JP2009207683A - X-ray device and rotary imaging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce X-ray exposure in rotary imaging. <P>SOLUTION: A simulated X-ray image data generation and correction part 6b positions CT voxel data in which the position information of the isocenter of the region of interest and the position information of the region of interest are embedded, generates the simulated X-ray images of a front face and a side face and calculates a correction amount for matching the isocenter of the region of interest and the isocenter of the device. When the position of a bed top plate 10 or a C arm 11 is corrected on the basis of the correction amount, the simulated X-ray image data generation and correction part 6b generates simulated X-ray image data at respective rotary imaging angles and calculates appropriate SID and FOV, a system control part 7 sets the SID and FOV, and the simulated X-ray image data generation and correction part 6b generates the simulated X-ray image data at the respective rotary imaging angles again and calculates an appropriate X-ray condition. Then, the system control part 7 sets the X-ray condition on the basis of the calculated X-ray condition and performs rotary imaging. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray apparatus and a rotational imaging method.

  Conventionally, angiography (angiography) has been performed in the diagnosis of cardiovascular diseases. In angiography, an angiographic image in which a blood vessel and an organ nourished by the blood vessel are emphasized in an area of interest that is a diagnosis target region by injecting a contrast medium from a catheter inserted into the blood vessel is angio X Images are taken by an X-ray apparatus called a line diagnostic apparatus.

  An X-ray apparatus is an apparatus that irradiates a subject lying on a bed with X-rays from an X-ray tube device, detects X-rays transmitted through the subject with an X-ray detector, and creates an X-ray image. An imaging method for digitally generating angiographic images in which blood vessels and organs are emphasized by a contrast agent based on X-ray information detected by an X-ray detector is called DA (Digital Angiography) imaging. Yes.

  Further, based on the X-ray information detected by the X-ray detector before the contrast agent injection and the X-ray information detected after the contrast agent injection, images before and after the contrast agent injection are created, and the blood vessels after the contrast agent injection An imaging method that digitally generates an image of only blood vessels and organs in a region of interest where a contrast agent spreads by subtracting an image before injection from a contrast image is called DSA (Digital Subtraction Angiography) imaging.

  In DA imaging and DSA imaging, the C-arm that holds the X-ray tube device and the X-ray detector is rotated around the subject to irradiate X-rays from a plurality of directions, and an angiographic image of the region of interest. Rotational shooting (rotating DA shooting, rotating DSA shooting) is performed in which images are taken from a plurality of directions. Furthermore, “3D DA imaging” and “3D DSA imaging” are also performed in which a three-dimensional image is generated based on angiographic images captured from a plurality of directions by rotational DA imaging and rotational DSA imaging.

  Here, when performing rotational imaging such as “rotating DA imaging”, “rotating DSA imaging”, “3D DA imaging”, and “3D DSA imaging” with the X-ray apparatus, the region of interest is viewed from the field of view during the rotational imaging. The operator of the X-ray apparatus needs to check the field of view at each rotational imaging angle so as not to come off. For this reason, the operator of the X-ray apparatus performs preliminary fluoroscopy of the subject, confirms whether or not the target region includes a region of interest at each rotation angle of view angle, and adjusts the position of the C-arm or bed. Need to do.

  On the other hand, in order to avoid X-ray exposure by preliminary fluoroscopy, for example, in Patent Document 1, a plurality of human tomographic images (X-ray CT images) are based on personal information (sex, age, height, weight, etc.) of a subject. A human body model of the subject is generated from the MRI image or the like, and the region of interest is centered on the field of view when rotation imaging is performed by an X-ray apparatus. A technique for adjusting the position is disclosed.

JP 2003-230556 A

  By the way, the above-described conventional technique has a problem in that the amount of X-ray exposure cannot always be reduced in rotational imaging.

  In other words, the above-described conventional technique adjusts the positions of the X-ray C-arm and the bed using the human body model created based on the personal information of the subject, However, it does not necessarily guarantee that the region of interest is included in the field of view at all rotational imaging angles when the subject is rotated and imaged. Re-imaging is performed, which increases the X-ray exposure dose.

  Therefore, the present invention has been made to solve the above-described problems of the prior art, and by using a three-dimensional medical image of the same subject, it is possible to reduce the X-ray exposure dose in rotational imaging. An object of the present invention is to provide an X-ray apparatus and a rotational imaging method.

  In order to solve the above-described problems and achieve the object, the present invention according to claim 1 is an X-ray tube apparatus that exposes X-rays to a subject, and X-rays that detect X-rays transmitted through the subject. An X-ray apparatus that rotates and detects a X-ray image including a region of interest of the subject from a plurality of directions, and is generated by the X-ray CT apparatus before the rotation imaging is performed. In addition, CT voxel data input means for receiving and inputting CT voxel data including the region of interest of the subject, and the CT voxel data inputted by the CT voxel data input means, the subject is actually arranged. A simulated X-ray image generating means for generating a simulated X-ray image in which the CT voxel data is projected for each rotational imaging angle at which the rotational imaging is performed, and the simulated X-ray image generation Correction amount calculation means for calculating a correction amount for correcting the position where the subject is arranged so that the region of interest is included in each of the simulated X-ray images generated by the stage, It is characterized by that.

  According to a fifth aspect of the present invention, an X-ray tube device that exposes X-rays to a subject and an X-ray detector that detects X-rays transmitted through the subject rotate to rotate the subject. A rotational imaging method in which an X-ray image including a region of interest is rotationally imaged from a plurality of directions, and includes the region of interest of the subject generated by an X-ray CT apparatus before the rotational imaging is performed. The CT voxel data input step for receiving and inputting voxel data, and the CT voxel data input by the CT voxel data input step are set at positions where the subject is actually arranged, and then the rotational imaging is performed. Generated by a simulated X-ray image generation step for generating a simulated X-ray image in which the CT voxel data is projected for each rotation imaging angle to be performed, and the simulated X-ray image generation step A correction amount calculating step of calculating a correction amount for correcting the position where the subject is arranged so that the region of interest is included in each of the simulated X-ray images. And

  According to the first or fifth aspect of the present invention, preliminary fluoroscopy for visual field confirmation at each rotational imaging angle can be avoided, and the X-ray exposure dose can be reduced in rotational imaging.

  Exemplary embodiments of an X-ray apparatus and a rotation imaging method according to the present invention will be described below in detail with reference to the accompanying drawings.

  First, the structure of the X-ray apparatus in a present Example is demonstrated using FIG. 1 and FIG. FIG. 1 is a perspective view of the X-ray apparatus in the present embodiment, and FIG. 2 is a functional block diagram showing the configuration of the X-ray apparatus in the present embodiment.

  As shown in FIG. 2, the X-ray apparatus 100 in this embodiment includes an X-ray high voltage generator 1, an X-ray source apparatus 2, an X-ray detector 3, a monitor 4, an image processing apparatus 5, The simulated image data generation unit 6, the system control unit 7, the operation unit 8, the mechanism control unit 9, the couch top 10, and the C arm 11 are further connected to the X-ray CT apparatus 200. Here, the X-ray source device 2, the X-ray detector 3, the monitor 4, the couch top 10 and the C arm 11 are configured in appearance as shown in the perspective view of FIG. 1.

  The X-ray high voltage generator 1 is a device that generates a high voltage to be supplied to the X-ray source device 2. As shown in FIG. 2, the X-ray tube device 2a described later is controlled by controlling the generated voltage and current. The X-ray controller 1a controls the output of the X-rays emitted from the X-ray, and the high-voltage generator 1b that generates a high voltage based on the control of the X-ray controller 1a.

  The X-ray source device 2 is a device that generates X-rays by a high voltage supplied from the X-ray high-voltage generator 1, and generates an X-ray and irradiates the subject P with an X-ray tube device 2a, An X-ray diaphragm 2b having diaphragm blades for narrowing the range of X-rays irradiated to the subject P from the tube apparatus 2a to the range including the region of interest to be diagnosed by the subject P with the diaphragm blades; Consists of The X-ray diaphragm 2b has an X-ray compensation filter for reducing the difference in brightness between the subject and its surroundings.

  The X-ray detector 3 is an apparatus that detects X-rays that have passed through the subject P. For example, planar detection that uses a TFT (thin film transistor) as a switching gate and converts the detected X-rays into digital data for each pixel. (FPD: Flat Panel Detector).

  The image processing apparatus 5 is an apparatus that processes an image using X-ray data detected and generated by the X-ray detector 3 and simulated X-ray image data generated by a simulated image data generation unit 6 described later. An image input unit 5a that receives and inputs data or simulated image data from the X-ray detector 3 or the simulated image data generation unit 6, and uses the data input by the image input unit 5a to perform contrast correction, brightness correction, sharpness correction, or the like. An image processing unit 5b that performs processing to process an image, an image storage unit 5c that stores an image processed by the image processing unit 5b, and an image output unit that displays an image stored in the image storage unit 5c on the monitor 4 5d.

  The monitor 4 is a display unit that displays an image generated by the image processing device 5.

  The couch top 10 is a plate on which the subject P lies, and the C arm 11 is an arm that holds the X-ray source device 2, the X-ray detector 3, and the like.

  The mechanism control unit 9 is a control unit that controls the movement of the X-ray diaphragm 2b, the couch top 10, the C arm 11, and the like, and the movement of the X-ray compensation filter that controls the movement of the X-ray compensation filter of the X-ray diaphragm 2b. Rotation of the control unit 9a, the X-ray diaphragm blade movement control unit 9b that controls the movement of the diaphragm blades of the X-ray diaphragm 2b, the bed top plate movement control unit 9c that controls the movement of the bed top plate 10, and the C-arm 11 An arm rotation / movement control unit 9d for controlling movement is provided. Note that the arm rotation / movement control unit 9d controls the movement of the C-arm 11 so that the SID (Source Image Distance) that is the distance between the focal point of the X-ray tube apparatus 2a and the X-ray detector 3 and the effective field of view. Adjustment control of FOV (Field of View) which is a size is also performed.

  The system control unit 7 instructs the X-ray apparatus 100 as a whole by instructing the X-ray control unit 1a, the mechanism control unit 9, a simulated X-ray image data creation / correction unit 6b, which will be described later, and the like based on an instruction from the operation unit 8. It is a control part to control. The operation unit 8 is a console that receives an instruction from an operator of the X-ray apparatus 100 and transmits the instruction of the operator to the system control unit 7.

  Here, the X-ray apparatus 100 according to the present embodiment uses the X-ray detector 3 to detect X-rays that are irradiated from the X-ray tube apparatus 2a and transmitted through the subject while rotating the C arm 11 around the subject P. Thus, the outline is to perform rotational imaging for imaging X-ray images from a plurality of directions of the subject P, and a three-dimensional medical image including the region of interest of the subject P generated by the X-ray CT apparatus 200 is configured. The main feature is that the simulated image data generation unit 6 using voxel data can reduce the amount of X-ray exposure in rotational imaging.

  In the present embodiment, the X-ray apparatus 100 will be described with respect to performing rotating DSA (Digital Subtraction Angiography) imaging by angiography (angiography), but the present invention is not limited to this. Rotating DA (Digital Angiography) imaging, “3D DA imaging”, and “3D DSA imaging” may be performed.

  This main feature will be described with reference to FIGS. 3 to 10 together with FIG. Here, FIG. 3 is a diagram for explaining the CT voxel data output from the CT voxel data output unit, and FIG. 4 explains the simulated X-ray image data generation processing of the simulated X-ray image data generation / correction unit. FIG. 5 is a diagram for explaining the alignment of CT voxel data by the simulated X-ray image data generation / correction unit. FIG. 6 is a diagram illustrating the simulation X-ray image data generation / correction unit. FIG. 7 is a diagram illustrating a coordinate system used for generating simulated image data, FIG. 7 is a diagram for explaining position adjustment by the system control unit, and FIG. 8 is a diagram for explaining adjustment of FOV and SID by the system control unit. FIG. 9 is a diagram for explaining adjustment of X-ray conditions by the system control unit, and FIG. 10 is a diagram for explaining rotational imaging.

  The X-ray CT apparatus 200 generates a three-dimensional X-ray CT image as a three-dimensional medical image from the two-dimensional X-ray CT image reconstructed based on the projection data indicating the intensity distribution of the X-ray transmitted through the subject P. It is a device to do. Here, in this embodiment, the X-ray CT apparatus 200 rotates a three-dimensional X-ray CT image including a region of interest as a diagnosis target of the subject P on which the rotation DSA imaging is performed by the X-ray apparatus 100. Before the start of this, the subject P is generated by imaging.

  Here, the operator of the X-ray apparatus 100 has a plurality of MPRs (Multi Planars) generated from CT voxel data constituting a three-dimensional X-ray CT image including the region of interest of the subject P generated by the X-ray CT apparatus 200. A reference image is referred to on a monitor provided in the X-ray CT apparatus 200, a center point (isocenter) of a region of interest in rotating DSA imaging is designated, and isocenter position information is embedded in CT voxel data.

  Further, the operator of the X-ray apparatus 100 refers to a plurality of MPR (Multi Planar Reformat) images or a three-dimensional X-ray CT image, and obtains region information of a target region (region of interest) for rotational DSA imaging using CT voxels. Embed in data.

  Then, the CT voxel data output unit 201 provided in the X-ray CT apparatus 200 converts, for example, CT voxel data in which the position information of the isocenter and the position information of the region of interest are embedded as shown in FIG. Output to the device 100. The isocenter position information and the region-of-interest position information are embedded as header information of CT voxel data, for example.

  In the present embodiment, the case where the X-ray CT apparatus 200 embeds the isocenter position information and the region-of-interest position information in CT voxel data with reference to a three-dimensional X-ray CT image has been described. The invention is not limited to this, but a database of PACS (Picture Archiving and Communication System), which is a system for managing data of various medical images, and an electronic medical record system for managing an electronic medical chart to which medical images are attached. In a database or the like, the position information of the isocenter and the position information of the region of interest may be embedded in the CT voxel data with reference to the three-dimensional X-ray CT image.

  The X-ray CT apparatus 200 only outputs CT voxel data. In the X-ray apparatus 100, the CT voxel output from the X-ray CT apparatus 200 is output with the position information of the isocenter and the position information of the region of interest. It may be a case where it is embedded in data.

  The simulated image data generation unit 6 includes a CT voxel data input unit 6a that receives and inputs CT voxel data output from the CT voxel data output unit 201 of the X-ray CT apparatus 200, and a CT voxel input by the CT voxel data input unit 6a. Simulated X-ray image data generation / correction unit 6b that generates simulated X-ray image data using the data and calculates various correction amounts for executing rotational imaging, and simulated X-ray image data generation / correction unit 6b And an image data output unit 6c for outputting the simulated X-ray image data generated by.

  The simulated X-ray image data generation / correction unit 6b sets the CT voxel data input by the CT voxel data input unit 6a to the position where the subject P is actually arranged, and then generates simulated X-ray image data. To do.

  Simulated X-ray image data generation processing will be described with reference to FIG. As shown in FIG. 4, the simulated X-ray image data generation / correction unit 6b receives CT voxel data in which isocenter position information and region-of-interest position information are embedded from the CT voxel data input unit 6a. (Yes in step S401), the system control unit 7 acquires the X-ray conditions currently set in the X-ray apparatus 100 and the current position information of the couchtop 10 and the C-arm 11 (step S402). .

  The X-ray condition is a setting condition of the voltage / current supplied from the high voltage generator 1b to the X-ray tube apparatus 2a, whereby the X-ray dose irradiated from the X-ray tube apparatus 2a. Is determined. Specifically, it is a numerical value expressed by “tube voltage (unit: kV)” and “product of tube current and X-ray irradiation seconds (unit: mAS)”.

  The position information of the couch top 10 is the vertical position and the left and right position of the couch top 10, and the position information of the C arm 11 is “CRA / CAU, LAO / RAO, SID”. is there. Here, “CRA” is the position of the C arm 11 viewed from the “head direction: cranial” of the subject, and “CAU” is the C arm viewed from the “tail direction: caudal” of the subject. 11 “LAO” means “left forward oblique” of the C arm 11 when viewed from the left of the subject, and “RAO” means from the right of the subject. This is the “right forward oblique” of the C-arm 11 when viewed.

  Then, the simulated X-ray image data generation / correction unit 6b performs alignment by setting the input CT voxel data at the position where the subject P is actually disposed (step S403). That is, the CT voxel data of the subject P photographed in the state of lying on the bed top 10 of the X-ray CT apparatus 200 is the position of the subject P lying on the bed top 10 of the X-ray apparatus 100 at the present time. Process to match.

  Specifically, the subject P lying on the couch top 10 in the current position is irradiated with X-rays from the current position of the C arm 11 in advance, and the image processing unit 5b performs X-rays. A line image is generated, and the simulated X-ray image data generating / correcting unit 6b is similar to the X-ray image in the position information of the couch top 10 and the C arm 11 at the present time as shown in FIG. Positioning is performed by placing CT voxel data at a position (coordinates) where a projection image is generated. For example, alignment is performed by arranging CT voxel data based on feature points of a specific organ (liver, heart, brain, etc.) in the region of interest.

  After that, the simulated X-ray image data generation / correction unit 6b generates simulated X-ray image data obtained by projecting the aligned CT voxel data (step S404), and ends the process. The simulated X-ray image data is output from the image data output unit 6c to the image input unit 5a, then processed as a simulated X-ray image by the image processing unit 5b, and stored in the image storage unit 5c. Thus, the image is displayed on the monitor 4 by the image output unit 5d.

  The simulated X-ray image data generation by the simulated X-ray image data generation / correction unit 6b in step S404 in FIG. 4 will be described with reference to FIG. 6 is a view of the subject P lying on the couch top 10 as viewed from the head. The coordinate system shown in FIG. 6 is such that the horizontal direction of the couch top 10 is the x-axis direction, and the couch top is The normal direction with respect to 10 is the y-axis direction, the body axis direction of the subject P is the z-axis direction, and the isocenter (center point of the subject P) position of the subject P as the patient to be diagnosed is the origin. That is, the coordinates (x0, y0, z0) of the isocenter of the subject P are set to (0, 0, 0).

  The simulated X-ray image data generating / correcting unit 6b calculates simulated X-image data by calculating X-ray image information at the position (x, y, z) of the X-ray detector 3 based on the set X-ray conditions. Is generated. That is, the CT values of the CT voxel data aligned with the coordinate system shown in FIG. 6 are converted from the X-ray tube device 2a at the position shown in FIG. 6 to the position (x, y) of the X-ray detector 3. , Z) is replaced with the X-ray absorption value when projected, and further, the replaced X-ray absorption value is corrected based on the X-ray condition.

  Then, the simulated X-ray image data generation / correction unit 6b integrates the corrected X-ray absorption value to project the CT voxel data on the position (x, y, z) of the X-ray detector 3. X-ray image information for the case is calculated. This is performed on the coordinates of all the detection surfaces of the X-ray detector 3 to generate simulated X-ray image data.

  Returning to FIG. 2, the simulated X-ray image data generation / correction unit 6b executes generation of such simulated X-ray image data step by step before the start of rotational imaging, and based on each simulated X-ray image data. To calculate a correction amount for rotational shooting.

  As the first-stage simulated X-ray image data, the simulated X-ray image data generation / correction unit 6b receives the position information of the center point (isocenter) of the region of interest and the position information of the region of interest input from the CT voxel data input unit 6a. Are aligned, and a plurality of simulated X-ray image data is generated at a predetermined rotational imaging angle among rotational imaging angles at which rotational imaging is performed.

  Specifically, a simulated X-ray image which is a front projection image when “LAO / RAO” and “CRA / CAU” are “0 °”, and “RAO = 0 °” and “CRA / CAU = 0 ° ”And a simulated X-ray image that is a projection image of the side surface. Here, the simulated X-ray image data generation / correction unit 6b also generates positional information in the simulated X-ray image of the region of interest of the subject P and the isocenter embedded in the CT voxel data.

  Then, the simulated X-ray image data generation / correction unit 6b uses the two simulated X-ray images generated as the first-stage simulated X-ray image data and is actually rotated by the X-ray apparatus 100. In addition, a correction amount for correcting the position where the subject P is arranged is calculated so that the region of interest is included in all the X-ray images.

  In other words, the simulated X-ray image data generation / correction unit 6b determines that the isocenter to be photographed (the isocenter embedded in the CT voxel data is projected on the front simulated X-ray image in the generated simulated X-ray image of the front. ) And the isocenter of the X-ray apparatus 100, the x-direction and z-direction positions shown in FIG. 6 are corrected so that the coordinates of the isocenter to be imaged and the isocenter of the X-ray apparatus 100 match. .

  Specifically, as shown in FIG. 7A, the simulated X-ray image data generation / correction unit 6 b has a shift amount between the isocenter of the region of interest to be imaged and the isocenter of the apparatus in the front simulated X-ray image. Is calculated, the system control unit 7 controls the bed top plate movement control unit 9c on the basis of the deviation amount notified from the simulated X-ray image data generation / correction unit 6b, whereby the longitudinal length of the bed top plate 10 is calculated. Adjust the lateral position. Alternatively, the system control unit 7 controls the arm rotation / movement control unit 9d to adjust the longitudinal and lateral positions of the C arm 11 based on the notified deviation amount.

  Further, the simulated X-ray image data generation / correction unit 6b uses the generated iso-X-ray image of the side surface based on the amount of shift between the iso-center of the region of interest to be imaged and the iso-center of the device and the X-ray device to be imaged. The position in the y direction shown in FIG. 6 is corrected so that the coordinates with 100 isocenters coincide.

  More specifically, as shown in FIG. 7B, the simulated X-ray image data generation / correction unit 6b has a shift amount between the isocenter of the region of interest to be imaged and the isocenter of the apparatus in the simulated X-ray image of the side surface. The simulated X-ray image data generation / correction unit 6b notifies the calculated shift amount to the system control unit 7, and the system control unit 7 controls the bed top plate movement control unit 9c to notify The height of the couch top 10 is adjusted based on the amount of deviation.

  The position adjustment of the couch top 10 or the position adjustment of the C-arm 11 is automatically processed by the system control unit 7 by the notification from the simulated X-ray image data generation / correction unit 6b as described above. The amount of deviation may be displayed on the monitor 4 together with the front and side simulated X-ray images, and an operator who refers to the monitor 4 inputs an adjustment instruction to the operation unit 8. In this case, the processing may be performed by the system control unit 7.

  Thus, the X-ray apparatus 100 in the present embodiment corrects the position of the subject P by adjusting the positions of the couch top 10 and the C-arm 11. Here, the system control unit 7 updates and stores the position information of the couch top 10 and the C-arm 11 moved by its own control.

  As the simulated X-ray image data of the second stage, the simulated X-ray image data generation / correction unit 6b is updated by the system control unit 7 after the position of the subject P is adjusted and corrected. Then, the position information of the C-arm 11 and the set X-ray conditions are read out, and simulated X-ray image data for each rotational imaging angle (for example, every 10 °) at which rotational imaging is performed is generated.

  The simulated X-ray image data generation / correction unit 6b displays all the regions of interest included in each simulated X-ray image for each rotational imaging angle generated as simulated X-ray image data at the second stage on the monitor 4. Thus, the enlargement ratio for correcting the SID and the FOV is calculated. That is, the simulated X-ray image data generation / correction unit 6b performs the alignment of the isocenter of the region of interest to be imaged with the isocenter of the apparatus, and then sets the simulated X-ray image data for each rotation imaging angle to 1 every 10 °. The range (region of interest) that is generated by the circumference is not projected in the simulated X-ray image on the monitor 4 and the maximum geometric magnification is obtained in all the images. An enlargement ratio (minimum enlargement value) is calculated.

  For example, as shown in FIG. 8, the simulated X-ray image data generation / correction unit 6b displays simulated X-rays displayed on the monitor 4 from the simulated X-ray image data when the C-arm 11 rotates every 10 °. A line image is estimated, and all of the simulated X-ray images are “RAO / LAO” “0 °” with an enlargement ratio “2”, “RAO” “90 °” with an enlargement ratio “0.7”, etc. When the enlargement factor is calculated and the minimum enlargement factor is calculated as “0.7”, and the FOV and SID for adjusting to the minimum enlargement factor are calculated, the system control unit 7 generates simulated X-ray image data The FOV and SID notified from the correction unit 6b are set. That is, the system control unit 7 adjusts the C arm 11 so as to match the set FOV and SID by controlling the arm rotation / movement control unit 9d. Here, the system control unit 7 updates and stores the position information of the C-arm 11 moved by its own control.

  As the simulated X-ray image data at the third stage, the simulated X-ray image data generation / correction unit 6b has the bed top plate 10 and the C arm 11 updated from the system control unit 7 after the FOV and SID are adjusted. Position information and set X-ray conditions are read out, and the simulated X for each rotational imaging angle (for example, every 10 °) at which rotational imaging is performed from the CT voxel data that has been aligned again. Line image data is generated.

  Then, the simulated X-ray image data generation / correction unit 6b displays each simulated X-ray image for each rotational imaging angle generated as the third-stage simulated X-ray image data on the monitor 4 with appropriate luminance. , “Tube voltage (unit: kV)” and “product of tube current and X-ray irradiation time (unit: mAS)” for correcting the dose of X-rays irradiated from the X-ray tube apparatus 2a are calculated. . That is, the simulated X-ray image data generation / correction unit 6b again generates simulated X-ray image data for each rotation imaging angle for one rotation every 10 ° after the FOV and SID are set, and the imaging range ( The luminance gain is calculated so that the luminance of the region of interest is appropriate in the simulated X-ray image on the monitor 4. Further, X-ray conditions for realizing each of the calculated luminance gains are calculated.

  For example, as shown in FIG. 9, the simulated X-ray image data generation / correction unit 6b displays the simulated X-ray image displayed on the monitor 4 from each of the simulated X-ray image data when the C-arm 11 rotates every 10 °. The X-ray condition for estimating the line image and realizing “RAO / LAO” appropriate “luminance gain: 1.6” is “80 kV, 160 mAS”, and “RAO” appropriate “luminance gain: 0”. When the X-ray conditions for all the simulated X-ray images are calculated such that the X-ray condition for realizing “.8” is “80 kV, 80 mAS”, the system control unit 7 generates simulated X-ray image data. Set the X-ray condition at each rotation imaging angle notified from the correction unit 6b.

  When the system control unit 7 receives a rotation DSA imaging start request from the operator via the operation unit 8, the system arm 7 adjusts the C-arm 11 adjusted to an appropriate position to the appropriate position. Rotating around the subject P lying on the plate 10 and irradiating from the X-ray tube apparatus 2a based on the set X-ray condition for each rotation imaging angle, and rotating DSA imaging is executed. Specifically, first, the rotation of the subject P is performed before the contrast agent is injected, and the rotation of the subject P is again performed after the contrast agent is injected and the contrast agent is spread in the region of interest. Then, a difference between the respective X-ray images is taken to generate a DSA image. 10A shows rotational imaging when the C-arm 11 is set on the head side of the patient who is the subject P and the C-arm 11 is rotated to perform imaging, and FIG. ) Shows rotational imaging when the C-arm 11 is set on the left side of the patient who is the subject P and the C-arm 11 is slid to perform imaging, and the system control unit 7 rotates or slides the C-arm 11. Then, control is performed such that rotation imaging is performed by irradiating the subject P with an appropriate dose of X-rays at each rotation imaging angle.

  Next, the process of the X-ray apparatus 100 in a present Example is demonstrated using FIG. FIG. 11 is a diagram for explaining processing of the X-ray apparatus in the present embodiment.

  As shown in FIG. 11, the X-ray apparatus 100 receives CT voxel data in which position information of the isocenter of the region of interest and position information of the region of interest are embedded from the X-ray CT apparatus 200 (Yes in step S1101). ), The simulated X-ray image data generation / correction unit 6b aligns the input CT voxel data (step S1102, see FIG. 5).

  Then, the simulated X-ray image data generation / correction unit 6b generates front and side simulated X-ray image data as the first-stage simulated X-ray image data from the aligned CT voxel data, A correction amount (shift amount) for matching the isocenter of the region of interest with the isocenter of the apparatus is calculated (step S1103).

  After that, when the position of the couchtop 10 or the C-arm 11 is corrected based on the calculated correction amount (Yes in step S1104), the simulated X-ray image data generation / correction unit 6b again performs CT voxel data. , The simulated X-ray image data at each rotational imaging angle is generated as the second-stage simulated X-ray image data, and in all the simulated X-ray images displayed on the monitor 4, An enlargement factor minimum value is calculated from the enlargement factors that display the entire region of interest and are maximized (step S1105). Here, the simulated X-ray image data generation / correction unit 6b calculates the SID and FOV to be further set based on the minimum enlargement factor.

  Subsequently, when the position of the C-arm 11 is adjusted by the system control unit 7 and the SID and FOV calculated by the simulated X-ray image data generation / correction unit 6b are set (Yes in step S1106), the simulated X-ray image The data generation / correction unit 6b generates simulated X-ray image data at each rotational imaging angle as simulated X-ray image data at the third stage based on the updated settings of the SID and FOV, and the monitor 4 An appropriate luminance gain for each of the displayed simulated X-ray images is calculated to calculate an X-ray condition (step S1107).

  After that, when the X-ray condition at each rotational imaging angle is set by the system control unit 7 based on the calculated X-ray condition (Yes at Step S1108), the operator performs rotation DSA via the operation unit 8. Upon receiving the imaging start request, the system control unit 7 executes rotational imaging (step S1109) and ends the process. In the case of rotational DSA imaging, rotational imaging is performed before and after the injection of contrast medium.

  As described above, in this embodiment, the simulated X-ray image data generation / correction unit 6b embeds the isocenter position information of the region of interest and the position information of the region of interest input from the X-ray CT apparatus 200. The CT voxel data is aligned, front and side simulated X-ray images are generated, and a correction amount for matching the isocenter of the region of interest with the isocenter of the apparatus is calculated. When the position of the couchtop 10 or the C-arm 11 is corrected based on the calculated correction amount, the simulated X-ray image data generation / correction unit 6b generates simulated X-ray image data at each rotational imaging angle. Thus, the SID and the FOV are calculated so that the entire region of interest is displayed and maximized in all simulated X-ray images displayed on the monitor 4.

  Then, the system control unit 7 sets the calculated SID and FOV, and the simulated X-ray image data generation / correction unit 6b uses the simulated X-ray at each rotation imaging angle based on the updated setting of the SID and FOV. Image data is generated, an appropriate luminance gain in each simulated X-ray image displayed on the monitor 4 is calculated, and an X-ray condition is calculated. Then, the system control unit 7 sets the X-ray condition at each rotational imaging angle based on the calculated X-ray condition, and executes the rotational imaging according to the instruction via the operation unit 8 of the operator. It is guaranteed that the region of interest of the subject P is always included in all the X-ray images captured by the imaging, and preliminary fluoroscopy for visual field confirmation at each rotation imaging angle and the region of interest are included in the X-ray image. Therefore, it is possible to avoid re-performing rotational imaging, and as described above, the X-ray exposure dose can be reduced in rotational imaging as described above.

  In addition, since it is guaranteed that the region of interest is displayed to the maximum extent possible in all the X-ray images captured by the rotational imaging, the rotational imaging is performed because the region of interest in the displayed X-ray image is small. It is possible to avoid redoing the image, and it is possible to reduce the X-ray exposure dose in rotational imaging.

  In addition, since it is possible to set appropriate X-ray conditions without actually irradiating X-rays, it is possible to reduce the amount of X-ray exposure in rotational imaging, and appropriate brightness at all rotational imaging angles. X-ray images can be generated, and the image quality of the X-ray images can be improved. Further, when “3D DA imaging” or “3D DSA imaging” is performed, the image quality of the X-ray image is improved, and therefore, artifacts when a three-dimensional image is formed can be reduced.

  In this embodiment, the position of the subject P is corrected using the isocenter of the region of interest embedded in the CT voxel data so that all the regions of interest are included in the X-ray image generated by rotational imaging. Although described above, the present invention is not limited to this, and accepts CT voxel data in which only the information of the region of interest is embedded, and sets this CT voxel data at the position where the subject P is actually arranged. Then, simulated X-ray image data is generated for each rotational imaging angle at which rotational imaging is performed, and the subject P is arranged so that the region of interest is included in each of the generated simulated X-ray image data. It may be a case where the existing position is corrected.

  That is, it is determined whether or not the region of interest is included in each of the generated simulated X-ray image data, and the correction amount (deviation amount) required for including the region of interest in all the simulated X-ray image data. Is calculated, the CT voxel data is moved, and the process of repeatedly generating simulated X-ray image data for each rotational imaging angle from the moved CT voxel data is repeated to calculate the final deviation amount. Thus, the position of the subject P may be corrected.

  Further, each component of each illustrated apparatus is functionally conceptual, and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed or arbitrarily distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. Further, all or any part of each processing function performed in each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

  Note that the rotational imaging method described in the present embodiment can be realized by executing a program prepared in advance on a computer such as a personal computer or a workstation. This program can be distributed via a network such as the Internet. The program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD and being read from the recording medium by the computer.

  As described above, the X-ray apparatus and the rotational imaging method according to the present invention are useful when imaging an X-ray image including a region of interest of a subject, and particularly reduce the X-ray exposure dose in rotational imaging. Suitable for that.

It is a perspective view of the X-ray apparatus in a present Example. It is a functional block diagram which shows the structure of the X-ray apparatus in a present Example. It is a figure for demonstrating the CT voxel data which a CT voxel data output part outputs. It is a figure for demonstrating the simulation X-ray image data generation process of the simulation X-ray image data production | generation / correction | amendment part. It is a figure for demonstrating the alignment of CT voxel data by the simulation X-ray image data production | generation / correction | amendment part. It is a figure which shows the coordinate system which a simulation X-ray image data production | generation / correction | amendment part uses for the production | generation of simulation image data. It is a figure for demonstrating the position adjustment by a system control part. It is a figure for demonstrating adjustment of FOV and SID by a system control part. It is a figure for demonstrating adjustment of the X-ray condition by a system control part. It is a figure for demonstrating rotation imaging | photography. It is a figure for demonstrating the process of the X-ray apparatus in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray high voltage generator 1a X-ray control part 1b High voltage generator 2 X-ray source apparatus 2a X-ray tube apparatus 2b X-ray aperture 3 X-ray detector 4 Monitor 5 Image processing apparatus 5a Image input part 5b Image processing part 5c Image storage unit 5d Image output unit 6 Simulated image data generation unit 6a CT voxel data input unit 6b Simulated X-ray image data generation / correction unit 6c Image data output unit 7 System control unit 8 Operation unit 9 Mechanism control unit 9a X-ray compensation Filter movement control unit 9b X-ray diaphragm blade movement control unit 9c Bed top plate movement control unit 9d Arm rotation / movement control unit 10 Bed top plate 11 C arm 100 X-ray device 200 X-ray CT device 201 CT voxel data output unit

Claims (5)

A plurality of X-ray images including a region of interest of the subject are rotated by rotating an X-ray tube apparatus that exposes the X-rays to the subject and an X-ray detector that detects the X-rays transmitted through the subject. An X-ray apparatus that rotates from a direction,
CT voxel data input means for receiving and inputting CT voxel data including the region of interest of the subject generated by the X-ray CT apparatus before the rotational imaging is performed;
The CT voxel data input by the CT voxel data input means is set at the position where the subject is actually arranged, and the CT voxel data is projected at each rotational imaging angle at which the rotational imaging is performed. Simulated X-ray image generation means for generating a simulated X-ray image,
Correction amount calculation for calculating a correction amount for correcting the position where the subject is arranged so that the region of interest is included in each of the simulated X-ray images generated by the simulated X-ray image generation unit Means,
An X-ray apparatus comprising: The CT voxel data input means receives and inputs CT voxel data including information of a center point that is the center of the region of interest,
The simulated X-ray image generation means sets the CT voxel data including the information on the center point input by the CT voxel data input means at the position where the subject is actually arranged, and then performs the rotational imaging. Generating a plurality of the simulated X-ray images at a predetermined rotational imaging angle among the rotational imaging angles performed,
The correction amount calculation means includes a position of the center point projected on each of the plurality of simulated X-ray images at the predetermined rotational imaging angle generated by the simulated X-ray image generation means, and a position of the imaging center point. The X-ray apparatus according to claim 1, wherein the correction amount is calculated based on a deviation amount. The simulated X-ray image generation means corrects the position of the subject based on the correction amount calculated by the correction amount calculation means, and then inputs the CT voxel input by the CT voxel data input means. After setting the data again at the position where the subject is actually arranged, a simulated X-ray image is generated for each rotational imaging angle at which the rotational imaging is performed,
The correction amount calculation unit is configured to display all the regions of interest included in the simulated X-ray images generated by the simulated X-ray image generation unit after correction based on the correction amount on a predetermined display unit. The X-ray apparatus according to claim 1, wherein a display correction amount for correcting a distance between the focal point of the X-ray tube apparatus and the X-ray detector and a size of an effective visual field is calculated. The simulated X-ray image generation means has a distance between the focal point of the X-ray tube apparatus corrected based on the display correction amount calculated by the correction amount calculation means and the X-ray detector, and a size of an effective visual field. Using the information, generate a simulated X-ray image for each rotational imaging angle at which the rotational imaging is performed from the CT voxel data set at the position where the subject is actually placed,
The correction amount calculation means is configured to display each of the simulated X-ray images generated by the simulated X-ray image generation means after correction based on the display correction amount at an appropriate luminance on the predetermined display unit. The X-ray apparatus according to claim 3, wherein a dose correction amount for correcting a dose of the ray is calculated. A plurality of X-ray images including a region of interest of the subject are rotated by rotating an X-ray tube apparatus that exposes the X-rays to the subject and an X-ray detector that detects the X-rays transmitted through the subject. A rotational shooting method that rotates from the direction,
CT voxel data input step of receiving and inputting CT voxel data including the region of interest of the subject generated by the X-ray CT apparatus before the rotational imaging is performed;
The CT voxel data input in the CT voxel data input step is set at the position where the subject is actually arranged, and the CT voxel data is projected at each rotational imaging angle at which the rotational imaging is performed. A simulated X-ray image generation step for generating a simulated X-ray image;
Correction amount calculation for calculating a correction amount for correcting the position where the subject is arranged so that the region of interest is included in each of the simulated X-ray images generated by the simulated X-ray image generation step Steps,
Rotation photography method characterized by including.

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