 10 while confirming the display contents.

  Next, the breast 20 of the subject 18 is positioned with respect to the mammography apparatus 10 (step S3). That is, after the breast 20 is placed on the imaging table 28, the compression plate 30 is gradually approached toward the imaging table 28, thereby positioning the breast 20 at a predetermined position between the imaging table 28 and the compression plate 30. .

  Next, the radiation source storage unit 24 is moved in the direction of arrow A according to the position of the breast 20 fixed between the imaging table 28 and the compression plate 30, and the radiation source 22 is moved in the horizontal direction of the solid state detector 44 in plan view. It adjusts so that it may be located in the chest wall 40 side in the center and the solid detector 44 (step S4).

  Next, the radiation source control unit 60 controls the tube voltage, the tube current, and the irradiation time according to the imaging conditions set in Step S1, drives the radiation source 22, and pre-irradiates the breast 20 with the radiation X (Step S5). ). The pre-irradiation is a process for obtaining a radiographic image used in the determination process of step S7 described later by irradiating the breast 20 with the radiation X for a short time.

  The radiation X that has passed through the compression plate 30, the breast 20 and the grid 42 is irradiated to the solid detector 44, which converts the radiation X into a radiation image and outputs it (step S6). In this case, since the marker 46 is disposed on the upper surface of the compression plate 30, the marker 46 is projected onto the radiographic image as the marker image 116 by irradiation with the radiation X. The radiation image is transmitted from the detector control unit 64 to the console 51 via the transmission / reception unit 66.

  The information processing unit 76 of the console 51 determines whether or not the position of the marker image 116 in the radiographic image is deviated from the normal position corresponding to the correct focal position of the radiation source 22 with respect to the solid detector 44, that is, at the normal position. On the other hand, it is determined whether or not the marker image 116 is displaced (step S7).

  5A to 6C illustrate display contents displayed on the screen 100 of the display unit 78 in the determination process of step S7.

  5A to 5C illustrate a case where no positional deviation has occurred, while FIGS. 6A to 6C illustrate a case where positional deviation has occurred.

  Here, FIGS. 5A and 6A show a case where the normal position of the marker image 106 stored in the marker image memory 86 is displayed on the screen 100, and FIGS. 5B and 6B show the radiation image from the mammography apparatus 10. FIG. This is the case when displayed on the screen 100.

  5C shows a case where a new image obtained by superimposing the images of FIGS. 5A and 5B on the information processing unit 76 is displayed on the screen 100. FIG. The case where the new image obtained by superimposing the image of FIG. 6B is displayed on the screen 100 is shown.

  In step S <b> 7, the information processing unit 76 generates a radiation image (see FIG. 5A and FIG. 6A) generated by pre-irradiation from the mammography apparatus 10 using the marker image 106 (see FIGS. 5A and 6A) generated based on the normal position read from the marker image memory 86. In the new radiographic image (see FIGS. 5C and 6C) obtained by superimposing and superimposing on FIG. 5B and FIG. 6B, the normal position of the marker image 106 and the position of the marker image 116 actually obtained It is determined whether or not the interval (difference) d is within a predetermined threshold.

  When the distance d exceeds the threshold (d> threshold), the information processing unit 76 has a positional deviation between the normal position of the marker image 106 and the position of the marker image 116 actually obtained. Next, based on the interval d, the interval between the correct focal position of the radiation source 22 and the current position of the radiation source 22 (ie, the amount of displacement) is determined. The amount of angular deviation along the arrow A direction is calculated. The information processing unit 76 transmits the calculated positional deviation amount (angle deviation amount) to the radiation source control unit 60 and the display operation unit 38 of the mammography apparatus 10 and also outputs them to the display unit 78. Thereby, the radiation source control unit 60 moves the radiation source 22 in the direction of the arrow A by the angle from the information processing unit 76 and adjusts the radiation source 22 to the correct focal position (step S8).

  On the other hand, in step S7, the information processing unit 76 determines that the interval d between the normal position of the marker image 106 and the position of the actually obtained marker image 116 in the new radiographic image obtained by superimposition is a predetermined threshold value. Is within the range (d ≦ threshold), there is no positional deviation between the normal position of the marker image 106 and the position of the actually obtained marker image 116, that is, the radiation source 22 has the correct focus. It is considered that it is located at a position (step S7: NO).

  By the way, the factors causing the above-described positional deviation are the stopping accuracy of the arm member 16, the mounting accuracy of the radiation source 22 with respect to the radiation source storage unit 24, the inclination of the grid 42, the deformation of the arm member 16, and the like in this step S7. Taking these factors into account, for example, when the distance between the correct focal position of the radiation source 22 and the solid state detector 44 (focus-detector distance, SID) is 650 mm, the amount of positional deviation is allowed. The value is set to about 5.7 mm (the allowable angle deviation amount is up to about 0.5 °), and the interval between the marker image 106 and the marker image 116 corresponding to the allowable value is set as the threshold value. .

  Next, the radiation source control unit 60 controls the tube voltage, the tube current, and the irradiation time according to the imaging conditions set in step S1 in a state where the radiation source 22 is located at the correct focal position, By driving and irradiating the breast 20 with the radiation X, a radiographic image is actually captured (step S9).

  The radiation X transmitted through the compression plate 30, the breast 20 and the grid 42 is irradiated to the solid detector 44, which converts the radiation X into a radiographic image and outputs it (step S10). The radiographic image is transmitted from the detector control unit 64 to the console 51 via the transmission / reception unit 66, and the information processing unit 76 of the console 51 performs predetermined image processing on the radiographic image, and the radiographic image after image processing is performed. Is displayed on the display unit 78. Further, the radiation image from the mammography apparatus 10 is also stored in the image memory 82.

  The marker 46 is projected onto the radiographic image as the marker image 116 by irradiation with the radiation X. However, as shown in FIGS. 5B and 6B, the marker image 116 is projected onto a portion that is not superimposed on the breast image 118. When the radiographic image after the image processing is transmitted from the console 51 to the viewer 54 via the in-hospital network 52, the presence of the marker image 116 does not hinder the interpretation diagnosis by the doctor in the viewer 54.

  As described above, according to the radiation imaging system 50 according to the present embodiment, the radiation source for the solid state detector 44 is based on the position of the marker image 116 in the radiation image obtained by actually irradiating the radiation X. Since the position shift amount (angle shift amount along the arrow A direction) from the correct focal position of 22 is calculated, the position shift amount can be accurately detected.

  Further, in the technique of Patent Document 1, the position of the focal point of the radiation source 22 with respect to the solid state detector 44 is aligned depending on the mechanical position accuracy during imaging (CC imaging, ML imaging, MLO imaging). Therefore, it is difficult to accurately position the radiation source 22 at the focal position. Even if the radiation source 22 can be accurately positioned, the radiation source storage unit 24 as a pedestal is deformed by the weight of the radiation source 22. There is a possibility that the position of the radiation source 22 is shifted from the focal position.

  On the other hand, in the present embodiment, since the position of the radiation source 22 can be accurately adjusted to the correct focal position based on the accurately detected positional deviation amount, the radiation source 22 is set to the focal position. Accurate positioning is possible.

  In addition, the information processing unit 76 of the console 51 reads the normal position corresponding to the correct focal position from the marker image memory 86, and superimposes the read marker image 106 at the normal position and the radiation image from the mammography apparatus 10 to create a new one. A radiographic image is generated, and in the generated new radiographic image, an interval d between the normal position of the marker image 106 and the position of the actually obtained marker image 116 is calculated, and based on the calculated interval d, Calculate the amount of displacement. Thereby, the amount of positional deviation can be calculated with high accuracy.

  Furthermore, since the radiation source control unit 60 of the mammography apparatus 10 automatically adjusts the position of the radiation source 22 to the correct focal position based on the amount of positional deviation, the focal position can be adjusted efficiently. .

  Furthermore, since the marker 46 is disposed at the irradiation position of the radiation X on the compression plate 30, the marker 46 can be reliably projected as a marker image 116 on the radiation image.

  Furthermore, since the marker 46 is projected as a marker image 116 in a region that is not superimposed on the breast image 118 in the radiographic image, it does not hinder interpretation diagnosis by a doctor.

  In the above description, the case where the radiation source control unit 60 automatically adjusts the radiation source 22 to the correct focal position has been described, but the display operation unit 38 and the display unit 78 may display the positional deviation amount. Alternatively, the screen display of FIGS. 5C and 6C may be performed, and an engineer who visually recognizes the display contents of the display operation unit 38 and the display unit 78 may adjust the radiation source 22 to the correct focal position. Even in this case, the radiation source 22 can be accurately positioned at the focal position.

  In the above description, the case of pre-irradiation has been described. However, the present embodiment is not limited to this, and the mammography apparatus 10 may be maintained on the imaging table 28 during maintenance, activation, or imaging. On the other hand, the present invention can also be applied to the case where the radiation X is irradiated from the radiation source 22 through the compression plate 30 with the compression plate 30 set to a predetermined height. In this case, the compression plate height detection unit 48 detects the height of the compression plate 30 with respect to the imaging base 28 and transmits it to the console 51, so that the information processing unit 76 uses the marker image 106 based on the detected height. The above-described determination process may be performed based on the interval d between the calculated normal position and the position of the marker image 116. Thereby, even if the compression plate 30 is set to an arbitrary height, the amount of positional deviation from the correct focal position of the radiation source 22 can be calculated.

  Furthermore, although the case where the marker images 106 and 116 are projected on the image area 102 has been described in this embodiment, the marker images 106 and 116 are projected on the non-image area 104 as illustrated in FIGS. 7A to 8C. May be. Since the non-image area 104 is an area where the doctor does not perform an interpretation diagnosis, the marker images 106 and 116 can be reliably prevented from interfering with the interpretation diagnosis.

  In the present embodiment, the case where the marker 46 is arranged on the upper surface of the compression plate 30 has been described. However, as shown in FIG. 9, two markers 46 and 130 are arranged at different heights on the compression plate 30. Also good.

  In this case, if the radiation source 22 is arranged at the correct focal position, the projected images of the markers 46 and 130 are projected as the marker images 116 and 132 at the same position in the radiation image (see FIG. 10A). On the other hand, when the radiation source 22 is displaced from the correct focal position, as shown in FIG. 10B, the two marker images 116 and 132 are projected at different positions at the interval d.

  Therefore, the information processing unit 76 may calculate the amount of positional deviation from the correct focal position based on the interval d. That is, the positions of the two markers 46 and 130 (the two marker images 116 and 132) function as information indicating the amount of positional deviation from the correct focal position, so that the marker image memory 86 is not necessary. In addition, since it is only necessary to photograph the marker images 116 and 132 of the two markers 46 and 130 having different heights, it is not necessary to photograph the marker images simultaneously with the mammography.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Mammography apparatus 18 ... Subject 20 ... Breast 22 ... Radiation source 24 ... Radiation source storage part 26 ... Radiation detector 28 ... Imaging stand 30 ... Compression plate 38 ... Display operation part 40 ... Chest wall 44 ... Solid state detector 46, 130 ... Marker 48 ... Compression plate height detection unit 50 ... Radiography system 51 ... Console 60 ... Radiation source control unit 76 ... Information processing unit 78 ... Display unit 86 ... Marker image memory 100 ... Screen 102 ... Image area 104 ... Non-image area 106 116: Marker image

Claims (7)

A radiation detector that detects radiation that has passed through the breast and converts it into a radiation image, an imaging table that houses the radiation detector and holds the breast, and compresses the breast by being displaced toward the imaging table A radiation imaging apparatus comprising a compression plate and a radiation source that outputs the radiation applied to the radiation detector and is movable with respect to the radiation detector;
Height detection means for detecting the height of the compression plate relative to the imaging table;
Disposed at a predetermined position of the compression plate definitive the irradiation area of the radiation, the marker is projected as a marker image in the radiation image by irradiation of the radiation,
Based on the detected height of the compression plate, the normal position of the marker image obtained by irradiation of the radiation from the position of the radiation source in CC imaging is calculated, and the calculated normal position and the CC based on the position of the marker image of the radiation in the image obtained by the irradiation of the radiation from the position of the radiation source at shooting, positional deviation amount from the correct focal position of the radiation source relative to the radiation detector calculating means for determining whether or not within a predetermined threshold value the interval, determine the distance between the position of the marker image and the normal position was determined that according to the,
A radiation imaging system comprising: The system of claim 1, wherein
The radiographic system, wherein the calculating means calculates the positional deviation amount based on the interval when it is determined that the interval exceeds the threshold value. The system of claim 2 , wherein
The radiation imaging apparatus further includes a position adjusting unit that adjusts the position of the radiation source to the correct focal position in the CC imaging based on the positional deviation amount ,
When it is determined that the interval exceeds the threshold, the calculation means calculates an angular deviation amount along the rotation direction of the radiation source with respect to the position of the radiation source in the CC imaging based on the interval. Operate,
It said position adjusting means, the angular shift amount computed as the positional deviation amount, radiography, characterized that you adjust the angle of the radiation source at the CC shooting angle corresponding to the correct focal position system. The system according to any one of claims 1 to 3 ,
The radiation imaging system further comprising output means for outputting the displacement amount and / or the radiation image to the outside. The system of claim 4 , wherein
The radiation imaging system according to claim 1, wherein the output means is a display means for displaying the displacement amount and / or the radiation image. The system according to any one of claims 1 to 5 ,
The radiation imaging system according to claim 1, wherein the marker is projected as the marker image in a region in the radiographic image that is not superimposed on a subject image indicating a subject, or a region in which an interpretation diagnosis is not performed by a doctor. In a state where the breast is held by an imaging table that houses the radiation detector, the breast is compressed by displacing the compression plate toward the imaging table,
CC imaging is performed by irradiating the radiation detector from the radiation source through the breast ,
The radiation detector converts the radiation into a radiation image,
If the marker disposed at a predetermined position of the compression plate definitive the irradiation area of the radiation, it is projected as a marker image in the radiation image by irradiation of the radiation from the position of the radiation source at the CC imaging ,
Based on the height of the compression plate relative to the imaging table detected by the height detection means, the normal position of the marker image obtained by irradiation of the radiation from the position of the radiation source in the CC imaging is calculated. ,
And computed the normal position, based on the position of the marker image of the radiation in the image obtained by the irradiation of the radiation from the position of the radiation source at the CC imaging, the radiation source relative to the radiation detector The distance between the normal position and the position of the marker image according to the amount of positional deviation from the correct focal position of
Amount of positional deviation detection method from the focus position of the radiation source, wherein the interval required to determine whether or not within a predetermined threshold.

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