JP7279336B2 - X-ray equipment - Google Patents

Description

The present invention is an X-ray imaging apparatus for positioning a subject on a subject placement section when performing treatment by irradiating a therapeutic beam to an affected area of the subject using a therapeutic beam irradiation apparatus. Regarding the device.

2. Description of the Related Art In radiation therapy in which radiation such as X-rays, electron beams, and particle beams is applied to an affected area such as cancer, it is necessary to accurately irradiate the affected area with radiation. When performing radiotherapy using a radiotherapy apparatus, a treatment plan is formulated prior to treatment. Then, when radiotherapy is performed, it is necessary to perform positioning so that the position of the patient matches that at the time of treatment planning. Positioning of a patient in a radiotherapy apparatus has conventionally been performed by a technician by manipulating the position of an examination table on which the patient is placed while visually confirming the position indicated by a laser marking device. On the other hand, in recent years, it has been proposed to position a patient using an X-ray image (see Patent Document 1).

At this time, in the positioning of the patient using X-ray images, the geometric arrangement of the X-ray imaging system in the treatment equipment is reproduced on the computer, and the three-dimensional image data collected by the X-ray CT equipment at the time of treatment planning is used. Using a DRR (Digital Reconstructed Radiography) image, which is a virtual perspective projection, and evaluating the similarity between the X-ray image taken by the X-ray imaging system and the DRR image (image registration), the current state of the patient The amount of deviation between the position and the position at the time of treatment planning is calculated. Since DRR is computationally expensive, US Pat.

JP 2013-99431 A

In the above-described conventional apparatus, once the subject is positioned and fixed, and treatment is started, the position of the subject is not confirmed. Therefore, even if the subject's body position or the like changes for some reason, the operator does not notice this and the treatment is continued. For this reason, the treatment beam may be irradiated to a position other than the position where treatment should be performed.

Moreover, when irradiating a tumor near the subject's lung with a therapeutic beam, the position of the tumor changes greatly according to the subject's respiration. Therefore, in such a case, the subject is continuously photographed from two different directions by the X-ray imaging unit, and the X-ray image including the markers placed in the body of the subject or the identification of the subject is obtained. An X-ray imaging apparatus is used that has a function called moving body tracking that tracks the position of a marker that moves along with the subject's body movement or the position of a specific site by acquiring an X-ray image that includes the site. . When an X-ray imaging apparatus having such a moving body tracking function is used, it is possible to prevent the treatment beam from being irradiated to a position other than the position where the treatment should be performed. The treated beam reaches the target location less frequently, and the subject receives extra X-ray exposure for motion tracking.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is an X-ray apparatus capable of properly irradiating a subject with a therapeutic beam even when the subject is displaced after the start of treatment. An object of the present invention is to provide an imaging device.

A first invention is to position a subject on a subject placement section when performing treatment by irradiating a therapeutic beam to an affected area of the subject using a therapeutic beam irradiation apparatus. A radiographic apparatus comprising a plurality of X-ray imaging systems each having an X-ray tube and an X-ray detector for detecting X-rays emitted from the X-ray tube and passing through a subject, An X-ray imaging unit that takes X-rays from two different directions, and simulates the geometric imaging conditions of the X-ray imaging system for the subject with respect to the CT image data of the subject created during treatment planning. a DRR image creating unit for creating a DRR image of the subject by performing a virtual perspective projection; A displacement amount of the subject is detected by comparing the image with the DRR image created by the DRR image creating unit, and the X-ray is detected while the subject is being treated. a position detection unit that detects the amount of positional deviation of the subject by comparing the X-ray image captured by the imaging unit and the DRR image created by the DRR image creation unit.

A second aspect of the invention is a movement for moving the subject placement section based on the amount of positional deviation of the subject detected by the position detection section when treatment is being performed on the subject. It is characterized by further comprising an indicator.

A third aspect of the present invention provides a warning display when the amount of displacement of the subject detected by the position detection unit during treatment of the subject exceeds a preset value. or to send a signal to stop the irradiation of the therapeutic beam to the therapeutic beam irradiation apparatus.

In a fourth aspect of the invention, the subject is continuously imaged from two different directions by the X-ray imaging unit, and an X-ray image including markers placed in the body of the subject or identification of the subject is performed. It further comprises a moving body tracking unit that tracks the position of the marker or the specific part that moves with the body movement of the subject by acquiring an X-ray image containing the part.

According to the first invention, it is possible to detect the positional deviation that occurs when the subject is being treated by the position detecting section.

According to the second aspect of the present invention, since the subject placement section is moved based on the positional deviation amount detected by the position detection section while the subject is undergoing treatment, the subject placement section is moved after the start of treatment. Even if the examiner is displaced, the examinee can be returned to the position positioned before the start of treatment, and the treatment beam can be properly irradiated to the examinee.

According to the third invention, when the amount of positional deviation detected by the position detection unit during treatment of the subject exceeds a preset value, a warning is displayed, or Since the treatment beam irradiation stop signal is transmitted to the treatment beam irradiation device, even if the position of the subject is displaced after the start of treatment, the irradiation of the treatment beam to an inappropriate position can be prevented. , it is possible to properly irradiate the subject with the treatment beam.

According to the fourth invention, by using the X-ray image acquired during moving body tracking, the X-ray image and the DRR image are compared while the subject is being treated, and the subject is can be detected. Therefore, it is possible to appropriately irradiate the subject with the therapeutic beam without causing excessive radiation exposure to the subject.

1 is a perspective view showing an X-ray imaging apparatus according to the present invention together with a therapeutic beam irradiation apparatus 90; FIG. 1 is a block diagram showing main control systems of an X-ray imaging apparatus according to the present invention; FIG. 4 is a flow chart showing an overview of the operation of the X-ray imaging apparatus during treatment of a subject; 4 is a schematic diagram showing a DRR image D created in a DRR image creation process; FIG. 1 is a schematic diagram showing an X-ray image X created in an X-ray imaging process; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an X-ray imaging apparatus according to the present invention together with a treatment beam irradiation apparatus 90. As shown in FIG.

The treatment beam irradiation apparatus 90 irradiates the subject on the medical examination table 27 with radiation, and has a gantry 92 installed swingably with respect to a base 91 installed on the floor of the treatment room. and a therapeutic beam irradiation unit 93 arranged on a gantry 92 for emitting a therapeutic beam. The gantry 92 is structured to be rotatable within a range of 360 degrees with respect to the base 91 together with the therapeutic beam irradiation unit 93 . Therefore, according to this therapeutic beam irradiation apparatus 90, by rotating the gantry 92 to an arbitrary angle with respect to the base 91, the irradiation direction of the therapeutic beam emitted from the therapeutic beam irradiation unit 93 can be changed. . Therefore, it is possible to irradiate the affected area such as a tumor of the subject with the treatment beam from various directions.

The X-ray imaging apparatus used together with this treatment beam irradiation apparatus 90 performs X-ray imaging for performing moving body tracking for specifying the position of the affected part of the subject. That is, during radiotherapy using the therapeutic beam irradiation apparatus 90 described above, it is necessary to accurately irradiate radiation to the affected area that moves with body movement caused by respiration or the like of the subject. For this reason, in this X-ray imaging apparatus, a subject is viewed from two different directions, and image recognition is performed on the fluoroscopic images to obtain a specific site of the subject or a specific site of the subject. By detecting the position of a marker placed nearby (hereinafter collectively referred to as "marker etc.") and calculating three-dimensional positional information of the marker etc., the marker etc. can be detected with high accuracy. , and moving object tracking. During this moving object tracking, X-rays are intermittently emitted at intervals of time T to perform X-ray imaging.

As one embodiment of the image recognition described above, an image of a marker indwelled near a specific site of a subject is registered in advance as a template, and the position of the marker is detected and tracked using this template. Template matching is used. It should be noted that instead of indwelling the marker in the vicinity of the affected area of the subject, moving body tracking may be adopted in which an image of a specific site such as a tumor on the subject is used as the marker.

Further, as another embodiment of this image recognition, a classifier is created by learning from a large number of pre-registered correct images and incorrect images for a marker or the like, and this classifier is used to recognize a marker or the like. It uses machine learning to detect and track your location. As such machine learning, for example, SVM (Support Vector Machine) can be used. This SVM is one of the most rapid and highly recognizable learning models among many techniques when performing pattern recognition. Also, as machine learning with excellent recognition performance, a neural network such as Boosting using Haar-like feature values or Deep Learning may be used instead of SVM.

This X-ray imaging apparatus includes a first X-ray tube 11a, a second X-ray tube 11b, a third X-ray tube 11c, a fourth X-ray tube 11d (collectively referred to as "X-ray tube 11"), and a first X-ray tube. A flat panel detector 21a, a second flat panel detector 21b, a third flat panel detector 21c, and a fourth flat panel detector 21d (collectively referred to as "flat panel detector 21") are provided. The X-rays emitted from the first X-ray tube 11a are detected by the first flat panel detector 21a after passing through the subject on the examination table 27. FIG. The first X-ray tube 11a and the first flat panel detector 21a constitute a first X-ray imaging system. The X-rays emitted from the second X-ray tube 11b are detected by the second flat panel detector 21b after passing through the subject on the examination table 27. FIG. The second X-ray tube 11b and the second flat panel detector 21b constitute a second X-ray imaging system. The X-rays emitted from the third X-ray tube 11c are detected by the third flat panel detector 21c after passing through the subject on the examination table 27. FIG. The third X-ray tube 11c and the third flat panel detector 21c constitute a third X-ray imaging system. The X-rays emitted from the fourth X-ray tube 11d are detected by the fourth flat panel detector 21d after passing through the subject on the examination table 27. FIG. The fourth X-ray tube 11d and the fourth flat panel detector 21d constitute a fourth X-ray imaging system.

When performing X-ray imaging for moving body tracking, two X-ray imaging systems out of the first X-ray imaging system, second X-ray imaging system, third X-ray imaging system, and fourth X-ray imaging system are used. selected and used. Then, each X-ray imaging system executes X-ray imaging from two directions by similar operations. Although the following description of the X-ray imaging operation is for one X-ray imaging system, the other X-ray imaging system performs similar operations.

The examination table 27 comprises a base 28 and a subject placement part 29, also called a couch. The subject placement section 29 is movable and rotatable in six axial directions with respect to the base section 28 .

FIG. 2 is a block diagram showing the main control system of the X-ray imaging apparatus according to the invention.

This X-ray imaging apparatus includes a control unit 30 that controls the entire apparatus. This control unit 30 is composed of a computer in which software is installed. The function of each part included in this control part 30 is realized by executing software installed in the computer.

This control unit 30 is connected to the X-ray tube 11, flat panel detector 21, examination table 27 and treatment beam irradiation device 90 described above. The control unit 30 is also connected to an operation unit 38 having an input mechanism such as a keyboard for executing various operations, and a display unit 39 having a liquid crystal display panel or the like. Furthermore, this control unit 30 is connected online or offline to a treatment planning device 99 that formulates a treatment plan prior to radiotherapy. The treatment planning device 99 acquires CT image data of the subject photographed by a CT imaging device (not shown). The control unit 30 acquires this CT image data from the treatment planning device 99 .

This control unit 30 includes an X-ray imaging control unit 31 for controlling X-ray imaging using an X-ray imaging system having an X-ray tube 11 and a flat panel detector 21, Create a DRR image of the subject by performing a virtual perspective projection that simulates the geometric imaging conditions of each X-ray imaging system for the subject on the CT image data of the region containing The unit 32 compares the X-ray image taken by the X-ray imaging system with the DRR image created by the DRR image creation unit 32 before the treatment is performed on the subject. In addition to detecting the amount, by comparing the X-ray image taken by the X-ray imaging system and the DRR image created by the DRR image creation unit 32 while the subject is being treated, a position detection unit 33 that detects the amount of positional deviation, a treatment beam irradiation instruction unit 34 that instructs the treatment beam irradiation device 90 to irradiate the treatment beam, and movement of the subject placement unit 29 on the examination table 27 and when the amount of displacement of the subject detected by the position detection unit 33 during treatment of the subject exceeds a preset value , a warning unit 36 that displays a warning on the display unit 39 or transmits a signal to stop treatment beam irradiation to the treatment beam irradiation device 90 via the treatment beam irradiation instruction unit 34, and the subject is different from the warning unit 36. Moving object tracking that tracks the position of markers, etc. that move along with body movements of the subject by acquiring X-ray images containing markers, etc., placed in the body of the subject by continuously photographing from two directions. a portion 37;

Next, operations such as positioning of the subject by the X-ray imaging apparatus having the above configuration will be described. FIG. 3 is a flow chart showing an outline of the operation of the X-ray imaging apparatus during treatment of the subject.

When starting treatment for a subject, first, a DRR image used for positioning the subject is created (step S1). When creating a DRR image, CT image data of the subject acquired from the treatment planning device 99 is used. This CT image data is three-dimensional voxel data that is a set of a plurality of two-dimensional CT image data. Then, a DRR image of the subject is created by performing virtual perspective projection simulating the geometric imaging conditions of each X-ray imaging system for the subject on the CT image data.

Next, X-ray imaging is performed to obtain an X-ray image used for positioning the subject (step S2). At this time, among the first to fourth X-ray imaging systems, the X-ray imaging system that simulates the geometrical imaging conditions at the time of creating the DRR image is used.

Then, by comparing the DRR image created in the DRR image creation process (step S1) and the X-ray image created in the X-ray imaging process (step S2), the first position detection of the subject is performed ( step S3).

FIG. 4 is a schematic diagram showing the DRR image D created in the DRR image creation process (step S1), and FIG. 5 is a schematic diagram showing the X-ray image X created in the X-ray imaging process (step S2). is.

In the DRR image D and the X-ray image X, an image of the bone part 41 and an image of the soft tissue 42 of the subject are displayed. The DRR image D and the X-ray image X will match when the subject is positioned at the appropriate position set during treatment planning. The position detection unit 33 detects the displacement amount of the subject based on the images of the subject's ribs in the DRR image D and the X-ray image X, and the like. Then, based on the amount of positional deviation detected by the position detection unit 33, the movement instruction unit 35 transmits a signal to the examination table 27, and by moving the subject placement unit 29 of the examination table 27, Perform patient positioning. At this time, after calculating the movement amount of the subject placement section 29 based on the detected positional deviation amount, the subject placement section 29 may be moved. X-ray imaging may be performed continuously from time to time.

When the position of the subject reaches the appropriate position set at the time of treatment planning, treatment of the subject is started (step S4). When starting treatment, moving body tracking is started to track the position of a marker or the like that moves with the subject's body movement (step S5). When performing X-ray imaging for moving body tracking, two X-ray imaging systems are selected from the first X-ray imaging system, the second X-ray imaging system, the third X-ray imaging system, and the fourth X-ray imaging system. For example, X-ray imaging is continuously performed at a frame rate of about 30 FPS (Frames Per Second). Then, using the captured X-ray images, the positions of markers and the like are continuously detected by template matching or machine learning.

This moving object tracking operation is continuously performed by the moving object tracking unit 37 until the treatment for the subject is completed (step S6). Then, during treatment of the subject, position detection of the subject is performed at regular time intervals (step S7). At this time, the position of the subject during treatment is detected by comparing the DRR image acquired in the DRR image creation step and the X-ray image acquired by continuous X-ray imaging for tracking the moving body. As for the X-ray images used for this position detection, among the X-ray images acquired at a frame rate of about 30 FPS, the X-ray images acquired every minute, for example, are used.

When performing this position detection, if the X-ray imaging system used among the first X-ray imaging system, the second X-ray imaging system, the third X-ray imaging system, and the fourth X-ray imaging system is changed, , a DRR image may be obtained again by performing virtual perspective projection simulating the geometric imaging conditions of these X-ray imaging systems.

Then, when the subject is positioned at the correct position as a result of the position detection of the subject, the position detection is executed at regular time intervals until the treatment is completed (steps S6 and S7). Then, when the treatment is completed, the moving body tracking operation is completed (step S8).

On the other hand, if the subject has moved from the correct position as a result of position detection of the subject, a positioning operation for moving the subject to the correct position is executed as one embodiment. In this positioning operation, the movement instructing unit 35 transmits a signal to the examination table 27 based on the amount of positional deviation detected by the position detection unit 33, and the subject placement unit 29 of the examination table 27 is moved. It is executed by Thereby, it becomes possible to continue the treatment for the subject.

Further, as another embodiment, the warning unit 36 transmits a signal to the display unit 39 based on the amount of positional deviation detected by the position detection unit 33, and displays a warning display on the display unit 39. The unit 36 transmits a treatment beam irradiation stop signal to the treatment planning device 99 via the treatment beam irradiation instruction unit 34 . This makes it possible to prevent the treatment beam from being applied to inappropriate positions.

As described above, according to the X-ray imaging apparatus according to the present invention, even during the treatment of the subject with the treatment beam, the displacement of the subject is continuously detected, and the treatment beam is irradiated to the subject. can be executed properly. At this time, since the X-ray image used for the position detection of the subject may be a part of the X-ray image obtained by tracking the moving body, the subject is not exposed to excessive radiation. .

In the above-described embodiment, an X-ray imaging apparatus that tracks a moving object is used, and an X-ray image obtained during tracking of the moving object is used to detect positional deviation during treatment. However, the present invention can be applied even when moving object tracking is not performed. In such a case, an X-ray image of the subject is acquired at regular intervals using an X-ray imaging system, and the X-ray image is compared with a previously acquired DRR image to detect positional deviation. The amount should be detected.

11a first X-ray tube 11b second X-ray tube 11c third X-ray tube 11d fourth X-ray tube 21a first flat panel detector 21b second flat panel detector 21c third flat panel detector 21d fourth flat panel detector 27 medical examination table 29 subject Person placement unit 30 Control unit 31 X-ray imaging control unit 32 DRR image creation unit 33 Position detection unit 34 Treatment beam irradiation instruction unit 35 Movement instruction unit 36 Warning unit 38 Operation unit 39 Display unit 90 Treatment beam irradiation device 99 Treatment planning device D DRR image X X-ray image

Claims (1)

An X-ray imaging apparatus for positioning a subject on a subject placement section when performing treatment by irradiating a therapeutic beam to an affected area of the subject using a therapeutic beam irradiation device, ,
Equipped with a plurality of X-ray imaging systems each having an X-ray tube and an X-ray detector for detecting X-rays emitted from the X-ray tube and passing through a subject, and performing X-ray imaging of the subject from two different directions. and an X-ray imaging unit that
By performing a virtual perspective projection that simulates the geometric imaging conditions of the X-ray imaging system for the subject on the CT image data of the subject created at the time of treatment planning, the subject a DRR image creating unit for creating a DRR image of
The subject is continuously imaged from two different directions by the X-ray imaging unit while the subject is being treated, and the marker is placed in the body of the subject. a moving body tracking unit that tracks the position of the marker or the specific part that moves with the subject's body movement by acquiring an X-ray image or an X-ray image that includes the specific part of the subject;
An X-ray image extracted from X-ray images continuously captured for tracking the position of the marker or the specific region by the moving body tracking unit while the subject is being treated. and a position detection unit that detects the amount of positional deviation of the subject by comparing the DRR image created by the DRR image creation unit;
a movement instruction unit that moves the subject placement unit based on the amount of displacement of the subject detected by the position detection unit when the subject is being treated;
When the positional deviation amount of the subject detected by the position detection unit while the subject is being treated exceeds a preset value, a warning is displayed, or a warning unit that transmits a therapeutic beam irradiation stop signal to the therapeutic beam irradiation device;
An X-ray imaging apparatus comprising:

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