JP7305334B2 - X-ray diagnostic system and reconstruction processing system - Google Patents

Description

Embodiments of the present invention relate to X-ray diagnostic systems and reconstruction processing systems.

2. Description of the Related Art X-ray diagnostic apparatuses that perform X-ray imaging by irradiating an object with X-rays and detecting the X-rays that have passed through the object are widely used in the medical field. As one method of acquiring an image in an X-ray diagnostic apparatus, a subject is positioned between an X-ray emission device and an X-ray detector so as to face each other, and the X-ray emission device and the X-ray detector are placed on the subject. There is a method of photographing by rotating around and reconstructing an image based on the results detected by an X-ray detector. If there is movement of the subject at the timing of X-ray exposure and detection, blurring or blurring occurs in the image acquired by reconstruction. As a technique for reducing the influence of this movement (body movement), there is body movement correction (APMC: Automatic Patient Motion Correction).

APMC corrects body motion by weighting the data detected by the X-ray detector and reconstructing it. However, since the above processing is performed regardless of the magnitude of movement of the subject, the timing of the movement, etc., there are cases where little effect can be obtained depending on the timing of the body movement. Therefore, when there is movement, the image is reconstructed from the projection data and then confirmed by the user, and the image is reconstructed including APMC processing. Alternatively, after reconstructing the image, the subject is again exposed to X-rays, and after re-imaging, the reconstruction of the image is performed.

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 on the movement of the subject.

According to one embodiment, the X-ray diagnostic system comprises:
a scanning unit that scans a subject using X-rays and collects projection data based on the X-rays;
a monitoring unit that monitors body motion of the subject in parallel with the scan and acquires body motion information corresponding to the projection data;
a reconstruction processing unit that performs reconstruction processing by applying a weight corresponding to the body motion information to the projection data to generate reconstructed image data;
Prepare.

1 is a block diagram showing an example of the overall configuration of an X-ray diagnostic system according to one embodiment; FIG. 4 is a flowchart illustrating an example of image reconstruction processing according to an embodiment; 4 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.

An X-ray diagnostic system and a reconstruction processing system according to this embodiment will be described below with reference to the drawings. In the following description, components having substantially the same functions and configurations are denoted by the same reference numerals, and redundant 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 one embodiment. The X-ray diagnostic system 1 is an example of a medical device equipped with an image processing device according to this embodiment, and the image processing device according to this embodiment can be applied to various X-ray diagnostic devices such as general imaging devices. The X-ray diagnostic system includes, for example, a gantry device 10 , a bed device 30 and a console device 40 .

The gantry 10 includes an X-ray generator 11, an X-ray detector 12, a rotor 13, an X-ray high voltage device 14, a gantry controller 15, a monitor 16, and a data collection circuit 18. Prepare.

The X-ray generator 11 is an X-ray irradiation unit that irradiates X-rays. For example, the X-ray generator 11 receives high-voltage power supply from the X-ray high-voltage device 14, and heats the anode (target) from the cathode (filament). It is configured with an X-ray tube (vacuum tube) that emits electrons.

The X-ray generator 11 is not limited to an X-ray tube. For example, instead of the X-ray tube, the X-ray generator 11 includes a focus coil that converges the electron beam generated from the electron gun, a deflection coil that electromagnetically deflects the electron beam, and the deflected electron beam that surrounds the half circumference of the subject P and collides with it. 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 circular arc around 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 arrays each having a plurality of X-ray detection elements arranged in the channel direction are arranged in the slice direction. The X-ray detector 12 detects X-rays emitted from the X-ray generator 11 and passing through the subject P, and outputs an electrical signal corresponding to the X-ray dose to the data acquisition circuit 18 .

Alternatively, the X-ray detector 12 may be an indirect conversion type detector including, for example, a grid, a scintillator array, and a photosensor array. The scintillator array includes a plurality of scintillators, and the scintillators are configured with scintillator crystals that output a photon amount of light corresponding to the amount of incident X-rays. The grid is arranged on the surface of the scintillator array on the X-ray incident side and includes an X-shielding plate having a function of absorbing scattered X-rays. The photosensor array has a function of converting the amount of light from the scintillator into an electrical signal, and is configured with photosensors such as photomultiplier tubes, for example.

The X-ray detector 12 is not limited to an indirect conversion type detector, and may be a direct conversion type detector provided with a semiconductor element that directly converts incident X-rays into electrical signals.

The rotating body 13 is rotatably directed around the center of the rotating body 13 as a rotation axis, and is rotationally driven 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 10 together with the rotating body 13 as a rotating part that rotates according to the rotational driving of the rotating body 13 . The rotating part is provided in a fixed part that is fixed to the gantry device 10, and is rotationally driven with respect to the fixed part.

In this embodiment, for example, the X-ray generator 11, the X-ray detector 12, and the rotor 13 are collectively referred to as a scanning unit. Note that the scanning unit may indicate the X-ray detector 12 in a narrow sense, or may be a concept including the X-ray high-voltage device 14, the data acquisition circuit 18, etc. described below in a broad sense. The scanning unit is a collection of modules or devices having the function of scanning the subject P using X-rays and collecting projection data based on X-rays, or modules or devices themselves. indicates

The X-ray high-voltage device 14 includes electric circuits such as a transformer and a rectifier, and has a function of generating a high voltage to be applied to the X-ray generator 11 . is provided with an X-ray control device for controlling the output voltage according to the X-rays emitted by the . The high voltage generator may be of 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 and an actuator. 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 receives an input signal and operates as a rotation mechanism that controls the rotation of the rotating body 13, controls the tilting of the gantry device 10, and operates the bed device 30 and the tabletop 33. control.

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

A data acquisition system (DAS) 18 includes an amplifier that amplifies electrical signals output from each X-ray detection element of the X-ray detector 12, and an A/D converter that converts the electrical signals into digital signals. and a D converter for generating detection data (pure raw data). The detection data generated by the data collection circuit 18 is transferred to the console device 40 . The data collection circuit 18 may also be connected to the monitoring unit 16 . 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 a 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 drive device 32 is a motor or actuator that moves the support frame in which the subject P has been re-cured in the longitudinal direction of the support frame 34 . A top plate 33 provided on the upper surface of the support frame 34 is a plate on which the subject P is placed.

The top plate 33 may be moved alone, or may be moved together with the support frame 34 of the bed device 30 . When this embodiment is applied to standing CT, a method of moving a patient moving mechanism corresponding to the tabletop 33 may be used.

When executing a scan (such as a helical scan or a positioning scan) that involves a relative change in the positional relationship between the imaging system of the gantry 10 and the top plate 33 , the relative change in the positional relationship is caused by driving the top plate 33 . may be performed by running the gantry device 10, or may be performed by a combination thereof.

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

The storage circuit 41 is implemented by, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. The storage circuit 41 stores projection data and reconstructed image data, for example. In this embodiment, the memory circuit 41 includes, for example, an image memory circuit 411, a body motion data memory circuit 412, and a program memory 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 motion data storage circuit 412 stores body motion data indicating whether or not the subject P has moved or indicating the magnitude of motion of the subject P for each image stored in the image storage circuit 411. circuit. The program storage circuit 413 is a circuit that stores various programs. Each of these memory circuits may not be provided as a separate memory circuit, and may be used by dividing an area corresponding to each memory circuit in one or more memories. It may be used as each memory circuit by securing a necessary capacity at the timing of the memory.

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 accepting 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, or 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, acquisition conditions for acquiring projection data, reconstruction conditions for reconstructing CT images, and image processing conditions for generating post-processed images from CT images. . For example, in the present embodiment, a parameter relating to weights, which will be described later, may be input. The input device 43 includes a mouse, trackball, keyboard, switches, buttons, 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 this embodiment, the processing circuitry 44 includes, for example, a system control function 441, a preprocessing function 442, a reconstruction processing function 443, an image acquisition function 444, an extraction function 445, a calculation function 446, a generation function 447, and a display function. 448.

In the embodiment in FIG. 1, each function performed by a system control function 441, a preprocessing function 442, a reconstruction processing function 443, an image acquisition function 444, an extraction function 445, a calculation function 446, a generation function 447, and a display function 448 The processing functions are stored in the program storage circuit 413 of the storage circuit 41 in the form of a computer-executable program. The processing circuit 44 is a processor that reads a program from the program storage circuit 413 of the storage circuit 41 and executes it, thereby implementing functions corresponding to each program. In other words, the processing circuit with each program read has each function shown in the processing circuit 44 of FIG.

1, the single processing circuit 44 has a system control function 441, a preprocessing function 442, a reconstruction processing function 443, an image acquisition function 444, an extraction function 445, a calculation function 446, a generation function 447, and a display function. Although the processing function performed by the function 448 has been described as being implemented, the processing circuit 44 may be configured by combining a plurality of independent processors, and the function may be implemented by each processor executing a program. good.

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

The preprocessing function 442 generates data by performing preprocessing such as logarithmic conversion processing, offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on the scanned data output from the data acquisition circuit 18. do. Data before preprocessing and data after preprocessing may be collectively referred to as projection data.

The preprocessing function 442 may further process the body motion data acquired by the monitoring unit 16 and output from the data acquisition circuit 18 to calculate weights for image reconstruction.

The reconstruction processing function 443 performs reconstruction processing using the filtered back projection method, the iterative reconstruction method, etc. on the projection data generated by the pre-processing function 442 to obtain a reconstructed image (CT image data ). Reconstruction is performed using weightings based on motion data. This reconstructed image is stored in the image storage circuit 411 of the storage circuit 41, for example. CT image data is an aggregate of CT values, and is an example of a medical image of multiple time phases in this embodiment. That is, the reconstructed image is stored in the image storage circuit 411 of the storage circuit 41 as an image including temporal elements.

The image acquisition function 444 acquires reconstructed images of multiple time phases stored in the image storage circuit 411 of the storage circuit 41, for example. Alternatively, data of reconstructed images of multiple time phases generated by the reconstruction processing function 443 is acquired. The extraction function 445 extracts a predetermined region of interest from the reconstructed image data of multiple time phases. A calculation function 446 calculates a CT value for a given region of interest. The generation function 447 generates an image in which, for example, 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 this embodiment, the processing circuit 44 is configured by, for example, a processor. Here, the term processor includes, for example, a CPU, a GPU (Graphics Processing Unit), an application-specific integrated circuit (ASIC: Application Specific Integrated Circuit), a programmable logic device (for example, a simple programmable logic device (SPLD: Simple Programmable Logic Device), Complex Programmable Logic Device (CPLD), or Field Programmable Gate Array (FPGA). The processor implements its functions by reading and executing programs stored in the storage circuit 41 . Note that the memory circuit 41 may directly incorporate the program into the circuit of the processor instead of storing the program. In this case, the processor implements its functions by reading and executing the program embedded in the circuit. The processor is not limited to be configured as a single processor circuit, but may be configured as one processor by combining a plurality of independent circuits to realize its function. Further, multiple components in FIG. 1 may be integrated into one or more processors to implement their functionality.

In the X-ray diagnostic system 1 of FIG. 1, the constituent elements of the console device 40 are housed in one housing, but these constituent elements of the console device 40 are not necessarily housed in one housing. There is no need to store them, and a plurality of them may be stored in separate housings. For example, a configuration having distributed processing circuits such as the preprocessing function 442 and the reconstruction processing function 443 may be employed. In other words, instead of performing multiple functions in a single console, console device 40 may have multiple functions performed by separate consoles.

In the X-ray diagnostic system 1, the X-ray generator 11 and the X-ray detector 12 are integrally arranged in a Rotate/Rotate-Type (third-generation CT) array that rotates around the subject P 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 generator 11 rotates around the subject P. is applicable to Furthermore, 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 that directs the X-ray irradiation section and the X-ray detection section with an arm. is also applicable 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 flowchart shows the processing from the start of scanning to the reconstruction of an image, and does not describe other controls such as control of the couch device, but other controls are 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, for example, when the user gives an instruction to start an operation via the input device 43 . This body motion monitoring may be started at least before the start of scanning or at the same timing as the start of scanning. That is, the monitoring may be continued from the timing when the subject P is positioned on the couch device 30, for example, separately from the activation of the scanning unit. Any implementation can be used as long as the acquisition of projection data by scanning and the acquisition of body motion 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 body movements of the subject P (S202). That is, the monitoring unit 16 monitors the body movement in parallel with the execution of scanning by the scanning unit. In this way, by performing scanning and monitoring in parallel, it is possible to associate the result of scanning with the obtained body movement data when there is body movement.

If the monitoring unit 16 does not detect body movement during monitoring (S204: NO), it continues monitoring body movement (S202).

On the other hand, if body movement is detected (S204: YES), body movement monitoring is continued (S202), and body movement is detected in the projection data acquired by the scanning unit, or the degree of body movement is detected. It is given and stored in the storage circuit 41 via the data collection circuit 18 . This implementation means may be performed by any means. For example, the projection data scanned by the scanning unit may be given the presence of body movement, and processing may be performed in the event of body movement in subsequent reconstruction processing. may As another example, the presence of 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 the reconstruction processing is performed based on the degree of body movement. You may

After obtaining the necessary projection data, the scanning unit ends the scanning (S104). Necessary projection data is, for example, data acquired while orbiting the cross section in the case of reconstructing an image of one or a plurality of cross sections; , are the data acquired in the helical scan in the region of interest. At this timing, the monitoring unit 16 may be notified of the end of scanning, and the monitoring unit 16 receiving the notification may end monitoring.

Next, the projection data are weighted (S106). Weighting is performed by the preprocessing function 442, for example, and weighting is performed for reconstruction based on body motion information given to each piece of projection data. The weight of the first projection data, which is the projection data in the view determined to have body motion, is made smaller than the weight of the second projection data, which is the projection data in the view determined to have no body motion. For example, when the weight of the second projection data is 1, the weight of the first projection data is set to 1-β for values where 0<β≦1.

Specifically, when calculating the integral (discretely, sum) of the projection data in the reconstruction process, the first projection data is integrated with a weight of 1-β, and the second projection data is calculated. Reconstruction is performed by performing calculations using the projection data as they are. When there are a plurality of pieces of first projection data, the value of β is not a constant value, but varies based on the magnitude (degree) of movement or the elapsed time after the start of body movement. good too. Also, even when there is only one piece of projection data to which body motion information is assigned, the weights may be added to the views before and after the view of the projection data so that the weights change gently.

Furthermore, the weight for the data opposite 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 opposing data, reconstruction can be performed without impairing the circular symmetry of the reconstructed image as a whole. As described above, when the views before and after the view for the first projection data are also weighted, the projection data opposing the weighted projection data may also be weighted.

A more detailed weighting example will be described later.

Next, the reconstruction processing function 443 performs image reconstruction based on the weighted projection data (S108). As for the reconstruction method, a general method such as filtered back projection is used, except for using weighted projection data. In addition, processing such as noise removal processing, which is performed during general reconstruction, may also be performed.

Note that the processing of S106 and the processing of S108 do not have to be separate processes, and the projection data may be weighted according to the body motion information at the timing of performing the processing of S108 for reconstruction. That is, the process of S106 may be executed at the same time as the process of S108, and in this case, the process of S106 may be omitted.

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

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

FIG. 3 is a flow chart showing the flow of processing according to the second embodiment. As described above, in the present embodiment, instead of assigning body motion information to projection data at the timing of acquisition, reference is made at the timing of weighting after the acquisition of projection data and body motion information is completed. is. In FIG. 3, the steps with the same reference numerals as in FIG. 2 perform the same processing.

Unlike the above-described embodiment, after detecting body motion (S204: YES), the process of storing body motion data (S206) is executed. The monitoring unit 16 senses the movement of the subject P, and when 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 . The monitoring unit 16 is not limited to this, but a device such as a memory for storing information is provided in the monitoring unit 16 to store body motion information during scanning, and after the scanning is completed, the body motion data storage circuit 412 stores the information collectively. may

When the projection data stored in the image storage circuit 411 are used for reconstruction after the scanning by the scanning unit is completed, the projection data are weighted according to the body motion information stored in the body motion data storage circuit 412 . to give In this way, body motion information and 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 executed by associating the body motion information with the data scanned based on the timing at which the body motion information was acquired.

The body motion information is, for example, the time since the scan was started, the information of the view from which the body motion information was acquired, etc., together with information that can be used to determine at least which projection data the body motion information is for. remembered. In this case, for example, if body motion information exists, the preprocessing function 442 determines which view's projection data the body motion data corresponds to, and based on this determination result, Calculate the weights for the projection data. The reconstruction processing function 443 performs reconstruction based on the calculated weights. As in the above-described embodiment, instead of the preprocessing function 442 calculating weights in advance and performing reconstruction, the reconstruction processing function 443 may calculate weights at the time of reconstruction. .

As described above, this embodiment can also achieve the same effect as the above-described embodiment. Furthermore, according to this embodiment, the scanned data and the obtained body movement information are not added at the time of scanning, and the body movement information can be stored separately, so that the processing at the time of scanning can be reduced. Become.

(Embodiments and Modifications of Weighting)
Next, a discussion of weighting and various embodiments of weighting are provided. In the following, body motion information in scanning during one rotation and the relationship between the weights thereof will be described. One rotation is represented by, for example, an angle of 360°, and the angle corresponding to the time region (scanned image) where body movement occurs, or the projection data including the time before and after the time when body movement occurs are weighted. Denote as θ° the angle at which the view that attaches is. As an implementation, it may be represented by a view for each scan instead of an angle. For example, when one rotation is n views, the views in which body movement occurs or the views to which weight is added are 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. As shown in FIG. The horizontal axis is the angle of the scan, in other words, the axis proportional to the view number, and the vertical axis is the weight added to the projection data. As shown in this graph, the image is reconstructed with the same weight, for example, a weight of 1, for the projection data scanned during one rotation. When the monitoring unit 16 senses the body motion of the subject P, the weights shown in FIG. 4 are changed according to the sensing or the degree of the sensed body motion.

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

Furthermore, it may be possible to detect the degree of movement. For example, the movement may be detected in units of 1 mm such as 1 mm, 1 mm to 2 mm, 2 mm to . . . In this case, for example, the weighting factor (the vertical axis of the graphs in FIGS. 5 to 13) may be changed according to the magnitude of motion. Note that the unit of 1 mm is just 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 or absence of body movement or the degree of body movement may be indicated based on the pressure applied to each area. When the monitoring unit 16 is a sound collector, body movement may be sensed based on the volume of the sound generated by the movement of the subject P whose sound is collected. Also, a plurality of monitoring means may be used to improve the accuracy of acquiring body motion information.

5 to 13 are diagrams showing examples of weighting.

FIG. 5 shows an example of weights when there is body movement between 360°-θ° and 360°. Thus, the weight between 360°-θ° and 360° is less than 1 and the opposite 180°-θ° is weighted greater than 1. In the example of FIG. 5, the weighting is between 0 and 2. In the projection data for the 180°-θ° view, a weight of 1 approaches 2 toward 180°. The approaching curves are, for example, smoothly connected functions such as sigmoid functions, sinc functions, and the like.

In the following figures, including FIG. 5, it is assumed that the body movement starts at the timing of 360°-θ°. , the weight may be applied to the projection data of , eg, 5° further back. 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 part of it, the influence of the body movement can be reduced, Image artifacts and the like can also be reduced.

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

FIG. 7 shows the weight when the subject P stops near the original position, instead of the end-stage view, when body movement occurs in the middle. In this case, the weight is changed between θ° during which the body motion occurs or between θ° including the surrounding views where the body motion occurs. In other words, the weighting is such that the graph of the general APMC weight is shifted to the timing when the body motion occurs.

Instead of weighting between 0 and 2, FIG. 8 attempts to weight between 1−α and 1+α using a predetermined value α where 0<α≦1. Weighting does not necessarily have to be between 0 and 2. For example, if the body movement is small, it is weighted using a relatively small value such as α = 0.2, and if the body movement is large, it is weighted using a relatively large value such as α = 0.8. do. By changing the weighting in this way, it becomes possible to perform more flexible and highly accurate correction. The degree of body movement, such as small or large, may be determined based on a threshold value determined in advance by the system. You can judge.

FIG. 9 connects the weights linearly instead of connecting them with a smooth curve. In this way, the connection does not necessarily have to be smooth (a differentiable state in the correction starting view), but may be linearly connected.

In FIG. 10, in addition to the weighting of the initial and final stages by conventional APMC, weighting is further performed by body movement. In this way, as background processing, conventional APMC weighting may be applied, and further weighting may be added when body movement is detected. By doing so, the weight of the projection data scanned in the middle period when there is relatively little movement is often increased, and the influence of body movement can be reduced when it occurs.

In FIG. 11, unlike the corrections up to FIG. 10, weights are reduced for areas where there are views in which body motion is detected. The weight ranges from 1-α to 1+α, but is not limited to this. may be set to 1+γ, and the weight may be smoothly or linearly reduced from 1+γ to 0 in a view in which body motion is detected or in a region including a view in which body motion is detected. Furthermore, in this case, after reconstruction, the reconstruction processing data may be normalized so that the average of the weights of all the projection data is one. It should be noted that other weights may also be set to values other than 1 as in the case of FIG.

FIG. 12 connects with a smooth curve in order to suppress the occurrence of artifacts even at the trailing edge. For example, specifying an angle φ smaller than θ, weighting less the projection data in views for the initial φ°, and weighting the projection data in views from 180° to 180°+φ°, as shown in the figure. is gently returned to 1.

In FIG. 13, the weight is changed by a step function, unlike those described so far. Thus, 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 may be stepped from 1 to 1+γ based on the timing of the view in which the body motion occurs, and then smoothly changed like the change in the coefficient of each weight described above.

FIG. 14 shows a display device 42 including an interface for changing weight-related parameters. The reconstructed result may be slightly blurred as shown in FIG. 14(a). As another example, artifacts may occur in the reconstructed image. In such a case, it is desirable for the user to change the degree of body motion correction. The interface shown in FIG. 14(a) allows the user to check the output reconstructed image and change the weighting parameters. The parameter can be changed using the input device 43 such as a keyboard, mouse, touch panel, or the like.

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 weight change bar 422 with the predetermined value α described above. By moving the bars of the weight change bar 422 , the reconstructed image is reconstructed again based on the weights assigned to the bars from moment to moment, and displayed in the display area 421 . In addition, instead of changing the reconstructed image in real time, for example, the image may be reconstructed and displayed at the timing when the user stops inputting or when the separately prepared preview button is pressed.

The parameter is not limited to α. For example, radio boxes such as those shown in the shape change box 423 are prepared, and by selecting these radio boxes, even if 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 graphs may be freely changed by the user. In this case, the value of θ itself may be changed.

Thus, by providing a user interface and allowing the user to change the weighting parameters while checking the reconstructed image, it is possible to obtain the image desired by the user. Further, the display device 42 may be provided with an OK button or the like that functions to decide 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 necessary buttons such as a parameter call button are provided so that the stored parameters can be reconfigured. good.

The above-described embodiments can be applied to cone beam projection as well as parallel beam projection and fan beam projection, for which projection data for a cross section can be obtained. Also, the above-described embodiments can be applied to both single slices and multislices. For example, when reconstruction is performed by cone beam projection, the above weighting may be applied to particular channels by view. In this case, it is possible to perform correction based on body motion even for scanning methods such as helical scanning.

Although all the above-described embodiments have been described as an X-ray diagnostic apparatus, projection data based on X-rays collected by a scanning unit that scans a subject P using X-rays, and body motion information corresponding to the projection data acquired by the monitoring unit 16 for monitoring the body motion of the subject P; It can be described as a reconstruction processing system comprising a reconstruction processing means 443 that performs reconstruction processing and generates reconstructed image data.

Furthermore, the scanning unit scans the subject P using X-rays, 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 scanning. Then, body motion information corresponding to the projection data is acquired, and the reconstruction processing means 443 performs reconstruction processing by applying a weight corresponding to the body motion information to the projection data, and generates reconstructed image data. , as an X-ray diagnostic method comprising steps.

Furthermore, the computer performs a scan using X-rays on the subject P, scans means for collecting projection data based on the X-rays, monitors the body movement of the subject P in parallel with the scan, and projects Monitoring means for acquiring body movement information corresponding to data, and reconstruction processing means for generating reconstructed image data by performing reconstruction processing by applying a weight corresponding to the body movement information to projection data. It can also be implemented as a program.

Although several embodiments have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. The novel apparatus and methods described herein can be embodied in many other forms. In addition, various omissions, substitutions, and alterations may be made to the forms of the apparatus and methods described herein without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms and variations that fall within the scope and scope of the invention.

1: X-ray diagnostic system,
10: gantry device, 11: X-ray generator, 12: X-ray detector, 13: rotator, 14: X-ray high-voltage device, 15: gantry controller, 16: monitoring unit, 18: data collection circuit,
30: bed device, 31: base, 32: bed driving device, 33: top plate, 34: support frame,
40: console device, 41: memory circuit, 42: display device, 43: input device, 44: processing circuit

Claims (17)

comprising a scanning unit, a monitoring unit, and a reconstruction processing unit,
The scanning unit
performing a scan using X-rays on the subject;
collecting projection data based on said X-rays;
The monitoring unit
monitoring body movement of the subject while performing the scan;
sensing the movement of the subject within a scan plane at the timing at which the subject is scanned by at least one of optical fluctuations, pressure fluctuations, and air vibration fluctuations;
acquiring body motion information corresponding to the projection data, the body motion information including information representing the presence or absence of the body motion and the degree of the body motion;
The reconstruction processing unit
Acquiring information of a scanned view corresponding to the timing when the body movement occurs and the timing before and after the body movement occurs;
setting a weight to be applied to the projection data in the view scanned by the scanning unit as a predetermined value when the body movement has not occurred;
When the body movement occurs,
setting a weight for the view at the timing at which the body movement occurred and the timing before and after the movement to be smaller than the predetermined value;
setting a weight for a view facing a view corresponding to each of the timing at which the body movement occurs and the timing before and after the movement to be greater than the predetermined value;
setting weights for other views to the predetermined value;
applying the weights to the projection data to perform reconstruction processing to generate reconstructed image data;
X-ray diagnostic system. For a value β greater than 0 and less than or equal to 1,
Let 1-β be a weight for the projection data in views corresponding to the timing at which the body movement occurs and the timing before and after the movement,
A weight of 1+β for the projection data in views respectively corresponding to the timing at which the body movement occurs and the timing before and after the body movement occurs,
An X-ray diagnostic system according to claim 1. For a given value α greater than 0 and less than or equal to 1,
weights for the projection data in the views corresponding to the timing at which the body movement occurs and the timings before and after the body movement have a minimum value of 1-α;
weights for the projection data in the views corresponding to the timing at which the body movement occurs and the timings before and after the movement have a maximum value of 1+α;
3. An X-ray diagnostic system according to claim 1 or claim 2. The reconstruction processing unit smoothly transitions the weighting of the projection data in the view based on the timing at which the body movement occurs.
An X-ray diagnostic system according to any one of claims 1 to 3. The weighting of the projection data in the views respectively corresponding to the timing at which the body movement occurred and the timings before and after the body movement is based on the weighting of the views corresponding to the timing at which the body movement occurred and the timings before and after the body movement. In the area, continuously changing by a sigmoid function or a sinc function,
5. The X-ray diagnostic system according to claim 1 . adding the body motion information acquired by the monitoring unit to the projection data at the timing when the scanning unit scans, and storing the projection data;
An X-ray diagnostic system according to any one of claims 1 to 5. The body motion 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. Performing reconstruction by adding weight based on the body movement information at the timing of configuration;
An X-ray diagnostic system according to any one of claims 1 to 5. When the body motion information acquired by the monitoring unit is information acquired in a predetermined region of the subject, the reconstruction processing unit performs apply weights and perform the reconstruction process,
An X-ray diagnostic system according to any one of claims 1 to 7. a display unit for displaying a reconstructed image based on the reconstructed image data reconstructed by the reconstruction processing unit;
an input unit for a user to check the reconstructed image displayed on the display unit and change a parameter related to weight;
further comprising
An X-ray diagnostic system according to any one of claims 1 to 8. an acquisition unit that acquires, from a scan unit, a group of projection data based on the X-rays, which is acquired by a scan unit that scans a subject using X-rays;
extracting the information assigned to the projection data group, and extracting the projection data corresponding to the extracted information from the projection data group at the timing when the body movement occurs and the timing before and after the body movement occurs; Get the information of the corresponding scanned view,
setting a weight to be applied to the projection data in the view scanned by the scanning unit as a predetermined value when the body movement has not occurred;
When the body movement occurs,
setting a weight for the view at the timing at which the body movement occurred and the timing before and after the movement to be smaller than the predetermined value;
setting a weight for a view facing a view corresponding to each of the timing at which the body movement occurs and the timing before and after the movement to be greater than the predetermined value;
setting weights for other views to the predetermined value;
applying the weights to the projection data to perform reconstruction processing to generate reconstructed image data;
a reconstruction processing unit;
A reconstruction processing system with a scanning unit that scans a subject using X-rays and collects projection data based on the X-rays;
The body movement of the subject is monitored while the scan is being performed, and the movement of the subject within the scan plane at the timing at which the subject is scanned is detected by optical fluctuations, pressure fluctuations, or pneumatic fluctuations. a monitoring unit that senses at least one of vibration fluctuations and obtains body motion information corresponding to the projection data, the body motion information including information representing the presence or absence of the body motion and the degree of the body motion; ,
Acquiring information of a scanned view corresponding to the timing when the body movement occurs and the timing before and after the body movement occurs;
setting a weight to be applied to the projection data in the view scanned by the scanning unit as a predetermined value when the body movement has not occurred;
When the body movement occurs,
setting a weight for the view at the timing at which the body movement occurred and the timing before and after the movement to be smaller than the predetermined value;
setting a weight for a view facing a view corresponding to each of the timing at which the body movement occurs and the timing before and after the movement to be greater than the predetermined value;
setting weights for other views to the predetermined value;
a reconstruction processing unit that performs reconstruction processing by applying the weights to the projection data to generate reconstructed image data;
A medical image processing apparatus comprising: the scanning unit
performing a scan of a subject using X-rays and acquiring projection data based on the X-rays;
The monitoring department
monitoring body movement of the subject while performing the scan;
sensing the movement of the subject within a scan plane at the timing at which the subject is scanned by at least one of optical fluctuations, pressure fluctuations, and air vibration fluctuations;
acquiring body motion information corresponding to the projection data, the body motion information including information representing the presence or absence of the body motion and the degree of the body motion;
The reconstruction processing unit
Acquiring information of a scanned view corresponding to the timing when the body movement occurs and the timing before and after the body movement occurs;
setting a weight to be applied to the projection data in the view scanned by the scanning unit as a predetermined value when the body movement has not occurred;
When the body movement occurs,
setting a weight for the view at the timing at which the body movement occurred and the timing before and after the movement to be smaller than the predetermined value;
setting a weight for a view facing a view corresponding to each of the timing at which the body movement occurs and the timing before and after the movement to be greater than the predetermined value;
setting weights for other views to the predetermined value;
applying the weights to the projection data to perform reconstruction processing to generate reconstructed image data;
Medical image processing method. scanned data obtained by performing a scan on a subject; an acquisition unit that acquires body movement information including information representing the degree of movement, the body movement information corresponding to the scanned data;
Acquiring information of a scanned view corresponding to the timing when the body movement occurs and the timing before and after the body movement occurs;
when the body movement has not occurred, a weight applied to the projection data in the view scanned by the scanning unit is set to a predetermined value;
When the body movement occurs,
setting a weight for the view at the timing at which the body movement occurred and the timing before and after the movement to be smaller than the predetermined value;
setting a weight for a view facing a view corresponding to each of the timing at which the body movement occurs and the timing before and after the movement to be greater than the predetermined value;
setting weights for other views to the predetermined value;
applying the weights to the projection data to perform reconstruction processing to generate reconstructed image data;
a reconstruction processing unit;
A medical image processing apparatus comprising: 14. The medical image processing apparatus according to claim 13, wherein the body motion information acquired at the timing of scanning is added to the scanned data and stored. storing the body motion information obtained for the scanned data independently of the scanned data and in association with the scanned data;
14. The medical image processing apparatus according to claim 13, wherein said reconstruction processing unit carries out reconstruction by adding a weight based on said body motion information at the timing of reconstructing an image. The reconstruction processing unit weights data belonging to the predetermined region in the scanned data when the acquired body motion information is information acquired in the predetermined region of the subject. 15. The medical image processing apparatus according to claim 13 or 14, which is applied to perform reconstruction processing. a display unit for displaying a reconstructed image based on the reconstructed image data reconstructed by the reconstruction processing unit;
an input unit for a user to check the reconstructed image displayed on the display unit and change a parameter related to weight;
16. The medical image processing apparatus according to any one of claims 13 to 15, further comprising:

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