JP2013180024A - X-ray imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the position of imaging so that a region of interest does not come out of an X-ray transmission image to be obtained even in an X-ray imaging apparatus having only one imaging system.SOLUTION: An X-ray imaging apparatus includes: a region-of-interest setting means which sets an region of interest of a body to be inspected, on a first X-ray transmission image obtained at a first position where an X-ray source and an X-ray detector are positioned, and calculates a characteristic quantity of the region of interest; a region-of-interest extracting means which extracts an region of interest corresponding to the first characteristic quantity of the region of interest, on a second X-ray transmission image obtained at a second position rotationally moved from the first position by a rotationally moving means; a region-of-interest position calculating means which calculates a spacial position of the region of interest by using positional information on the first and second X-ray sources and X-ray detectors, positional information on a first region of interest and positional information on a second region of interest; an imaging system position correcting quantity calculating means which calculates the movement correcting quantity of the X-ray source and the X-ray detector based on the spacial position of the region of interest; and an imaging system position controlling means the positions of the X-ray source and the X-ray detector are corrected based on the movement correcting quantity.

Description

  The present invention relates to an X-ray imaging apparatus having a rotation imaging function that performs X-ray imaging while rotating around a subject, and particularly relates to alignment of an X-ray source and an X-ray detector with respect to the subject.

  In the X-ray imaging device, an X-ray source that generates X-rays and an X-ray detector that detects transmitted X-rays irradiated from the X-ray source and transmitted through the subject are installed at both ends of the arm. There is one that acquires an X-ray transmission image of a subject from an arbitrary angle by rotating the.

  In addition, there are two X-ray sources and two X-ray detectors each, and using these two imaging systems, X-ray transmission images can be acquired simultaneously from two angles with respect to the subject. There is an X-ray imaging device.

  In Patent Document 1, in a biplane X-ray imaging apparatus, when an X-ray transmission image of a subject is acquired by rotating the arm, the center of rotation of the arm is aligned with the region of interest of the subject. It describes that the region of interest of the subject is always positioned at the center of the acquired X-ray transmission image regardless of the rotation angle.

Japanese Patent No. 4703119

  However, in Patent Document 1, when the center of rotation of the arm is aligned with the region of interest of the subject, the spatial position of the region of interest is searched using the positions of two imaging systems arranged at different angles. An X-ray imaging apparatus that has only one set of a radiation source, an X-ray detector, and an arm cannot detect the spatial position of the region of interest. Therefore, depending on the rotation angle of the arm, there is a fear that the region of interest of the subject may be deviated from the acquired X-ray transmission image.

  In view of the above problems, the present invention provides an X-ray image acquired by the region of interest when acquiring an X-ray transmission image of the region of interest of the subject by rotating the arm even in an X-ray imaging apparatus having only one imaging system. An object of the present invention is to provide an X-ray imaging apparatus that controls the position of an imaging system so as not to deviate from a line transmission image.

  In order to solve the above-described problem, the X-ray imaging apparatus according to the present invention provides an object of interest on a first X-ray transmission image acquired at a first position where an X-ray source and an X-ray detector are located. On the second X-ray transmission image acquired at the second position obtained by setting the region and calculating the region of interest feature amount in the region of interest, and the second position rotated and rotated from the first position by the rotation moving unit. A region of interest extraction means for extracting a region of interest having a region of interest feature amount equivalent to the region of interest feature amount in the region of interest on the first X-ray transmission image calculated by the region of interest setting means; and the first and second regions Using the position information of the X-ray source and the X-ray detector, the position information of the region of interest set at the first position, and the position information of the region of interest extracted at the second position, the spatial position of the region of interest is determined. Region-of-interest calculation means to calculate and region of interest calculated by the region-of-interest calculation means Imaging system position correction amount calculation means for calculating the movement correction amount of the X-ray source and X-ray detector based on the spatial position, and the position of the X-ray source and X-ray detector are corrected based on the movement correction amount. Photographing system position control means.

  According to the present invention, even in an X-ray imaging apparatus having only one imaging system, when an X-ray transmission image of a region of interest of a subject is acquired by rotating an arm, the region of interest deviates from the X-ray transmission image acquired. It is possible to provide an X-ray imaging apparatus that controls the position of the imaging system so that there is no such problem.

1 is a schematic configuration diagram showing an X-ray imaging apparatus 1 to which the present invention is applied. FIG. 3 is a diagram for explaining a configuration of an imaging unit control unit 100. FIG. 4 is a diagram for explaining the configuration of an imaging system position correction amount setting unit 400. FIG. 4 is a diagram for explaining imaging system position correction amount setting means 400. The flowchart figure for demonstrating the operation | movement order of this invention. The flowchart figure for demonstrating the operation | movement order at the time of setting a region of interest. An example of the image display at the time of setting a region of interest by point input. An example of the image display at the time of setting a region of interest by region input. The flowchart figure for demonstrating the operation | movement order at the time of extracting a region of interest. The figure for demonstrating the calculation method of the spatial position coordinate of a region of interest. The figure for demonstrating the calculation method of the spatial position coordinate of a region of interest. The flowchart figure for demonstrating the operation | movement order at the time of calculating the spatial position coordinate of a region of interest. The figure for demonstrating the calculation method of a position correction amount. The flowchart for demonstrating the operation | movement order at the time of calculating a position correction amount.

  Hereinafter, embodiments of an X-ray imaging apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In all the drawings for explaining the embodiments of the present invention, those having the same function are denoted by the same reference numerals, and repeated explanation thereof is omitted.

FIG. 1 is a schematic configuration diagram of an X-ray imaging apparatus to which the present invention is applied.
The X-ray imaging apparatus 1 of the present invention controls the respective components of the imaging unit 10 that irradiates the subject 2 with X-rays to acquire an X-ray transmission image of the subject 2, and the X A control calculation unit 20 that controls the position of the imaging system, which will be described later, based on the line transmission image, an image reconstruction calculation of the X-ray CT image, and the X-ray transmission image and X-ray CT created by the control calculation unit 20 A display device 30 for displaying images and the like, and an information input device 40 for inputting various parameters necessary for imaging such as X-ray transmission images and X-ray CT images displayed on the display device 30. Prepare.

  The imaging unit 10 includes a bed 11 on which the subject 2 is installed, an X-ray source 12 that irradiates the subject 2 lying on the bed 11 with X-rays, and a cone in the direction of X-ray irradiation from the X-ray source 12. A collimator 13 that is controlled in a quadrangular pyramid shape or a multi-sided pyramid shape, and an X-ray detector that outputs an X-ray transmission image by detecting X-rays that are installed opposite to the X-ray source 12 and pass through the subject 2 14, a C-shaped arm 15 that supports the X-ray source 12 and the X-ray detector 14 facing each other, an arm moving mechanism 16 that supports and moves the C-shaped arm 15, and an arm moving mechanism 16 And a wheel 19 that is installed in the main body 17 and that allows the main body 17 to move relative to the floor surface 18. The X-ray imaging apparatus 1 of the present invention is configured to have one imaging system including one X-ray source 12 and X-ray detector 14 respectively.

  The X-ray detector 14 forms a flat panel detector (FPD) using a TFT element, an X-ray image intensifier that converts an X-ray transmission image into a visible light image, and an image of the X-ray image intensifier. It is composed of an optical lens and an X-ray detector composed of a combination of a CCD TV camera or the like that captures a visible light image of an X-ray image intensifier imaged by the optical lens.

  The arm moving mechanism 16 moves the arm 15 and arranges the X-ray source 12 and the X-ray detector 14 at an arbitrary position while facing the subject 2. Here, for the sake of explanation, it is assumed that the left-right direction of FIG. 1 is the X axis, the vertical direction is the Y axis, and the depth direction is the Z axis, which are orthogonal to each other. The arm moving mechanism 16 includes a parallel moving means that translates the X-ray source 12 and the X-ray detector 14 in the X-axis direction, the Y-axis direction, or the Z-axis direction with the X-ray source 12 and the X-ray detector 14 facing each other. Rotation movement means for rotating the X axis or the Z axis as the rotation axis while having the detector 14 facing each other is provided. As shown in FIG. 1, when the center of rotation is the center of rotation 3, the X-ray source 12 and the X-ray detector 14 rotate in the direction of arrow A.

  The control calculation unit 20 includes an imaging unit control unit 100 that controls each of the above-described components of the imaging unit 10, an image collection unit 200 that collects and stores an X-ray transmission image output from the imaging unit 10, and an imaging unit 10. X-ray transmission of the region of interest of the subject 2 at multiple angles while rotating the arm 15 and the imaging geometric information calculation means 300 for calculating the geometric position information of the imaging system when the X-ray transmission image is acquired An imaging system position correction amount setting unit 400 for setting an imaging system position correction amount necessary for the region of interest initially set when acquiring an image to be included in an X-ray transmission image to be always acquired, and an image An image reconstruction that reconstructs the X-ray CT image of the subject 2 from the X-ray transmission image collected by the acquisition means 200 and the geometric position information of the imaging system calculated by the imaging geometry information calculation means 300. And a configuration means 500.

The display device 30 is configured by a CRT, a liquid crystal monitor, or the like, and the X-ray CT image of the subject 2 created by the image reconstruction means 500 is displayed by the display device 30. When the X-ray transmission image of the subject 2 is displayed, the reconstruction calculation by the image reconstruction unit 500 is not performed, and the X-ray transmission image collected by the image collection unit 200 is output to the display device 30 as it is. .
The information input device 40 is configured with a mouse, a keyboard, a trackball, or the like.

Next, details of the photographing unit control means 100 will be described with reference to FIG.
The imaging unit control means 100 uses the parallel moving means of the arm moving mechanism 16 to parallel to the X-axis direction, the Y-axis direction, or the Z-axis direction while the X-ray source 12 and the X-ray detector 14 are disposed facing each other. Using the imaging system position control means 101 that controls the amount of movement when moving, and the rotational movement means of the arm moving mechanism 16, the X-ray source 12 and the X-ray detector 14 are placed facing each other, while the X axis or Z The imaging system rotation control means 102 that controls the rotational movement amount when rotating about the axis as the rotation axis, and the output amount of X-rays emitted from the X-ray source 12 and the start and stop of X-ray irradiation are controlled. X-ray irradiation control means 103, bed control means 104 for adjusting the position of the subject 2 by controlling the position of the bed 11, and detection system control for controlling the X-ray detection timing by the X-ray detector 14, etc. Means 105.

  The imaging system position control means 101 controls the arm moving mechanism 16 by the operator's operation of the information input device 40 and the like, and is calculated by the imaging system position correction amount calculation means 404 in the imaging system position correction amount setting means 400 described later. The arm moving mechanism 16 is controlled on the basis of the corrected amounts of the X-ray source 12 and the X-ray detector 14.

Next, details of the photographing system position correction amount setting means 400 will be described with reference to FIGS.
FIG. 4 (a) is acquired by the X-ray detector 14 when the X-ray source 12 is placed downward, the X-ray detector 14 is placed upward, and the part 601 of the subject 2 is imaged on the Y axis. FIG. 6 is a diagram showing an X-ray transmission image 600 and an X-ray transmission image of a part 601 on the X-ray transmission image 600 as a region of interest 602. Here, for the sake of explanation, the positions of the X-ray source 12 and the X-ray detector 14 shown in FIG.

  FIG. 4 (b) is obtained by the X-ray detector 14 when the X-ray source 12 and the X-ray detector 14 are rotated clockwise from the first position with respect to the rotation center 3 by the rotational movement means. FIG. 6 is a view showing an X-ray transmission image of a region 601 displayed on an X-ray transmission image 603 displayed as a region of interest 603. Here, for the sake of explanation, the positions of the X-ray source 12 and the X-ray detector 14 shown in FIG.

  FIG. 4 (c) shows an X-ray transmission image 604 acquired by the X-ray detector 14 when the X-ray source 12 and the X-ray detector 14 are further rotated clockwise from the second position. FIG. 6 is a view showing an X-ray transmission image of a displayed region 601 as a region of interest 605. Here, for the sake of explanation, the positions of the X-ray source 12 and the X-ray detector 14 shown in FIG.

  FIG. 4D shows an X-ray transmission image 606 acquired by the X-ray detector 14 when the X-ray source 12 and the X-ray detector 14 are moved upward from the third position. FIG. 6 is a view showing an X-ray transmission image of a region 601 displayed in FIG. Here, for the sake of explanation, the positions of the X-ray source 12 and the X-ray detector 14 when moved upward are defined as a fourth position.

  The imaging system position correction amount setting unit 400 sets a region of interest 602 on the X-ray transmission image 600 acquired at the first position, and calculates a region of interest feature amount in the set region of interest 602. The region-of-interest setting unit 401 that is equivalent to the region of interest 602 set on the X-ray transmission image 600 on the X-ray transmission image 603 acquired at 401 and the second position rotated and moved from the first position by the rotation moving unit. Region-of-interest extracting means 402 for extracting a region of interest 603 having a region-of-interest feature amount equivalent to the region-of-interest feature amount in the region of interest 602 on the X-ray transmission image 600 calculated by From the first and second position information calculated by the calculation means 300, the position information of the region of interest 602 set at the first position, and the position information of the region of interest 603 extracted at the second position, the region of interest 601 Region-of-interest position calculating means 403 for calculating the spatial position of From the third position necessary for the region of interest 602 set at the first position to enter the X-ray transmission image 604 acquired at the third position when moving from the position to the third position. An imaging system position correction amount calculation unit 404 that calculates a position correction amount based on the spatial position of the region of interest 601 calculated by the region of interest position calculation unit 403.

  In addition, the imaging system position correction amount calculation unit 404 can be used even when the region of interest 602 set at the first position enters the X-ray transmission image 604 acquired at the third position without performing position correction. If the position of the region of interest 603 on the X-ray transmission image 603 extracted at the second position has moved relative to the position of the region of interest 602 on the X-ray transmission image 600 set at the first position, A position correction amount that is approximate to the position of the region of interest 601 set on the X-ray transmission image 600 at the position 1 or required to return to the same position may be calculated. As a result, the subject can be rotated and photographed without the position of the region of interest 601 on the X-ray transmission image 600 set at the first position greatly moving.

  In the first position shown in FIG. 4 (a), the X-ray transmission image 602 of the region of interest 601 of the subject 2 is located at the center of the X-ray transmission image 600. In the second position shown in FIG. 4B, the X-ray transmission image 603 of the region of interest 601 of the subject 2 is located to the left of the center of the X-ray transmission image 600. In the third position shown in FIG. 4 (c), the X-ray transmission image 605 of the region of interest 601 of the subject 2 is located at the left end of the X-ray transmission image 600, and deviates from the half X-ray transmission image 604. .

  The imaging system position correction amount setting unit 400 calculates the spatial position of the region of interest 601 from the first and second positions, so that the X-ray transmission image 605 of the region of interest 601 is the X-ray transmission image 604 at the third position. It can be calculated before moving to the third position. Furthermore, the position correction amount necessary to prevent the deviation is calculated, and the fourth position shown in FIG. 4 (d) is obtained without moving from the second position to the third position using the imaging system position control means 101. The X-ray source 12 and the X-ray detector 14 can be moved to positions. In the fourth position shown in FIG. 4D, the X-ray transmission image 607 of the region of interest 601 of the subject 2 is located at the center of the X-ray transmission image 606.

  In the present embodiment, the first position for setting the region of interest has been described as the case where the X-ray source 12 is disposed on the Y axis and the X-ray detector 14 is disposed on the Y axis. The position rotated at an angle of may be the first position for setting the region of interest.

  Further, a region-of-interest extraction position setting unit that allows the operator to arbitrarily set a second position for extracting a region of interest equivalent to the region of interest set at the first position may be provided. Thereby, the extraction accuracy of the region of interest can be appropriately adjusted. The second position is set using a rotation angle from the first position. When performing rotational imaging of the subject 2 from a plurality of angles using the rotational movement means, depending on the setting angle of the second position, an X-ray transmission image of the subject 2 even at an angle between the first and second positions Is acquired.

Next, the operation sequence of the X-ray imaging apparatus 1 of the present invention will be described using the flowchart shown in FIG.
In step S501, the positions of the X-ray source 12 and the X-ray detector 14 are adjusted by the operator so that the desired region of interest of the subject 2 is positioned approximately at the center on the acquired X-ray transmission image.

  In step S502, an X-ray transmission image of the subject 2 is acquired at the adjusted position. At this time, the geometric position information of the X-ray source 12 and the X-ray detector 14 is calculated by the imaging geometric information calculation means 300.

  In step S503, the operator selects a region of interest on the acquired X-ray transmission image, and the region-of-interest setting unit 401 sets the region selected by the operator as a region of interest, and the region of interest in the set region of interest. The area feature amount is calculated. Details regarding the setting of the region of interest will be described later using FIG. 6-8.

  In step S504, the X-ray source 12 and the X-ray detector 14 are rotationally moved by the rotational movement means.

  In step S505, an X-ray transmission image of the subject 2 is acquired at the rotationally moved position. At this time, the geometric position information of the X-ray source 12 and the X-ray detector 14 is calculated by the imaging geometric information calculation means 300.

  In step S506, the region of interest extraction unit 402 extracts a region of interest having a region of interest feature amount equivalent to the region of interest feature amount calculated in step S503. Details regarding the extraction of the region of interest will be described later with reference to FIG.

  In step S507, the region-of-interest position calculation means 403 uses the position information on the X-ray transmission image of the region of interest set in step S503, the position information on the X-ray transmission image of the region of interest extracted in step S506, From this, the spatial position of the region of interest set in step S503 is calculated. Details regarding the spatial position calculation method will be described later with reference to FIGS.

  In step S508, when the X-ray transmission image is acquired at the position where the X-ray source 12 and the X-ray detector 14 are rotated and moved by the rotation moving means by the imaging system position correction amount calculation means 404, the X-ray transmission image is obtained. A rotation angle at which the region of interest set in step S502 does not enter is calculated, and a position correction amount necessary for the region of interest to enter at the rotation angle is calculated. Details regarding the method of calculating the position correction amount will be described later with reference to FIGS.

  In step S509, the X-ray source 12 and the X-ray detector 14 are moved by the parallel moving means of the arm moving mechanism 16 together with the rotational movement of the arm moving mechanism 16 based on the calculated position correction amount. .

  In step S510, an X-ray transmission image of the subject 2 is acquired at a position where movement is desired. At this time, the geometric position information of the X-ray source 12 and the X-ray detector 14 is calculated by the imaging geometric information calculation means 300.

  In step S511, it is determined whether an X-ray transmission image of the subject 2 has been acquired within a preset rotation angle range. If completed, the process proceeds to step S512, and if not completed, the process returns to step S504.

  In step S512, it is determined whether to create an X-ray CT image using a plurality of X-ray transmission images acquired at different angles of the subject 2. If it is to be created, the process proceeds to step S513. If it is not to be created, the process proceeds to step S514.

  In step S513, an X-ray CT image is created by image reconstruction calculation and displayed on the created X-ray CT image display device 30.

  In step S514, the acquired X-ray transmission image is displayed on the display device 30.

Next, the detailed operation sequence in step S503 will be described with reference to FIGS.
As shown in the flowchart of FIG. 6, step S503 includes steps S503-1 to S503-10.
In step S503-1, the X-ray transmission image acquired in step S502 is displayed on the display device 30.

  In step S503-2, for the X-ray transmission image displayed on the display device 30, the operator selects a region of interest using the information input device 40, here the mouse 702. If there is an input of the region of interest within a predetermined time after the X-ray transmission image is displayed on the display device 30, the process proceeds to step S503-3, and if there is no input, the process proceeds to step S503-4. FIG. 7 shows a state in which a region of interest is being input as a point with respect to the X-ray transmission image 700 displayed on the display device 30 by the cross cursor 701 using the mouse 702, and FIG. A state in which a region of interest is being input in the region with respect to the X-ray transmission image 700 displayed on the display device 30 by the region cursor 801 is shown.

  In step S503-3, the region-of-interest setting unit 401 determines whether the input region of interest is a point input or a region input and its input type. If the determination result is a point input, the process proceeds to step S503-5. If the determination result is a region input, the process proceeds to step S503-6.

  In step S503-4, the region-of-interest setting unit 401 is based on at least one of an average value and a standard deviation of pixels in a preset region including the image center of the X-ray transmission image displayed on the display device 30. Calculate the connected area. A connected area refers to an area composed of pixels in which a difference between pixel values of adjacent pixels is within a predetermined range set in advance. Here, the connected region is calculated starting from the searched pixel.

  In step S503-5, the region-of-interest setting unit 401 calculates a connected region based on the pixel value of the input point. Here, the connected region is calculated starting from the input pixel.

  In step S503-6, the region-of-interest setting unit 401 calculates the average value, standard deviation, and barycentric coordinates of the pixel values in the pixels of the input region.

  In step S503-7, the region-of-interest setting unit 401 calculates a connected region based on the calculated average value, standard deviation, and barycentric coordinates. In this case, a region composed of pixels within the range set by the average value and the standard deviation calculated from the difference value between adjacent pixel values starting from the calculated barycentric coordinates is defined as a connected region.

  In step S503-8, the region-of-interest setting unit 401 displays the calculated connected region on the display device 30 as a region-of-interest candidate.

  In step S503-9, the operator determines whether or not resetting is necessary for the region of interest displayed on the display device 30, and inputs that fact using the information input device 40. If it is input that resetting is unnecessary in the displayed region of interest, the process proceeds to step S503-10. If it is input that resetting is necessary, the process returns to step S503-3.

  In step S503-10, the region-of-interest setting unit 401 calculates a region-of-interest feature amount in the region of interest displayed on the display device 30. The region-of-interest feature amount indicates the number of pixels forming the region of interest, the barycentric coordinates of the region of interest, the average value of the pixel values in the region of interest, the standard deviation of the pixel values in the region of interest, and the like.

  Next, the detailed operation sequence of step S506 will be described using the flowchart of FIG. Step S506 includes steps S506-1 to S506-4.

  In step S506-1, the region-of-interest extraction unit 402 calculates the pixel average value (Iave1) of the X-ray transmission image acquired in step S502 and the pixel average value (Iave2) of the X-ray transmission image acquired in step S505. From this, the pixel average value magnification indicating the magnification of the pixel average value (Iave2) with respect to the pixel average value (Iave1) is calculated.

  In step S506-2, the region-of-interest extracting unit 402 calculates a value related to the pixel value among the region-of-interest feature quantities of the X-ray transmission image calculated in step S503, in this case, the pixel average value magnification to the average value of the pixel values. Is set as a search feature amount using the converted average value obtained by multiplying the values and a value other than the average value of the pixel values calculated in step S503. As one of the search feature values, a value obtained by multiplying an average value of pixel values by a pixel average value magnification is a relative value between the X-ray transmission image acquired in step S502 and the X-ray transmission image acquired in step S505. This is to eliminate the influence caused by the difference in pixel values.

  In step S506-3, the region-of-interest extraction unit 402 sets an allowable amount for the search feature amount. The allowable amount is set as an individual value for each search feature amount (number of pixels forming the region of interest, converted average value, standard deviation) excluding the barycentric coordinates. The allowable amount is calculated by a value obtained by multiplying the value by a predetermined coefficient.

  In step S506-4, the region-of-interest extraction unit 402 extracts a region of interest corresponding to the region of interest set in step S503 in the X-ray transmission image acquired in step S505 using the search feature amount including the allowable amount. To do.

Next, the detailed operation sequence in step S507 will be described with reference to FIG.
FIG. 10 shows the positional relationship among the X-ray focal point 1201 of the X-ray source 12, the X-ray detector 14, the bed 11, and the region of interest 1000 of the subject 2 when the X-ray transmission image is acquired in step 502. FIG. FIG. 11 shows the positional relationship among the X-ray focal point 1201 of the X-ray source 12, the X-ray detector 14, the bed 11, and the region of interest 1000 of the subject 2 when the X-ray transmission image is acquired in step 505. FIG. The positions of the X-ray focal point 1201 and the X-ray detector 14 in FIG. 11 are rotated from the position shown in FIG. 10 about the rotation center 3 (C1x, C1y, C1z) by the rotation angle β2 in the rotation direction β. Position. FIG. 12 is a flowchart for explaining the detailed operation sequence of step S507.

  In step S507-1, the spatial position coordinates (S1x, S1y, S1z) of the X-ray focal point 1201 when the region-of-interest position calculation means 403 acquired the X-ray transmission image in step S502, and the X-ray transmission image in step S505. The spatial position coordinates (S2x, S2y, S1z) of the X-ray focal point 1201 at the time of acquiring are calculated.

  In step S507-2, the region-of-interest position calculation means 403 calculates the centroid position coordinates (u1, v1) of the region of interest calculated in step S503 and the centroid position coordinates (u2, v2) of the region of interest calculated in step S506. The coordinates (P1x, P1y, P1z) and the coordinates (P2x, P2y, P2z) in the dimensional space are calculated.

  In step S507-3, the region-of-interest position calculation means 403 includes a straight line 1001 passing through the spatial position coordinates (S1x, S1y, S1z) of the X-ray focal point 1201 and the centroid position coordinates (P1x, P1y, P1z) in the three-dimensional space. The straight line 1101 passing through the spatial position coordinates (S2x, S2y, S2z) of the X-ray focal point 1201 and the barycentric position coordinates (P2x, P2y, P2z) in the three-dimensional space is calculated, and the intersection (Qx, By calculating Qy, Qz), the spatial position coordinates of the region of interest 1000 are calculated.

Next, the detailed operation sequence of step S508 will be described with reference to FIGS.
The positions of the X-ray focal point 1201 and the X-ray detector 14 in FIG. 13 are the positions when rotating around the rotation center 3 (C1x, C1y, C1z) at the rotation angle β3 (> β2). FIG. 14 is a flowchart for explaining the detailed operation sequence of step S508.

  In step S508-1, the imaging system position correction amount calculation means 404, when further rotated from the rotation angle β2, the X-ray focal point 1201 (S3x, S3y, S3z) and the spatial position coordinates (Qx, Qy, The rotation angle at which the X-ray detector 14 does not come on the extended line of the straight line 1300 connecting with Qz) is calculated. In the case of the present embodiment, the angle is set as the rotation angle β3 (> β2).

  In step S508-2, the imaging system position correction amount calculation unit 404 connects the X-ray focal point 1201 (S3x, S3y, S3z) and the spatial position coordinates (Qx, Qy, Qz) of the region of interest 1000 at the rotation angle β3. A position correction amount of the rotation center 3 (C1x, C1y, C1z) necessary for the X-ray detector 14 to come on the extended line of the straight line 1300 is calculated. At this time, the position correction amount may be calculated so that the rotation center 3 is matched with the spatial position coordinates (Qx, Qy, Qz) of the region of interest 1000. As shown in FIG. 13, by moving the rotation center from the rotation center 3 (C1x, C1y, C1z) to the rotation center 4 (C4x, C4y, C4z), at the rotation angle β3, the X-ray focal point 1201 (S4x, S4y, S4z) and the X-ray detector 14 can be positioned on an extension of a straight line 1301 connecting the region of interest 1000 (Qx, Qy, Qz). Thereby, in the X-ray transmission image acquired at the rotation angle β3, the center of gravity position coordinate of the region of interest moves from (u3, v3) to (u4, v4), and can be put in the X-ray transmission image.

  As described above, the X-ray imaging apparatus of the present invention sets the region of interest from the X-ray transmission image acquired at the first position, and then sets first from the X-ray transmission image acquired at the rotationally moved position. By extracting the position of the region of interest, the spatial coordinates of the region of interest in the subject can be obtained, so even in an X-ray imaging apparatus with only one imaging system, the initially set region of interest is acquired. The subject can be rotated and photographed without being removed from the line transmission image.

  1 X-ray imaging device, 2 subject, 3 and 4 center of rotation, 10 imaging unit, 11 bed, 12 X-ray source, 13 collimator, 14 X-ray detector, 15 arm, 16 arm moving mechanism, 17 body, 18 floor Surface, 19 wheels, 20 control calculation unit, 30 display device, 40 information input device, 100 imaging unit control unit, 101 imaging system position control unit, 102 imaging system rotation control unit, 103 X-ray irradiation control unit, 104 bed control unit , 105 detection system control means, 200 image collection means, 300 photographing geometry information calculation means, 400 photographing system position correction amount setting means, 401 region of interest setting means, 402 region of interest extraction means, 403 region of interest position calculation means, 404 photographing System position correction amount calculation means, 500 image reconstruction means, 600, 603, 604, 606, 700 X-ray transmission image, 601 part, 602, 605, 607 region of interest, 701 crosshair cursor, 702 mouse, 801 area cursor, 1000 Region of interest, 1201 X-ray focus, 1300, 1301 straight line

Claims (10)

An X-ray source that irradiates the subject with X-rays, and an X-ray that is disposed opposite to the X-ray source, detects X-rays transmitted through the subject, and outputs an X-ray transmission image of the subject A detector, rotational movement means for rotationally moving the subject with the X-ray source and the X-ray detector facing each other, the X-ray source and the X-ray when the X-ray transmission image is acquired In an X-ray imaging apparatus having imaging geometry information calculating means for calculating geometric position information of a detector,
The region of interest of the subject is set on the first X-ray transmission image acquired at the first position where the X-ray source and the X-ray detector are located, and the region-of-interest feature quantity in the region of interest is calculated. Interested area setting means,
The region-of-interest feature amount in the region of interest on the calculated first X-ray transmission image on the second X-ray transmission image acquired at the second position rotated and moved from the first position by the rotation moving means. A region of interest extraction means for extracting a region of interest having a region of interest feature equivalent to
Position information of the first and second X-ray sources and X-ray detectors, position information of the region of interest set at the first position, position information of the region of interest extracted at the second position, Region-of-interest position calculating means for calculating the spatial position of the region of interest based on
An imaging system position correction amount calculating means for calculating a movement correction amount of the X-ray source and the X-ray detector based on the calculated spatial position of the region of interest;
An X-ray imaging apparatus comprising: an imaging system position control unit that corrects positions of the X-ray source and the X-ray detector based on the movement correction amount. The photographing system position correction amount calculating means includes:
Necessary for the region of interest set on the first X-ray transmission image to enter the third X-ray transmission image acquired at the third position rotated and moved from the second position by the rotation moving means. Calculating the movement correction amount from the third position based on the calculated spatial position of the region of interest,
The photographing system position control means includes:
An imaging system position control means for correcting the positions of the X-ray source and the X-ray detector at the third position based on the movement correction amount;
The X-ray imaging apparatus according to claim 1, comprising:   The imaging system position correction amount calculating means is configured so that the position of the region of interest set on the first X-ray transmission image is the same or approximate on the third X-ray transmission image acquired at the third position. The X-ray imaging apparatus according to claim 2, wherein a movement correction amount from the third position is calculated based on the calculated spatial position of the region of interest so as to be a position.   4. The X-ray according to claim 1, wherein the movement correction amount calculated by the imaging system position correction amount calculation unit is a movement amount of a rotation center of the rotation movement unit. 5. Shooting device.   The movement correction amount calculated by the imaging system position correction amount calculation unit is on a straight line connecting the X-ray focal point of the X-ray source and the spatial position of the region of interest calculated by the region of interest position calculation unit. The X-ray imaging apparatus according to claim 1, wherein a position correction amount necessary for the X-ray detector to come is calculated.   The region-of-interest feature amount calculated by the region-of-interest setting means is any one of an average value, a standard deviation, and a barycentric coordinate of pixel values of pixels of the region of interest set on the first X-ray transmission image. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging apparatus includes:   A region-of-interest extraction position setting unit is provided for setting the second position for extracting a region of interest equivalent to the region of interest set at the first position by using an rotation angle from the first position. The X-ray imaging apparatus according to any one of claims 1 to 6, wherein:   The region-of-interest setting means is connected based on at least one of an average value and a standard deviation of pixels in a preset region including the image center on the first X-ray transmission image acquired at the first position. The X-ray imaging apparatus according to claim 1, wherein a region is calculated, and the region-of-interest feature amount is calculated based on the connected region.   The region-of-interest setting means calculates a connected region based on a pixel value specified by point input by an operator on the first X-ray transmission image acquired at the first position displayed on the display device, The X-ray imaging apparatus according to claim 1, wherein the region-of-interest feature amount is calculated based on a connected region.   The region-of-interest setting means is at least one of an average value and a standard deviation of pixels in a region designated by the operator on the first X-ray transmission image acquired at the first position displayed on the display device. The X-ray imaging apparatus according to claim 1, wherein a connected region is calculated based on the connected region, and the region-of-interest feature quantity is calculated based on the connected region.

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