JP2017131310A - X-ray fluoroscopic apparatus, and imaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray fluoroscopic apparatus and an imaging method, which do not require sensors to be attached to a subject, can detect a periodic movement of the subject without being affected by a change in the concentration distribution of an X-ray image due to a change in a dose and a change in a quantum noise quantity of each frame of continuous X-rays, and execute imaging using the detected movement period.SOLUTION: An X-ray fluoroscopic apparatus 1 calculates a movement period of a subject 3 by analyzing a time-series image group acquired by fluoroscopic imaging for a predetermined time, and controls imaging based on the calculated movement period. The movement period is calculated by creating a frequency band image group in which a specific space frequency band is extracted from each image of the time-series image group, calculating a temporal change in image statistic information from the created frequency band image group, and executing frequency analysis for the temporal change in the image statistic information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an X-ray fluoroscopic imaging apparatus and an imaging method, and more particularly to X-ray fluoroscopic imaging of a part having periodic body movement.

  In an examination using an X-ray fluoroscopic apparatus, body movement caused by the subject's breathing may affect the interpretation of the captured image. For this reason, it is common to perform imaging while the patient is holding his breath. However, in subjects who are difficult to hold their breath due to a decrease in respiratory function or in tests under sedation, the subject cannot hold his breath according to the operator's instructions. When the subject performs imaging under free breathing, for example, a method of attaching a body surface-installed sensor as described in Patent Document 1, monitoring the respiratory cycle, and performing imaging while synchronizing with the cycle There is. There is also a method of detecting respiratory motion from the amount of change in the density histogram of the continuous X-ray image and feeding it back to imaging.

JP 2008-253765 A

  However, in Patent Document 1, preparation work before inspection such as attachment of a respiratory sensor to the subject, wiring, and the like increase and inspection efficiency decreases. Further, a respiratory cable or the like tends to be an obstacle when the surgeon accesses the subject. Furthermore, in the above-described method for detecting respiratory movement from the amount of change in the density histogram, if a change occurs in the concentration histogram due to, for example, a change in dose for each frame of continuous X-rays or a change in the amount of quantum noise, the respiratory cycle is erroneous. It may be detected. In that case, the imaging was performed at a time phase different from the respiratory time phase intended by the surgeon, which was a problem.

  The present invention has been made in view of the above-described problems, and the object of the present invention is that it is not necessary to attach sensors to a subject, and dose change or quantum for each frame in continuous X-ray imaging. X-ray fluoroscopic imaging apparatus and imaging capable of detecting a periodic motion of a subject without being affected by a change in density distribution of an X-ray image due to a change in noise amount and performing imaging using the detected motion cycle Is to provide a method.

  A first invention for achieving the above-described object is an X-ray source that irradiates a subject with X-rays, an X-ray detector that is disposed opposite to the X-ray source and detects transmitted X-rays transmitted through the subject, An image processing unit that generates an image based on transmitted X-rays detected by the X-ray detector, and a time-series image group obtained by fluoroscopic imaging for a predetermined time, thereby analyzing the movement cycle of the subject. An X-ray fluoroscopic apparatus comprising: a motion cycle calculation unit to be calculated; and a control unit that controls imaging based on the calculated motion cycle.

  The second invention is based on the step of irradiating the subject with X-rays, the step of detecting the transmitted X-rays transmitted through the subject with an X-ray detector, and the transmitted X-rays detected by the X-ray detector. A step of generating an image, a step of calculating a motion cycle of the subject by analyzing a time-series image group obtained by fluoroscopy for a predetermined time, and a step of controlling shooting based on the calculated motion cycle And a photographing method characterized by comprising:

  According to the present invention, it is not necessary to attach sensors to the subject, and the subject is not affected by changes in the dose distribution for each frame or changes in the density distribution of the X-ray image due to changes in the amount of quantum noise in continuous X-ray imaging. It is possible to provide an X-ray fluoroscopic imaging apparatus and an imaging method capable of detecting a periodic motion of the image and performing imaging using the detected motion cycle.

1 is a block diagram showing a configuration of an X-ray fluoroscopic apparatus 1 according to the present invention. Flowchart explaining the flow of motion cycle calculation processing Example of a continuous fluoroscopic recording image group 40 composed of n frames of fluoroscopic recording images A1 to An Setting example of region of interest 20 for reference image B Example of time-series image statistical information 41 obtained from the fluoroscopic recording image group 40 Example of time-series image statistical information 43 after frequency conversion Timing chart showing the procedure for reconstructing a tomographic image by imaging in the respiratory phase (second embodiment) The figure which shows the example of the apparatus attitude | position in imaging | photography of FIG. Timing chart showing a procedure for classifying continuous imaging data into a plurality of respiratory time phases and reconstructing a tomogram (third embodiment) Timing chart showing a procedure of processing for obtaining a DSA image by subtracting a mask image of a simultaneous phase and a live image (fourth embodiment) Setting example of multiple regions of interest 21 Example of time-series image statistical information obtained from a plurality of regions of interest 21

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
First, the configuration of an X-ray fluoroscopic apparatus 1 according to the present invention will be described with reference to FIG.

  As shown in FIG. 1, the X-ray fluoroscopic apparatus 1 includes an X-ray source composed of a high voltage generator 101 and an X-ray tube 102, an X-ray diaphragm device 103, a table 105 on which a subject 3 is placed, and an X-ray detector. 106, a system control unit 120, an X-ray control unit 121, an image processing unit 122, a storage unit 123, a motion cycle calculation unit 124, an image generation unit 125, a display unit 130, and an operation unit 131.

  The X-ray source includes an X-ray tube 102 and a high voltage generator 101. The X-ray tube 102 receives power supply from the high voltage generator 101 and generates X-rays. The X-ray source may be provided with an X-ray filter or the like that selectively transmits X-rays having specific energy. The operation of the X-ray source is controlled by the X-ray control unit 121.

  The X-ray control unit 121 controls the X-ray tube current, the X-ray tube voltage, and the like according to the X-ray control signal transmitted from the system control unit 120. Note that the X-ray tube 102 and the high voltage generation unit 101 may be configured integrally or separately. Further, the X-ray tube 102 and the X-ray diaphragm device 103 may be provided integrally.

  The X-ray diaphragm 103 has a plurality of shielding plates for narrowing the irradiation field of X-rays generated from the X-ray tube 102. The X-ray diaphragm device 103 narrows down the X-ray irradiation field irradiated to the subject 3 by moving a plurality of shielding plates according to a control signal from the system control unit 120.

  The X-ray detector 106 is configured by arranging a plurality of detection elements for detecting X-rays on a two-dimensional array, and X-rays transmitted from the X-ray tube 102 and transmitted through the subject 3 (transmission X-rays). X-ray signal corresponding to the amount of incident light is detected and sent to the image processing unit 122.

  The image processing unit 122 performs image processing on the X-ray signal output from the X-ray detector 106 to generate and output an X-ray image. Image processing includes gamma conversion, gradation conversion processing, image enlargement / reduction processing, and the like. The X-ray image generated by the image processing unit 122 is output to the storage unit 123 and the display unit 130.

  The X-ray fluoroscopic imaging apparatus 1 of the present invention has a fluoroscopic recording function and an imaging recording function. The fluoroscopic recording function is a function for generating a fluoroscopic image (a fluoroscopic recording image group) including moving images by continuously irradiating the subject 3 with X-rays. The imaging / recording function is a function for generating an X-ray image that is a still image by irradiating the subject 3 with X-rays for a moment. The image processing unit 122 generates a fluoroscopic recording image group including a plurality of frames of fluoroscopic images in the fluoroscopic recording function, and generates a photographic image that is one X-ray image in the radiographic recording function.

  The storage unit 123 stores the X-ray image (a fluoroscopic recording image group or a captured image) generated by the image processing unit 122. Further, in addition to programs relating to fluoroscopy and photographing, various fluoroscopic conditions, and photographing conditions, programs and data necessary for calculation of a motion cycle and execution of various photographing procedures described later are stored.

  The motion cycle calculation unit 124 calculates a motion cycle of the subject 3 by analyzing a series of fluoroscopic recording image groups obtained by the above-described fluoroscopic recording function. The movement of the subject 3 is a body movement showing a periodic movement such as a respiratory movement. The motion cycle is the periodic body motion cycle. The calculated motion cycle is notified to the X-ray control unit 121 and the image generation unit 125.

  The motion cycle calculation unit 124 creates a specific frequency band image that is an image obtained by extracting a specific spatial frequency band from each image of a series of fluoroscopic recording image groups by a frequency filter. Further, the temporal change of the image statistical information is calculated from the created specific frequency band image group, and the motion period is calculated by frequency analysis of the temporal change of the image statistical information.

  Here, as for the specific spatial frequency band to be extracted, it is desirable that an appropriate band corresponding to the imaging region is held and set in advance. Alternatively, any band input by the operator may be used. Also, when setting an appropriate band according to the imaging region, it is desirable to read out a filter for extracting the set frequency band and adjust it according to the enlargement ratio of the image.

  As the image statistical information obtained from the above-described specific frequency band image group, it is desirable to use any one or a combination of, for example, the average of pixel values, variance, skewness, sharpness, and mode value.

The procedure for calculating the motion cycle will be described later.
The motion cycle calculated by the motion cycle calculation unit 124 is notified to the X-ray control unit 121 and the display unit 130 and used for imaging control and display control.

  The image generation unit 125 generates an image such as a tomographic image using the image generated by the image processing unit 122 and stored in the storage unit 123. The generated image is stored in the storage unit 123 and displayed on the display unit 130.

  The display unit 130 includes a display device such as a CRT or a liquid crystal panel, and displays an X-ray image of the subject 3 generated by the image processing unit 122 and an image such as a tomographic image generated by the image generation unit 125.

  The operation unit 131 includes an input device such as a keyboard, a mouse, and a joystick, and inputs a command from the operator to the system control unit 120. The operation unit 131 may be a touch panel type operation unit formed integrally with the display unit 130.

The system control unit 120 is a CPU (Central
A processing unit (ROM), a read only memory (ROM), a random access memory (RAM), and the like. The system control unit 120 controls the operation of X-ray irradiation based on the input signal input from the operation unit 131, and detects and data of X-rays transmitted through the subject 3 (hereinafter abbreviated as “transmitted X-rays”). The acquisition operation is controlled, and the movement operation of the X-ray tube 102, the X-ray detector 106, and the table 105 is controlled.

  In the present invention, the X-ray source (high voltage generator 101, X-ray tube 102, X-ray diaphragm device 103) and X-ray detector 106 are arranged in a state of facing each other with a table 105 interposed therebetween. For example, an X-ray tube 102 is fixed to one end of an arm (not shown), and an X-ray detector 106 is fixed to the other end. In addition, the position of the X-ray tube 102 can be moved by tilting or moving the arm by a moving mechanism (not shown) so that the arm 3 can be tilted to a predetermined tilt angle. The X-ray detector 106 is also moved horizontally or rotated in conjunction with the inclination of the X-ray tube 102 (see FIG. 8).

  Next, the procedure of the motion cycle calculation process will be described with reference to the flowchart of FIG. In the example of FIG. 2, calculation of a motion cycle will be described using respiratory motion as an example of periodic body motion.

  First, the system control unit 120 starts fluoroscopic imaging, and stores the created fluoroscopic recording image group in the storage unit 123. At this time, the operator places the subject 3 on the table 105 and performs positioning based on the acquired fluoroscopic image. Thereafter, fluoroscopic imaging for n frames is performed at a fluoroscopy rate FR [frame / second] for at least a time corresponding to one respiratory cycle. As illustrated in FIG. 3, the motion cycle calculation unit 124 reads a time-series fluoroscopic recording image group 40 including images A1 to An for n frames from the image processing unit 122 (step S101).

  Next, the motion cycle calculation unit 124 sets one arbitrary image as the reference image B from the read fluoroscopic recording image group 40 (A1 to An) (step S102). Furthermore, as shown in FIG. 4, the region of interest 20 is set at an arbitrary position of the reference image B (step S103).

  Next, the motion cycle calculation unit 124 extracts the regions corresponding to the region of interest 20 set in the reference image B from the images A1 to An of the fluoroscopic recording image group 40 as the region of interest 20, respectively. Then, a filtering process for extracting a specific spatial frequency band (unit: Line / pixel) is performed on the region of interest 20 of each extracted image (step S104). By performing the filtering process in step S104, the influence of noise can be reduced.

  In step S104, the specific spatial frequency band to be extracted is a spatial frequency band that moves in synchronization with the breathing motion of the human body and has a spatial frequency component at a location that is easily captured as an X-ray image. For example, a rib, a diaphragm, a pulmonary blood vessel, or the like is preferable as a location that moves in synchronization with the breathing motion of the human body and is easily captured as an X-ray image. It is desirable that the filter for extracting these spatial frequency bands can be selected by an operator from a plurality of options. A setting value of an appropriate spatial frequency band corresponding to the imaging region (rib, diaphragm, pulmonary blood vessel, etc.) is held in the storage unit 123 in advance, and the system control unit 120 allows the operator to select an imaging region from a plurality of options. Alternatively, it is desirable to provide a user interface for inputting (selecting) the spatial frequency band.

  For example, the system control unit 120 stores a data table in which a spatial frequency band to be extracted for each imaging region is predetermined in the storage unit 123, and displays a screen for selecting an imaging region on the display unit 130 as a user interface. When an imaging region is selected on the screen, the system control unit 120 determines a spatial frequency band filter corresponding to the region with reference to the data table, and uses the filter in step S104.

  In addition, even in the same imaging region, the spatial frequency varies depending on the magnification of the image. For this reason, it is assumed that the spatial frequency band in the reference apparatus posture is stored as a reference value in the above-described data table. The reference apparatus orientation may be, for example, when the distance between the X-ray detector 106 and the table 105 is minimum and the distance between the X-ray tube 102 and the X-ray detector 106 is maximum. An image enlargement ratio is calculated from information on the distance between the X-ray detector 106 and the table 105 at the time of fluoroscopic image recording and the distance between the X-ray tube 102 and the X-ray detector 106, and the above-described reference is calculated based on the calculated enlargement ratio. By dividing the value, a spatial frequency suitable for the enlargement ratio of the image is obtained. Accordingly, it is possible to easily set an appropriate filter corresponding to the image enlargement ratio and the imaging region.

  By the filter processing in step S104, a frequency band image group that is an image obtained by extracting a specific spatial frequency band from each of the images A1 to An, B of the series of fluoroscopic recording image groups 40 is created.

  Next, the motion cycle calculation unit 124 calculates image statistical information from each frequency band image created in step S104 (step S105). As the image statistical information, an average value, a variance value, a skewness, a sharpness, a mode value, or the like may be used. For example, the sharpness is preferable because a highly accurate result can be obtained. The image statistical information calculated from the region of interest 20 of the series of fluoroscopic recording image groups 40 is calculated as time series data as shown in FIG. Hereinafter, a graph showing image statistical information in time series is referred to as time series image statistical information 41. In the graph of the time-series image statistical information 41 in FIG. 5, the horizontal axis represents the frame number (time), and the vertical axis represents the statistical value.

  The motion cycle calculation unit 124 calculates the temporal change data Sub1 to Subn of the difference between the image statistical information of the reference image B and the statistical information of the other images A1 to An (step S106). In addition, the motion cycle calculation unit 124 performs frequency conversion on the temporal change data of the differences Sub1 to Subn calculated in Step S106 (Step S107).

  In step S107, the motion cycle calculation unit 124 converts the frequency change data of the difference value of one or a plurality of statistical information using the following formula (1), and the frequency (unit is [1 / frame]). The intensity fSUB (k) is calculated.

The intensity fSUB (k) obtained by the processing in step S107 is frequency conversion data of time-series image statistical information, and is represented as a graph 43 shown in FIG. 6, for example.
For the intensity fSUB (k) calculated in step S107, the motion period calculation unit 124 calculates a frequency k that is the maximum intensity (frequency peak) among frequencies of 0 Hz or higher, and sets the frequency k as the motion period Freq (step). S108). The motion cycle calculation unit 124 notifies the calculated motion cycle Freq to the X-ray control unit 121 and the display unit 130.

The motion cycle is obtained by the procedure of steps S101 to S108 described above.
By calculating the motion cycle of the subject 3 by the method of the first embodiment, motion information can be calculated from the image without attaching sensors such as a respirometer to the subject 3. In addition, it is possible to detect the movement cycle of the subject 3 without being affected by changes in the X-ray image density distribution due to changes in the dose of continuous X-rays for each frame or changes in the amount of quantum noise.

  The system control unit 120 can apply the motion cycle Freq calculated in step S107 to various imaging methods. Application to each imaging method will be described as second to fourth embodiments.

[Second Embodiment]
The motion cycle calculated by the method of the first embodiment can be applied to, for example, respiratory synchronization imaging. FIG. 7 is a timing chart of the respiratory synchronization imaging according to the second embodiment, and FIG. 8 is a diagram illustrating an imaging posture in the respiratory synchronization imaging according to the second embodiment.

  As shown in FIG. 7, in the period Phase 1, the X-ray control unit 121 continuously irradiates the subject 3 with X-rays. The image processing unit 122 generates a fluoroscopic image based on the transmission X-ray data obtained from the X-ray detector 106 during the same period as the period during which X-rays are irradiated, and the generated fluoroscopic image is stored as a fluoroscopic recording image group. 123. The length of the period Phase1 is set to a length equal to or longer than one respiratory cycle. After the continuous irradiation and fluoroscopic recording, the motion cycle calculation unit 124 reads the fluoroscopic recording image group recorded in the storage unit 123, and calculates the respiratory cycle based on the fluoroscopic recording image group by the method of the first embodiment. To do. The motion cycle calculation unit 124 converts the calculated respiratory cycle Freq [1 / Nframe] into units using the following equation (2), and notifies the X-ray control unit 121 as the respiratory synchronization imaging cycle Tsync [1 / sec]. .

In the next period Phase 2, the X-ray control unit 121 irradiates X-rays intermittently for each respiratory synchronization imaging cycle Tsync notified by the motion cycle calculation unit 124. At this time, the system control unit 120 moves the X-ray source and the X-ray detector 106 at a constant speed or rotates at a constant speed, and irradiates the subject 3 with X-rays from different angles at each irradiation timing. Each time the X-ray is irradiated, the image processing unit 122 generates a captured image based on the transmitted X-ray amount detected by the X-ray detector 106. The generated captured image is stored in the storage unit 123 as the saved image IMG _REC .

  In the next period Phase 3, the image generation unit 125 reconstructs a tomographic image using images (captured images) obtained from a plurality of angles stored in the storage unit 123. The image processing unit 122 outputs the created tomographic image to the display unit 130. The display unit 130 displays a tomographic image.

  Through the above processing, a tomographic image can be reconstructed using X-ray images that are taken at the same timing in the respiratory time phase and have different projection angles. Therefore, it is possible to obtain a tomographic image that is not affected by body movement due to respiration.

[Third Embodiment]
The motion cycle calculated by the method of the first embodiment can be applied to, for example, a process of classifying continuous imaging data for each time phase and reconstructing a tomographic image for each time phase. FIG. 9 is a timing chart of respiratory synchronization imaging and image reconstruction according to the third embodiment.

  As shown in FIG. 9, in the period Phase 1, the X-ray control unit 121 continuously irradiates the subject 3 with X-rays as in the second embodiment. The image processing unit 122 generates the fluoroscopic recording image group 40 based on the transmission X-ray data obtained from the X-ray detector 106 and stores the generated fluoroscopic recording image group 40 during the same period as the X-ray irradiation period. Recorded in the unit 123. After the end of the continuous irradiation, the motion cycle calculation unit 124 reads the fluoroscopic recording image group 40 recorded in the storage unit 123, and based on the read fluoroscopic recording image group 40, the respiratory cycle Freq [ 1 / Nframe] is calculated. Further, unit conversion is performed using the above-described formula (2), and the respiratory synchronization imaging cycle Tsync [1 / sec] is notified to the X-ray control unit 121.

In the next period Phase2, the X-ray control unit 121 continuously emits X-rays. At this time, the system control unit 120 changes the angle at which the subject 3 is projected by moving or rotating the positions of the X-ray tube 102 and the X-ray detector 106 at a constant speed. During the image processing unit 122 which X-rays are irradiated to generate a pickup image by the above-described image pickup rate FR, the storage unit 123 the generated pickup image as an archival image IMG _REC.

In the next period Phase 3, the image processing unit 122 converts the stored image IMG _REC stored in the storage unit 123 into a plurality of patterns (the number of patterns) as shown in the following equation (3) based on the respiratory synchronization imaging cycle Tsync and the imaging rate FR. X) to the respiratory time phase image group IMGsync (X).

  X = FR ÷ Tsync (3)

  In the example of FIG. 9, the number of classification patterns is X = 2, the fluoroscopic image obtained in the breathing time phase indicated by the broken line is classified into the classification pattern A, and the fluoroscopic image obtained in the breathing time phase indicated by the alternate long and short dash line is classified into the classification pattern. Classify into B. For example, in the case of breathing, it can be considered that classification pattern A is classified as expiratory period and classification pattern B is classified as inhalation period. The number X of classification patterns is not limited to two, and may be three or more.

  In the next period Phase4, the image generation unit 125 performs image reconstruction processing on each of the image groups classified into X patterns in the respiratory time phase (hereinafter referred to as respiratory time phase image group IMGsync (X)). Reconstruct tomographic images at each respiratory phase. The image generation unit 125 outputs the created tomographic image for each respiratory time phase to the display unit 130. The display unit 130 displays a tomographic image for each respiratory time phase.

  As described above, according to the third embodiment, images taken from various projection angles can be acquired in a plurality of respiratory phases. Therefore, if a tomographic image is reconstructed using the same images for each respiratory time phase, it is possible to obtain a plurality of tomographic images of respiratory time phases that are not affected by body movement due to respiration.

[Fourth Embodiment]
The motion cycle calculated by the method of the first embodiment can be applied to, for example, DSA (Digital Subtraction angiography) imaging. FIG. 10 is a shooting timing chart according to the fourth embodiment.

  As shown in FIG. 10, in the period Phase 1, the X-ray control unit 121 continuously irradiates the subject 3 with X-rays as in the first to third embodiments. The image processing unit 122 generates the fluoroscopic recording image group 40 based on the transmission X-ray data obtained from the X-ray detector 106 and stores the generated fluoroscopic recording image group 40 during the same period as the X-ray irradiation period. Recorded in the unit 123. The motion cycle calculation unit 124 reads the fluoroscopic recording image group 40 recorded in the storage unit 123, and calculates the respiratory cycle Freq [1 / Nframe] based on the fluoroscopic recording image group 40 by the method of the first embodiment. Then, unit conversion is performed using the above equation (2), and the X-ray control unit 121 is notified as a respiratory synchronization imaging cycle Tsync [1 / sec].

  In the next period Phase2, the X-ray control unit 121 captures a continuous mask image at a predetermined imaging rate FR for one cycle of the respiratory cycle time T, and stores it in the storage unit 123 as a stored mask image group MaskIMG. A mask image is an image obtained before contrast agent injection. The respiratory cycle time T is obtained by the following equation (4).

  The image processing unit 122 converts the saved mask image group MaskIMG stored in the storage unit 123 into an X-pattern respiratory time phase mask image group based on the respiratory synchronization imaging cycle Tsync and the imaging rate FR as shown in the above equation (3). Classify into MaskIMGsync (X).

  In the example of FIG. 10, as an example, seven patterns of respiratory time phase mask image groups MaskIMGsync (1) to MaskIMGsync (7) are classified. Hereinafter, in order to simplify the notation, the respiration time phase mask images of each pattern are denoted as M1 to M7, respectively.

  In the next period Phase3, continuous X-ray irradiation is performed while injecting a contrast agent, and a continuous live image LiveIMG is acquired at the imaging rate FR. The acquired live image LiveIMG is sequentially stored in the storage unit 123. In addition, the image processing unit 122 uses the saved live image group LiveIMG stored in the storage unit 123 as an X pattern breathing time phase live as shown in the above equation (3) based on the breathing synchronization shooting cycle Tsync and the shooting rate FR. The image group is classified into LiveIMGsync (X). In the example of FIG. 10, the number of classification patterns X = 7 as in the mask image, and classification is made into seven patterns of respiratory time phase live image groups LiveIMGsync (1) to LiveIMGsync (7). Hereinafter, in order to simplify the notation, the breathing time phase live image group of each pattern is referred to as L1 to L7.

  The image processing unit 122 creates a DSA image by subtracting the mask images M1 to M7 and the live images L1 to L7 from each other in the same respiratory time phase. The image processing unit 122 displays the created DSA image on the display unit 130 and stores it in the storage unit 123.

  As described above, according to the fourth embodiment, a contrast agent is injected after obtaining a mask image by continuous X-ray irradiation for at least one motion cycle based on the motion cycle calculated in the period Phase1. A live image is obtained by continuously irradiating X-rays. Then, the DSA image is obtained by taking the difference between the mask image before the contrast agent injection and the live image after the contrast agent injection for the same movement time phase. This makes it possible to create a DSA image that is free from body motion blur due to breathing.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described.
In the motion cycle calculation process of the first embodiment, the operator sets an arbitrary region of interest 20 and calculates a motion cycle using an image in the region of interest. However, the region of interest to be set is one. There is no limitation, and a plurality may be set. In the fifth embodiment, processing for determining an optimal motion cycle among motion cycles calculated from each of a plurality of regions of interest 21 set will be described.

The region of interest set in step S103 of the flowchart of FIG. 2 is arranged in the reference image B as m (1 <m) regions of interest 21 of the same size, for example, as shown in FIG. The region of interest 21 may be arranged manually by the operator, or may be arranged at an arbitrary position of the reference image B by the system control unit 120.
2 for each of the m regions of interest (frequency filter processing, statistical information calculation for each image, statistical information difference Sub1 to Subn between the reference image B and the other images A1 to An). Calculation, frequency conversion of differences Sub1 to Subn, and calculation of respiratory cycle Freq (m) from frequency peak).

  Thereafter, the motion cycle calculation unit 124 sets the value that is the mode value among the respiratory cycles Freq (m) obtained in the m regions of interest as the respiratory cycle. The calculated respiratory cycle is notified to the X-ray control unit 121 and the image generation unit 125 as in the first embodiment.

  The image generation unit 125 controls to irradiate X-rays intermittently at a predetermined breathing time phase by using the obtained breathing cycle, as in the second to fourth embodiments. By classifying into respiratory time phases, it is possible to reconstruct a tomographic image of each respiratory time phase or create a DSA image.

  According to the fluoroscopic imaging apparatus 1 of the fifth embodiment, the most appropriate breathing cycle can be calculated by setting a plurality of regions of interest without the operator specifying the region of interest.

  The preferred X-ray fluoroscopic apparatus of the present invention has been described above in each embodiment, but the present invention is not limited to the above-described embodiment. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

DESCRIPTION OF SYMBOLS 1 ... X-ray fluoroscopic imaging device 3 ... Subject 20 ... Area of interest 40 ... Perspective recording image group 41 ... Time series image statistical information 43 ... Time Sequence image statistical information frequency conversion 101... High voltage generator 102... X-ray tube 103... X-ray diaphragm device 105. Unit 121 ... X-ray control unit 122 ... image processing unit 123 ... storage unit 124 ... motion cycle calculation unit 125 ... image generation unit 130 ... display unit 131 ... operation unit

Claims (13)

An X-ray source that irradiates the subject with X-rays;
An X-ray detector arranged to face the X-ray source and detecting transmitted X-rays transmitted through the subject;
An image processing unit that generates an image based on transmitted X-rays detected by the X-ray detector;
A motion cycle calculation unit that calculates a motion cycle of the subject by analyzing a time-series image group obtained by fluoroscopic imaging for a predetermined time;
A control unit that controls shooting based on the calculated movement cycle;
An X-ray fluoroscopic apparatus comprising: The motion cycle calculation unit
A frequency band image group that is an image obtained by extracting a specific spatial frequency band from each image of the time-series image group is created, and a temporal change in image statistical information is calculated from the created frequency band image group, and the image statistical information The X-ray fluoroscopic apparatus according to claim 1, wherein the motion cycle is calculated by performing frequency analysis of a change with time. A setting unit for setting a region of interest at an arbitrary position in the image;
The X-ray fluoroscopic imaging apparatus according to claim 1, wherein the motion cycle calculation unit calculates the motion cycle based on an image in a region of interest set by the setting unit. The setting unit sets a plurality of regions of interest at arbitrary positions in the image,
4. The motion cycle calculation unit calculates the motion cycle based on an image in each region of interest set by the setting unit, and sets the frequency with the highest frequency as the motion cycle. X-ray fluoroscopic apparatus.   The motion cycle calculation unit sets an arbitrary image of the image group as a reference image, and the image statistical information obtained from the image statistical information obtained from the reference image and another image group other than the reference image. The X-ray fluoroscopic imaging apparatus according to claim 2, wherein the motion period is calculated by performing frequency analysis of a change with time of the difference from the information.   The X-ray fluoroscopic imaging apparatus according to claim 2, further comprising a filter adjustment unit that adjusts a filter for extracting the specific spatial frequency band in accordance with an enlargement ratio of an image. .   The X-ray fluoroscopic imaging apparatus according to claim 2, further comprising an input unit that receives an input of an imaging region or the specific spatial frequency band.   8. The image statistical information according to claim 2, wherein any one or a combination of average, variance, skewness, sharpness, and mode is used as the image statistical information. X-ray fluoroscopic equipment. A moving mechanism for moving the X-ray irradiation position;
The control unit irradiates the subject with X-rays intermittently at a timing determined based on the movement cycle while changing the X-ray irradiation position by the moving mechanism. The X-ray fluoroscopic imaging apparatus according to claim 8. A moving mechanism for moving the X-ray irradiation position;
The control unit irradiates X-rays while changing the X-ray irradiation position by the moving mechanism,
Generate images from a plurality of X-ray irradiation angles, classify the generated images into a plurality of motion time phases based on the motion cycle, and use each of the classified plurality of image groups tomographic images of each motion time phase The X-ray fluoroscopic apparatus according to claim 1, further comprising an image generation unit that reconstructs the image. The control unit irradiates X-rays with a period of at least one motion cycle before contrast medium injection as a first period, and further irradiates X-rays with a predetermined period after contrast medium injection as a second period,
The image processing unit generates a plurality of motion time phase pre-contrast injection images from the time-series image group obtained in the first period, stores the images in the storage unit, and is obtained in the second period. An image after injection of contrast medium for each movement time phase is generated from a time series of image groups, and each movement time phase is subtracted for each same movement time phase from the image before contrast medium injection and the image after injection of contrast medium. The X-ray fluoroscopic imaging apparatus according to claim 1, further comprising an image generation unit configured to generate a contrast image. Irradiating a subject with X-rays;
Detecting transmitted X-rays transmitted through the subject with an X-ray detector;
Generating an image based on transmitted X-rays detected by the X-ray detector;
Calculating a movement period of the subject by analyzing a time-series image group obtained by fluoroscopic imaging for a predetermined time;
Controlling shooting based on the calculated motion period;
A photographing method characterized by comprising: A frequency band image group obtained by extracting a specific spatial frequency band from each image of the time-series image group is created, a temporal change of image statistical information is calculated from the created frequency band image group, and the time series of the image statistical information is calculated. The imaging method according to claim 12, wherein the motion cycle is calculated by frequency-analyzing a change.

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