JP2020078462A - X-ray diagnostic system and reconstruction processing system - Google Patents

Abstract

To perform highly accurate correction by acquiring data for the motion of a subject.SOLUTION: An X-ray diagnostic system includes: a scan unit which executes scanning using the X-ray to a subject to collect projection data on the basis of the X-ray; a monitoring unit which monitors the body motion of the subject in parallel with the scanning to acquire body motion information corresponding to the projection data; and a reconstruction processing unit which performs reconstruction processing by applying the weight according to the body motion information to the projection data to generate reconstruction image data.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention relate to an X-ray diagnostic system and a reconstruction processing system.

  An X-ray diagnostic apparatus that performs X-ray imaging by irradiating a subject with X-rays and detecting X-rays that have passed through the subject is widely used in the medical field. As one of the image acquisition methods in the X-ray diagnostic apparatus, the subject is positioned so as to face between the X-ray emitting device and the X-ray detector, and the X-ray emitting device and the X-ray detector are attached to the subject. There is a method of taking an image by rotating around and reconstructing an image based on the result detected by the X-ray detector. If the subject moves at the timing of X-ray exposure and detection, blurring or blurring occurs in the image acquired by reconstruction. As a method of reducing the influence of this movement (body movement), there is body movement correction (APMC).

  When performing reconstruction, APMC corrects body movement by weighting the data detected by the X-ray detector and performing reconstruction. However, since the above processing is performed regardless of the magnitude of the movement of the subject, the timing of the movement, etc., almost no effect may be obtained depending on the timing of the body movement. Therefore, if there is movement, the user confirms the image after reconstructing the image from the projection data and reconstructs the image including the APMC process. Alternatively, after the image is reconstructed, the subject is again exposed to X-rays, re-imaging is performed, and then the image is re-constructed.

JP, 2012-34972, A

  The present embodiment provides an X-ray diagnostic system and a reconstruction processing system that perform highly accurate correction by acquiring data regarding the movement of a subject.

According to one embodiment, the X-ray diagnostic system comprises
A scan unit that executes a scan using X-rays on a subject and collects projection data based on the X-rays;
A monitoring unit that monitors the body movement of the subject in parallel with the scan and acquires body movement information corresponding to the projection data,
A reconstruction processing unit that applies reconstruction weights to the projection data by applying weights according to the body movement information and generates reconstructed image data;
Equipped with.

The block diagram which shows an example of the whole structure of the X-ray diagnostic system which concerns on one Embodiment. 6 is a flowchart illustrating an example of image reconstruction processing according to an embodiment. 9 is a flowchart showing another example of image reconstruction processing according to an embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the weight which concerns on one Embodiment. The figure which shows an example of the parameter change which concerns on one Embodiment.

  Hereinafter, the X-ray diagnostic system and the reconstruction processing system according to the present embodiment will be described with reference to the drawings. In the following description, components having almost the same functions and configurations are designated by the same reference numerals, and duplicate description will be given only when necessary.

(First embodiment)
FIG. 1 is a diagram illustrating the overall configuration of an X-ray diagnostic system 1 according to an embodiment. The X-ray diagnostic system 1 is an example of a medical apparatus including the image processing apparatus according to the present embodiment, and the image processing apparatus according to the present embodiment can be applied to various X-ray diagnostic apparatuses such as a general imaging apparatus. The X-ray diagnostic system includes, for example, a gantry device 10, a bed device 30, and a console device 40.

  The gantry device 10 includes an X-ray generator 11, an X-ray detector 12, a rotating body 13, an X-ray high-voltage device 14, a gantry controller 15, a monitoring unit 16, and a data acquisition circuit 18. Prepare

  The X-ray generator 11 is an X-ray irradiator that performs X-ray irradiation, and receives high-voltage power from the X-ray high-voltage device 14 to generate heat from the cathode (filament) toward the anode (target). An X-ray tube (vacuum tube) for irradiating electrons is provided.

  The X-ray generator 11 is not limited to the X-ray tube. For example, the X-ray generator 11 collides with a focus coil that converges an electron beam generated from an electron gun, a deflection coil that electromagnetically deflects the electron beam, and a deflected electron beam that surrounds a half circumference of the subject P instead of the X-ray tube. And a target ring for generating X-rays.

  The X-ray detector 12 includes, for example, a plurality of X-ray detection element arrays in which a plurality of X-ray detection elements are arranged in the channel direction along one arc centering on the focal point of the X-ray tube. The X-ray detector 12 has a structure in which a plurality of X-ray detection element rows in which a plurality of X-ray detection elements are arranged in the channel direction are arranged in the slice direction. The X-ray detector 12 detects the X-rays that have been emitted from the X-ray generator 11 and passed through the subject P, and outputs an electric signal corresponding to the X-ray dose to the data acquisition circuit 18.

  In addition, the X-ray detector 12 may be, for example, an indirect conversion type detector including a grid, a scintillator array, and an optical sensor array. The scintillator array includes a plurality of scintillators, and the scintillator includes a scintillator crystal that outputs a photon amount of light according to the incident X-ray dose. The grid is provided on the surface of the scintillator array on the X-ray incident side and includes an X shield plate having a function of absorbing scattered X-rays. The photosensor array has a function of converting into an electric signal according to the amount of light from the scintillator, and is configured to include a photosensor such as a photomultiplier tube, for example.

  The X-ray detector 12 is not limited to the indirect conversion type detector, and may be a direct conversion type detector including a semiconductor element that directly converts an incident X-ray into an electric signal.

  The rotating body 13 is rotatably instructed with the center of the rotating body 13 as a rotation axis, and is driven to rotate under the control of the gantry control device 15. The X-ray generator 11 and the X-ray detector 12 are provided in the gantry device 10 together with the rotating body 13 as a rotating unit that rotates according to the rotational drive of the rotating body 13. The rotating part is provided in the fixed part fixed to the gantry device 10, and is rotationally driven with respect to the fixed part.

  In the present embodiment, for example, the X-ray generator 11, the X-ray detector 12, and the rotating body 13 are collectively referred to as a scanning unit. The scanning unit may indicate the X-ray detector 12 in a narrow sense, or may include the X-ray high-voltage device 14, the data acquisition circuit 18, and the like described below in a broad sense. The scanning unit is a set of modules or devices having a function of performing a scan using X-rays on the subject P in this way and collecting projection data based on X-rays, or the module or device itself. Indicates.

  The X-ray high-voltage device 14 includes an electric circuit such as a transformer and a rectifier, and has a function of generating a high voltage applied to the X-ray generator 11, and the X-ray generator 11. And an X-ray control device that controls the output voltage according to the X-rays emitted by the. The high voltage generator may be a transformer type or an inverter type.

  The gantry control device 15 includes a processing circuit including a CPU (Central Processing Unit) and the like, and a drive mechanism including a motor, an actuator, and the like. The gantry control device 15 has a function of receiving an input signal from an input device attached to the console device 40 or the gantry device 10 and controlling the operation of the gantry. For example, the gantry control device 15 operates as a rotation mechanism that controls the rotation of the rotating body 13 in response to an input signal, controls the tilting of the gantry device 10, and operates the bed device 30 and the top plate 33. Take control.

  The monitoring unit 16 monitors the subject P, and when the subject P has a movement, acquires the body movement information that is information about the movement. The monitoring unit 16 includes devices such as an optical camera, a pressure sensor, and a sound collector that can detect the movement of the subject P. The monitoring unit 16 may be provided in the gantry device 10 or the bed device 30, for example. The monitoring unit 16 is installed at a position on the plane on which the rotating body 13 rotates so as not to interfere with scanning, and detects the movement of the subject P on the scan plane at the timing at which the subject P is scanned. That is, the monitoring unit 16 monitors the body movement of the subject P in parallel with the scanning by the scanning unit and acquires the body movement information corresponding to the projection data. The acquired data is transmitted to the console device 40 via a wireless or wired route.

  The data acquisition circuit (DAS: Data Acquisition System) 18 is an amplifier that amplifies an electric signal output from each X-ray detection element of the X-ray detector 12, and an A/A that converts the electric signal into a digital signal. At least a D converter is provided to generate detection data (pure raw data). The detection data generated by the data collection circuit 18 is transferred to the console device 40. Further, the data collection circuit 18 may be connected to the monitoring unit 16, and in this case, the data collection circuit 18 also collects the body movement information acquired by the monitoring unit 16 and transfers it to the console device 40.

  The bed device 30 is a device for placing and moving the subject P to be scanned, and includes a base 31, a bed driving device 32, a top plate 33, and a support frame 34.

  The base 31 is a housing that supports the support frame 34 so as to be vertically movable. The bed driving device 32 is a motor or an actuator that moves the support frame on which the subject P has been cured in the long axis direction of the support frame 34. The top plate 33 provided on the upper surface of the support frame 34 is a plate on which the subject P is placed.

  As for the top plate 33, only the top plate 33 may be moved, or a method of moving the support frame 34 of the bed apparatus 30 may be used. When the present embodiment is applied to the upright CT, a method of moving a patient moving mechanism corresponding to the top plate 33 may be used.

  When performing a scan (helical scan, positioning scan, etc.) that involves a relative change in the positional relationship between the imaging system of the gantry device 10 and the top plate 33, the relative change in the positional relationship drives the top plate 33. May be performed, the gantry device 10 may be moved, or a combination thereof may be performed.

  The console device 40 includes a storage circuit 41, a display device 42, an input device 43, and a processing circuit 44.

  The storage circuit 41 is realized by, for example, a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, or the like. The storage circuit 41 stores, for example, projection data and reconstructed image data. In the present embodiment, the storage circuit 41 includes, for example, an image storage circuit 411, a body movement data storage circuit 412, and a program storage circuit 413.

  The image storage circuit 411 is a circuit that stores image data of medical images captured by the gantry device 10. The body movement data storage circuit 412 stores, for each image stored in the image storage circuit 411, body movement data indicating whether the subject P has moved or indicating the magnitude of movement of the subject P. Circuit. The program storage circuit 413 is a circuit that stores various programs. Each of these storage circuits may not be provided as a separate storage circuit, and may be used by dividing an area corresponding to each storage circuit in one or a plurality of memories, or It may be used as each memory circuit by securing a necessary capacity at the timing.

  The display device 42 displays various information. The display device 42 outputs, for example, a medical image (CT image) generated by the processing circuit 44, a GUI (Graphical User Interface) for receiving various operations from the operator, and the like. The display device 42 includes a liquid crystal display, a CRT (Cathode Ray Tube), a plasma display, and the like.

  The input device 43 receives various input operations from the operator, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuit 44. The input device 43 receives from the operator, for example, collection conditions for collecting projection data, reconstruction conditions for reconstructing CT images, image processing conditions for generating post-processed images from CT images, and the like. .. For example, in the present embodiment, parameters relating to weights described below may be input. The input device 43 includes a mouse, a trackball, a keyboard, a switch, a button, a joystick and the like. Alternatively, the display device 42 and the input device 43 described above may include a touch panel or the like capable of both display and input.

  The processing circuit 44 controls the overall operation of the X-ray diagnostic system 1 according to the electric signal of the input operation output from the input device 43. In the present embodiment, the processing circuit 44 includes, for example, the system control function 441, the preprocessing function 442, the reconstruction processing function 443, the image acquisition function 444, the extraction function 445, the calculation function 446, the generation function 447, and the display function. 448.

  In the embodiment in FIG. 1, the system control function 441, the preprocessing function 442, the reconstruction processing function 443, the image acquisition function 444, the extraction function 445, the calculation function 446, the generation function 447, and the display function 448 are performed. The processing functions are stored in the program storage circuit 413 of the storage circuit 41 in the form of a program executable by a computer. The processing circuit 44 is a processor that realizes a function corresponding to each program by reading the program from the program storage circuit 413 of the storage circuit 41 and executing the program. In other words, the processing circuit in the state where each program is read out has the respective functions shown in the processing circuit 44 of FIG.

  In FIG. 1, the system control function 441, the preprocessing function 442, the reconstruction processing function 443, the image acquisition function 444, the extraction function 445, the calculation function 446, the generation function 447, and the display in the single processing circuit 44 are displayed. Although it has been described that the processing function performed by the function 448 is realized, the processing circuit 44 may be configured by combining a plurality of independent processors and each processor may execute the program to realize the function. Good.

  Among these functions, the system control function 441 controls various functions of the processing circuit 44 based on the input operation received from the operator via the input device 43.

  The pre-processing function 442 generates data that has been subjected to pre-processing such as logarithmic conversion processing, offset correction processing, interchannel sensitivity correction processing, and beam hardening correction for the scanned data output from the data collection circuit 18. To do. The data before preprocessing and the data after preprocessing may be collectively referred to as projection data.

  The pre-processing function 442 may further process the body movement data output from the data collection circuit 18 and acquired by the monitoring unit 16 to calculate weights for image reconstruction.

  The reconstruction processing function 443 performs reconstruction processing using the filtered backprojection method, the successive approximation reconstruction method, or the like on the projection data generated by the preprocessing function 442 to obtain a reconstruction image (CT image data). ) Is generated. Reconstruction is performed using weighting based on body movement data. The reconstructed image is stored in, for example, the image storage circuit 411 of the storage circuit 41. The CT image data is a set of CT values, and is an example of medical images of a plurality of phases in the present embodiment. That is, the reconstructed image is stored in the image storage circuit 411 of the storage circuit 41 as an image including a temporal element.

  The image acquisition function 444 acquires, for example, reconstructed images of a plurality of time phases stored in the image storage circuit 411 of the storage circuit 41. Alternatively, data of reconstructed images of a plurality of time phases generated by the reconstruction processing function 443 is acquired. The extraction function 445 extracts a predetermined region of interest from the data of the reconstructed images of a plurality of time phases. The calculation function 446 calculates a CT value regarding a predetermined region of interest. The generation function 447 generates, for example, an image in which CT values are arranged in spatial position and time series along a predetermined region of interest. The display function 448 generates a display image based on the image generated by the generation function 447 and displays it on the screen of the display device 42.

  As described above, in the present embodiment, the processing circuit 44 is composed of, for example, a processor. Here, the word processor means, for example, a CPU, a GPU (Graphics Processing Unit), an application-specific integrated circuit (ASIC), a programmable logic device (for example, a simple programmable logic device (SPLD: Simple Programmable). Logic Device), a complex programmable logic device (CPLD: Complex Programmable Logic Device), or a field programmable gate array (FPGA: Field Programmable Gate Array). The processor realizes the function by reading and executing the program stored in the storage circuit 41. The storage circuit 41 may directly incorporate the program in the circuit of the processor, instead of storing the program. In this case, the processor realizes the function by reading and executing the program incorporated in the circuit. The processor is not limited to being configured as a single circuit of the processor, and may be configured as a single processor by combining a plurality of independent circuits to realize the function thereof. Furthermore, the plurality of constituent elements in FIG. 1 may be integrated into one or a plurality of processors to realize their functions.

  In the X-ray diagnostic system 1 of FIG. 1, the components of the console device 40 are stored in one housing, but these components of the console device 40 are not necessarily stored in one housing. There is no need to be present, and there may be a plurality of units stored in separate housings. For example, the processing circuits such as the preprocessing function 442 and the reconstruction processing function 443 may be dispersedly provided. In other words, the console device 40 may execute a plurality of functions by different consoles instead of executing a plurality of functions by a single console.

  Further, in the X-ray diagnostic system 1, an X-ray generator 11 and an X-ray detector 12 are integrally arranged, and rotate/rotate-type (third generation CT) that rotates around the subject P and is arrayed in a ring shape. There are various types such as Stationary/Rotate-Type (fourth generation CT) in which a large number of X-ray detection elements are fixed and the X-ray generation device 11 rotates around the subject P, and any type is used in the present embodiment. Can be applied to. Further, the X-ray diagnostic system 1 is not limited to the X-ray CT system described above, and may be an X-ray angiography system in which an X-ray irradiation unit and an X-ray detection unit are instructed by an arm. Can also be applied to this embodiment.

  FIG. 2 is a flowchart showing the flow of processing from acquisition of X-ray projection data to image reconstruction according to this embodiment. This flow chart shows the processing from the start of scanning to the reconstruction of the image, and other controls such as the control of the bed apparatus are not described, but other controls are also appropriately performed in parallel. ..

  First, the scanning unit starts scanning the subject P (obtaining projection data) (S100). In parallel with this, the monitoring unit 16 starts monitoring the body movement of the subject P (S200). These operations are synchronously controlled when, for example, the user gives an instruction to start the operation via the input device 43. The start of body movement monitoring may be executed at least immediately before the start of scanning or at the same timing as the start of scanning. That is, separately from the activation of the scan unit, for example, the monitoring may be continued from the timing when the subject P is positioned on the bed apparatus 30. It suffices if the implementation is such that the timing of acquisition of projection data by scanning and the timing of acquisition of body movement information by monitoring can be synchronized.

  Next, the scanning unit scans the subject P (S102). While the scanning unit is scanning the subject P, the monitoring unit 16 monitors the body movement of the subject P (S202). That is, the monitoring unit 16 monitors the body movement in parallel with the execution of the scan by the scanning unit. In this way, by performing scanning and monitoring in parallel, it is possible to associate the scan result with the acquired body movement data when there is body movement.

  If the body movement is not sensed during the monitoring (S204: NO), the monitoring unit 16 continues to monitor the body movement (S202).

  On the other hand, when the body movement is detected (S204: YES), the body movement is continuously monitored (S202), and the projection data acquired by the scanning unit indicates whether the body movement is detected or the degree of the body movement. It is given and stored in the storage circuit 41 via the data collection circuit 18. This mounting means may be performed by any means, for example, by adding that the projection data scanned by the scanning unit has a body motion, and performing a process when there is a body motion in a subsequent reconstruction process. May be. As another example, the fact that there is a body movement is added to the projection data, and data indicating the degree of body movement is stored in the body movement data storage circuit 412, and processing is performed based on the degree of body movement in the reconstruction processing. You may

  When the necessary projection data is acquired, the scanning unit ends the scanning (S104). The necessary projection data is, for example, data acquired while orbiting the cross section when reconstructing an image of one cross section or a plurality of cross sections, and when data is acquired by a helical scan method. , Data acquired in a helical scan in a necessary area. At this timing, the monitoring unit 16 may be notified that the scan has been completed, or the monitoring unit 16 that has received the notification may end the monitoring.

  Next, the projection data is weighted (S106). The weighting is performed by, for example, the pre-processing function 442, and weighting is performed when performing reconstruction based on the body movement information given to each projection data. The first projection data, which is the projection data in the view determined to have the body motion, has a smaller weight than the second projection data, which is the projection data in the view determined to have no body motion. For example, assuming that the weight of the second projection data is 1, 1-β is set as the weight for the first projection data for the value 0<β≦1.

  Specifically, when the integral (discretely, sum) of the projection data in the process of performing reconstruction is calculated, 1-β is added as a weight and calculated for the first projection data. The projection data is used as it is for calculation to perform reconstruction. When there are a plurality of pieces of first projection data, the value of β is not a constant value but changes based on the magnitude (degree) of movement or the elapsed time from the start of body movement. Good. Further, even when there is only one piece of projection data to which body movement information is added, weights may be added to the views before and after the view of the projection data so that the weight changes gently.

  Further, the weight for the data facing the first projection data, for example, the third projection data acquired in the view shifted by 180° may be 1+β. In this way, by making the weights symmetrical between the opposing data, it is possible to reconstruct the image without impairing the circular symmetry of the reconstructed image as a whole. As described above, when the weights are added to the views before and after the view with respect to the first projection data, the weight may be added to the projection data opposite to the weighted projection data.

  A more detailed example of weighting will be described later.

  Next, the reconstruction processing function 443 executes image reconstruction based on the weighted projection data (S108). Regarding the reconstruction method, a general method such as filter backprojection is used, except that weighted projection data is used. In addition, processing executed during general reconstruction such as noise removal processing may be performed.

  The process of S106 and the process of S108 need not be separate processes, and may be reconstructed by weighting the projection data according to the body movement information at the timing of performing the process of S108. That is, the process of S106 may be executed at the timing of performing the process of S108, and in this case, the process of S106 can be omitted.

  As described above, according to the present embodiment, the timing at which the body movement information of the subject P acquired by the monitoring unit 16 is added to and stored in the projection data acquired by the scanning unit, and the image reconstruction is performed. In the above, by performing the weighting based on the body movement information and performing the reconstruction from the projection data, it becomes possible to perform the reconstruction of the image in which the influence of the movement of the subject P is reduced. From this, even when the subject P moves, it is possible to perform correction according to the motion, and it is possible to acquire an image of a level that allows diagnosis. Furthermore, since it is possible to reduce the frequency of re-imaging even when diagnosis is possible, it is possible to reduce the amount of X-ray exposure to the patient.

(Second embodiment)
In the above-described first embodiment, the body movement information is added to the projection data acquired by the scanning unit at the timing based on the body movement data acquired by the monitoring unit 16, but in the present embodiment, the scanning is performed. This eliminates the need to add body motion information to projection data at the timing of.

  FIG. 3 is a flowchart showing the flow of processing according to the second embodiment. As described above, in the present embodiment, the body movement information is not added to the projection data at the acquired timing, but is referred to at the weighting timing after the acquisition of the projection data and the body movement information is completed. Is. In FIG. 3, steps designated by the same reference numerals as those in FIG. 2 perform similar processing.

  Unlike the above-described embodiment, after the body motion is sensed (S204: YES), the process of storing the body motion data (S206) is executed. The monitoring unit 16 senses the movement of the subject P and, when the body movement information is obtained, transmits a signal by wire or wirelessly and stores the body movement information in the body movement data storage circuit 412. However, the present invention is not limited to this, and a device for storing information such as a memory is provided in the monitoring unit 16 to store the body movement information during the scan, and the body movement data storage circuit 412 collectively stores the information after the scan. May be.

  After the scanning by the scanning unit is completed, when the reconstruction is performed using the projection data stored in the image storage circuit 411, the projection data is weighted according to the body movement information stored in the body movement data storage circuit 412. Is given. In this way, the body movement information and the projection data may not be associated in real time during scanning, but may be associated at the timing of reconstruction. As described above, the association is performed by associating the data scanned based on the timing at which the body movement information is acquired and the body movement information with each other.

  The body movement information is, for example, the time from the start of the scan, the information of the view from which the body movement information was acquired, and the like, together with the information that can be used to determine whether or not the projection data is the body movement information. Remembered. In this case, for example, when the body movement information is present, the preprocessing function 442 determines which view the body movement data corresponds to the projection data of the view, and based on the determination result, Calculate the weight for the projection data. The reconstruction processing function 443 performs reconstruction based on the calculated weight. Note that, as in the above-described embodiment, the preprocessing function 442 may calculate the weight at a timing when the reconfiguration processing function 443 performs the reconfiguration, instead of calculating the weight in advance and performing the reconfiguration. .

  As described above, according to this embodiment, the same operation as that of the above-described embodiments can be achieved. Further, according to the present embodiment, since the scanned data and the acquired body movement information can be stored separately without being added at the time of scanning, it is possible to reduce the processing at the time of scanning. Become.

(Embodiment and modification of weighting)
Next, a description of weighting and various embodiments of weighting will be described. In the following, the relationship between the body movement information in the scan during one rotation and the weights thereof will be described. One rotation is represented by, for example, an angle of 360°, and weights projection data including an angle corresponding to a time region (scanned image) in which body movement occurs or time before and after the time when body movement occurs. The angle at which the view to which is added exists is represented as θ°. As an implementation, a view for each scan may be used instead of an angle. For example, when one rotation is n views, the view in which the body motion has occurred or the view to which weight is added is θ/360 views among the n views.

  FIG. 4 is a graph showing weights when the monitoring unit 16 does not detect the movement of the subject P. The horizontal axis is an angle proportional to the scan angle, that is, the view number, and the vertical axis is the weight added to the projection data. As shown in this graph, the projection data scanned during one rotation is reconstructed with the same weight, for example, one weight. When the monitoring unit 16 detects the body movement of the subject P, the weight shown in FIG. 4 is changed depending on the detection or the degree of the detected body movement.

  For example, when the monitoring unit 16 is a camera, the body movement is detected by monitoring the image. If there is movement, it is determined that there is movement, and if there is no movement, it is determined that there is no movement. When a body movement is detected, weighting is calculated as in the example shown in FIGS. 5 to 13, and the reconstruction processing function 443 adds it to the projection data as a weight when the image is reconstructed.

  Further, it may be one that can detect the degree of movement. For example, the movement may be detected in units of 1 mm, such as -1 mm, 1 mm-2 mm, 2 mm-... In this case, for example, the coefficient serving as the basis of weighting (vertical axis of the graphs in FIGS. 5 to 13) may be changed according to the magnitude of the movement. Note that the unit of 1 mm is merely an example, and the scale of the degree of movement is not limited to this.

  When the monitoring unit 16 is a pressure sensor, the presence/absence of the body movement or the degree of the body movement may be displayed based on the pressure applied to each area. When the monitoring unit 16 is a sound collector, the body movement may be sensed based on the volume of the sound generated by the movement of the subject P that has collected the sound. In addition, the accuracy of obtaining the body movement information may be increased by using a plurality of monitoring means.

  5 to 13 are diagrams showing examples of weighting.

  FIG. 5 is an example of weights when there is a body movement between 360°-θ° and 360°. In this way, the weight between 360°-θ° and 360° is set smaller than 1, and the weight between the opposite 180°-θ° is set larger than 1. In the example of FIG. 5, weighting is performed between 0 and 2. In the projection data for the 180°-θ° view, a weight of 1 approaches 2 towards 180°. The approaching curve is a smoothly connected function such as a sigmoid function or a sinc function.

  In the following figures including FIG. 5, it is assumed that the body movement starts from the timing of 360°−θ°, but in this case, the view of 180°−θ° and the view of 360°−θ° Prior to the projection data of, for example, the view of 5° may be traced back and weighted. In this way, by giving a margin to the timing at which the body movement is sensed and weighting it, or conversely, by weighting only a part of it, the influence of the body movement can be reduced, and It is also possible to reduce image artifacts and the like.

  FIG. 6 shows a case where θ is larger than that in FIG. In such a case, the range for calculating the weighting coefficient becomes large, and weighting is performed as a smoother curve.

  FIG. 7 shows the weights when the subject P stops near the original position due to body movement in the middle, not in the final view. In this case, the weight is changed between θ° where the body movement is occurring or between θ° including the peripheral view where the body movement is occurring. That is, the weighting is performed as if the graph of the weight of the general APMC is shifted at the timing when the body movement occurs.

  In FIG. 8, weighting is not performed between 0 and 2, but weighting is performed between 1-α and 1+α using a predetermined value α that is 0<α≦1. The weighting does not necessarily have to be between 0 and 2. For example, when the body movement is small, weighting is performed using a relatively small value such as α=0.2, and when the body movement is large, weighting is performed using a relatively large value such as α=0.8. To do. In this way, by changing the weighting, it becomes possible to perform more flexible and highly accurate correction. As for the degree of small or large body movement, the degree of body movement may be determined based on a threshold value determined in advance by the system, or while the user confirms the reconstructed image as described later. You may judge.

  In FIG. 9, the weights are connected not linearly but in a linear manner. In this way, it is not always necessary to connect smoothly (a differentiable state in the correction start view), and they may be connected linearly.

  FIG. 10 shows weighting by body movement in addition to the initial weighting by the conventional APMC and the terminal weighting. In this way, as background processing, the weight of the conventional APMC may be applied, and when the body movement is detected, the weight may be added. By doing so, the weight of the projection data scanned in the middle period, which often has relatively few movements, can be made heavy, and the influence of body movements can be reduced.

  11 is different from the correction up to FIG. 10 in that the weight is reduced in the region where the view in which the body motion is detected exists. The weight is from 1-α to 1+α, but is not limited to this. For example, using a value γ according to a predetermined value or the degree of body movement, the area where the body movement cannot be detected is weighted. May be set to 1+γ, and the weight may be smoothly or linearly reduced from 1+γ to 0 in the view in which the body movement is detected or the area including the view in which the body movement is detected. Furthermore, in this case, after reconstruction, the reconstruction processing data may be normalized so that the average of the weights of all projection data becomes 1. As with the case shown in FIG. 11, the reference may be set to a value other than 1 for other weights.

  In FIG. 12, connection is made with a smooth curve in order to suppress the occurrence of artifacts even at the fall. For example, an angle φ smaller than θ is specified, as shown in the figure, the weight for the projection data in the view for the initial φ° is reduced, and the weight for the projection data in the view from 180° to 180°+φ° is set. Is to gently return to 1.

  FIG. 13 is different from the one described so far in that the weight is changed by the step function. As described above, the weight does not necessarily have to be changed continuously, and may be changed discontinuously. Further, it may be (step function)×(function of the above weight). That is, it is possible to step from 1 to 1+γ based on the timing of the view in which the body movement has occurred, and then gradually change like the above-described change of the coefficient of each weight.

  FIG. 14 is a diagram showing a display device 42 including an interface for changing a parameter relating to weight. The reconstructed result may be slightly blurred as shown in FIG. As another example, there is a case where an artifact or the like has occurred in the image resulting from the reconstruction. In such a case, it is desired that the user change the degree of body movement correction. With the interface shown in FIG. 14A, the user can change the parameters related to the weight by checking the output reconstructed image. The parameters can be changed by using, for example, the input device 43 such as a keyboard, a mouse, and a touch panel.

  For example, while observing the reconstructed image displayed in the display area 421 of the display device 42, the user changes the weight by moving the bar of the weight changing bar 422 to the predetermined value α described above. By moving the bar of the weight change bar 422, the reconstructed image is reconstructed every moment based on the weight specified in the bar and is displayed in the display area 421. Instead of changing the reconstructed image in real time, the image may be reconstructed and displayed, for example, at the timing when the user stops inputting or when a separately prepared preview button is pressed.

  The parameter is not limited to α, and for example, even if a radio box as shown in the shape change box 423 is prepared and these radio boxes are selected, the shape whose weight changes can be changed. Good. More specifically, the graphs shown in FIGS. 5 to 13 may be displayed, and the displayed graph may be freely changed by the user. In this case, the value of θ itself may be changed.

  As described above, by providing the user interface and allowing the user to change the weight parameter while checking the reconstructed image, it is possible to obtain the image desired by the user. In addition, the display device 42 may be provided with a determination button or the like that functions to determine and save the reconstructed image displayed in the display area 421. Furthermore, even if a parameter storage button is provided so that parameters can be set under the same conditions, and a parameter call button, etc., and other necessary buttons are provided so that reconstruction can be performed using the stored parameters. Good.

  The above-described embodiment can be applied not only to parallel beam projection and fan beam projection for which projection data for a cross section can be acquired, but also to cone beam projection, for example. Further, the above-described embodiment can be applied to both a single slice and a multi slice. For example, when the reconstruction is performed by cone beam projection, the above-described weighting may be applied to a specific channel depending on the view. In this case, the correction based on the body movement can be performed even in the scan method such as the helical scan.

  Although the above-described embodiments are all described as X-ray diagnostic apparatuses, projection data based on X-rays collected by a scan unit that executes a scan on the subject P using X-rays, and in parallel with the scan. An acquisition unit that acquires the body movement information corresponding to the projection data, which is obtained by the monitoring unit 16 that monitors the body movement of the subject P, and a weight corresponding to the body movement information is applied to the projection data and the reproduction is performed again. It can be described as a reconfiguration processing system including a reconfiguration processing unit 443 that performs reconfiguration processing and generates reconfigured image data.

  Further, the scanning unit performs a scan using X-rays on the subject P, collects projection data based on the X-rays, and the monitoring unit 16 monitors the body movement of the subject P in parallel with the scan. Then, the body movement information corresponding to the projection data is acquired, and the reconstruction processing unit 443 applies the weight corresponding to the body movement information to the projection data to perform the reconstruction processing to generate the reconstructed image data. The method can also be applied as an X-ray diagnostic method including steps.

  Furthermore, the computer executes a scan using X-rays on the subject P and collects projection data based on the X-rays. The body movement of the subject P is monitored and projected in parallel with the scanning. It functions as a monitoring unit that obtains body movement information corresponding to the data, a reconstruction processing unit that applies a weight corresponding to the body movement information to the projection data and performs reconstruction processing to generate reconstructed image data. It can also be implemented as a program.

  Although some embodiments have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel apparatus and method described herein may be implemented in various other forms. Further, various omissions, substitutions, and changes can be made to the modes of the apparatus and method described in the present specification without departing from the scope of the invention. The appended claims and their equivalents are intended to cover such forms and modifications as are included in the scope of the invention and adopted.

1: X-ray diagnostic system,
10: gantry device, 11: X-ray generator, 12: X-ray detector, 13: rotating body, 14: X-ray high voltage device, 15: gantry control device, 16: monitoring unit, 18: data acquisition circuit,
30: Bed device, 31: Base, 32: Bed driving device, 33: Top plate, 34: Support frame,
40: console device, 41: storage circuit, 42: display device, 43: input device, 44: processing circuit

Claims (12)

A scan unit that executes a scan using X-rays on a subject and collects projection data based on the X-rays;
A monitoring unit that monitors the body movement of the subject in parallel with the scan, and acquires body movement information corresponding to the projection data,
A reconstruction processing unit that applies reconstruction weights to the projection data by applying weights according to the body movement information and generates reconstructed image data;
X-ray diagnostic system including. The body movement information includes information indicating the presence or absence of the body movement or the degree of the body movement,
The reconstruction processing unit, with respect to the first projection data collected when there is the body movement, when the body movement is not present or the body movement is more than the body movement in the first projection data. The X-ray diagnostic system according to claim 1, wherein a weight smaller than the weight for the second projection data acquired when is smaller than is applied. The scanning unit collects the projection data for each of a plurality of views of the subject,
The X-ray diagnosis according to claim 2, wherein a weight larger than the weight for the second projection data is applied to the third projection data acquired for the view opposite to the view when the first projection data was acquired. system.   The X-ray diagnostic system according to claim 3, wherein the third projection data is data projected at a position shifted by 180° with respect to the view of the first projection data. For a value β that is greater than 0 and less than or equal to 1,
The X-ray diagnostic system according to claim 3 or 4, wherein when the weight for the first projection data is 1-β, the weight for the third projection data is 1+β. For a given value α that is greater than 0 and less than or equal to 1,
The minimum value of the weight for the first projection data is 1-α,
The weight of the third projection data has a maximum value of 1+α,
The X-ray diagnostic system according to any one of claims 3 to 5.   The weighting for the first projection data is continuously changed by a sigmoid function, a sinc function, or a linear function in a region where the body movement to which the first projection data belongs and which is changed by a step function. The X-ray diagnostic system according to any one of claims 3 to 6.   The X-ray diagnostic system according to claim 1, wherein the body movement information acquired by the monitoring unit is added to the projection data and stored at the timing of scanning by the scanning unit.   The body movement information acquired by the monitoring unit for the projection data scanned by the scanning unit is stored independently of the projection data and in association with the projection data, and the reconstruction processing unit reconstructs an image. The X-ray diagnostic system according to any one of claims 1 to 7, wherein a weight is added based on the body movement information at the timing of configuration and reconstruction is performed.   When the body movement information acquired by the monitoring unit is information acquired in a predetermined region of the subject, the reconstruction processing unit, in the projection data, with respect to data belonging to the predetermined region. 9. The X-ray diagnostic system according to claim 1, wherein the reconstruction processing is performed by applying weights. A display unit for displaying a reconstructed image based on the reconstructed image data reconstructed by the reconstructing processing unit;
A user confirms the reconstructed image displayed on the display unit, and an input unit that changes a parameter related to weight,
The X-ray diagnostic system according to any one of claims 1 to 10, further comprising: The projection data based on the X-rays collected by a scan unit that performs a scan using X-rays on the subject, and the projections acquired by a monitoring unit that monitors the body movement of the subject in parallel with the scan. An acquisition unit that acquires body movement information corresponding to the data,
A reconstruction processing unit that applies reconstruction weights to the projection data by applying weights according to the body movement information and generates reconstructed image data;
Reconstruction processing system equipped with.