X-ray imaging system and x-ray imaging method

Abstract

An X-ray imaging system (100) includes: an X-ray imaging apparatus (1) having an X-ray irradiation unit (10) and an X-ray detector (11); and a portable terminal (2) disposed near the X-ray detector. The portable terminal includes: a feature-point detection unit (20) that optically detects a feature point in the X-ray irradiation unit; a controller (21) that acquires at least one of information about the relative positions of the X-ray irradiation unit and the X-ray detector and information about the relative angles of the X-ray irradiation unit and the X-ray detector on the basis of the feature point; and a display (22) that displays the information acquired by the controller.

Description

X-ray imaging system and X-ray imaging method

[0001] The present invention relates to an X-ray imaging system and an X-ray imaging method.

[0002] 2. Description of the Related Art Conventionally, an X-ray imaging system has been known, and such an X-ray imaging system is disclosed in, for example, International Publication No. 2009 / 142166.

[0003] The above-mentioned WO 2009 / 142166 discloses an X-ray diagnostic apparatus including an X-ray source that irradiates X-rays, an X-ray detector that detects the X-rays and outputs the detected X-rays as image data, and a direct X-ray dose calculation means that calculates a pixel value corresponding to the direct X-ray dose to be detected by the X-ray detector based on the distance from the X-ray source to the X-ray detector. The above-mentioned WO 2009 / 142166 also discloses a configuration in which an operator uses a tape measure to measure the distance from the X-ray source to the X-ray detector.

[0004] International Publication No. 2009 / 142166

[0005] Although not disclosed in WO 2009 / 142166, when emitting X-rays from an X-ray source (X-ray irradiator), imaging conditions such as the distance between the X-ray irradiator and the X-ray detector, the tube voltage, and the tube current are set. If the distance between the X-ray irradiator and the X-ray detector differs from the set imaging conditions, the X-ray dose detected by the X-ray detector changes. In this case, it is necessary to adjust the distance between the X-ray irradiator and the X-ray detector so that the X-ray irradiator is positioned appropriately for the imaging conditions. However, as disclosed in WO 2009 / 142166, if the surgeon (operator) uses a tape measure to measure the distance from the X-ray irradiator to the X-ray detector, the operator must both adjust the relative position of the X-ray irradiator and measure the distance from the X-ray irradiator to the X-ray detector, which increases the burden on the operator. Furthermore, if the subject moves while adjusting the relative position of the X-ray irradiator, the relative position of the subject's imaging region with respect to the X-ray detector will change. In this case, the imaging site may become unclear, necessitating reimaging. Therefore, in order to prevent reimaging, it is preferable for the operator to adjust the position of the X-ray irradiator while checking the subject. However, when the operator uses a tape measure to measure the distance from the X-ray irradiator to the X-ray detector, the operator's line of sight moves significantly. This large line of sight movement poses the inconvenience of making it difficult for the operator to adjust the relative positions of the X-ray irradiator and the X-ray detector while checking the subject.

[0006] Although not disclosed in International Publication No. 2009 / 142166, the X-ray irradiation angle may be changed depending on the region of the subject being imaged. In this case, the operator changes the angle of the X-ray irradiator relative to the X-ray detector to change the X-ray irradiation angle. Although not disclosed in International Publication No. 2009 / 142166, a configuration is known in which the angle of the X-ray irradiator is acquired and displayed on a display unit provided in the X-ray irradiator. However, when the angle of the X-ray irradiator is displayed on a display unit provided in the X-ray irradiator, the operator must check the display unit when adjusting the angle of the X-ray irradiator. As a result, adjusting the X-ray irradiation angle requires a large amount of movement of the operator's line of sight, making it difficult to adjust the X-ray irradiation angle while checking the subject.

[0007] These problems result in an increased burden on the operator when adjusting the position of the X-ray irradiation unit, such as adjusting the relative position between the X-ray irradiation unit and the X-ray detector and adjusting the X-ray irradiation angle, and in making it difficult to adjust the position of the X-ray irradiation unit while checking the subject.

[0008] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide an X-ray imaging system and an X-ray imaging method that can reduce the burden on the operator when adjusting the position of the X-ray irradiation unit and that can adjust the position of the X-ray irradiation unit while checking the subject.

[0009] According to a first aspect of the present invention, there is provided an X-ray imaging system including an X-ray imaging apparatus having an X-ray irradiator that irradiates an examinee with X-rays and an X-ray detector that detects the X-rays irradiated from the X-ray irradiator, and a portable terminal disposed near the X-ray detector, wherein the portable terminal includes a feature point detector that optically detects feature points in the X-ray irradiator, a control unit that acquires, based on the feature points detected by the feature point detector, at least one of information regarding the relative position between the X-ray irradiator and the X-ray detector and information regarding the relative angle between the X-ray irradiator and the X-ray detector, and a display unit that displays the information acquired by the control unit. Note that the vicinity of the X-ray detector includes the position of the X-ray detector itself and the vicinity of the position of the X-ray detector.

[0010] An X-ray imaging method in a second aspect of the present invention is an X-ray imaging method in an X-ray imaging system equipped with an X-ray imaging device having an X-ray irradiation unit that irradiates X-rays onto a subject and an X-ray detector that detects the X-rays irradiated from the X-ray irradiation unit, and includes the steps of optically detecting characteristic points in the X-ray irradiation unit while a mobile terminal is placed near the X-ray detector, acquiring at least one of information regarding the relative position between the X-ray irradiation unit and the X-ray detector and information regarding the relative angle between the X-ray irradiation unit and the X-ray detector based on the detected characteristic points, and displaying the acquired information on a display unit of the mobile terminal.

[0011] In the X-ray imaging system according to a first aspect of the present invention and the X-ray imaging method according to a second aspect, when displaying information regarding the relative position of the X-ray irradiator and the X-ray detector, the information regarding the relative position of the X-ray irradiator and the X-ray detector is displayed on a display unit of a portable device disposed near the X-ray detector. Therefore, the operator can adjust the position of the X-ray irradiator while checking the display unit. This reduces the burden on the operator compared to a configuration in which, for example, relative position information is acquired using a tape measure. Furthermore, since at least one of information regarding the relative position of the X-ray irradiator and the X-ray detector and information regarding the relative angle between the X-ray irradiator and the X-ray detector is displayed on a display unit of the portable device disposed near the X-ray detector, the operator can adjust the relative position of the X-ray irradiator and / or the relative angle of the X-ray irradiator while keeping their eyes fixed on the X-ray detector and the portable device. Therefore, the operator's line of sight movement is reduced when adjusting the relative position of the X-ray irradiator and / or the relative angle of the X-ray irradiator. Furthermore, when imaging a subject, the subject's imaging region is positioned between the X-ray irradiator and the X-ray detector, and on the X-ray detector side. Therefore, when adjusting the position of the X-ray irradiator while directing the line of sight toward the X-ray detector and the mobile terminal, the subject's imaging region will be within the operator's field of view. Therefore, the operator can adjust the position of the X-ray irradiator while checking the subject. As a result, it is possible to reduce the burden on the operator when adjusting the position of the X-ray irradiator, and to adjust the position of the X-ray irradiator while checking the subject.

[0012] FIG. 1 is a block diagram showing a configuration of an X-ray imaging system according to an embodiment. FIG. 2 is a schematic diagram showing a configuration of an X-ray imaging device included in the X-ray imaging system according to an embodiment. FIG. 3 is a schematic diagram for explaining a planar marker provided in the X-ray imaging device according to an embodiment. FIG. 4 is a schematic diagram for explaining a position at which the planar marker is provided according to an embodiment. FIG. 5 is a schematic diagram for explaining a feature point image. FIG. 6 is an example of a screen on which a portable terminal according to an embodiment displays a distance between focus detection planes and an irradiation angle. FIG. 7 is a schematic diagram for explaining a configuration in which a portable terminal displays a distance between focus detection planes and an irradiation angle in the vicinity of an X-ray detector according to an embodiment. FIG. 8 is a schematic diagram for explaining a configuration in which a control unit according to an embodiment acquires a distance between focus detection planes in an in-plane detection mode. FIG. 9 is a schematic diagram for explaining a configuration in which a control unit according to an embodiment acquires a distance between focus detection planes and an irradiation angle in an in-plane detection mode. FIG. 10 is a schematic diagram for explaining a configuration in which a control unit according to an embodiment acquires a distance between focus detection planes in a non-in-plane detection mode. FIG. 11 is a schematic diagram for explaining a configuration in which a control unit according to an embodiment acquires a distance between focus detection planes and an irradiation angle in a non-in-plane detection mode. FIG. 12 is a schematic diagram for explaining a configuration in which a control unit according to an embodiment acquires a distance between focus detection planes and an irradiation angle in a non-in-plane detection mode. FIG. 13 is a schematic diagram for explaining a holding member according to an embodiment. FIG. 1 is a schematic diagram illustrating a configuration for capturing an image while holding an X-ray detector and a portable terminal with a holding member according to an embodiment. FIG. 1 is a schematic diagram illustrating a configuration for acquiring a distance between focal feature points by calibration with a control unit according to an embodiment. FIG. 2 is an example screen when the control unit displays a message to a user when performing calibration by placing an X-ray irradiator at a predetermined position. FIG. 3 is an example screen when the control unit displays a message to a user when performing calibration by placing an X-ray irradiator at an arbitrary position. FIG. 4 is a flowchart illustrating processing by a control unit according to an embodiment for displaying a distance between focus detection planes and an irradiation angle. FIG. 5 is a flowchart illustrating calibration processing by a control unit according to an embodiment for acquiring a distance between focal feature points.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0014] 1 , the X-ray imaging system 100 includes an X-ray imaging device 1 and a portable terminal 2. The X-ray imaging system 100 also includes a tabletop 4, a holding member 5, and a tabletop moving mechanism 6.

[0015] The X-ray imaging device 1 includes an X-ray irradiation unit 10 and an X-ray detector 11. The X-ray imaging device 1 also includes a device control unit 12, an irradiation unit moving mechanism 13, and a detector moving mechanism 14.

[0016] The X-ray irradiation unit 10 is configured to irradiate X-rays onto a subject 90 (see FIG. 2 ). The X-ray irradiation unit 10 also includes an X-ray source 10 a that generates X-rays for irradiating the subject 90 with X-rays, and a collimator 10 b that adjusts the irradiation range of the X-rays.

[0017] The X-ray source 10a includes, for example, an X-ray generating device such as an X-ray tube, etc. The collimator 10b is provided to adjust the size and shape of the irradiation range of the X-rays irradiated from the X-ray source 10a.

[0018] The collimator 10b has a flat plate shape and is provided with an opening in the center thereof. The collimator 10b is formed by forming an opening in a flat plate made of, for example, a lead material.

[0019] The X-ray detector 11 is configured to detect X-rays irradiated from the X-ray irradiation unit 10. The X-ray detector 11 is, for example, a flat panel detector (FPD), and detects X-rays that have passed through the subject 90. The X-ray detector 11 is also portable and configured to be able to be carried by the operator.

[0020] The device control unit 12 is configured to control the entire X-ray imaging device 1. Specifically, the device control unit 12 is configured to control X-ray irradiation by the X-ray irradiation unit 10 (X-ray source 10a), such as starting and stopping X-ray irradiation, control changing the X-ray irradiation range by the X-ray irradiation unit 10 (collimator 10b), control detection by the X-ray detector 11, control movement of the X-ray irradiation unit 10 by the irradiation unit moving mechanism 13, and control movement of the X-ray detector 11 by the detector moving mechanism 14, etc.

[0021] The device control unit 12 is configured with a processor such as a CPU (Central Processing Unit), FPGA (Field-Programmable Gate Array), or circuitry, and memories such as a ROM (Read Only Memory) and RAM (Random Access Memory). The device control unit 12 is also configured to receive detection signals from the encoder and potentiometer included in the irradiation unit moving mechanism 13. The device control unit 12 is also configured to control the motor and electromagnetic brake included in the irradiation unit moving mechanism 13. The device control unit 12 is also configured to control the motor and electromagnetic brake included in the detector moving mechanism 14.

[0022] The irradiation unit moving mechanism 13 is configured so that an operator can move the X-ray irradiation unit 10. The detailed configuration of the irradiation unit moving mechanism 13 will be described later.

[0023] The detector moving mechanism 14 movably holds the X-ray detector 11. Therefore, by moving the X-ray detector 11 with the detector moving mechanism 14, the X-ray detector 11 can be placed at a position corresponding to the part of the subject 90 to be imaged.

[0024] The mobile terminal 2 includes a feature point detection unit 20, a control unit 21, and a display unit 22. The mobile terminal 2 also includes an input reception unit 23 and a storage unit 24.

[0025] The feature point detection unit 20 is configured to optically detect feature points in the X-ray irradiation unit 10. Details of the feature points and the feature point detection unit 20 will be described later.

[0026] The control unit 21 is configured to control the mobile terminal 2. The control unit 21 is configured with a processor such as a CPU, FPGA, or circuitry, and memories such as ROM and RAM. The control unit 21 is also configured to acquire at least one of information regarding the relative position between the X-ray irradiation unit 10 and the X-ray detector 11 and information regarding the relative angle between the X-ray irradiation unit 10 and the X-ray detector 11. Details of the configuration by which the control unit 21 acquires the information regarding the relative position and the information regarding the relative angle will be described later.

[0027] The display unit 22 is configured to display information acquired by the control unit 21. The display unit 22 is, for example, a display device such as a liquid crystal monitor or an organic EL (Electro Luminescence) monitor.

[0028] The input receiving unit 23 is configured to receive an operation input from an operator. The input receiving unit 23 is, for example, a touch pad. In this embodiment, the input receiving unit 23 is configured as a touch panel integrally formed with the display unit 22.

[0029] The storage unit 24 is configured to store a distance between focal feature points 32, which will be described later. The storage unit 24 also stores various programs (not shown) executed by the control unit 21. The storage unit 24 includes a non-volatile storage device, such as a hard disk drive (HDD) or a solid state drive (SSD).

[0030] The top board 4 is configured so that the subject 90 can be placed thereon. The configuration of the top board 4 will be described in detail later.

[0031] The top moving mechanism 6 is configured to move the top 4 and change the position of the subject 90 relative to the X-ray detector 11. The configuration of the top moving mechanism 6 will be described in detail later.

[0032] (Configuration of X-ray Imaging Apparatus and Top Plate Moving Mechanism) As shown in FIG. 2 , in the X-ray imaging apparatus 1, the X-ray irradiator 10 is supported so as to be suspended from the ceiling by an irradiation unit moving mechanism 13. The X-ray irradiator 10 is supported so as to be movable within the imaging room by the irradiation unit moving mechanism 13. The irradiation unit moving mechanism 13 includes motors and electromagnetic brakes (not shown) corresponding to the X, Y, and Z directions, respectively. The X-ray irradiator 10 is configured to be movable in the X, Y, and Z directions by an operator. In the example shown in FIG. 2 , the vertical direction is defined as the Z direction, the upward direction as the Z1 direction, and the downward direction as the Z2 direction. Furthermore, one of two directions mutually orthogonal to the Z direction is defined as the X direction, and the other as the Y direction. Furthermore, one of the X directions is defined as the X1 direction, and the other as the X2 direction. Furthermore, one of the Y directions is defined as the Y1 direction, and the other as the Y2 direction.

[0033] The X-ray irradiator 10 is configured to be rotatable about the Z-axis while held by the irradiator-moving mechanism 13. The X-ray irradiator 10 is configured to be rotatable about the Y-axis while held by the irradiator-moving mechanism 13. Therefore, the X-ray irradiator 10 is configured to be able to change the direction and angle of X-ray irradiation. The irradiator-moving mechanism 13 is equipped with a motor and an electromagnetic brake (not shown) corresponding to each of the two rotatable axes (Y-axis and Z-axis) of the X-ray irradiator 10. The irradiator-moving mechanism 13 is equipped with an encoder and a potentiometer (not shown) corresponding to each of the two rotatable axes (Y-axis and Z-axis) of the X-ray irradiator 10. When an operator moves the X-ray irradiator 10, the irradiator-moving mechanism 13 according to this embodiment moves the X-ray irradiator 10 in a direction corresponding to the direction of the operating force input by the operator.

[0034] 2, the mobile terminal 2 is placed near the X-ray detector 11. Note that in the example shown in FIG. 2, the mobile terminal 2 and the X-ray detector 11 are hatched differently from each other, but this is not to show a cross section of the mobile terminal 2 and the X-ray detector 11, but rather to improve the visibility of the mobile terminal 2 and the X-ray detector 11 in FIG.

[0035] The tabletop 4 has a support surface 4a on which the subject 90 rests. The tabletop moving mechanism 6 is equipped with motors and electromagnetic brakes (not shown) corresponding to the X, Y, and Z directions, respectively. The tabletop 4 is configured to be movable in each of the X, Y, and Z directions by the tabletop moving mechanism 6.

[0036] The detector moving mechanism 14 is provided on the lower side (Z2 direction side) of the tabletop 4 and includes a detector holding unit 14a capable of holding the X-ray detector 11. The detector moving mechanism 14 is configured to move the detector holding unit 14a in the X and Y directions, thereby moving the X-ray detector 11 held by the detector holding unit 14a in the X and Y directions. The X-ray imaging apparatus 1 according to this embodiment is capable of performing imaging with the X-ray detector 11 placed on the mounting surface 4a of the tabletop 4, imaging with the X-ray detector 11 placed on the detector holding unit 14a, and imaging with the X-ray detector 11 held by the holding member 5 (see FIG. 1 ).

[0037] Here, imaging conditions such as tube voltage and tube current are adjusted so that the X-rays irradiated from the X-ray irradiator 10 have a dose corresponding to the distance between the X-ray irradiator 10 and the X-ray detector 11. If the X-ray irradiator 10 is placed in a position that is inappropriate for the imaging conditions, the X-ray dose detected by the X-ray detector 11 may be insufficient. Furthermore, if the X-ray irradiator 10 is placed in a position that is inappropriate for the imaging conditions, the X-ray dose detected by the X-ray detector 11 may be excessive. In both cases where the X-ray dose is insufficient or excessive, reimaging is required, which may result in unnecessary exposure of the subject 90. Therefore, when imaging the subject 90 using the X-ray imaging device 1, the operator adjusts the position of the X-ray irradiator 10 so that the X-ray irradiator 10 is placed in a predetermined position.

[0038] Furthermore, in order to check the treatment status of the affected area (imaged area) of the subject 90, the same affected area of ​​the subject 90 may be imaged after a predetermined number of days have passed, and follow-up observation may be performed. When follow-up observation is performed, it is preferable to adjust the position of the X-ray irradiation unit 10 so that the imaged area of ​​the subject 90 is imaged in the same way.

[0039] Furthermore, when adjusting the position of the X-ray irradiation unit 10, if imaging is performed with the imaging region shifted due to the body movement of the subject 90, the visibility of the specified imaging region may be reduced, and imaging may need to be performed again. Therefore, the operator adjusts the position of the X-ray irradiation unit 10 while checking whether the imaging region has shifted due to the body movement of the subject 90.

[0040] For example, if an operator uses a tape measure or the like provided on the X-ray irradiator 10 to measure the distance between the X-ray irradiator 10 and the X-ray detector 11, the operator must measure the distance each time the position of the X-ray irradiator 10 is moved, which increases the burden on the operator. Furthermore, when a tape measure is used to measure the distance between the X-ray irradiator 10 and the X-ray detector 11, the operator's line of sight must move significantly. Furthermore, if the distance between the X-ray irradiator 10 and the X-ray detector 11 is measured using a distance meter that uses infrared or laser light and displayed on the X-ray irradiator 10, the operator's line of sight must move significantly. Furthermore, if the angle at which the X-ray irradiator 10 is positioned is displayed, the operator's line of sight must move significantly. This increases the burden on the operator and reduces the efficiency of adjusting the position of the X-ray irradiator 10.

[0041] Therefore, in this embodiment, the X-ray imaging system 100 (see FIG. 1 ) is configured to acquire, via the mobile terminal 2 (see FIG. 1 ) arranged near the X-ray detector 11, at least one of information regarding the relative position between the X-ray irradiator 10 and the X-ray detector 11 and information regarding the relative angle between the X-ray irradiator 10 and the X-ray detector 11. Specifically, the control unit 21 (see FIG. 1 ) is configured to acquire, based on the feature points detected by the feature point detection unit 20 (see FIG. 1 ), at least one of information regarding the relative position between the X-ray irradiator 10 and the X-ray detector 11 and information regarding the relative angle between the X-ray irradiator 10 and the X-ray detector 11. The control unit 21 is then configured to perform control to display the acquired information on the display unit 22 (see FIG. 1 ).

[0042] The information about the relative position is a focus detection plane distance 30 (see FIG. 8), which is the distance from the X-ray focal position 10c (see FIG. 8) of the X-ray irradiation unit 10 to the detection plane 11a (see FIG. 8) of the X-ray detector 11. The information about the relative angle is an X-ray irradiation angle 41 (see FIG. 9) with respect to the detection plane 11a. In this embodiment, the control unit 21 is configured to acquire at least one of the focus detection plane distance 30 and the irradiation angle 41 based on the feature point.

[0043] In this embodiment, the control unit 21 captures an image of the feature points while the portable terminal 2 is placed near the X-ray detector 11. The portable terminal 2 is placed near the X-ray detector 11 while facing the X-ray irradiation unit 10. The control unit 21 is configured to acquire at least one of the focus detection plane distance 30 and the irradiation angle 41 based on the captured feature points.

[0044] (Feature Points) Next, feature points according to this embodiment will be described with reference to Fig. 3. In this embodiment, the feature points include planar markers 3 having shapes that allow for identifiable directions. As shown in Fig. 3, the planar markers 3 are rectangular figures. Information that can be acquired by photographing the planar markers 3 with a camera or the like is pre-recorded on the planar markers 3. The planar markers 3 are so-called AR markers.

[0045] (Layout of Planar Marker) FIG. 4 is a schematic diagram of the X-ray irradiator 10 as viewed from below (Z2 direction side). As shown in FIG. 4, the planar marker 3 is provided on an end surface 10d of the X-ray irradiator 10 on the X-ray emission direction side. In the example shown in FIG. 4, the planar marker 3 is provided on an end surface 10d of the collimator 10b on the X-ray emission direction side. In this embodiment, the planar marker 3 is provided in the same plane as the irradiation window 10e of the collimator 10b, through which X-rays are irradiated. The planar marker 3 may be provided at a position other than the end surface 10d, as long as it moves integrally with the X-ray irradiator 10 and can be photographed by the feature point detection unit 20 (see FIG. 1). For example, the planar marker 3 may be provided on a handle of the X-ray irradiator 10.

[0046] (Feature Point Image) The feature point detection unit 20 (see FIG. 1) is an imaging unit that captures a feature point image 50, which is an image of the planar marker 3, as shown in FIG. 5. The imaging unit is, for example, an optical camera. That is, the feature point detection unit 20 acquires the feature point image 50 by capturing an image of the planar marker 3 provided on the end surface 10d (see FIG. 4) on the X-ray emission side of the X-ray irradiation unit 10 (see FIG. 4).

[0047] The size of the planar marker 3 shown in the feature point image 50 changes in accordance with the focus detection plane distance 30 (see FIG. 8 ). Furthermore, the shape of the planar marker 3 shown in the feature point image 50 changes based on the X-ray irradiation angle 41 (see FIG. 9 ). Therefore, in this embodiment, when acquiring the focus detection plane distance 30, the control unit 21 (see FIG. 1 ) is configured to acquire the feature point detection plane distance 31 based on the size of the planar marker 3 in the feature point image 50. Furthermore, when acquiring the irradiation angle 41, the control unit 21 is configured to acquire the irradiation angle 41 based on the shape of the planar marker 3 in the feature point image 50.

[0048] (Display of focus detection surface distance and illumination angle on mobile terminal) The example shown in FIG. 6 is an example of a screen 22a when the display unit 22 (see FIG. 1) displays the focus detection surface distance 30 (see FIG. 8) and the illumination angle 41 (see FIG. 9). When the control unit 21 (see FIG. 1) acquires only the focus detection surface distance 30, the display unit 22 displays only the focus detection surface distance 30. When the control unit 21 acquires only the illumination angle 41, the display unit 22 displays only the illumination angle 41. When the control unit 21 acquires both the focus detection surface distance 30 and the illumination angle 41, the display unit 22 displays both the focus detection surface distance 30 and the illumination angle 41. The screen 22a shown in FIG. 6 displays both the focus detection surface distance 30 and the illumination angle 41.

[0049] (Arrangement of portable terminal and X-ray detector during position adjustment) In this embodiment, as shown in Fig. 7 , when an operator adjusts the arrangement of the X-ray irradiation unit 10 (see Fig. 1 ), the portable terminal 2 is arranged near the X-ray detector 11. Also, as shown in Fig. 7 , the X-ray detector 11 has a rectangular shape. Also, the portable terminal 2 has a rectangular shape.

[0050] (Same-Plane Detection Mode and Non-Same-Plane Detection Mode) In this embodiment, the X-ray imaging device 1 can perform both imaging with the X-ray detector 11 placed on the support surface 4a of the tabletop 4 and imaging with the X-ray detector 11 held in the detector holding unit 14a (see FIG. 2). That is, the X-ray imaging device 1 can perform imaging with the portable terminal 2 and the X-ray detector 11 placed in the same plane, and imaging with the portable terminal 2 and the X-ray detector 11 placed in different planes.

[0051] Therefore, in this embodiment, the control unit 21 is configured to switch between a same-plane detection mode and a non-same-plane detection mode. The same-plane detection mode is a detection mode in which control is performed to cause the feature point detection unit 20 to detect feature points in a state in which a predetermined side 2 a of the portable terminal 2 and a predetermined side 11 b of the X-ray detector 11 are arranged parallel to each other in the same plane. In the example shown in Fig. 7 , the portable terminal 2 and the X-ray detector 11 are arranged so that the side 2 a, which is the long side of the portable terminal 2, and the side 11 b, which is the long side of the X-ray detector 11, are parallel to each other.

[0052] The non-in-plane detection mode is a detection mode in which control is performed to cause the feature point detection unit 20 to detect feature points while a predetermined side 2 a of the portable terminal 2 and a predetermined side 11 b of the X-ray detector 11 are arranged parallel to each other on planes that are parallel to each other and have different positions in the direction of the X-ray irradiation axis 80 (see Figure 8).

[0053] (Acquisition of the distance between focus detection planes and the irradiation angle in the same-plane detection mode) With reference to FIGS. 8 and 9 , a configuration in which the control unit 21 (see FIG. 1 ) acquires the distance between focus detection planes 30 (see FIG. 8 ) and the irradiation angle 41 (see FIG. 9 ) in the same-plane detection mode will be described. Note that FIGS. 8 and 9 describe a configuration in which the control unit 21 acquires the distance between focus detection planes 30 and the irradiation angle 41 using a PQR coordinate system, which is a coordinate system different from the XYZ coordinate system. The P direction and the R direction are two directions that are perpendicular to each other in the plane in which the portable terminal 2 is placed. Furthermore, the Q direction is a direction along the normal to the portable terminal 2. Also, in FIG. 8 , the irradiation axis 80 of the X-rays irradiated from the X-ray irradiator 10 is illustrated by a dashed line. Furthermore, the normal 81 of the planar marker 3 is illustrated by a dashed line. Note that, as shown in FIG. 8 , the planar marker 3 is provided in the X-ray irradiator 10 such that the normal 81 is parallel to the irradiation axis 80 of the X-rays.

[0054] 8 is a case where the X-ray irradiation angle 41 (see FIG. 9) is 0 degrees. That is, in the example shown in FIG. 8, X-rays are irradiated from the normal direction of the detection surface 11a of the X-ray detector 11.

[0055] 8, the control unit 21 (see FIG. 1) is configured to acquire, based on the feature point, a feature point-to-detection-plane distance 31, which is the distance between the feature point and the detection plane 11a. The control unit 21 is also configured to acquire a focus-to-detection-plane distance 30 based on the acquired feature point-to-detection-plane distance 31 and a focus-to-feature point distance 32, which is the distance between the focal position 10c and the feature point.

[0056] The control unit 21 acquires a distance 33 between the mobile device 2 and the planar marker 3 based on the size of the planar marker 3 shown in the feature point image 50 (see FIG. 5 ). The control unit 21 also acquires an angle 40 with respect to the normal direction when the planar marker 3 is viewed from the mobile device 2 based on the shape of the planar marker 3 shown in the feature point image 50. The control unit 21 then acquires a distance 34 between the mobile device 2 and the planar marker 3 in the Q direction based on the distance 33 and the angle 40.

[0057] Here, the size of the planar marker 3 shown in the feature point image 50 changes depending on the distance 33 between the mobile device 2 and the planar marker 3. Furthermore, the shape of the planar marker 3 shown in the feature point image 50 is distorted depending on the angle of the corner 40. Therefore, the size and shape of the planar marker 3 shown in the feature point image 50 correspond to the distance 33 and the angle of the corner 40. Therefore, the size and shape of the planar marker 3 shown in the feature point image 50 correspond to the distance 33 and the angle of the corner 40 and are stored in advance in the storage unit 24. By comparing the size and shape of the planar marker 3 shown in the feature point image 50 with the information stored in the storage unit 24, the control unit 21 can obtain the distance 33 between the planar marker 3 and the mobile device 2 and the angle of the corner 40 with respect to the normal direction when the planar marker 3 is viewed from the mobile device 2.

[0058] 8 , in the same-plane detection mode, the mobile terminal 2 and the X-ray detector 11 are arranged in the same plane (PR plane). Therefore, the distance 34 can be regarded as the feature point detection plane distance 31.

[0059] Furthermore, the distance between focus feature points 32 is a design value or is acquired in advance and stored in the storage unit 24 (see FIG. 1 ). Therefore, in the intra-plane detection mode, the control unit 21 is configured to acquire the distance between focus detection planes 30 based on the distance between focus feature points 32 and the distance between feature point detection planes 31 stored in the storage unit 24.

[0060] 8, for convenience, the thickness of the planar marker 3 in the Q direction is exaggerated. However, the actual thickness of the planar marker 3 is very small compared to the acquired inter-feature point detection plane distance 31. In other words, the thickness of the planar marker 3 is within the allowable error range when calculating the inter-focus detection plane distance 30, and can be ignored when calculating the inter-focus detection plane distance 30.

[0061] 8 , for convenience, the thickness of the portable terminal 2 and the thickness of the X-ray detector 11 are illustrated as being the same, but the thickness of the portable terminal 2 and the thickness of the X-ray detector 11 do not have to be the same. There may be a difference in thickness between the portable terminal 2 and the X-ray detector 11 as long as the difference in thickness falls within the allowable range of error in the focus detection plane distance 30. Note that if the difference in thickness between the portable terminal 2 and the X-ray detector 11 does not fall within the allowable range of error in the focus detection plane distance 30, the difference in thickness between the portable terminal 2 and the X-ray detector 11 may be acquired in advance and used to correct the acquired focus detection plane distance 30.

[0062] Next, referring to FIG. 9 , a configuration will be described in which the control unit 21 (see FIG. 1 ) acquires the focus-detection-plane distance 30 (see FIG. 8 ) and the irradiation angle 41 when the X-rays irradiated from the X-ray irradiator 10 are irradiated in a state inclined with respect to the detection surface 11 a of the X-ray detector 11. Note that the example shown in FIG. 9 illustrates a state in which the X-ray irradiator 10 is inclined in the rotational direction around the R direction. Also, in FIG. 9 , an irradiation axis 80 of the X-rays irradiated from the X-ray irradiator 10 is illustrated by a dashed line. Also, a normal 81 to the planar marker 3 is illustrated by a dashed line. Also, a normal 82 to the detection surface 11 a is illustrated by a dashed line.

[0063] 9, the intersection of the normal 81 of the planar marker 3 and the end face 10d of the X-ray irradiation unit 10 is designated as point A. The intersection of the irradiation axis 80 and the end face 10d is designated as point B. The intersection of the normal 81 and a line (dashed line 84) extending from point B in the P direction is designated as point C. The intersection of the irradiation axis 80 and a perpendicular line 83 dropped from point A to the detection surface 11a is designated as point D. The intersection of the perpendicular line 83 dropped from point A to the detection surface 11a and the detection surface 11a is designated as point E. The intersection of the irradiation axis 80 and the detection surface 11a is designated as point F.

[0064] The control unit 21 acquires the distance 34 between the mobile terminal 2 and the planar marker 3 in the Q direction based on the size and shape of the planar marker 3 shown in the feature point image 50 (see FIG. 5 ). Here, the X-ray irradiation angle 41 is the angle between the normal 82 to the detection surface 11a and the irradiation axis 80. The planar marker 3 shown in the feature point image 50 is distorted in shape depending on the irradiation angle 41. Therefore, the control unit 21 can acquire the X-ray irradiation angle 41 based on the shape of the planar marker 3 shown in the feature point image 50. Note that even when the X-ray irradiator 10 is tilted in the rotational direction around the P direction, it is possible to acquire the irradiation angle 41 with a similar configuration, and therefore detailed description thereof will be omitted.

[0065] Here, when the X-ray irradiation angle 41 is other than 0 degrees, the distance between focus detection planes 30 (see FIG. 8 ) is the sum of the distance between focal feature points 32 and the length of side BF. Furthermore, when the magnitude of the irradiation angle 41 is θ, the length of side BF can be obtained by the following formula (1). The length of the side CE can be obtained by the following equation (2). The length of side AC can be obtained by the following equation (3). Here, α is the angle of angle ABC. Due to the relationship of the sum of the interior angles of a triangle, the angle of angle ABC is the angle obtained by subtracting the angle of angle BAC from 90 degrees. Furthermore, the angle of angle BAC can be obtained by subtracting the angle of angle 42, which is the angle formed by normal line 81 and perpendicular line 83, from 90 degrees. Therefore, the angle of angle ABC is equal to the angle of angle 42. Furthermore, due to the relationship of alternate angles, the angle of angle 42 is equal to the angle of angle BDC. Furthermore, due to the relationship of opposite angles, the angle of angle BDC and the angle of angle EDF are equal. Furthermore, due to the relationship of alternate angles, the angle of angle EDF and the irradiation angle 41 are equal. Therefore, the angle of angle 42 is equal to the irradiation angle 41. In other words, the angle of angle ABC is equal to the irradiation angle 41.

[0066] Furthermore, the length of side AB is the distance 35 between the X-ray irradiation axis 80 and the normal 81, and is a known value determined when the planar marker 3 is placed in the X-ray irradiation unit 10. If the length of side AB is "a," the focus detection plane distance 30 can be obtained by the following equation (4). Here, SID is the distance between focus detection planes 30. Furthermore, D1 is the distance between focus feature points 32. Furthermore, Q1 is the distance 34 between the portable terminal 2 and the planar marker 3 in the Q direction.

[0067] (Acquisition of the distance between focus detection surfaces and the illumination angle in the non-intra-plane detection mode) Next, with reference to Figures 10 and 11, we will explain the configuration in which the control unit 21 (see Figure 1) acquires the distance between focus detection surfaces 30 (see Figure 10) and the illumination angle 41 (see Figure 11) in the non-intra-plane detection mode.

[0068] 10 is an example where the X-ray irradiation angle 41 (see FIG. 11 ) is 0 degree. In this embodiment, the control unit 21 is configured to acquire a terminal-to-detector distance 36, which is the distance between the mobile terminal 2 and the X-ray detector 11, in the non-in-plane detection mode, and to acquire a focus-to-detection-plane distance 30 based on the acquired terminal-to-detector distance 36, a focus-to-feature-point distance 32, and a feature-to-detection-plane distance 31.

[0069] Specifically, as shown in FIG. 10 , in the non-co-planar detection mode, the portable terminal 2 and the X-ray detector 11 are arranged on different planes in the direction of the X-ray irradiation axis 80. When the portable terminal 2 and the X-ray detector 11 are arranged on the same plane, the feature point detection plane distance 31 can be acquired based on the planar marker 3 shown in the feature point image 50 (see FIG. 5 ), as described in the co-planar detection mode. The terminal-detector distance 36 is a known value determined when the X-ray detector 11 is arranged on the detector holding unit 14 a (see FIG. 2 ), and is input by the operator or stored in advance in the storage unit 24 by the operator. Therefore, in the non-co-planar detection mode, the control unit 21 acquires the focus detection plane distance 30 based on the feature point detection plane distance 31 and the terminal-detector distance 36, which are assumed to be on the same plane as the portable terminal 2, as shown by a virtual detector 11 c illustrated by a dashed line. The configuration in which the control unit 21 acquires the feature point detection plane distance 31 is the same as the configuration described with reference to FIG. 8, and therefore a detailed description thereof will be omitted.

[0070] Next, a configuration in which the control unit 21 (see FIG. 1) acquires the focus detection plane distance 30 (see FIG. 10) in the non-in-plane detection mode when the X-ray irradiation angle 41 is not 0 degrees will be described with reference to FIG. 11. Note that the configuration in which the control unit 21 acquires the irradiation angle 41 in the non-in-plane detection mode is similar to the configuration in which the control unit 21 acquires the irradiation angle 41 in the in-plane detection mode, and therefore detailed description thereof will be omitted.

[0071] 11 , a virtual detector 11c is shown by a dashed line when it is assumed that the X-ray detector 11 is arranged in the same plane as the portable terminal 2. The intersection of the virtual detector 11c and a perpendicular line 83 is shown by point E. The intersection of the virtual detector 11c and the irradiation axis 80 is shown by point F. The intersection of the perpendicular line 83 and the detection surface 11a of the X-ray detector 11 is shown by point G. The intersection of the X-ray irradiation axis 80 and the detection surface 11a of the X-ray detector 11 is shown by point H.

[0072] In the example shown in FIG. 11 , the distance between focus detection planes 30 (see FIG. 10 ) is the sum of the distance between focus feature points 32 and the length of side BH. The length of side BH is the sum of the lengths of sides BF and FH. The length of side BF can be obtained using a configuration similar to that described using FIG. 9 . Furthermore, the length of side FH can be obtained using the following formula (5). Here, D2 is the terminal-to-detector distance 36. Therefore, the focus detection plane distance 30 can be obtained by the following equation (6).

[0073] As a result, the control unit 21 can obtain the distance 34 and the illumination angle 41 based on the planar marker 3 shown in the feature point image 50 (see Figure 5), thereby obtaining the focus detection plane distance 30 and the illumination angle 41 in both the same-plane detection mode and the non-same-plane detection mode.

[0074] 12 , the holding member 5 has a detector holding member 5a, a terminal holding member 5b, a support 5c, and legs 5d. The detector holding member 5a is configured to hold the X-ray detector 11. The detector holding member 5a is, for example, a holding mechanism that holds the X-ray detector 11. Note that the detector holding member 5a may be configured in any way as long as it is capable of holding the X-ray detector 11.

[0075] Furthermore, the terminal holding member 5b is configured to hold the portable terminal 2. The terminal holding member 5b is, for example, a gripping mechanism that grips the portable terminal 2. Note that the terminal holding member 5b may be configured in any manner as long as it is capable of holding the portable terminal 2.

[0076] Furthermore, the support 5c is configured to hold the detector holding member 5a and the terminal holding member 5b. Furthermore, the leg 5d is configured to hold the support 5c. In this embodiment, the holding member 5 is arranged on the tabletop 4 (see FIG. 13 ), and is configured to hold the X-ray detector 11 and the portable terminal 2 so that a predetermined side 11b of the X-ray detector 11 and a predetermined side 2a of the portable terminal 2 are parallel to each other in the same plane at a position different from the tabletop 4.

[0077] (Example of Imaging Using a Holding Member) FIG. 13 illustrates an example of acquiring the focus detection plane distance 30 (see FIG. 8 ) and the irradiation angle 41 (see FIG. 9 ) when imaging a subject 90 using a holding member 5. As shown in FIG. 13 , when imaging the knee of the subject 90 from an oblique direction, X-rays are irradiated from a diagonally downward direction, as indicated by the irradiation axis 80. Therefore, the X-ray detector 11 needs to be positioned differently from the tabletop 4. In this case, as shown in FIG. 13 , the holding member 5 holds the portable terminal 2 in the same plane as the X-ray detector 11. By imaging the planar marker 3 using the portable terminal 2 (feature point detection unit 20 (see FIG. 1 )) while the portable terminal 2 is held in the same plane as the X-ray detector 11 by the holding member 5, the control unit 21 (see FIG. 1 ) can acquire the focus detection plane distance 30 and the irradiation angle 41. In the state illustrated in FIG. 13 , the control unit 21 acquires the focus detection plane distance 30 and the irradiation angle 41 using the same-plane detection mode illustrated in FIGS. 8 and 9 . In the example shown in FIG. 13, the subject 90 supports the support 5c with his / her hands (not shown), thereby placing the holding member 5 on the support surface 4a of the top board 4.

[0078] 14 , the distance between focal feature points 32 is the distance between the planar marker 3 and the focal position 10c of the X-ray irradiator 10. The focal position 10c of the X-ray irradiator 10 is a predetermined position depending on the type of X-ray source 10a. Therefore, the distance between focal feature points 32 is determined by providing the planar marker 3 on the end face 10d of the X-ray irradiator 10 (collimator 10b) on the X-ray emission direction side. In addition, the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3 is also determined when the planar marker 3 is provided.

[0079] When design data of the X-ray imaging device 1 (see FIG. 1 ) and the like are available, the distance 37 between the X-ray focal position 10c and the end face 10d on the X-ray emission direction side can be acquired from the design data of the X-ray irradiation unit 10. In this case, the control unit 21 (see FIG. 1 ) acquires the distance 37 between the focal position 10c and the end face 10d input by the operator as the distance between focal feature points 32. Then, the control unit 21 stores the acquired distance between focal feature points 32 in the storage unit 24 (see FIG. 1 ).

[0080] Furthermore, when the planar marker 3 is placed, the operator can measure the distance from the X-ray irradiation axis 80 to the normal 81, thereby obtaining the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3. Therefore, the control unit 21 obtains the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3 input by the operator, and stores it in the memory unit 24. Note that the control unit 21 may obtain the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3 based on the planar marker 3 depicted in the feature point image 50 (see FIG. 5 ), as will be described later.

[0081] (Calibration) On the other hand, if design data or the like of the X-ray imaging device 1 is unavailable, it is not possible to acquire from the design data the distance between the X-ray focal position 10c of the X-ray irradiator 10 and the end face 10d on the emission direction side of the X-ray irradiator 10. Furthermore, depending on the shape of the X-ray irradiator 10, it may be difficult to measure the distance between the X-ray focal position 10c of the X-ray irradiator 10 and the end face 10d on the emission direction side of the X-ray irradiator 10 using a tape measure. Therefore, the control unit 21 acquires the distance between focal feature points 32 by calibration.

[0082] Specifically, the control unit 21 is configured to acquire the distance between focus feature points 32 based on the input value of the distance between focus detection planes 30 received by the input receiving unit 23 (see Figure 1) and the distance between feature point detection planes 31.

[0083] 14 , when performing calibration, the operator places the X-ray irradiation unit 10 at a predetermined position or at an arbitrary position, and then places the portable terminal 2 so that the center 2b of the portable terminal 2 is aligned with the X-ray irradiation axis 80. The control unit 21 acquires the feature point detection plane-to-plane distance 31 using the same-plane detection mode.

[0084] When disposing the X-ray irradiator 10 at a predetermined position, the operator adjusts the position of the X-ray irradiator 10 using a measuring tool such as a tape measure so that the inter-focus detection plane distance 30 is a predetermined distance. When disposing the X-ray irradiator 10 at an arbitrary position, the operator uses a measuring tool such as a tape measure to actually measure the inter-focus detection plane distance 30. The control unit 21 then obtains the difference between the inter-focus detection plane distance 30 that is preset to result in the predetermined position or the inter-focus detection plane distance 30 input by the operator and the inter-feature point detection plane distance 31 obtained in the in-plane detection mode, thereby obtaining the inter-focus feature point distance 32.

[0085] Furthermore, the control unit 21 acquires the angle 43 relative to the normal direction when the planar marker 3 is viewed from the mobile terminal 2, based on the shape of the planar marker 3 shown in the feature point image 50. Then, the control unit 21 acquires the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3 using the following equation (7): Here, D3 is the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3. Also, θ is the angle of the angle 43.

[0086] The control unit 21 stores the acquired focal feature point distance 32 and the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3 in the storage unit 24 (see FIG. 1).

[0087] (Calibration Performed with X-Ray Irradiation Unit Disposed at a Predetermined Position) A screen 22b shown in FIG. 15 is an example of a screen displayed on the display unit 22 (see FIG. 1) when calibration is performed with the X-ray irradiator 10 (see FIG. 14) disposed at a predetermined position. A message 60 indicating that the X-ray irradiator 10 will be disposed at a predetermined position is displayed on the screen 22b. In the example shown in FIG. 15, the message 60 indicates that the X-ray irradiator 10 should be disposed so that the inter-focus detection plane distance 30 is 100 cm. The inter-focus detection plane distance 30 displayed in the message 60 is set in advance and stored in the storage unit 24 (see FIG. 1). The inter-focus detection plane distance 30 displayed in the message 60 is merely an example and need not be 100 cm.

[0088] After positioning the X-ray irradiation unit 10 according to the message 60 displayed on the screen 22b, the operator performs an operation input to start calibration. When the operation input to start calibration is performed, the control unit 21 (see FIG. 1) starts acquiring a feature point detection plane distance 31 (see FIG. 14) in the same plane detection mode. The control unit 21 also acquires a focus feature point distance 32 (see FIG. 14) based on the acquired feature point detection plane distance 31 and a preset focus detection plane distance 30 (see FIG. 14).

[0089] 16 is an example of a screen displayed on the display unit 22 (see FIG. 1) when performing calibration by placing the X-ray irradiator 10 (see FIG. 14) at an arbitrary position. Screen 22c displays a message 61 that indicates that the focus detection plane distance 30 is measured after the X-ray irradiator 10 is placed, and prompts the user to input the measured focus detection plane distance 30 (see FIG. 14).

[0090] After measuring and inputting the distance between focus detection planes 30 in accordance with the message 61 displayed on the screen 22c, the operator performs an operation input to start calibration. When the operation input to start calibration is performed, the control unit 21 (see FIG. 1) starts acquiring the distance between feature point detection planes 31 (see FIG. 14) in the intra-plane detection mode. The control unit 21 also acquires the distance between focus feature points 32 (see FIG. 14) based on the acquired distance between feature point detection planes 31 and the input distance between focus detection planes 30.

[0091] (Processing for Displaying Distance Between Focus Detection Planes and Illumination Angle) Next, with reference to Fig. 17 , a process in which the feature point detection unit 20 (Fig. 1) and the control unit 21 (see Fig. 1) acquire the distance between focus detection planes 30 (see Fig. 8 ) and the illumination angle 41 (see Fig. 9 ) and display them on the display unit 22 (see Fig. 1 ) will be described. Note that the process shown in Fig. 17 is started when the operator places the mobile terminal 2 (see Fig. 8 ) on the placement surface 4a (see Fig. 2 ) of the top board 4 (see Fig. 2 ), selects the in-plane detection mode or the non-in-plane detection mode, and then performs an operation input to start displaying the distance between focus detection planes 30 and the illumination angle 41.

[0092] In step 101, the feature point detection unit 20 optically detects feature points in the X-ray irradiation unit 10 (see FIG. 9 ) with the portable terminal 2 placed near the X-ray detector 11. Specifically, the feature point detection unit 20 acquires a feature point image 50 (see FIG. 5 ) by capturing an image of the end face 10d (see FIG. 4 ) of the X-ray irradiation unit 10. If a planar marker 3 (see FIG. 8 ) is provided within the imaging field of view of the feature point detection unit 20, the planar marker 3 will appear in the feature point image 50.

[0093] In step 102, the control unit 21 determines whether or not a feature point (a planar marker 3) is shown in the feature point image 50. If the planar marker 3 is not shown in the feature point image 50, the processing of step 102 is repeated. If the planar marker 3 is shown in the feature point image 50, the processing proceeds to step 103.

[0094] In step 103, the control unit 21 acquires the feature point detection surface distance 31 (see FIG. 8 ). In this embodiment, the control unit 21 acquires the distance 34 (see FIG. 8 ) between the mobile device 2 and the surface marker 3 in the Q direction (the direction in which the normal 81 (see FIG. 8 ) of the mobile device 2 extends) based on the size of the surface marker 3 shown in the feature point image 50 (see FIG. 5 ). Note that the distance 34 between the mobile device 2 and the surface marker 3 in the Q direction can be considered to be the same distance as the feature point detection surface distance 31. Therefore, the control unit 21 acquires the distance 34 between the mobile device 2 and the surface marker 3 in the Q direction as the feature point detection surface distance 31.

[0095] In step 104, the control unit 21 determines whether the mode is the same-plane detection mode. If the mode is the same-plane detection mode, the process proceeds to step 105. If the mode is not the same-plane detection mode, the process proceeds to step 106. That is, if the mode is the non-same-plane detection mode, the process proceeds to step 106.

[0096] In step 105, the control unit 21 acquires the focal feature point distance 32 (see FIG. 9) and the distance 35 (see FIG. 9) between the X-ray irradiation axis 80 (see FIG. 9) and the normal 81 (see FIG. 9) of the planar marker 3 (see FIG. 9). Specifically, the control unit 21 acquires the focal feature point distance 32 and the distance 35 between the X-ray irradiation axis 80 and the normal 81 of the planar marker 3, which are stored in the memory unit 24 (see FIG. 1).

[0097] Furthermore, when the process proceeds from step 104 to step 106, in step 106, the control unit 21 acquires the focal feature point distance 32, the distance 35 between the X-ray irradiation axis 80 and the normal line 81 of the planar marker 3, and the terminal-to-detector distance 36 (see FIG. 10 ). Specifically, the control unit 21 acquires the focal feature point distance 32, the distance 35 between the X-ray irradiation axis 80 and the normal line 81 of the planar marker 3, and the terminal-to-detector distance 36 stored in the memory unit 24.

[0098] In step 107, the control unit 21 acquires, based on the detected feature points, at least one of information regarding the relative position between the X-ray irradiator 10 and the X-ray detector 11 and information regarding the relative angle between the X-ray irradiator 10 and the X-ray detector 11. In this embodiment, the control unit 21 acquires both information regarding the relative position and information regarding the relative angle.

[0099] In this embodiment, the control unit 21 also acquires the focus detection plane distance 30 (see FIG. 8 ) as information relating to the relative position. The control unit 21 also acquires the illumination angle 41 (see FIG. 9 ) as information relating to the relative angle. The control unit 21 acquires the illumination angle 41 based on the shape of the planar marker 3 shown in the feature point image 50.

[0100] In addition, when the in-plane detection mode is selected and the illumination angle 41 is 0 degrees, the control unit 21 obtains the focus detection plane distance 30 by adding the feature point detection plane distance 31 and the focus feature point distance 32.

[0101] Furthermore, when the in-plane detection mode is selected and the illumination angle 41 is other than 0 degrees, the control unit 21 obtains the inter-focus detection plane distance 30 based on the above formula (4).

[0102] In addition, when the non-intra-plane detection mode is selected and the illumination angle 41 is 0 degrees, the control unit 21 obtains the focus detection plane distance 30 by adding the feature point detection plane distance 31, the focus feature point distance 32, and the terminal detector distance 36.

[0103] Furthermore, when the non-intra-plane detection mode is selected and the illumination angle 41 is other than 0 degrees, the control unit 21 obtains the inter-focus detection plane distance 30 based on the above formula (6).

[0104] Next, in step 108, the control unit 21 controls the display unit 22 of the portable terminal 2 to display the acquired information. In this embodiment, the control unit 21 controls the display unit 22 to display the focus detection plane distance 30 and the illumination angle 41. Thereafter, the processing ends.

[0105] In this embodiment, the feature point detection unit 20 and the control unit 21 repeat the processes of steps 101 to 108 described above until adjustment of the placement of the X-ray irradiator 10 is completed. That is, the control unit 21 sequentially acquires at least one of information relating to the relative position and information relating to the relative position in step 107 each time the relative position and the relative angle of the X-ray irradiator 10 change. Furthermore, the control unit 21 performs control to sequentially display the acquired information in step 108 each time the relative position and the relative angle of the X-ray irradiator 10 change.

[0106] (Calibration Process) Next, with reference to Fig. 18 , a calibration process in which the control unit 21 (see Fig. 1 ) acquires the inter-focal feature point distance 32 (see Fig. 14 ) and stores it in the storage unit 24 (see Fig. 1 ) will be described. Note that the process of storing the inter-focal feature point distance 32 shown in Fig. 18 is started based on an operation input by the operator to select a mode between a mode for accepting input of the inter-focal feature point distance 32 and a mode for acquiring the inter-focal feature point distance 32 by measurement.

[0107] In step 200, the control unit 21 acquires the mode selected by the operator.

[0108] In step 201, the control unit 21 determines whether the mode is a mode for accepting input of the distance between focal feature points 32 or a mode for acquiring the distance between focal feature points 32 by measurement. If the mode is a mode for accepting input of the distance between focal feature points 32, the process proceeds to step 210. If the mode is a mode for acquiring the distance between focal feature points 32 by measurement, the process proceeds to step 202.

[0109] In step 202, the control unit 21 determines whether or not the mode is one in which the X-ray irradiator 10 (see FIG. 1) is to be placed at a predetermined position. If the mode is one in which the X-ray irradiator 10 is to be placed at a predetermined position, the process proceeds to step 203. If the mode is not one in which the X-ray irradiator 10 is to be placed at a predetermined position, the process proceeds to step 205. That is, if the mode is one in which the X-ray irradiator 10 is to be placed at an arbitrary position, the process proceeds to step 205.

[0110] In step 203, the control unit 21 controls the display unit 22 (see FIG. 1) to display a message 60 (see FIG. 15) instructing the X-ray irradiation unit 10 to be placed at a predetermined position.

[0111] In step 204, the control unit 21 determines whether or not there has been an operational input indicating that the placement of the X-ray irradiation unit 10 at the predetermined position has been completed. If there has been no operational input indicating that the placement of the X-ray irradiation unit 10 at the predetermined position has been completed, the process of step 204 is repeated. If there has been an operational input indicating that the placement of the X-ray irradiation unit 10 at the predetermined position has been completed, the process proceeds to step 207.

[0112] Also, when the processing proceeds from step 202 to step 205, in step 205, the control unit 21 places the X-ray irradiation unit 10 at an arbitrary position, measures the distance between focus detection planes 30, and controls the display unit 22 to display a message 61 (see Figure 16) prompting the user to input the measured distance between focus detection planes 30 (see Figure 8).

[0113] In step 206, the control unit 21 determines whether or not there has been input of the inter-focus detection plane distance 30. If there has been no input of the inter-focus detection plane distance 30, the processing of step 206 is repeated. If there has been input of the inter-focus detection plane distance 30, the processing proceeds to step 207.

[0114] Next, in step 207, the control unit 21 acquires the inter-focus detection plane distance 30. When the process proceeds to step 207 via steps 203 and 204, the control unit 21 acquires the preset inter-focus detection plane distance 30 from the storage unit 24. When the process proceeds to step 207 via steps 205 and 206, the control unit 21 acquires the inter-focus detection plane distance 30 input by the operator.

[0115] In step 208, the feature point detection unit 20 optically detects feature points in the X-ray irradiation unit 10. Specifically, the feature point detection unit 20 photographs the planar marker 3 (see FIG. 8) and acquires a feature point image 50 (see FIG. 5). Also in step 208, the control unit 21 acquires a feature point detection inter-plane distance 31 (see FIG. 8). Specifically, the control unit 21 acquires the feature point detection inter-plane distance 31 based on the size of the planar marker 3 shown in the feature point image 50.

[0116] In step 209, the control unit 21 obtains the difference between the focus detection plane distance 30 obtained in step 207 and the feature point detection plane distance 31 obtained in step 208, thereby obtaining the focus feature point distance 32. Thereafter, the processing proceeds to step 211.

[0117] Furthermore, when the process proceeds from step 200 to step 210, the control unit 21 determines whether or not the inter-focus feature point distance 32 has been input in step 210. If the inter-focus feature point distance 32 has not been input, the process of step 210 is repeated. If the inter-focus feature point distance 32 has been input, the process proceeds to step 211.

[0118] In step 211, the control unit 21 stores the acquired inter-focus feature point distance 32 in the storage unit 24. Then, the processing ends. Note that either the processing of step 207 or the processing of step 208 may be performed first.

[0119] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0120] In this embodiment, as described above, the X-ray imaging system 100 includes an X-ray imaging device 1 having an X-ray irradiation unit 10 that irradiates X-rays onto a subject 90 and an X-ray detector 11 that detects the X-rays irradiated from the X-ray irradiation unit 10, and a portable terminal 2 that is placed near the X-ray detector 11. The portable terminal 2 includes a feature point detection unit 20 that optically detects feature points in the X-ray irradiation unit 10, a control unit 21 that acquires, based on the feature points detected by the feature point detection unit 20, at least one of information regarding the relative position between the X-ray irradiation unit 10 and the X-ray detector 11 and information regarding the relative angle between the X-ray irradiation unit 10 and the X-ray detector 11, and a display unit 22 that displays the information acquired by the control unit 21.

[0121] As a result, when displaying information about the relative positions of the X-ray irradiator 10 and the X-ray detector 11, the information about the relative positions of the X-ray irradiator 10 and the X-ray detector 11 is displayed on the display unit 22 of the portable terminal 2 placed near the X-ray detector 11. Therefore, the operator can adjust the position of the X-ray irradiator 10 while checking the display unit 22. This reduces the burden on the operator compared to a configuration in which, for example, relative position information is acquired using a tape measure. Furthermore, because at least one of information about the relative positions of the X-ray irradiator 10 and the X-ray detector 11 and information about the relative angle between the X-ray irradiator 10 and the X-ray detector 11 is displayed on the display unit 22 of the portable terminal 2 placed near the X-ray detector 11, the operator can adjust the relative position of the X-ray irradiator 10 and / or the relative angle of the X-ray irradiator 10 while keeping their eyes directed toward the X-ray detector 11 and the portable terminal 2. Therefore, the movement of the operator's line of sight is reduced when adjusting the relative position of the X-ray irradiator 10 and / or the relative angle of the X-ray irradiator 10. Furthermore, when imaging the subject 90, the imaging region of the subject 90 is positioned between the X-ray irradiator 10 and the X-ray detector 11 and on the X-ray detector 11 side. Therefore, when adjusting the position of the X-ray irradiator 10 while directing the line of sight toward the X-ray detector 11 and the portable terminal 2, the imaging region of the subject 90 is within the field of view of the operator. Therefore, the operator can adjust the position of the X-ray irradiator 10 while checking the subject 90. As a result, the burden on the operator can be reduced when adjusting the position of the X-ray irradiator 10, and the operator can adjust the position of the X-ray irradiator 10 while checking the subject 90.

[0122] Furthermore, in this embodiment, as described above, the X-ray imaging method is an X-ray imaging method in an X-ray imaging system 100 equipped with an X-ray imaging device 1 having an X-ray irradiation unit 10 that irradiates X-rays onto a subject 90 and an X-ray detector 11 that detects the X-rays irradiated from the X-ray irradiation unit 10, and includes the steps of optically detecting feature points in the X-ray irradiation unit 10 while a portable terminal 2 is placed near the X-ray detector 11, acquiring at least one of information regarding the relative position between the X-ray irradiation unit 10 and the X-ray detector 11 and information regarding the relative angle between the X-ray irradiation unit 10 and the X-ray detector 11 based on the detected feature points, and displaying the acquired information on a display unit 22 of the portable terminal 2.

[0123] This makes it possible to provide an X-ray imaging method that can reduce the burden on the operator when adjusting the position of the X-ray irradiation unit 10, similar to the above-mentioned X-ray imaging system 100, and that can adjust the position of the X-ray irradiation unit 10 while checking the subject 90.

[0124] Furthermore, in the above embodiment, the following additional effects can be obtained by configuring as follows.

[0125] That is, in the present embodiment, as described above, the information regarding the relative position is the focus detection plane distance 30, which is the distance from the X-ray focal position 10c of the X-ray irradiator 10 to the detection surface 11a of the X-ray detector 11, and the information regarding the relative angle is the X-ray irradiation angle 41 with respect to the detection surface 11a. The control unit 21 is configured to acquire at least one of the focus detection plane distance 30 and the irradiation angle 41 based on the feature point. As a result, at least one of the focus detection plane distance 30 and the irradiation angle 41 is displayed on the display unit 22. Therefore, when the focus detection plane distance 30 is displayed on the display unit 22, the operator can adjust the relative position of the X-ray irradiator 10 while checking the focus detection plane distance 30 displayed on the display unit 22. Therefore, compared to a configuration in which the focus detection plane distance 30 is measured using a tape measure, for example, the operator can easily grasp the difference between the focus detection plane distance 30 in the current arrangement of the X-ray irradiator 10 and the focus detection plane distance 30 where the X-ray irradiator 10 should be located while checking the subject 90. Furthermore, it is possible to prevent the operator's line of sight from moving too much, which in turn prevents a decrease in the efficiency of adjusting the relative position of the X-ray irradiator 10 when adjusting the relative position of the X-ray irradiator 10 to achieve the predetermined inter-focus detection plane distance 30.

[0126] Furthermore, when the irradiation angle 41 is displayed on the display unit 22, the operator can adjust the relative angle of the X-ray irradiator 10 while checking the irradiation angle 41 displayed on the display unit 22. Therefore, compared to a configuration in which the irradiation angle 41 is displayed on the X-ray irradiator 10, for example, the operator can easily grasp the difference between the irradiation angle 41 at the current position of the X-ray irradiator 10 and the irradiation angle 41 at which the X-ray irradiator 10 should be positioned while checking the subject 90. Furthermore, it is possible to prevent the operator from moving his or her line of sight too much. As a result, it is possible to prevent a decrease in the efficiency of adjusting the relative angle of the X-ray irradiator 10 when adjusting the relative angle of the X-ray irradiator 10 to the predetermined irradiation angle 41.

[0127] Furthermore, in this embodiment, as described above, the control unit 21 is configured to acquire the feature point inter-detection plane distance 31, which is the distance between the feature point and the detection plane 11a, based on the feature point, and to acquire the focus-detection plane distance 30 based on the focus-feature point inter-plane distance 32, which is the distance between the focal position 10c and the feature point, and the acquired feature point inter-detection plane distance 31. Here, the focus-feature point inter-plane distance 32 is determined to a unique value when the feature point is set in the X-ray irradiation unit 10. In other words, the focus-feature point inter-plane distance 32 is a known value when the feature point inter-detection plane distance 31 is acquired. Therefore, by acquiring the feature point inter-detection plane distance 31, the control unit 21 can easily acquire the focus-detection plane distance 30 from the acquired feature point inter-detection plane distance 31 and the known value of the focus-feature point inter-plane distance 32.

[0128] Furthermore, in this embodiment, as described above, the feature point includes a planar marker 3 provided on the end surface 10d of the X-ray irradiator 10 on the X-ray emission direction side and having a shape whose direction can be identified, the feature point detection unit 20 is an imaging unit that captures a feature point image 50 that is an image of the planar marker 3, and the control unit 21 is configured to acquire the feature point detection plane distance 31 based on the size of the planar marker 3 in the feature point image 50 when acquiring the focus detection plane distance 30, and to acquire the irradiation angle 41 based on the shape of the planar marker 3 in the feature point image 50 when acquiring the irradiation angle 41. As a result, the feature point detection plane distance 31 is acquired based on the size of the planar marker 3 that appears in the feature point image 50, and thus the focus detection plane distance 30 can be easily acquired by acquiring the feature point image 50. Furthermore, the irradiation angle 41 is acquired based on the shape of the planar marker 3 that appears in the feature point image 50, and thus the irradiation angle 41 can be easily acquired by acquiring the feature point image 50.

[0129] In the present embodiment, as described above, the portable terminal 2 further includes a storage unit 24 that stores the focal feature point distance 32. The control unit 21 is configured to acquire the focal feature point distance 30 based on the focal feature point distance 32 and the feature point detection plane distance 31 stored in the storage unit 24. When design data or the like of the X-ray irradiator 10 is available, information on the distance from the X-ray focal position 10c to the end face 10d of the X-ray irradiator 10 on the X-ray emission direction side can be acquired. Therefore, by providing a feature point on the end face 10d of the X-ray irradiator 10 on the X-ray emission direction side, the focal feature point distance 32 can be acquired from the design data or the like of the X-ray irradiator 10. Even when the design data of the X-ray irradiator 10 is unavailable, the focal feature point distance 32 can be acquired by calibration or the like. Therefore, the design data or the focal feature point distance 32 acquired by calibration or the like can be stored in advance in the storage unit 24. Therefore, by configuring as described above, the control unit 21 can easily obtain the distance between focus feature points 32 stored in the memory unit 24 and the distance between feature point detection planes 31, thereby obtaining the distance between focus detection planes 30.

[0130] In the present embodiment, as described above, the portable terminal 2 further includes an input receiving unit 23 that receives an operation input from the operator. The control unit 21 is configured to acquire the focal-feature-point-to-focal-point distance 32 based on the input value of the focal-feature-point-to-focal-point distance 30 and the feature-feature-point-to-focal-point detection-plane distance 31 received by the input receiving unit 23. Here, if it is difficult to obtain design data of the X-ray irradiator 10, it may be difficult to acquire information about the distance from the X-ray focal position 10c to the end face 10d of the X-ray irradiator 10 on the X-ray emission direction side. Therefore, by acquiring the focal-feature-point-to-focal-point distance 32 based on the input value of the focal-feature-point-to-focal-point distance 30 received by the input receiving unit 23 and the feature-feature-point-to-focal-point detection-plane distance 31 as described above, the focal-feature-point-to-focal-point distance 32 can be easily acquired even when it is difficult to obtain design data. As a result, the present invention can be easily applied to an X-ray imaging device 1 that has already been installed but for which design data cannot be acquired.

[0131] Furthermore, in this embodiment, as described above, the X-ray detector 11 has a rectangular shape, the portable terminal 2 has a rectangular shape, and the control unit 21 is configured to switch between a same-plane detection mode in which the feature point detection unit 20 detects feature points while a predetermined side 2 a of the portable terminal 2 and a predetermined side 11 b of the X-ray detector 11 are arranged parallel to each other in the same plane, and a non-same-plane detection mode in which the feature point detection unit 20 detects feature points while a predetermined side 2 a of the portable terminal 2 and a predetermined side 11 b of the X-ray detector 11 are arranged parallel to each other in planes that are parallel to each other but at different positions in the direction of the X-ray irradiation axis 80. This makes it possible to obtain the focus detection plane distance 30 and the irradiation angle 41 whether the portable terminal 2 and the X-ray detector 11 are arranged in the same plane or in different planes, thereby improving the flexibility of the arrangement of the X-ray detector 11. As a result, the convenience (usability) for the operator can be improved.

[0132] Furthermore, in this embodiment, as described above, the control unit 21 is configured to acquire the inter-focus detection plane distance 30 in the in-plane detection mode based on the inter-focus feature point distance 32 and the inter-feature point detection plane distance 31. Here, in the in-plane detection mode, the portable terminal 2 and the X-ray detector 11 are arranged on the same plane, so the inter-focus detection plane distance 30 is the sum of the inter-focus feature point detection plane distance 31 and the inter-focus feature point distance 32. Therefore, with the above configuration, the control unit 21 can easily acquire the inter-focus detection plane distance 30 in the in-plane detection mode by acquiring the inter-feature point detection plane distance 31.

[0133] Furthermore, as described above, this embodiment further includes the tabletop 4 having the placement surface 4a on which the subject 90 is placed, and the holding member 5 that is disposed on the tabletop 4 and holds the X-ray detector 11 and the portable terminal 2 so that a predetermined side 11b of the X-ray detector 11 and a predetermined side 2a of the portable terminal 2 are parallel to each other in the same plane at a position different from the tabletop 4. This makes it possible to dispose the portable terminal 2 and the X-ray detector 11 at a position different from the placement surface 4a of the tabletop 4, so that at least one of the focus detection plane distance 30 and the irradiation angle 41 can be easily obtained even when the X-ray detector 11 is disposed somewhere other than the placement surface 4a of the tabletop 4 for imaging. Therefore, for example, even when the X-ray detector 11 is disposed somewhere other than the placement surface 4a of the tabletop 4 for imaging, such as when imaging the knee of the subject 90 from an oblique direction, at least one of the focus detection plane distance 30 and the irradiation angle 41 can be displayed on the display unit 22. As a result, even when photographing the knee of the subject 90 from an oblique direction, it is possible to reduce the burden on the operator and prevent a decrease in the efficiency of adjusting the relative position of the X-ray irradiation unit 10.

[0134] Furthermore, in the present embodiment, as described above, the control unit 21 is configured to acquire the terminal-to-detector distance 36, which is the distance between the portable terminal 2 and the X-ray detector 11, in the non-coplanar detection mode, and to acquire the focus-detection-plane distance 30 based on the acquired terminal-to-detector distance 36, the focal feature point distance 32, and the feature point detection plane distance 31. Here, in the non-coplanar detection mode, the focus-detection-plane distance 30 is the sum of the distance 34 between the feature point and the portable terminal 2 and the terminal-to-detector distance 36, which is the distance between the portable terminal 2 and the X-ray detector 11. That is, in the non-coplanar detection mode, the focus-detection-plane distance 30 is the sum of the focal feature point distance 32, the feature point detection plane distance 31, and the terminal-to-detector distance 36. Furthermore, the terminal-to-detector distance 36 is a distance determined when the X-ray detector 11 is positioned, and therefore is a known value when adjusting the position of the X-ray irradiator 10. Therefore, even if the portable terminal 2 and the X-ray detector 11 are placed on a non-coplanar surface, the control unit 21 can easily obtain the distance between the feature point detection planes 31 and the distance between the terminal and the detectors 36, thereby obtaining the distance between the focus detection planes 30.

[0135] Furthermore, in this embodiment, as described above, in the step of acquiring at least one of information regarding the relative position and information regarding the relative angle, at least one of information regarding the relative position and information regarding the relative angle is sequentially acquired each time the relative position and relative angle of the X-ray irradiator 10 change, and in the step of displaying the acquired information on the portable terminal 2, the acquired information is sequentially displayed. As a result, each time the relative position and relative angle of the X-ray irradiator 10 change, at least one of information regarding the relative position and information regarding the relative angle is sequentially updated and displayed on the portable terminal 2, allowing the operator to adjust the placement of the X-ray irradiator 10 while checking the sequentially updated information. As a result, the operator can efficiently adjust the placement of the X-ray irradiator 10.

[0136] [Modifications] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and further includes all modifications (modifications) within the meaning and scope of the claims.

[0137] For example, in the above embodiment, an example of a configuration in which the control unit 21 acquires both the focus detection plane distance 30 and the illumination angle 41 has been described, but the present invention is not limited to this. It is sufficient to acquire at least one of the focus detection plane distance 30 and the illumination angle 41, and it is not necessary to acquire both.

[0138] Furthermore, in the above embodiment, an example of a configuration in which the feature point is the planar marker 3 is shown, but the present invention is not limited to this. The feature point may be something other than the planar marker 3 as long as it can be detected by the feature point detection unit 20 and the distance and angle between the mobile terminal 2 and the feature point can be obtained. For example, the feature point may be the shape of the end face 10d of the X-ray irradiator 10 on the side in the X-ray emission direction.

[0139] Furthermore, in the above embodiment, an example of a configuration in which the planar marker 3 is provided on the end surface 10d of the X-ray irradiator 10 on the side in the X-ray emission direction has been shown, but the present invention is not limited to this. The planar marker 3 may be provided on a part of the X-ray irradiator 10 other than the end surface 10d on the side in the X-ray emission direction, as long as it is a member that moves integrally with the X-ray irradiator 10. For example, the planar marker 3 may be provided on a grip portion of the X-ray irradiator 10, etc.

[0140] Furthermore, in the above embodiment, an example of a configuration has been shown in which the control unit 21 acquires the feature point detection surface-to-surface distance 31 and the irradiation angle 41 based on the size and shape of the planar marker 3 depicted in the feature point image 50, but the present invention is not limited to this. For example, the control unit 21 may be configured to acquire, from the planar marker 3 depicted in the feature point image 50, the position coordinates of the planar marker 3 in the three axial directions in the PQR coordinate system and the angles in the rotational directions around each axial direction of the planar marker 3, and thereby acquire the feature point detection surface-to-surface distance 31 and the irradiation angle 41.

[0141] Furthermore, in the above embodiment, an example of a configuration in which the feature point detection unit 20 is an optical camera has been described, but the present invention is not limited to this. For example, the feature point detection unit 20 may be an infrared sensor that detects feature points using infrared rays. Furthermore, the feature point detection unit 20 may be a LiDAR (Light Detection and Ranging) sensor that detects feature points using laser light. Note that, if the feature point detection unit 20 is an infrared sensor or a LiDAR sensor, it can detect the shape of an object, but it is difficult to detect an image such as the planar marker 3. Therefore, if the feature point detection unit 20 is an infrared sensor or a LiDAR sensor, the shape of the end face 10d of the X-ray irradiator 10 on the X-ray emission direction side may be used as the feature point.

[0142] Furthermore, in the above embodiment, an example has been described in which the control unit 21 acquires the inter-focus detection plane distance 30 using the inter-focus feature point distance 32 input by the operator and stored in advance in the storage unit 24. However, the present invention is not limited to this. For example, the control unit 21 may be configured to acquire the inter-focus detection plane distance 30 using the inter-focus feature point distance 32 input by the operator every time the inter-focus detection plane distance 30 is acquired. However, if the operator inputs the inter-focus feature point distance 32 every time the inter-focus detection plane distance 30 is acquired, the burden on the operator increases. Therefore, it is preferable that the control unit 21 acquires the inter-focus detection plane distance 30 using the inter-focus feature point distance 32 stored in the storage unit 24.

[0143] In addition, in the above embodiment, an example of a configuration in which the storage unit 24 stores one inter-focal feature point distance 32 has been described, but the present invention is not limited to this. For example, the storage unit 24 may be configured to store a plurality of inter-focal feature point distances 32 for each type of X-ray imaging device 1. In this case, the storage unit 24 may store information for identifying the type of X-ray imaging device 1 and the inter-focal feature point distances 32 in association with each other.

[0144] Furthermore, when the storage unit 24 is configured to store a plurality of focal feature point distances 32 for each type of X-ray imaging device 1, the type of planar marker 3 may be different for each type of X-ray imaging device 1, and the storage unit 24 may be configured to store the planar marker 3 and the focal feature point distances 32 in association with each other for each type of X-ray imaging device 1. In this case, the control unit 21 may be configured to determine the type of X-ray imaging device 1 according to the type of planar marker 3.

[0145] Furthermore, in the above embodiment, an example was shown in which the control unit 21 is configured to switch between the in-plane detection mode and the non-in-plane detection mode, but the present invention is not limited to this. For example, the control unit 21 may be configured to be unable to switch between the in-plane detection mode and the non-in-plane detection mode. However, if the control unit 21 is unable to switch between the in-plane detection mode and the non-in-plane detection mode, the mobile terminal 2 and the X-ray detector 11 must be placed on the same plane, which reduces the degree of freedom in placing the X-ray detector 11. Therefore, it is preferable that the control unit 21 be configured to be able to switch between the in-plane detection mode and the non-in-plane detection mode.

[0146] Furthermore, in the above embodiment, an example of a configuration in which the X-ray imaging system 100 includes the holding member 5 has been described, but the present invention is not limited to this. The X-ray imaging system 100 does not have to include the holding member 5. However, if the X-ray imaging system 100 does not include the holding member 5, it may be difficult to hold the portable terminal 2 and the X-ray detector 11 parallel to each other in the same plane, depending on the region of the subject 90 being imaged. Therefore, it is preferable that the X-ray imaging system 100 includes the holding member 5.

[0147] Furthermore, in the above embodiment, for convenience of explanation, the process of acquiring and displaying the focus detection plane distance 30 and the irradiation angle 41 using the X-ray imaging apparatus 1 of the present invention, and the process of acquiring the focus feature point distance 32, have been described using a flow-driven flowchart in which the processes are performed in order according to a processing flow, but the present invention is not limited to this. In the present invention, the process of acquiring and displaying the focus detection plane distance 30 and the irradiation angle 41 using the X-ray imaging apparatus 1, and the process of acquiring the focus feature point distance 32, may be performed by event-driven processing in which processing is performed on an event-by-event basis. In this case, the processes may be performed completely event-driven, or may be performed in a combination of event-driven and flow-driven processing.

[0148] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0149] (Item 1) An X-ray imaging system comprising: an X-ray imaging device having an X-ray irradiation unit that irradiates a subject with X-rays and an X-ray detector that detects the X-rays irradiated from the X-ray irradiation unit; and a portable terminal placed near the X-ray detector, wherein the portable terminal has: a feature point detection unit that optically detects feature points in the X-ray irradiation unit; a control unit that acquires at least one of information regarding the relative position between the X-ray irradiation unit and the X-ray detector and information regarding the relative angle between the X-ray irradiation unit and the X-ray detector based on the feature points detected by the feature point detection unit; and a display unit that displays the information acquired by the control unit.

[0150] (Item 2) The X-ray imaging system described in Item 1, wherein the information regarding the relative position is a distance between focus detection planes, which is the distance from the focal position of the X-ray of the X-ray irradiation unit to the detection plane of the X-ray detector, and the information regarding the relative angle is an irradiation angle of the X-ray with respect to the detection plane, and the control unit is configured to acquire at least one of the distance between focus detection planes and the irradiation angle based on the feature point.

[0151] (Item 3) The X-ray imaging system according to Item 2, wherein the control unit is configured to acquire a feature point detection plane distance, which is the distance between the feature point and the detection plane, based on the feature point, and to acquire the focus detection plane distance based on the focus feature point distance, which is the distance between the focus position and the feature point, and the acquired feature point detection plane distance.

[0152] (Item 4) The X-ray imaging system according to item 2 or 3, wherein the feature point includes a planar marker provided on an end surface of the X-ray irradiation unit on the side in the X-ray emission direction and having a shape whose direction can be identified, the feature point detection unit is an imaging unit that captures a feature point image in which the planar marker is captured, and the control unit is configured to, when acquiring the focus detection plane distance, acquire the feature point detection plane distance based on the size of the planar marker in the feature point image, and when acquiring the irradiation angle, acquire the irradiation angle based on the shape of the planar marker in the feature point image.

[0153] (Item 5) The X-ray imaging system according to any one of Items 2 to 4, wherein the portable terminal further includes a memory unit that stores the distance between focal feature points, and the control unit is configured to acquire the distance between focal feature points based on the distance between focal feature points and the distance between feature point detection planes stored in the memory unit.

[0154] (Item 6) The X-ray imaging system according to any one of Items 2 to 5, wherein the portable terminal further includes an input receiving unit that receives an operation input from an operator, and the control unit is configured to acquire the distance between focus feature points based on the input value of the distance between focus detection planes received by the input receiving unit and the distance between feature point detection planes.

[0155] (Item 7) The X-ray imaging system according to any one of Items 2 to 6, wherein the X-ray detector has a rectangular shape, the portable terminal has a rectangular shape, and the control unit is configured to switch between a same-plane detection mode in which control is performed to cause the feature point detection unit to detect the feature points in a state in which a predetermined side of the portable terminal and a predetermined side of the X-ray detector are arranged parallel to each other in the same plane, and a non-same-plane detection mode in which control is performed to cause the feature point detection unit to detect the feature points in a state in which a predetermined side of the portable terminal and a predetermined side of the X-ray detector are arranged parallel to each other in planes that are parallel to each other but at different positions in the X-ray irradiation axis direction.

[0156] (Item 8) The X-ray imaging system according to Item 7, wherein the control unit is configured to acquire the distance between focus detection planes based on the distance between focus feature points and the distance between feature point detection planes in the same plane detection mode.

[0157] (Item 9) The X-ray imaging system according to Item 8, further comprising: a tabletop having a surface on which a subject rests; and a holding member disposed on the tabletop and holding the X-ray detector and the portable terminal so that a predetermined side of the X-ray detector and a predetermined side of the portable terminal are parallel to each other within the same plane at a position different from the tabletop.

[0158] (Item 10) The X-ray imaging system according to Item 7, wherein the control unit is configured to acquire a terminal-to-detector distance, which is the distance between the mobile terminal and the X-ray detector, in the non-in-plane detection mode, and to acquire the focal point detection plane distance based on the acquired terminal-to-detector distance, the focal point feature point distance, and the feature point detection plane distance.

[0159] (Item 11) An X-ray imaging method in an X-ray imaging system equipped with an X-ray imaging device having an X-ray irradiation unit that irradiates X-rays onto a subject and an X-ray detector that detects the X-rays irradiated from the X-ray irradiation unit, the X-ray imaging method comprising: a step of optically detecting a feature point in the X-ray irradiation unit while a mobile terminal is placed near the X-ray detector; a step of acquiring at least one of information regarding the relative position between the X-ray irradiation unit and the X-ray detector and information regarding the relative angle between the X-ray irradiation unit and the X-ray detector based on the detected feature point; and a step of displaying the acquired information on a display unit of the mobile terminal.

[0160] (Item 12) The X-ray imaging method according to Item 11, wherein, in the step of acquiring at least one of information regarding the relative position and information regarding the relative angle, at least one of information regarding the relative position and information regarding the relative angle is acquired sequentially each time the relative position of the X-ray irradiation unit and the relative angle of the X-ray irradiation unit change, and, in the step of displaying the acquired information on the mobile terminal, the acquired information is displayed sequentially.

[0161] REFERENCE SIGNS LIST 1 X-ray imaging device 2 Portable terminal 3 Planar marker (feature point) 4 Top plate 4a Placement surface 5 Holding member 10 X-ray irradiation unit 11 X-ray detector 20 Feature point detection unit 21 Control unit 22 Display unit 23 Input reception unit 24 Memory unit 30 Distance between focus detection planes 31 Distance between feature point detection planes 32 Distance between focus feature points 36 Distance between terminal detectors 41 Irradiation angle 50 Feature point image 80 Irradiation axis 90 Subject 100 X-ray imaging system

Claims

1. An X-ray imaging device including a feature point and having an X-ray irradiation unit that irradiates an examinee with X-rays, and an X-ray detector that detects the X-rays irradiated from the X-ray irradiation unit; a portable terminal disposed near the X-ray detector, The mobile terminal an imaging unit that captures an image of the feature points to obtain a feature point image; a feature point detection unit that detects the feature points based on the feature point image; a control unit that acquires, based on the feature points detected by the feature point detection unit, at least one of information regarding the relative position between the X-ray irradiator and the X-ray detector and information regarding the relative angle between the X-ray irradiator and the X-ray detector; and a display unit that displays information acquired by the control unit.

2. the information about the relative position is a focal point detection surface distance, which is a distance from a focal point position of the X-ray irradiation unit to a detection surface of the X-ray detector; the information about the relative angle is an irradiation angle of the X-ray with respect to the detection surface; The X-ray imaging system according to claim 1 , wherein the control unit is configured to acquire at least one of the inter-focus detection plane distance and the irradiation angle based on the feature point.

3. 3. The X-ray imaging system according to claim 2, wherein the control unit is configured to acquire a feature point detection plane distance, which is a distance between the feature point and the detection plane, based on the feature point, and to acquire the focus detection plane distance based on the focus feature point distance, which is a distance between the focus position and the feature point, and the acquired feature point detection plane distance.

4. the characteristic point includes a planar marker provided on an end surface of the X-ray irradiation unit on the side of the X-ray emission direction, the planar marker having a shape that allows the direction to be identified; the feature point image is an image in which the planar marker appears, 4. The X-ray imaging system of claim 3, wherein the control unit is configured to, when acquiring the distance between focus detection planes, acquire the distance between feature point detection planes based on the size of the planar marker in the feature point image, and when acquiring the irradiation angle, acquire the irradiation angle based on the shape of the planar marker in the feature point image.

5. the portable terminal further includes a storage unit that stores the distance between the focal feature points; 5. The X-ray imaging system according to claim 4, wherein the control unit is configured to acquire the distance between focus detection planes based on the distance between focus feature points and the distance between feature point detection planes stored in the storage unit.

6. the mobile terminal further includes an input receiving unit that receives an operation input from an operator; 6. The X-ray imaging system according to claim 5, wherein the control unit is configured to acquire the distance between focus feature points based on an input value of the distance between focus detection planes accepted by the input accepting unit and the distance between feature point detection planes.

7. the X-ray detector has a rectangular shape; The mobile terminal has a rectangular shape, 3. The X-ray imaging system according to claim 2, wherein the control unit is configured to switch between a same-plane detection mode in which the control unit controls the feature point detection unit to detect the feature points while a predetermined side of the portable terminal and a predetermined side of the X-ray detector are arranged parallel to each other in the same plane, and a non-same-plane detection mode in which the control unit controls the feature point detection unit to detect the feature points while a predetermined side of the portable terminal and a predetermined side of the X-ray detector are arranged parallel to each other in planes that are parallel to each other but at different positions in the X-ray irradiation axis direction.

8. 8. The X-ray imaging system according to claim 7, wherein the control unit is configured to acquire the distance between focus detection planes based on the distance between focus feature points and the distance between feature point detection planes in the same plane detection mode.

9. a top plate having a placement surface on which a subject is placed; 9. The X-ray imaging system according to claim 8, further comprising: a holding member that is placed on the tabletop and that holds the X-ray detector and the portable terminal so that a predetermined side of the X-ray detector and a predetermined side of the portable terminal are parallel to each other in the same plane at a position different from the tabletop.

10. 8. The X-ray imaging system according to claim 7, wherein the control unit is configured to acquire a terminal-to-detector distance, which is a distance between the mobile terminal and the X-ray detector, in the non-in-plane detection mode, and to acquire the focus detection plane distance based on the acquired terminal-to-detector distance, the focus feature point distance, and the feature point detection plane distance.

11. The X-ray imaging system described in Claim 1, wherein when the portable terminal is placed near the X-ray detector, both the imaging unit and the display unit face the X-ray irradiation unit.

12. An X-ray imaging method in an X-ray imaging system equipped with an X-ray imaging device having an X-ray irradiation unit that includes a feature point and irradiates X-rays onto a subject, and an X-ray detector that detects the X-rays irradiated from the X-ray irradiation unit, acquiring a feature point image by capturing an image of the feature points; detecting the feature points based on the feature point image while the mobile terminal is placed near the X-ray detector; acquiring, based on the detected feature points, at least one of information regarding a relative position between the X-ray irradiator and the X-ray detector and information regarding a relative angle between the X-ray irradiator and the X-ray detector; and displaying the acquired information on a display unit of the mobile terminal.

13. in the step of acquiring at least one of information regarding the relative position and information regarding the relative angle, each time the relative position of the X-ray irradiator and the relative angle of the X-ray irradiator change, at least one of information regarding the relative position and information regarding the relative angle is acquired sequentially; The X-ray imaging method according to claim 12 , wherein the step of displaying the acquired information on the mobile terminal includes displaying the acquired information sequentially.