JP2014030506A - Medical image processor, x-ray photographing device, and medical image processing program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical image processor capable of generating a DSA image with higher picture image even in a part affected by both breathing and heart beat, such as a heart.SOLUTION: A medical image processor relating to an embodiment includes: image acquisition means; and differential image generation means. The image acquisition means acquires first X-ray image data and second image X-ray image data of a subject which are collected during a period when the heart beats with a predetermined heart rate, breathing phases corresponding to each other. The differential image generation means generates differential image data by differential processing of the first X-ray image data and the second X-ray image data.

Description

  Embodiments described herein relate generally to a medical image processing apparatus, an X-ray imaging apparatus, and a medical image processing program.

  As one of imaging methods in an X-ray imaging apparatus, DSA (Digital Subtraction Angiography) is known. DSA is a technique for collecting differential image data of X-ray image data before and after injection of a contrast medium into a subject for diagnosis. That is, X-ray image data is collected as mask image data for generating difference image data before injection of a contrast agent. On the other hand, X-ray contrast (contrast) image data is collected by administering a contrast medium. Then, DSA image data is generated for diagnosis by differential processing between the X-ray contrast image data and the mask image data.

  By generating such DSA image data, it is possible to acquire image data from which a shadow unnecessary for blood vessel observation is removed. That is, it is possible to obtain diagnostic image data in which blood vessels stained with a contrast agent are selectively depicted. For this reason, an image useful for blood vessel diagnosis can be displayed.

  However, when collecting DSA image data in a region such as the heart where breathing or heartbeat affects, there is a movement between the mask image data and the X-ray contrast image data that are subject to differential processing due to the influence of breathing and heartbeat. May occur. Therefore, X-ray image data is collected by synchronous imaging synchronized with a respiratory signal and an electrocardiogram (ECG) signal, and DSA is performed using mask image data and X-ray contrast image data of appropriate cardiac phase and respiratory phase. A technique for generating image data has been devised.

JP 2012-61307 A JP 2011-67342 A JP 2009-291313 A

  However, in regions where respiration and heartbeat are affected, such as the heart, the respiratory cycle and heartbeat cycle are different, so DSA image data that is effective for diagnosis can be generated even using imaging techniques such as respiratory synchronization and ECG synchronization. There is a problem that can not be.

  Therefore, the present invention provides a medical image processing apparatus, an X-ray imaging apparatus, and a medical apparatus capable of generating DSA image data with better image quality even in a part that affects both respiration and heartbeat, such as the heart. An object is to provide an image processing program.

A medical image processing apparatus according to an embodiment of the present invention includes an image acquisition unit and a difference image generation unit. The image acquisition means acquires first X-ray image data and second X-ray image data of a subject that are collected during a period in which the heart is beating at a specific heart rate and whose respiratory phases correspond to each other. The difference image generation means generates difference image data by a difference process between the first X-ray image data and the second X-ray image data.
The X-ray imaging apparatus according to the embodiment of the present invention includes an image collection unit and a difference image generation unit. The image collecting means collects first X-ray image data and second X-ray image data of a subject whose respiratory phases correspond to each other during a period in which the heart beats at a specific heart rate. The difference image generation means generates difference image data by a difference process between the first X-ray image data and the second X-ray image data.
The medical image processing program according to the embodiment of the present invention causes a computer to function as an image acquisition unit and a difference image generation unit. The image acquisition means acquires first X-ray image data and second X-ray image data of a subject that are collected during a period in which the heart is beating at a specific heart rate and whose respiratory phases correspond to each other. The difference image generation means generates difference image data by a difference process between the first X-ray image data and the second X-ray image data.

1 is a configuration diagram of a medical image processing apparatus and an X-ray imaging apparatus according to an embodiment of the present invention. The functional block diagram which shows the detailed function of the medical image processing apparatus shown in FIG. The figure which shows an example of the ECG signal acquired by the electrocardiograph shown in FIG. The figure which shows an example of the respiration signal acquired by the respiration sensor shown in FIG. 3 is a time chart showing a flow when road map image data is generated by the medical image processing apparatus and the X-ray imaging apparatus shown in FIG. 1. 6 is a flowchart illustrating an example of a flow including determination processing for collecting and storing mask image data illustrated in FIG. 5. 6 is a flowchart showing an example of a flow including data processing for collecting and displaying the road map image data shown in FIG. 5. 2 is a time chart showing a flow when DSA image data is generated by the medical image processing apparatus and the X-ray imaging apparatus shown in FIG. 1. 2 is a time chart showing a flow in the case of detecting a displacement of a device in the medical image processing apparatus and the X-ray imaging apparatus shown in FIG. 10 is a flowchart illustrating an example of a flow including determination processing for collecting the reference image data for detecting misalignment illustrated in FIG. 9. 10 is a flowchart showing a flow of device misregistration detection processing shown in FIG. 9;

  A medical image processing apparatus, an X-ray imaging apparatus, and a medical image processing program according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a configuration diagram of a medical image processing apparatus and an X-ray imaging apparatus according to an embodiment of the present invention.

  The X-ray imaging apparatus 1 includes an imaging system 2, a control system 3, a data processing system 4, an input device 5, and a display device 6. The imaging system 2 includes an X-ray irradiation unit 7, an X-ray detector 8, a drive mechanism 9, and a bed 10. The control system 3 includes a high voltage generator 3A, a photographing position controller 3B, and a system controller 3C.

  The X-ray irradiation unit 7 includes an X-ray tube, and is disposed to face the X-ray detector 8 with the subject O set on the bed 10 interposed therebetween. The X-ray irradiation unit 7 and the X-ray detector 8 can change the angle and relative position with respect to the subject O while maintaining the relative position by driving the drive mechanism 9. Specifically, the X-ray irradiation unit 7 and the X-ray detector 8 are fixed to both ends of a C-shaped arm having a rotation function. The X-ray irradiation unit 7 is configured to irradiate X-rays from a predetermined angle toward the subject O with an X-ray tube, and the X-ray detector 8 can detect X-rays transmitted through the subject O. The

  Further, the inclination and position of the top plate of the bed 10 can be adjusted by the drive mechanism 9. Therefore, not only the angle of the X-ray irradiation unit 7 and the X-ray detector 8 with respect to the object O but also the angle of the top plate can be adjusted to change the X-ray irradiation direction with respect to the object O. it can.

  A respiration sensor 11 and an electrocardiograph 12 are attached to the subject O set on the bed 10. Further, a contrast medium injection device 13 for injecting a contrast medium into the subject O is provided in the vicinity of the subject O set on the bed 10.

  The high voltage generator 3 </ b> A of the control system 3 is an apparatus that irradiates the subject O with X-rays having desired energy by applying a high voltage to the X-ray tube of the X-ray irradiation unit 7. The photographing position control device 3B is a device that outputs a control signal to the drive mechanism 9 for control. That is, the rotation angle and position of the X-ray irradiation unit 7 and the X-ray detector 8 and the inclination and position of the top plate of the bed 10 are controlled by control signals output from the imaging position control device 3B to the drive mechanism 9.

  The system control unit 3 </ b> C is a system that controls each component of the X-ray imaging apparatus 1 including the high voltage generation apparatus 3 </ b> A, the imaging position control apparatus 3 </ b> B, and the data processing system 4. In particular, the system control unit 3C is configured to be able to acquire contrast agent information indicating whether or not a contrast agent is being injected from the contrast agent injection device 13.

  The data processing system 4 includes an A / D (analog to digital) converter 14 and a computer 15. The computer 15 functions as the medical image processing apparatus 15 by executing a medical image processing program. In other words, the medical image processing apparatus 15 is built in the X-ray imaging apparatus 1.

  However, an independent medical image processing apparatus having a similar function may be connected to the X-ray imaging apparatus 1 via a network. Further, a circuit may be used to configure the medical image processing apparatus 15 incorporated in the X-ray imaging apparatus 1 or the medical image processing apparatus connected to the X-ray imaging apparatus 1 via a network.

  FIG. 2 is a functional block diagram showing detailed functions of the medical image processing apparatus 15 shown in FIG.

  The medical image processing apparatus 15 includes an image generation unit 16, an image acquisition unit 17, an image data storage unit 18, a contrast determination unit 19, a heart rate determination unit 20, a respiratory information acquisition unit 21, a mask image storage unit 22, and a mask image determination unit. 23, a difference image creation unit 24, a misregistration detection image storage unit 25, a misregistration detection image determination unit 26, a misregistration detection unit 27, and a display processing unit 28.

  The image generation unit 16 has a function of taking X-ray detection data digitized through the A / D converter 14 from the X-ray detector 8 and generating X-ray image data by performing data processing. In addition, when X-ray detection data is collected with administration of a contrast agent, X-ray contrast image data is generated, and when X-ray detection data is collected without administration of a contrast agent, X-ray non-contrast image data is generated.

  The image acquisition unit 17 has a function of acquiring the X-ray image data generated by the image generation unit 16. In particular, in an independent medical image processing apparatus connected to the X-ray imaging apparatus 1 via a network, the image generation unit 16 can be omitted. In this case, the image acquisition unit 17 has a function of acquiring X-ray image data from the image generation unit 16 provided in the X-ray imaging apparatus 1 via the network.

  The image data storage unit 18 is a storage device that stores the X-ray image data acquired by the image acquisition unit 17. At the time of imaging, X-ray image data is sequentially stored in the image data storage unit 18 as live image data in real time.

  The contrast determination unit 19 has a function of determining whether or not the contrast medium is being injected by acquiring contrast medium information indicating whether or not the contrast medium is being injected from the system control unit 3C.

  The heart rate determination unit 20 has a function of acquiring a heart rate from the electrocardiograph 12 and determining whether or not it is a period in which the heart is beating at a predetermined specific heart rate. The period in which the heart is beating at a specific heart rate is a period of tachycardia. The tachycardia state can be defined as a case where the heart rate is 100 bpm (beats per minute) or more in numerical values.

  FIG. 3 is a diagram showing an example of an ECG signal acquired by the electrocardiograph 12 shown in FIG.

  In FIG. 3, the vertical axis indicates the amplitude of the ECG signal, and the horizontal axis indicates time. As shown in FIG. 3, the ECG signal is a signal in which the peaks of the Q wave, the R wave, and the S wave repeatedly appear. The heart rate of the ECG signal is normally about 60 bmp, but if a high frequency stimulation is applied to the heart using a pacing catheter, the heart becomes tachycardia. In the example shown in FIG. 3, the heart rate is about 180 bmp.

  A heart in tachycardia beats in small increments. Accordingly, in a heart in a tachycardia state, the position change during one heartbeat due to the movement of the heartbeat is extremely less than in a heart not in a tachycardia state. As a result, in a heart that is in a tachycardia state, a change in position due to a heartbeat can be ignored.

  It is known from experience that rapid pacing always causes the heart to fibrillate at the same position. Further, it is known that if the continuous period is about 30 seconds, rapid pacing is repeated repeatedly without causing any adverse effects on the patient.

  The heart rate can be calculated by measuring the time interval from the peak of the Q wave, R wave, or S wave of the ECG signal to the next peak in the electrocardiograph 12. However, as another method, instead of obtaining the heart rate, only the tachycardia period may be detected. For example, when a tachycardia state is artificially generated using a pacing catheter, the heart rate determination unit 20 acquires an electrode signal of the pacing catheter and determines whether the heart is in a tachycardia state. be able to.

  The respiration information acquisition unit 21 has a function of acquiring a respiration signal from the respiration sensor 11 and obtaining respiration information including at least one of a respiration phase and a respiration cycle. The respiration information is used to specify and select X-ray image data that is a target of difference processing for generating difference image data. Therefore, from the viewpoint of improving the selection accuracy of X-ray image data, it is desirable to acquire the respiratory phase at each time. However, it is also possible to obtain only one or both of the rest inspiratory position and the rest expiratory position by obtaining at least the respiratory cycle.

  FIG. 4 is a diagram illustrating an example of a respiration signal acquired by the respiration sensor 11 illustrated in FIG. 1.

  In FIG. 4, the vertical axis represents the amplitude of the respiratory signal, and the horizontal axis represents time. As shown in FIG. 4, the respiratory signal is a signal that repeats a resting inspiratory position and a resting expiratory position at a period different from the period of the ECG signal.

  Respiration information such as a respiration phase can be obtained based on a respiration signal as shown in FIG. In particular, when performing a procedure such as aortic valve replacement (TAVR: Trans-catheter Aortic Valve Implantation or TAVI: Trans-catheter Aortic Valve Implantation), the respiratory system is always controlled by general anesthesia. Therefore, it is possible to acquire the respiratory signal as a periodic signal.

  However, respiratory information can also be acquired by other known methods. For example, a method for acquiring respiratory information by signal processing on a signal from a ventilator and a method for acquiring respiratory information by image processing on X-ray image data are known. When these methods are used, the respiratory information acquisition unit 21 is configured to acquire information necessary for acquiring respiratory information from components such as the ventilator and the image data storage unit 18 and obtain respiratory information. .

  Based on the determination result in the contrast determination unit 19, the determination result in the heart rate determination unit 20, and the respiration information obtained in the respiration information acquisition unit 21, the mask image storage unit 22 beats the heart at a specific heart rate. X-ray image data for at least one breath of the tachycardia period is acquired from the image data storage unit 18 and stored as mask image data of a plurality of frames corresponding to at least one breath.

  In practice, the mask image data storage destination is also the image data storage unit 18, and the mask image storage unit 22 supplies identification information indicating mask image data to the X-ray image data stored in the image data storage unit 18. You may make it add.

  The mask image data is X-ray image data for use in difference processing for generating difference image data. Typical examples of the difference image data are road map image data and DSA image data.

  Roadmap image data is an image that includes mask image data in a state in which a contrast medium has been injected into a blood vessel in advance, and includes a difference process between the live image data and the mask image data that are acquired without injection of contrast medium. This is image data obtained by rendering blood vessels on live image data by processing. On the other hand, DSA image data is generated by a difference process between mask image data collected before injection of a contrast agent and X-ray contrast image data collected by administering the contrast agent.

  Therefore, when the road map image data is a target to be generated as diagnostic image data, X-ray image data for at least one respiratory cycle during contrast that may be used for generation of the road map image data is a mask image. Stored as data. On the other hand, when the DSA image data is a target to be generated as diagnostic image data, X-ray image data for at least one breathing period during non-contrast imaging that may be used for generating DSA image data is mask image data. Is remembered as The determination as to whether the X-ray image data has been collected during contrast or non-contrast can be made based on the determination result in the contrast determination unit 19.

  Based on the determination result in the contrast determination unit 19, the determination result in the heart rate determination unit 20, and the respiration information obtained in the respiration information acquisition unit 21, the mask image determination unit 23 beats the heart at a specific heart rate. The mask image data corresponding to the respiratory phase of the X-ray image data collected as the live image data for generating the difference image data during the period is acquired from the mask image storage unit 22, and road map image data, DSA image data, etc. It has a function of determining as mask image data for difference processing for generating difference image data.

  The difference image creation unit 24 obtains X-ray image data collected as live image data from the image data storage unit 18, and obtains mask image data corresponding to the respiratory phase of the live image data from the mask image determination unit 23. In addition, it has a function of generating difference image data such as road map image data and DSA image data by difference processing between live image data and mask image data. That is, the difference image creating unit 24 collects difference image data by performing a difference process between live image data and mask image data, which are collected in a heart tachycardia state in which a change in position due to pulsation can be ignored, and whose respiratory phases can be regarded as equivalent. Configured to generate.

  The live image data can be collected as X-ray image data of a plurality of frames for an arbitrary period of not less than one breath period but not less than two breath periods. Accordingly, the difference image data can also be generated as a plurality of frames of X-ray image data corresponding to an arbitrary respiratory cycle.

  The difference image data created in the difference image creation unit 24 can be displayed on the display device 6 through the display processing unit 28. Further, the difference image data can be stored in the image data storage unit 18 as necessary.

  The misalignment detection image storage unit 25 is obtained by the determination result in the heart rate determination unit 20 and the respiration information acquisition unit 21 when instruction information is given from the input device 5 or from the input device 5 through the system control unit 3C. Based on the respiration information, X-ray image data for at least one respiration period of the period corresponding to the tachycardia state in which the heart is beating at a specific heart rate is acquired from the image data storage unit 18 for detecting displacement Has a function of storing as X-ray image data serving as a reference. When the reference image data for detecting misregistration is either X-ray contrast image data or X-ray non-contrast image data, the determination result in the contrast determination unit 19 can be referred to when the reference image data is stored.

  The misalignment detection image determination unit 26 is obtained by the determination result in the heart rate determination unit 20 and the respiratory information acquisition unit 21 when instruction information is given from the input device 5 or from the input device 5 through the system control unit 3C. Based on the respiration information, reference image data corresponding to the respiration phase of the X-ray image data collected during a period in which the heart is beating at a specific heart rate is acquired from the misalignment detection image storage unit 25, and the misalignment is detected. It has a function of determining as reference image data used for detection processing.

  The positional deviation detection unit 27 is an X-ray image that is a device positional deviation detection target acquired from the image data storage unit 18 when instruction information is given from the input device 5 or from the input device 5 through the system control unit 3C. A function for detecting an index corresponding to the position or position of the device from both the data and the reference image data for detecting the position shift determined by the position shift detection image determination unit 26, and an index corresponding to the detected position or position of the device Is detected between the X-ray image data and the reference image data.

  For example, the device position shift between the X-ray image data to be detected and the reference image data for detecting position shift is, for example, a device position shift amount equal to or greater than a certain distance by threshold processing for the shift amount between device positions. It can be detected as a case. In addition to image processing for extracting the device outline, such as edge extraction processing, the device position is detected by detecting a marker attached to the device and using the marker position as the device position. it can.

  However, instead of detecting the position of the device, the position shift of the device can also be detected by obtaining an index indicating the amount of position shift of the device between the X-ray image data to be detected and the reference image data. . For example, a signal amount or size in an area in which luminance considered as an area occupied by a device in reference image data such as difference image data is equal to or less than a certain value can be defined as a reference value. Then, a signal amount or size in an area where the luminance that is considered to be an area occupied by the device is determined as a comparison value from the X-ray image data that is a detection target of the device positional deviation is obtained as a comparison value. If there is a divergence as described above, it can be determined that the device has been displaced. In other words, the amount of signal or the amount of change in size in a region where the luminance is below a certain value can be used as an index indicating the amount of positional deviation of the device.

  Note that a signal amount or a change in size in a region where the luminance considered to be a region occupied by a blood vessel is larger than a certain value can be used as an index indicating the amount of positional deviation of the device. However, depending on the degree of staining of the contrast agent, the signal amount or size in a region where the luminance is greater than a certain value may change. Therefore, it is desirable to detect the positional deviation of the device based on a change in signal amount or size in the area occupied by the device.

  In this case, the signal amount or size in the region occupied by the device is ideally zero before the device is inserted. For this reason, it is also possible to execute error processing for excluding the reference image data before device insertion from the device misregistration detection processing by threshold processing. Alternatively, when the amount of signal or size change in the area occupied by the device exceeds a threshold value, error processing can be executed so that it is not detected as a device displacement.

  Note that the threshold processing for detecting the positional deviation of the device is not limited to the difference between the indices according to the position of the device or the position, but may be performed on the ratio.

  In addition, examples of a device that is a detection target of displacement include an artificial valve, a balloon, or a catheter that is an indwelling target at the position of the aortic valve in TAVR.

  Then, the positional deviation detection unit 27 outputs warning information to the display device 6 or other output device when a positional deviation of the device is detected between the live image data and the reference image data for positional deviation detection. Configured as follows. As warning information, in addition to image information such as a message, voice information and lighting or blinking of a warning lamp can be cited.

  The display processing unit 28 is a necessary image for displaying the desired X-ray image data such as the difference image data generated by the difference image creating unit 24 and the X-ray image data stored in the image data storage unit 18. It has a function of processing and outputting to the display device 6. Display image processing includes display processing such as gradation processing and spatial filter processing. Further, the X-ray image data to be displayed can be instructed to the display processing unit 28 from the input device 5 or from the input device 5 through the system control unit 3C.

  It is sufficient that the live image data and the mask image data collected for generating the difference image data can be collected only during a tachycardia period in which the heart is beating at a specific heart rate. Therefore, controlling the imaging system 2 so that the subject O is irradiated with X-rays only during a tachycardia state where the heart is beating at a specific heart rate leads to a reduction in exposure of the subject O. Therefore, the control system 3 obtains a determination result as to whether or not the heart is beating at a specific heart rate from the heart rate determination unit 20, and is applied only during a period in which the heart is beating at a specific heart rate. The imaging system 2 can be controlled so that the specimen O is irradiated with X-rays.

  In the medical image processing apparatus 15 having the above configuration, at least the image acquisition unit 17, the heart rate determination unit 20, the respiratory information acquisition unit 21, and the mask image determination unit 23 have a heart beat at a specific heart rate. It functions as an image acquisition means for acquiring the first X-ray image data and the second X-ray image data of the subject O that are collected during a certain period and whose respiratory phases correspond to each other. In addition, at least the difference image creation unit 24 functions as difference image generation means for generating difference image data by difference processing between the first X-ray image data and the second X-ray image data.

  Therefore, when the medical image processing apparatus 15 is configured by a computer, a medical image processing program that causes the computer to function as an image acquisition unit and a difference image generation unit is installed in the computer.

  Furthermore, the image acquisition means cooperates with the imaging system 2 and the control system 3, so that the X-ray imaging apparatus 1 has a respiratory phase corresponding to each other during a period in which the heart is beating at a specific heart rate. A function as an image collecting means for collecting the first X-ray image data and the second X-ray image data of the specimen O is provided.

  In addition, at least by the misalignment detection image determination unit 26 and the misalignment detection unit 27, a plurality of X-ray image data is collected from a plurality of frames of X-ray image that are collected during a period in which the heart is beating at a specific heart rate and whose respiratory phases correspond to each other. The medical image processing apparatus 15 and the X-ray imaging apparatus 1 are provided with a function as a positional deviation detection means for outputting warning information to the output device when a positional deviation of the device between the X-ray image data of the frames is detected.

  The image acquisition means is configured to acquire first X-ray image data of a plurality of frames for one breathing period, and acquire second X-ray image data of a plurality of frames for two breathing periods or more. The difference image generation means can be configured to repeatedly use the first X-ray image data of a plurality of frames for one respiration cycle for the difference processing.

  The image acquisition means is configured to acquire the X-ray contrast image data and the X-ray non-contrast image data as the first X-ray image data and the second X-ray image data, and the difference image generation means Road map image data or DSA image data can be generated as the image data.

  Furthermore, the image acquisition means of the X-ray imaging apparatus 1 can be configured to irradiate the subject O with X-rays only during a period in which the heart is beating at a specific heart rate.

  However, if the medical image processing apparatus 15 and the X-ray imaging apparatus 1 have the same functions as those described above, the medical image processing apparatus 15 and the X-ray imaging apparatus 1 can be configured by other components.

  Next, operations and effects of the medical image processing apparatus 15 and the X-ray imaging apparatus 1 will be described.

  First, a case where a road map image is generated and displayed by the medical image processing apparatus 15 and the X-ray imaging apparatus 1 will be described as an example.

  FIG. 5 is a time chart showing a flow when road map image data is generated by the medical image processing apparatus 15 and the X-ray imaging apparatus 1 shown in FIG.

  As shown in FIG. 5, when road map image data is collected, live image data is collected without contrast after injecting a contrast medium in advance and collecting mask image data.

  Specifically, a tachycardia state in which the heart rate of the heart becomes a specific heart rate is artificially created using a pacing catheter during a predetermined period from time t0 to time t1. Furthermore, a contrast medium is injected within a tachycardia state in which the heart rate of the heart is a specific heart rate. Then, X-ray contrast image data for at least one respiratory cycle is collected as mask image data within the contrast agent injection period.

  Next, a tachycardia state in which the heart rate of the heart becomes a specific heart rate is artificially created using a pacing catheter during a predetermined period from time t1 to time t2. Further, live image data is sequentially collected without contrast within a tachycardia state in which the heart rate of the heart is a specific heart rate.

  When live image data is collected, mask image data that can be regarded as having the same respiratory phase is selected for each frame. That is, the respiration synchronization process of the mask image data is executed. Then, difference processing for subtracting the live image data from the mask image data corresponding to the respiratory phase is sequentially executed for each frame. That is, the difference process with the synchronization of the respiratory phase is executed. Thus, a plurality of frames of road map image data corresponding to each respiratory phase are sequentially generated.

  Similar collection of live image data, selection of mask image data corresponding to the respiratory phase, and generation of road map image data by difference processing can be performed over a plurality of respiratory cycles. Thereby, generation and display of road map image data over a plurality of breathing cycles becomes possible.

  FIG. 6 is a flowchart illustrating an example of a flow including determination processing for collecting and storing mask image data illustrated in FIG.

  First, in step S1, the subject O is set on the top plate of the bed 10, and X-ray imaging of the subject O is executed. Specifically, a control signal corresponding to the imaging condition is output from the imaging position control device 3B of the control system 3, and the drive mechanism 9 is driven. Thereby, the X-ray irradiation part 7 and the X-ray detector 8 are positioned in a predetermined position. On the other hand, a high voltage is applied from the high voltage generator 3 </ b> A of the control system 3 to the X-ray tube of the X-ray irradiation unit 7. Thereby, X-rays are exposed from the X-ray tube to the imaging region of the subject O. X-rays transmitted through the subject O are detected by the X-ray detector 8.

  Next, an X-ray detection signal is output from the X-ray detector 8 to the medical image processing apparatus 15 via the A / D converter 14. Accordingly, digitized X-ray detection data is acquired in the image generation unit 16. The image generation unit 16 generates X-ray image data by performing known data processing on the X-ray detection data.

  The X-ray image data generated by the image generation unit 16 is given to the image acquisition unit 17. Then, the image acquisition unit 17 writes and stores the acquired X-ray image data in the image data storage unit 18.

  Next, in step S2, the contrast determination unit 19 obtains the contrast agent information indicating whether or not the contrast agent is being injected from the system control unit 3C, thereby determining whether or not the contrast agent is being injected. judge. This determination is sequentially executed for each frame every time X-ray image data is collected.

  When capturing mask image data for road map image data, a contrast agent is injected from the contrast agent injection device 13 into the subject O in a state where rapid pacing of the heart has been applied in advance. For this reason, if the collected X-ray image data is mask image data, the contrast determination unit 19 determines that the X-ray image data is collected during the contrast.

  In this case, in step S3, the heart rate determination unit 20 determines whether or not the X-ray image data is collected during a period in which the heart is beating at a specific heart rate corresponding to the tachycardia state. 12 based on the heart rate acquired from 12. If the X-ray image data is mask image data, since it is collected during rapid pacing of the heart, it is determined that the X-ray image data was collected during a period in which the heart is beating at a specific heart rate.

  In this case, in step S4, the mask image storage unit 22 determines whether or not acquisition of X-ray image data for one cycle of respiration has been completed. If it is determined that the acquisition of X-ray image data for one respiratory cycle has not been completed, in step S5, the X-rays collected when the mask image storage unit 22 is performing contrasting and has a specific heart rate. Save the image data as mask image data.

  On the other hand, if the acquired X-ray image data is not mask image data, it is not determined that the acquired X-ray image data was acquired during contrast and during a specific heart rate period. For this reason, in step S6, it is preserve | saved in the image data memory | storage part 18 as non-mask image data. Even when the acquisition of X-ray image data for one respiratory cycle is completed, the image data is stored in the image data storage unit 18 as non-mask image data in step S6.

  When displaying X-ray image data stored as mask image data or non-mask image data, in step S7, the display processing unit 28 acquires the X-ray image data and performs gradation processing necessary for display. Image processing such as spatial filter processing is performed. In step S8, the display processing unit 28 outputs the X-ray image data after the image processing to the display device 6. As a result, the X-ray image data stored as mask image data or non-mask image data is displayed on the display device 6.

  When such determination processing is sequentially executed for each frame of the X-ray image data, as a result, the mask image storage unit 22 stores the X-ray image data for one cycle of breathing that is collected during the period of contrast and during a specific heart rate. Are stored as mask image data.

  FIG. 7 is a flowchart showing an example of a flow including data processing for collecting and displaying the road map image data shown in FIG. The same steps as those in the flowchart shown in FIG.

  When roadmap image data is collected, live image data is collected without contrast during rapid pacing of the heart. Specifically, X-ray imaging is executed in step S1. As a result, the X-ray image data is stored in the image data storage unit 18.

  Next, in step S3, the heart rate determination unit 20 determines whether or not the X-ray image data is collected during a specific heart rate period. If the X-ray image data is for road map image data, it is collected during rapid pacing of the heart, so it is determined that the X-ray image data was collected during a specific heart rate period.

  In step S10, the collected X-ray image data is stored in the image data storage unit 18 as X-ray image data for difference processing.

  Next, in step S <b> 11, the mask image determination unit 23 determines that the collected X-ray image data has a specific heart rate period based on the determination result acquired from the heart rate determination unit 20 and the determination result in the contrast determination unit 19. It is determined that the image data is the live image data for differential processing collected without contrast. Subsequently, the mask image determination unit 23 recognizes the respiratory phase of the collected live image data for differential processing based on the respiratory information obtained by the respiratory information acquisition unit 21.

  Therefore, the mask image determination unit 23 acquires mask image data corresponding to the respiratory phase of the live image data for difference processing from the mask image storage unit 22. Then, the acquired mask image data is determined as mask image data for difference processing.

  In step S <b> 12, the difference image creation unit 24 executes a difference process between the live image data and the mask image data selected by the mask image determination unit 23. As a result, road map image data is generated.

  On the other hand, when it is determined that the live image data is not collected during the specific heart rate period, the live image data is stored in the image data storage unit 18 as live image data that is not for differential processing.

  When displaying road map image data or live image data that is not for differential processing, the display processing unit 28 performs necessary image processing in step S7. In step S8, road map image data after image processing or live image data not for difference processing is displayed on the display device 6.

  When data processing including such determination processing is sequentially executed for each frame of live image data, road map images can be sequentially displayed on the display device 6.

  Next, a case where a DSA image is generated and displayed by the medical image processing apparatus 15 and the X-ray imaging apparatus 1 will be described.

  FIG. 8 is a time chart showing a flow when DSA image data is generated by the medical image processing apparatus 15 and the X-ray imaging apparatus 1 shown in FIG.

  As shown in FIG. 8, when DSA image data is collected, mask image data is collected in advance without contrast, and then a contrast agent is injected to collect live image data. Therefore, DSA image data can be generated and displayed in the same flow as when road map image data is generated and displayed.

  That is, after collecting mask image data for one respiratory cycle in a specific heart rate period in a non-contrast manner beforehand, live image data for an arbitrary respiratory cycle can be collected in a specific heart rate period and during imaging. it can. Then, DSA image data can be sequentially generated and displayed by the difference processing between the mask image data accompanied by respiratory synchronization and the live image data.

  In the medical image processing apparatus 15 and the X-ray imaging apparatus 1, in addition to the display of the difference image such as the road map image and the DSA image, it is possible to detect the positional deviation of the device. The position shift can be detected in parallel with the generation and display of the difference image.

  As a specific example, in TAVR, there is a case where time is provided after the artificial valve is positioned while referring to an X-ray image such as a road map image and before the artificial valve is expanded. In this case, rapid pacing or X-ray irradiation may be interrupted. If the position of the prosthetic valve moves between the positioning and expansion of the prosthetic valve, the procedure becomes an obstacle. Therefore, it is possible to collect X-ray image data for detecting a positional deviation of a device such as an artificial valve, and to detect the positional deviation of the device using the X-ray image data for detecting the positional deviation.

  FIG. 9 is a time chart showing a flow in the case of detecting a device displacement in the medical image processing apparatus 15 and the X-ray imaging apparatus 1 shown in FIG.

  As shown in FIG. 9, rapid pacing can be performed during a predetermined period from time t1 to time t1 ′ after positioning of the artificial valve to provide a specific heart rate period. Furthermore, live image data for at least one respiratory cycle can be collected as reference image data for detecting displacement in a specific heart rate period. The reference image data for detecting misalignment can be X-ray contrast image data or X-ray non-contrast image data depending on the type of X-ray image data to be detected for misalignment.

  For example, when roadmap image data is collected, X-ray non-contrast image data can be collected as reference image data for detecting displacement. On the other hand, when DSA image data is collected, X-ray contrast image data can be collected as reference image data for detecting displacement.

  When the collection of the reference image data for detecting the displacement is completed, the live image data can be collected by performing rapid pacing for device confirmation. Specifically, rapid pacing can be performed during a predetermined period from time t1 ′ to time t2 to provide a specific heart rate period. Furthermore, during a specific heart rate period, live image data for an arbitrary respiratory cycle can be collected as image data to be detected for positional deviation of the device.

  Next, the reference image data corresponding to the respiratory phase corresponding to the X-ray image data to be detected as the device displacement is selected. That is, the respiration synchronization process of the reference image data is executed. Then, an index corresponding to the position or position of a device such as a prosthetic valve before expansion is detected by an arbitrary method from both X-ray image data and reference image data, which are detection targets of device positional deviation. Examples of the index corresponding to the position of the device include the size of the device area and the signal amount.

  Next, the detected position of the device or an index corresponding to the position is compared between the X-ray image data that is a detection target of the device position shift and the reference image data. When it is determined that the distance between the device positions or the difference between the indices is greater than or equal to the threshold value or exceeds the threshold value, it is recognized that the device has been displaced. When a device position shift is detected, warning information is output.

  FIG. 10 is a flowchart illustrating an example of a flow including a determination process for collecting the reference image data for detecting misalignment illustrated in FIG. Steps similar to those in the flowchart shown in FIG.

  FIG. 10 shows an example in which live image data for one respiratory cycle collected during a specific heart rate period is stored as reference image data for detecting a positional deviation of the device for generation of roadmap image data. Yes. Therefore, in step S3, it is determined whether or not it is a specific heart rate period.

  If it is determined that the period is a specific heart rate, in step S20, the misalignment detection image storage unit 25 determines whether or not to detect misalignment of the device. This determination can be made based on whether or not a misregistration detection image storage unit 25 is instructed to perform misregistration detection from the input device 5 or from the input device 5 through the system control unit 3C.

  If it is determined that the positional deviation detection is to be executed, the positional deviation detection image storage unit 25 acquires the collected live image data from the image data storage unit 18 in step S21, and detects the positional deviation of the device. Save as reference image data.

  When the collection of live image data is executed longer than the period of one respiration cycle, as in the case of storing the mask image data shown in FIG. 6, one respiration cycle as shown in step S4 in FIG. A step of determining whether or not the minute reference image data has been stored can be provided.

  When such a determination process is performed for each frame of the captured live image data, the live image data for one period of breath collected during a specific heart rate period is used as reference image data for detecting the positional deviation of the device. The misregistration detected image storage unit 25 can store the image. Actually, identification information indicating that the image data is the reference image data for detecting the positional deviation of the device may be added to the live image data stored in the image data storage unit 18.

  Regardless of whether the image is stored as reference image data, road map image data can be sequentially generated using live image data collected during a specific heart rate period as image data for difference processing.

  FIG. 11 is a flowchart showing the flow of the device misregistration detection process shown in FIG. The same steps as those in the flowchart shown in FIG.

  FIG. 11 shows an example of the case where the device positional deviation is detected using the reference image data stored in the flow shown in FIG. Even in the case of detecting misalignment, it is determined in step S3 whether or not it is a specific heart rate period.

  If it is determined that the period is a specific heart rate, in step S20, the misalignment detection image determination unit 26 determines whether or not to detect misalignment of the device. This determination can be performed based on whether or not an instruction to execute misregistration detection is given to the misregistration detection image determination unit 26 from the input device 5 or from the input device 5 through the system control unit 3C.

  If it is determined that the position shift detection is to be performed, the position shift detection image determination unit 26 is collected in the X-ray imaging in step S1 based on the respiration information obtained in the respiration information acquisition unit 21 in step S30. Recognize the respiratory phase of live image data. Next, the misregistration detection image determination unit 26 acquires reference image data corresponding to the breathing phase of the live image data from the misregistration detection image storage unit 25 and determines it as reference image data used for the device misregistration detection process. .

  Next, in step S <b> 31, the misregistration detection unit 27 is used to detect the misregistration determined in the live image data and misregistration detection image determination unit 26 to be detected from the device misregistration acquired from the image data storage unit 18. An index corresponding to the position of the device or the position is detected from both of the reference image data. Subsequently, the positional deviation detection unit 27 compares the detected position of the device or an index corresponding to the position between the live image data and the reference image data.

  Next, in step S <b> 32, the positional deviation detection unit 27 determines whether or not the positional deviation amount of the device is equal to or greater than a certain value by threshold processing for the position or index difference or ratio corresponding to the device position.

  If it is determined that the amount of positional deviation of the device is greater than or equal to a certain value, in step S33, the positional deviation detection unit 27 selects any message, voice, optical information, etc. indicating that the positional deviation of the device has been detected. Are output to the display device 6 or other output devices. Thereby, even if a device in which movement of an artificial valve or the like, which is not desirable after positioning and before expansion, should move, it is possible to easily know the movement of the device.

  In addition, live image data collected during a specific heart rate period can be used as image data for differential processing, and road map image data can be sequentially generated and displayed.

  In other words, the medical image processing apparatus 15 and the X-ray imaging apparatus 1 as described above generate differential image data by differential processing with respiratory synchronization of only image data collected during a specific heart rate period. is there.

  For this reason, according to the medical image processing apparatus 15 and the X-ray imaging apparatus 1, a difference image can be generated with a good image quality even in a part such as the heart where respiration and heartbeat are affected at different periods. Can do.

  That is, the positional shift of the mask image data with respect to the live image data due to the influence of the motion of the heart can be suppressed by executing rapid pacing during imaging to bring the heart into a tachycardia state. In particular, collecting image data in a higher heart rate period leads to a reduction in displacement. On the other hand, displacement of the mask image data such as blood vessels due to the influence of respiration with respect to the live image data can be suppressed by respiration synchronization.

  In other words, since ECG synchronization for adjusting the cardiac phase is not performed prior to the difference processing, it is possible to avoid a positional shift between the image data due to the difference between the heartbeat and breathing cycles. Then, a difference image can be generated by difference processing between image data with less positional deviation. For this reason, it is possible to effectively support procedures such as artificial valve positioning in TAVR.

  Further, in the medical image processing apparatus 15 and the X-ray imaging apparatus 1, it is sufficient to collect X-ray images only during a specific heart rate period, so that X-rays are irradiated only during a specific heart rate period. Patient and operator exposure can be reduced. Furthermore, it is possible to reduce the amount of contrast medium injected.

  Furthermore, the medical image processing apparatus 15 and the X-ray imaging apparatus 1 can detect a device position shift. For this reason, even when a device in which movement of an artificial valve or the like after positioning and before expansion is not desirable is left for a certain period, the movement of the device can be easily detected. Further, not only an organ or organ position shift due to movement of the subject O such as heartbeat or respiration, but also adverse effects on the procedure due to device position shift can be suppressed.

  Although specific embodiments have been described above, the described embodiments are merely examples, and do not limit the scope of the invention. The novel methods and apparatus described herein can be implemented in a variety of other ways. Various omissions, substitutions, and changes can be made in the method and apparatus described herein without departing from the spirit of the invention. The appended claims and their equivalents include such various forms and modifications as are encompassed by the scope and spirit of the invention.

DESCRIPTION OF SYMBOLS 1 X-ray imaging apparatus 2 Imaging system 3 Control system 3A High voltage generator 3B Imaging position control apparatus 3C System control part 4 Data processing system 5 Input device 6 Display apparatus 7 X-ray irradiation part 8 X-ray detector 9 Drive mechanism 10 Bed DESCRIPTION OF SYMBOLS 11 Respiration sensor 12 Electrocardiograph 13 Contrast agent injection apparatus 14 A / D converter 15 Medical image processing apparatus (computer)
16 Image generation unit 17 Image acquisition unit 18 Image data storage unit 19 Contrast determination unit 20 Heart rate determination unit 21 Respiration information acquisition unit 22 Mask image storage unit 23 Mask image determination unit 24 Difference image creation unit 25 Misalignment detection image storage unit 26 Misalignment detection image determination unit 27 Misalignment detection unit 28 Display processing unit O Subject

Claims (7)

Image acquisition means for acquiring first X-ray image data and second X-ray image data of a subject collected during a period when the heart is beating at a specific heart rate and corresponding to each other in respiratory phase;
Differential image generation means for generating differential image data by differential processing of the first X-ray image data and the second X-ray image data;
A medical image processing apparatus comprising: The image acquisition means is configured to acquire first X-ray image data of a plurality of frames for one respiration cycle, while acquiring second X-ray image data of a plurality of frames for two respiration cycles,
The medical image processing apparatus according to claim 1, wherein the difference image generation unit is configured to repeatedly use the first X-ray image data of a plurality of frames for one cycle of respiration for the difference processing.   Device misalignment between the plurality of frames of X-ray image data was detected from the plurality of frames of X-ray image data collected during a period in which the heart beats at the specific heart rate. The medical image processing apparatus according to claim 1, further comprising a positional deviation detection unit that causes the output device to output warning information. The image acquisition means is configured to acquire X-ray contrast image data and X-ray non-contrast image data as the first X-ray image data and the second X-ray image data,
The medical image processing apparatus according to any one of claims 1 to 3, wherein the difference image generation unit is configured to generate road map image data or DSA image data as the difference image data. Image collection means for collecting first X-ray image data and second X-ray image data of a subject whose respiratory phases correspond to each other during a period in which the heart is beating at a specific heart rate;
Differential image generation means for generating differential image data by differential processing of the first X-ray image data and the second X-ray image data;
An X-ray imaging apparatus comprising:   The X-ray imaging apparatus according to claim 5, wherein the image collecting unit is configured to irradiate the subject with X-rays only during a period in which the heart is beating at the specific heart rate. Computer
Image acquisition means for acquiring first X-ray image data and second X-ray image data of a subject collected during a period when the heart is beating at a specific heart rate and corresponding to each other in respiratory phase; and Differential image generation means for generating differential image data by differential processing of the first X-ray image data and the second X-ray image data;
Medical image processing program to function as

Images