JP2018079011A - Radioscopic method and radioscopic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radioscopic method and a radioscopic apparatus capable of detecting the position of a marker or a specific site even when a subject turns into a respiratory condition deviating from a normal respiratory condition.SOLUTION: In an image collection process, an image including a marker or a specific site is collected at a predetermined frame rate as a subject is taking a deep breath. When the subject is taking a deep breath, the marker or the specific site moves in a range wider than when the subject is breathing normally. The movement of the marker or the specific site is photographed in every stroke, and the image is collected. Thus, even when the subject turns into a respiratory condition deviating from a normal respiratory condition, the position of the marker or the specific site can be detected.SELECTED DRAWING: Figure 4

Description

  This invention detects the X-rays irradiated from the X-ray tube and passed through the subject with an X-ray detector, and collects images including the specific part of the subject to detect the position of the specific part, The present invention relates to an X-ray fluoroscopy method and an X-ray fluoroscopy device for tracking the movement of a specific part.

  In radiation therapy in which radiation such as X-rays or electron beams is applied to an affected area such as a tumor, it is necessary to accurately irradiate the affected area with radiation. However, not only the subject may move the body, but the affected part itself may move. For example, a tumor near the lung moves greatly based on respiration. For this reason, a radiotherapy apparatus having a configuration in which a gold marker having a spherical shape is placed near a tumor, the position of the marker is detected by an X-ray fluoroscope, and irradiation of therapeutic radiation is controlled has been proposed. (See Patent Document 1).

  In such a radiotherapy apparatus, a first X-ray fluoroscopic mechanism composed of a first X-ray tube and a first X-ray detector and a second X-ray fluoroscopic mechanism composed of a second X-ray tube and a second X-ray detector are used. A marker placed in the body is photographed, and three-dimensional position information is obtained using a two-dimensional fluoroscopic image by the first X-ray fluoroscopic mechanism and a two-dimensional fluoroscopic image by the second X-ray fluoroscopic mechanism. Then, X-ray fluoroscopy is continuously performed, and the three-dimensional position information of the marker is calculated in real time, thereby detecting the marker of the part accompanying movement with high accuracy. Then, by controlling the irradiation of the therapeutic radiation based on the detected marker position information, it is possible to execute the radiation irradiation with high accuracy according to the movement of the tumor. When obtaining the position information of this marker, template matching using a template image is executed.

  By the way, in order to detect the movement of the tumor using the marker as described above, it is necessary to place the marker in advance in the body of the subject. For this reason, in recent years, a method of omitting the placement of the marker by using a specific part such as a tumor region of the patient instead of the marker has been proposed.

Japanese Patent No. 3053389

  In a conventional X-ray fluoroscopic apparatus used in such a radiotherapy apparatus, an image including a marker or a specific part is acquired at a predetermined frame rate in a state where the subject is performing normal breathing. Create a template based on. However, when treatment is actually being performed on the subject, the respiratory state may deviate from the normal respiratory state. In such a case, there arises a problem that the position of the marker or the specific part is lost at the time of template matching.

  The present invention has been made to solve the above-described problem, and detects the position of a marker or a specific part even when a subject's breathing state changes from a normal breathing state to a breathing state. It is an object of the present invention to provide an X-ray fluoroscopy method and an X-ray fluoroscopy device capable of performing the above-mentioned.

  According to a first aspect of the present invention, an X-ray detector that detects X-rays irradiated from an X-ray tube and passed through a subject, and an image including a marker placed in the body of the subject or identification of the subject An X-ray fluoroscopy method for detecting the position of the marker or the specific part by collecting an image including the part and tracking the movement of the specific part, where the subject is taking a deep breath, An image collecting process for collecting an image including the marker or the specific part, and a basic image showing the marker or the specific part is created based on the image including the marker or the specific part collected in the image collecting step. A basic image storing step for storing the X-ray, and X-rays emitted from the X-ray tube and passing through the subject are detected by the X-ray detector, and an image including the marker or the specific part is collected. And a position detecting step of detecting a position of the marker or the specific part using the image obtained in the fluoroscopic step and the basic image stored in the basic image storing step. To do.

  In the second invention, the basic image is a template, and the position of the marker or the specific part is detected by template matching in the position detection step.

  In the third invention, the basic image is a correct image used for machine learning, and the position detection step detects the position of the marker or the specific part using machine learning.

  In a fourth aspect of the present invention, in the image collection step, an image including the marker or the specific part is collected at a predetermined frame rate in either the subject inhalation step or the subject exhalation step. To do.

  In a fifth aspect of the present invention, in the image collection step, images including the marker or the specific part are collected at a predetermined frame rate in both the inhalation step of the subject and the exhalation step of the subject.

  A sixth invention includes an X-ray tube and an X-ray detector that detects X-rays irradiated from the X-ray tube and passed through the subject, and collects an image including a specific part of the subject. Thus, the X-ray fluoroscopic apparatus detects the position of the specific part and tracks the movement of the specific part, and collects an image including the marker or the specific part in a state where the subject takes a deep breath. An image collection unit; a basic image storage unit that creates and stores a basic image indicating the marker or the specific part based on an image including the marker or the specific part collected by the image collection unit; and the X Using the image including the marker or the specific part collected by the X-ray tube and the X-ray detector and a plurality of basic images stored in the basic image storage unit, the position of the marker or the specific part Detect Characterized by comprising a 置検 out portion.

  According to the first and sixth inventions, the position of the marker or the specific part can be detected even when the respiratory state of the subject becomes a respiratory state deviating from the normal respiratory state.

  According to the second invention, it is possible to accurately detect the position of the marker or the specific part by template matching.

  According to the third invention, it is possible to efficiently detect the position of the marker or the specific part by machine learning.

  According to the fourth aspect of the invention, it is possible to collect a marker or an image of a specific part when the respiratory state deviates from the normal respiratory state in correspondence with the respiratory phase to which the treatment beam is irradiated.

  According to the fifth aspect, it is possible to collect a marker or an image of a specific part when the respiratory state deviates from the normal respiratory state over the entire region of the respiratory phase.

1 is a perspective view showing an X-ray fluoroscopic apparatus according to the present invention together with a radiation irradiation apparatus 90. FIG. It is a block diagram which shows the main control systems of the X-ray fluoroscope which concerns on 1st Embodiment of this invention. It is a flowchart which shows the moving body tracking operation | movement which uses the X-ray fluoroscope which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the relationship between a subject's breathing state, X-ray fluoroscopy, and the irradiation state of a treatment beam. It is a block diagram which shows the main control systems of the X-ray fluoroscope which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the moving body tracking operation | movement using the X-ray fluoroscope which concerns on 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an X-ray fluoroscopic apparatus according to the present invention together with a radiation irradiation apparatus 90. The X-ray fluoroscopic apparatus and the radiation irradiation apparatus 90 constitute a radiotherapy apparatus.

  The radiation irradiation device 90 irradiates the subject on the examination table 29, also called a couch, with radiation, and is installed so as to be swingable with respect to the base 91 installed on the floor of the treatment room. The gantry 92 is provided with a head 93 that emits a treatment beam disposed in the gantry 92. According to this radiation irradiation apparatus 90, the irradiation direction of the treatment beam irradiated from the head 93 can be changed by the gantry 92 swinging with respect to the base 91. For this reason, it becomes possible to irradiate the treatment beam from various directions with respect to the affected part such as a tumor in the subject.

  The X-ray fluoroscope used together with the radiation irradiating apparatus 90 performs X-ray fluoroscopy for tracking a moving body that specifies the position of an affected part of a subject. That is, at the time of radiotherapy using the radiation irradiation apparatus 90 described above, it is necessary to accurately irradiate the affected area that moves with the body movement of the subject. For this reason, a gold marker having a spherical shape or the like placed near the tumor is registered in advance, and the region including the marker is continuously X-rayed to obtain the three-dimensional position information of the marker. By calculating, the marker is detected with high accuracy, so-called moving body tracking is performed.

  In addition, instead of the marker, a part having a specific shape such as a tumor in the subject is registered in advance as a specific part, and the specific part is detected with high accuracy by calculating the three-dimensional position information of the specific part. Techniques have also been proposed. Thus, instead of placing a marker in the vicinity of an affected area in a conventional subject, a moving body tracking method that uses an image of a specific site such as a tumor in the subject as a marker is called markerless tracking. .

  The X-ray fluoroscopic apparatus includes a first X-ray tube 11a and a second X-ray tube 11b, and a first flat panel detector 21a and a second flat panel detector 21b. The X-rays irradiated from the first X-ray tube 11a pass through the subject on the examination table 29 and are then detected by the first flat panel detector 21a. Further, the X-rays irradiated from the second X-ray tube 11b pass through the subject on the examination table 29 and then detected by the second flat panel detector 21b.

  FIG. 2 is a block diagram showing a main control system of the X-ray fluoroscopic apparatus according to the first embodiment of the present invention. Note that the X-ray fluoroscopic apparatus according to the first embodiment performs tracking of moving objects using template matching.

  This X-ray fluoroscopic apparatus is equipped with a CPU that performs logical operations, a ROM that stores operation programs necessary for controlling the apparatus, a RAM that temporarily stores data during control, and the like, and controls the entire apparatus. The unit 30 is provided. The control unit 30 is connected to the first X-ray tube 11a and the second X-ray tube 11b described above, and the first flat panel detector 21a and the second flat panel detector 21b.

  The control unit 30 includes an image collection unit 31 and a template matching unit 32. The image collecting unit 31 collects an image including a marker placed in the body of the subject or a specific part of the subject at a predetermined frame rate in a state where the subject takes a deep breath. The template matching unit 32 also stores a template creation unit 33 that creates a plurality of templates indicating markers or specific parts based on the images including the markers or specific parts collected by the image collecting unit 31, and these templates. The position of the marker or specific part is detected by multi-template matching in which a plurality of templates stored in the template storage part 34 are applied to an image including the marker or specific part collected in the fluoroscopy process. And a matching unit 35.

  Next, an operation for performing moving body tracking for detecting the position of a specific part that moves with the body movement of the subject by using the X-ray fluoroscope having the above-described configuration will be described. FIG. 3 is a flowchart showing a moving body tracking operation using the X-ray fluoroscopic apparatus according to the first embodiment of the present invention. The following operation uses both an X-ray imaging system composed of the first X-ray tube 11a and the first flat panel detector 21a and an X-ray imaging system composed of the second X-ray tube 11b and the second flat panel detector 21b. In the following, only one of them will be described. The following operations are similarly performed for the two X-ray imaging systems.

  When moving body tracking is performed by the X-ray fluoroscopic apparatus according to the present invention, first, an image collecting process is performed by the image collecting unit 31 shown in FIG. 2 (step S11). In this image collection process, the subject is placed on the examination table 29, and an image including the marker or specific part of the subject is taken at a predetermined frame rate in a state where the subject takes a deep breath. To collect a plurality of images.

  FIG. 4 is a schematic diagram showing the relationship between the breathing state of the subject and the irradiation state of fluoroscopy and treatment beams.

  In the above-described image collection process in the X-ray fluoroscopic apparatus according to the present invention, as shown with a circle in FIG. 4, in a state where the subject takes a deep breath, a marker or a specific part is set at a predetermined frame rate. Collect including images. During deep breathing by the subject, the marker or specific part moves in a wider range than during normal breathing of the subject. This movement of the marker or specific part is photographed in all strokes, and the image is collected.

  This image collection process is executed only in any one of the inhalation process and the exhalation process of the subject including the respiratory phase for irradiating the treatment beam described later. As a result, it is possible to collect a marker or an image of a specific part when the respiratory state of the subject becomes a respiratory state deviating from the normal respiratory state, corresponding to the respiratory phase to which the treatment beam is irradiated. Become. For this reason, it is possible to accurately detect the position of the marker or the specific part at the time of irradiation of the treatment beam while reducing the number of images to be collected.

  As another embodiment, the image collection process may be executed in both the inhalation process and the exhalation process of the subject. When such a configuration is adopted, it is always possible to accurately detect the position of the marker or a specific part when the respiratory state of the subject becomes a respiratory state deviating from the normal respiratory state. It becomes.

  Next, a plurality of templates for template matching are created based on a plurality of X-ray images obtained by this image collection process (step S12). The created templates for template matching correspond to the basic image in the present invention, and are stored in the template storage unit 34 shown in FIG. 2 (step S13). This template covers the entire process in which the marker or the specific site is moved by the subject taking a deep breath.

  When the above preparation process is completed, the subject is placed on the examination table 29 again, and the moving body is tracked by fluoroscopy with the X-ray fluoroscopy device according to the present invention. To start radiotherapy.

  When starting radiotherapy, first, fluoroscopy is performed (step S14). This X-ray fluoroscopy is performed at a predetermined frame rate, for example, about 30 fps (frame per second). Thereby, an image including a marker or a specific part is acquired at a predetermined frame rate.

  And the position of a marker or a specific site | part is detected by performing multi template matching with respect to each of the several image obtained at the X-ray fluoroscopy process by the matching part 35 shown in FIG. 2 (step S15). That is, the position of the marker or specific part is specified for each image by applying a plurality of templates stored in the template storage unit 34 to each image acquired at a predetermined frame rate.

  At this time, as described above, the plurality of templates stored in the template storage unit 34 include the entire stroke of movement of the marker or the specific part corresponding to the inhalation process or the exhalation process or all processes in which the subject takes a deep breath. Has been created. Therefore, even when the subject's breathing is disturbed after starting radiation therapy, the position of the marker or specific part can be detected even when the subject's breathing state deviates from the normal breathing state. Is possible.

  Then, with the tracking of the position of the marker or specific part being continued by template matching, as shown in FIG. 4, when the subject's respiratory phase becomes a preset phase, The treatment beam is irradiated. The tracking of the position of this marker or specific part is continued until the treatment is completed (step S16).

  Next, another embodiment of the present invention will be described. FIG. 5 is a block diagram showing a main control system of the X-ray fluoroscopic apparatus according to the second embodiment of the present invention. Note that the X-ray fluoroscopic apparatus according to the second embodiment performs moving body tracking using machine learning.

  The control unit 30 of the X-ray fluoroscopic apparatus according to the second embodiment includes an image collection unit 31 and a machine learning unit 42. As in the first embodiment described above, the image collection unit 31 is configured to display an image including a marker placed in the body of the subject or a specific part of the subject in a state where the subject has taken a deep breath at a predetermined frame rate. Collect with. The machine learning unit 42 also creates a correct image creating unit 43 that creates a plurality of correct images indicating the markers or specific parts based on the images including the markers or specific parts collected by the image collecting unit 31, and correct answers of these correct answers. A correct image storage unit 44 that stores an image together with an incorrect image, a learning unit 45 that creates one classifier by machine learning based on the correct image and the incorrect image stored in the correct image storage unit 44, and a fluoroscopy process And a detection unit 46 that detects the position of the marker or the specific part by machine learning using the discriminator created in the learning step with respect to the image including the marker or the specific part collected in (1).

  FIG. 6 is a flowchart showing a moving body tracking operation using the X-ray fluoroscopic apparatus according to the second embodiment of the present invention. As in the case of the first embodiment, the following operations are performed from the X-ray imaging system including the first X-ray tube 11a and the first flat panel detector 21a, the second X-ray tube 11b, and the second flat panel detector 21b. However, in the following, only one of them will be described. The following operations are similarly performed for the two X-ray imaging systems.

  When performing moving body tracking, first, an image collecting process is executed by the image collecting unit 31 shown in FIG. 5 (step S21). In this image collection process, the subject is placed on the examination table 29, and an image including the marker or specific part of the subject is taken at a predetermined frame rate in a state where the subject takes a deep breath. To collect a plurality of images.

  Then, a plurality of correct images for machine learning are created based on the plurality of X-ray images obtained by the image collecting step (step S22). The created correct images for machine learning are stored together with the incorrect images in the correct image storage unit 44 shown in FIG. 5 (step S23). This correct answer image covers the entire process in which the marker or the specific part is moved by the subject taking a deep breath. This correct image corresponds to the basic image of the present invention.

  Next, the learning unit 45 shown in FIG. 5 creates a classifier by machine learning based on the correct image and the incorrect image stored in the correct image storage unit 44 (step S24). In this machine learning step, one classifier for machine learning is created by performing learning using a plurality of correct images stored in the correct image storage unit 44. This learning process requires a certain amount of time. However, after the imaging including the marker or the specific site in the subject has been completed in advance, the learning process is performed during the time until the actual radiotherapy is performed, thereby burdening the subject. There is no need to spend.

  As machine learning used in this embodiment, for example, SVM (Support Vector Machine / support vector machine) can be used. This SVM is one of the learning models with the most rapid recognition performance and high recognition performance among many methods when performing pattern recognition. Further, as machine learning with excellent speed, a neural network such as AdaBoost (AdaBoost) based on Haar-like feature amount or Deep Learning (deep learning) may be used instead of SVM.

  When the above preparation process is completed, the subject is placed on the examination table 29 again, and the moving body is tracked by fluoroscopy with the X-ray fluoroscopy device according to the present invention. To start radiotherapy.

  When starting radiotherapy, first, fluoroscopy is performed (step S25). This fluoroscopy is executed at a predetermined frame rate of, for example, about 30 fps, as in the first embodiment described above. Thereby, an image including a marker or a specific part is acquired at a predetermined frame rate.

  Then, for each of the plurality of images obtained in the X-ray fluoroscopy process, the position of the marker or specific part is detected by using machine learning by the detection unit 46 shown in FIG. 5 (step S26). That is, for each image acquired at a predetermined frame rate, the position of the marker or specific part is specified by machine learning using the discriminator created in the learning step.

  At this time, as described above, the plurality of correct images stored in the correct image storage unit 34 are created corresponding to all processes in which the subject took a deep breath. Therefore, even when the subject's breathing is disturbed after starting radiation therapy, the position of the marker or specific part can be detected even when the subject's breathing state deviates from the normal breathing state. Is possible.

  Then, with the tracking of the position of the marker or specific part being continued by machine learning, as shown in FIG. 4, when the subject's respiratory phase becomes a preset phase, The treatment beam is irradiated. The tracking of the position of this marker or specific part is continued until the treatment is completed (step S27).

11a 1st X-ray tube 11b 2nd X-ray tube 21a 1st flat panel detector 21b 2nd flat panel detector 29 Examination table 30 Control part 31 Image collection part 32 Template matching part 33 Template preparation part 34 Template storage part 35 Matching part 42 Machine learning Unit 43 correct image creation unit 44 correct image storage unit 45 learning unit 46 detection unit

Claims (6)

X-rays irradiated from the X-ray tube and passed through the subject are detected by an X-ray detector, and an image including a marker placed in the subject's body or an image including a specific portion of the subject is collected. An X-ray fluoroscopy method for detecting the position of the marker or the specific part by tracking the movement of the specific part,
An image collecting step for collecting an image including the marker or the specific part in a state where the subject is taking a deep breath; and
A basic image storage step of creating and storing a basic image indicating the marker or the specific part based on the image including the marker or the specific part collected in the image collecting step;
A fluoroscopy step of detecting X-rays irradiated from the X-ray tube and passing through the subject with the X-ray detector, and collecting an image including the marker or the specific part;
A position detecting step for detecting the position of the marker or the specific part using the image obtained in the fluoroscopic step and the basic image stored in the basic image storing step;
X-ray fluoroscopy method characterized by including. The X-ray fluoroscopy method according to claim 1,
The X-ray fluoroscopy method, wherein the basic image is a template, and the position of the marker or the specific part is detected by template matching in the position detection step. The X-ray fluoroscopy method according to claim 1,
The X-ray fluoroscopy method in which the basic image is a correct image used for machine learning, and the position detection step detects the position of the marker or the specific part using machine learning. In the X-ray fluoroscopy method in any one of Claims 1-3,
In the image collection step, an X-ray fluoroscopic apparatus that collects an image including the marker or the specific part at a predetermined frame rate in either the subject inhalation step or the subject exhalation step. In the X-ray fluoroscopy method in any one of Claims 1-3,
An X-ray fluoroscopic apparatus that collects an image including the marker or the specific part at a predetermined frame rate in both the subject inhalation step and the subject exhalation step in the image collection step. An X-ray tube; and an X-ray detector that detects X-rays irradiated from the X-ray tube and passed through the subject, and collecting the image including the specific site of the subject, thereby acquiring the specific site An X-ray fluoroscopy device that detects the position of and tracks the movement of the specific part,
In a state where the subject takes a deep breath, an image collecting unit that collects an image including the marker or the specific part;
A basic image storage unit that creates and stores a basic image indicating the marker or the specific part based on the image including the marker or the specific part collected by the image collecting unit;
Using the image including the marker or the specific part collected by the X-ray tube and the X-ray detector and the plurality of basic images stored in the basic image storage unit, the marker or the specific part A position detector for detecting the position of
An X-ray fluoroscopic apparatus comprising:

Images