JP6727644B2 - Moving object tracking device and radiation irradiation system - Google Patents

Description

The present invention relates to a radiation irradiation system for irradiating a diseased part such as a tumor with radiation such as a particle beam for treatment, and a moving object tracking device suitable for such a radiation irradiation system.

As an example of a moving body pursuit irradiating device that can calculate the position of a tumor moving around in the trunk in real time and automatically, and can secure a substantially necessary accuracy without depending on the absolute accuracy of a mechanical system, Patent Document Reference numeral 1 denotes an imaging device that simultaneously captures a tumor marker embedded in the vicinity of the tumor from first and second directions to obtain first and second captured images, and digitized first and second captured images. The template matching by the grayscale normalization cross-correlation method that operates the template image of the tumor marker registered in advance is executed at the real-time level of the predetermined frame rate, and the tumor marker first An image input recognition processing unit that calculates the first and second two-dimensional coordinates, a central processing unit that calculates the three-dimensional coordinates of the tumor marker based on the calculated first and second two-dimensional coordinates, and A moving object pursuit irradiating device including an irradiation control unit that controls irradiation of a therapeutic beam of a linac based on three-dimensional coordinates of a tumor marker is described.

Patent No. 3053389

There is known a method of irradiating a patient such as cancer with radiation such as particle beams and X-rays. Particle beams include proton beams and carbon beams. The irradiation system used for irradiation forms a dose distribution suitable for the shape of a target such as a tumor in a patient's body fixed on a patient bed called a couch.

As a method of forming a dose distribution in a radiation irradiation system, a scanning irradiation method in which a fine particle beam is scanned by an electromagnet to form a dose distribution has begun to spread.

By the way, when a target such as a tumor moves by breathing or the like, it becomes difficult to accurately irradiate the particle beam. Therefore, in recent years, gate irradiation has been realized in which the particle beam is irradiated only when the target is within a predetermined range (gate range).

The above-mentioned Patent Document 1 describes a method called moving body tracking irradiation in which gate irradiation is performed based on the position of a marker embedded near the affected area. The marker used in gate irradiation as described in Patent Document 1 is, for example, a metal sphere having a diameter of about 2 mm.

In the moving body tracking irradiation, gate irradiation is performed based on the position of the tracking target such as the marker embedded near the affected area or the target itself. The position of a tracking target such as a marker is measured using captured images of X-rays in two intersecting directions. The position of the tracking target in the captured image is detected by a method called template matching.

This template matching is a method of comparing an image of a tracking target prepared in advance called a template image with a captured image, and detecting a pattern closest to the template image in the captured image. In this method, the position where the two lines connecting the position on the X-ray measuring device showing the tracking target and the imaging X-ray generator are closest to each other is regarded as the position where the tracking target exists. At the time of this template matching, the captured image and the template image are compared, and the degree of similarity such as standardized cross-correlation is evaluated as a matching score.

Here, Patent Document 1 described above discloses a method of setting a search area and performing template matching only inside the search area to reduce the calculation amount of the marker position determination. However, a method for recognizing a marker from a state in which the marker is not recognized has not been examined.

Therefore, the operator manually sets the search area in the state where the marker is not recognized, but if this setting can be omitted, the treatment time can be shortened.

An object of the present invention is to provide a moving body tracking device and a radiation irradiation system capable of shortening treatment time in moving body tracking.

In order to solve the above problems, for example, the configurations described in the claims are adopted.
The present invention includes a plurality of means for solving the above problems. To give an example thereof, an X-ray imaging device that images a plurality of tracking targets, and an imaged image captured by the X-ray imaging device, the identified in the captured image captured when creating a treatment plan by radiation more based on the position information of the tracking object and a control device for determining the position of said plurality of tracking object, the control device, the position information A region for searching the position of the tracking target is set based on, and the positions of the plurality of tracking targets are obtained by searching the tracking target in the region, and the plurality of tracking targets are first based on the recognized position of the tracking target, to correct the unrecognized said region of said target object and said Rukoto.

According to the present invention, treatment time can be shortened in moving body tracking.

It is the whole proton beam irradiation system lineblock diagram. It is a conceptual diagram which a moving body tracking device acquires a picked-up image. It is a conceptual diagram in which a moving body tracking device calculates the position of a marker from a captured image. It is a conceptual diagram which sets the search area|region of the marker in a comparative example. It is a conceptual diagram which sets the search area|region of the marker in a comparative example. FIG. 6 is a diagram showing a display portion of an X-ray imaged image of the console when setting a marker search area in the first embodiment. FIG. 6 is a diagram showing a change display portion of the matching score of the console when setting the marker search area in the first embodiment. FIG. 8 is a diagram showing a change display portion of the common perpendicular length of the console when setting the marker search area in the first embodiment. FIG. 6 is a diagram showing a display portion of an X-ray imaged image of the console when setting a marker search area in the first embodiment. FIG. 6 is a diagram showing a change display portion of the matching score of the console when setting the marker search area in the first embodiment. FIG. 8 is a diagram showing a change display portion of the common perpendicular length of the console when setting the marker search area in the first embodiment. FIG. 6 is a diagram showing a display portion of an X-ray imaged image of the console when setting a marker search area in the first embodiment. FIG. 6 is a diagram showing a change display portion of the matching score of the console when setting the marker search area in the first embodiment. FIG. 8 is a diagram showing a change display portion of the common perpendicular length of the console when setting the marker search area in the first embodiment. FIG. 6 is a diagram showing a display portion of an X-ray imaged image of the console when setting a marker search area in the first embodiment. FIG. 6 is a diagram showing a change display portion of the matching score of the console when setting the marker search area in the first embodiment. FIG. 8 is a diagram showing a change display portion of the common perpendicular length of the console when setting the marker search area in the first embodiment. FIG. 3 is a conceptual diagram showing a screen of a console in the first embodiment. 5 is a conceptual diagram showing a parameter setting screen used for searching for markers in the first embodiment. FIG. FIG. 9 is a conceptual diagram showing a method of setting a marker search area in the second embodiment. FIG. 8 is a diagram showing a distance between a planned position and a detected position of a marker in the second embodiment.

Embodiments of a moving body tracking device and a radiation irradiation system of the present invention will be described below with reference to the drawings.

<Example 1>
A first embodiment of the moving body tracking device and the radiation irradiation system of the present invention will be described with reference to FIGS. 1 to 11.

The present invention can be applied to a radiation irradiation system such as an X-ray irradiation system or a proton beam irradiation system. In this embodiment, a proton irradiation system will be described as an example with reference to FIG.

As shown in FIG. 1, the proton beam irradiation system which is one of the embodiments of the present invention includes a proton beam generator 10, a beam transport system 20, an irradiation nozzle 22, a moving body tracking device 38, a couch 27, and an irradiation control device 40. Prepare The proton beam irradiation device for irradiating a target with a proton beam includes a proton beam generator 10, a beam transport system 20, and an irradiation nozzle 22.

The proton beam generator 10 includes an ion source 12, a linac 13, and a synchrotron 11. The synchrotron 11 includes a deflection electromagnet 14, a quadrupole electromagnet (not shown), a high frequency acceleration device 18, a high frequency emission device 19, and an emission deflector 17. The ion source 12 is connected to the linac 13, and the linac 13 is connected to the synchrotron 11. In the proton beam generator 10, the protons generated by the ion source 12 are accelerated by the linac 13 in the previous stage and are incident on the synchrotron 11. The proton beam further accelerated by the synchrotron 11 is emitted to the beam transport system 20.

The beam transport system 20 includes a plurality of deflection electromagnets 21 and a quadrupole electromagnet (not shown), and is connected to the synchrotron 11 and the irradiation nozzle 22. Further, a part of the beam transport system 20 and the irradiation nozzle 22 are installed in a cylindrical gantry 25, and can rotate together with the gantry 25. The proton beam emitted from the synchrotron 11 is converged by the quadrupole electromagnet while passing through the beam transport system 20, and is deflected by the deflection electromagnet 21 to enter the irradiation nozzle 22.

The irradiation nozzle 22 includes two scanning electromagnets, a dose monitor, and a position monitor. The scanning electromagnets are installed in directions orthogonal to each other and can deflect the proton beam so that it reaches a desired position in a plane perpendicular to the beam axis at the target position. The dose monitor measures the amount of irradiated proton rays. The position monitor can detect the position where the proton beam has passed. The proton beam that has passed through the irradiation nozzle 22 reaches a target in the irradiation target 26. When treating a patient such as cancer, the irradiation target 26 represents the patient, and the target represents the tumor or the like.

The bed on which the irradiation target 26 is placed is called a couch 27. The couch 27 can move in directions of three orthogonal axes based on an instruction from the irradiation control device 40, and can further rotate about each axis. The position of the irradiation target 26 can be moved to a desired position by these movements and rotations.

The irradiation controller 40 is connected to the proton beam generator 10, the beam transport system 20, the irradiation nozzle 22, the moving body tracking controller 41, the couch 27, the storage device 42, the console 43, etc. It controls devices such as the transport system 20 and the irradiation nozzle 22.

The moving body tracking device 38 includes a first X-ray imaging device, a second X-ray imaging device, and a moving body tracking control device 41. The first X-ray imaging device includes an imaging X-ray generation device 23A that captures a captured image of a marker (tracking target) 29 in the irradiation target 26 and an X-ray measuring device 24A. The second X-ray imaging device includes an imaging X-ray generation device 23B that captures a captured image of the marker 29 and an X-ray measuring device 24B.

The first X-ray imaging device and the second X-ray imaging device are installed so that their X-ray paths intersect. The two pairs of imaging X-ray generators 23A and 23B and the X-ray measuring instruments 24A and 24B are preferably installed in directions orthogonal to each other, but they may not be orthogonal to each other. Further, the imaging X-ray generators 23A and 23B and the X-ray measuring devices 24A and 24B do not necessarily have to be arranged inside the gantry 25, and even if they are arranged at a fixed place such as a ceiling or a floor. good.

The moving body tracking control device 41 calculates the position of the marker 29 based on the signal input from the X-ray imaging device, and then determines whether or not to permit the emission of the proton beam based on the position of the marker 29. The determination is made and a signal indicating whether or not the proton beam irradiation is possible is transmitted to the irradiation control device 40.

More specifically, as shown in FIG. 2, the moving body tracking control device 41 irradiates the marker 29 with the X-rays generated from the imaging X-ray generator 23A, and the two-dimensional X-rays passing through the marker 29. The marker 29 is imaged by measuring the dose distribution with the X-ray measuring device 24A. The marker 29 is imaged by irradiating the marker 29 with the X-ray generated from the imaging X-ray generator 23B and measuring the two-dimensional dose distribution of the X-ray passing through the marker 29 by the X-ray measuring device 24B. .. The moving body tracking control device 41 calculates the three-dimensional position of the marker 29 embedded in the irradiation target 26 from the captured images acquired by the X-ray measuring devices 24A and 24B, and obtains the position of the target based on the result. Further, it is determined whether or not the obtained target position is within a predesignated gate range (irradiation permitted range). If it is determined that the target position is within the gate range, a gate-on signal is output to the irradiation control device. It transmits to 40 and permits emission. On the other hand, when it is determined that the target position is not within the gate range, a gate-off signal is transmitted and emission is not permitted. The irradiation control device 40 controls the emission of the proton beam based on the gate-on signal and the gate-off signal generated by the moving body tracking control device 41.

Acquisition of captured images by the first X-ray imaging apparatus and the second X-ray imaging apparatus is performed at a constant interval of 30 Hz, for example. The acquired captured image shows the marker 29 embedded in the body, and in this embodiment, the position of the marker 29 in the irradiation target 26 is specified by template matching with the template image of the marker 29 prepared in advance. Since it takes time to search if the entire range of the captured image is searched, the marker 29 can be detected only within a range of a predetermined size centered on the position of the marker 29 in the immediately previous captured image (hereinafter, also referred to as a search area). Search for a location.

In FIG. 3, the line 28A connecting the position of the marker 29 detected by the template matching on the X-ray measuring device 24A and the imaging X-ray generator 23A and the position of the marker 29 on the X-ray measuring device 24B and the imaging X-ray generation. A line 28B connecting the device 23B is shown. The two lines 28A and 28B ideally intersect at one point, and the intersection is the position where the marker 29 exists. However, in reality, the two lines 28A and 28B usually have a twisted relationship without intersecting each other due to the influence of the accuracy of template matching and the installation error of the X-ray imaging apparatus. A common perpendicular line can be drawn at a position where the two lines 28A and 28B having the twisted relationship are closest to each other. This common perpendicular is called the common perpendicular. The middle point of this common perpendicular is the position of the marker 29.

Here, when the marker 29 is not correctly detected on at least one of the captured images, the common perpendicular line becomes long. When the length of the common perpendicular 30 exceeds a preset threshold value, it is highly possible that the marker 29 cannot be accurately detected, and the moving body tracking control device 41 determines that the position of the marker 29 is within the gate range. A gate-off signal is transmitted to the irradiation control device 40 to stop irradiation of the proton beam.

A feature of the moving body tracking control device 41 of the present embodiment resides in the method of detecting the markers 29 when the imaging of the plurality of markers 29 is started.

In the conventional method, as described above, a method of recognizing the marker 29 from the state in which the marker 29 is not recognized has not been studied. Therefore, when the operator manually sets the search area in a state where the marker 29 is not recognized, a method is conceivable in which the operator uses the input device such as a mouse to indicate the search area.

As a method of setting the search area for the marker 29 by the moving body tracking control device 41, a method of starting the search for the position of the marker 29 immediately after the start of imaging based on the planned position of the marker 29 on the captured image can be considered. Here, the planned position refers to the position of the marker 29 specified at the time of treatment planning. In the moving body pursuit irradiation, it can be considered that the marker 29 is set as a reference position for irradiating a proton beam when the marker 29 is within a certain range. In this embodiment, the planned position is the center of the search area.

First, a method for starting the search for one marker 29 will be described as a comparative example with reference to FIGS. 4 and 5. FIG. 4 shows one of the two captured images, and FIG. 5 shows the captured image when the marker 29 enters the search area 35. When the imaging of the marker 29 is started by the two X-ray imaging devices, the moving body tracking control device 41 sets the search area 35 on the captured image with the planned position as the center, as shown in FIG. When the marker 29 moves along the locus 33 and enters the search area 35 as shown in FIG. 5, it is determined that the marker 29 has been recognized.

In contrast to the case where there is one marker 29 as described in the above comparative example, the present embodiment is directed to the case where there are a plurality of markers 29. In the present embodiment, a case where there are three markers 29-1, 29-2 and 29-3 will be described as an example with reference to FIGS. 6A to 9C.

The moving body tracking device 38 holds information on the planned positions of the markers 29-1, 29-2, 29-3 on the captured image before the image capturing is started.

First, a method of identifying the planned position on the captured image will be described. When irradiating a proton beam, the treatment planning device determines the position of the isocenter on the CT image for treatment planning. When the position of the isocenter is determined, the three-dimensional positional relationship between the position of the isocenter and the position of the marker 29-1 on the CT image for treatment planning is determined. Next, the planned position when the three-dimensional CT image is converted into the two-dimensional image is obtained. When the direction in which the imaging X-rays are emitted is determined using the two pairs of X-ray imaging devices, the planned position of the marker 29-1 on the captured image is obtained.

Specifically, the position on the captured image corresponding to the point where the straight line connecting the X-ray source for imaging and the marker 29-1 intersects the image receiving surface of the X-ray measuring device 24 is the planned position in the captured image. For the markers 29-2 and 29-3, the planned position on the captured image is similarly obtained.

It is assumed that the markers 29-1, 29-2, and 29-3 are periodically moving as shown by the locus 33 in FIG. 6A. When the imaging is started, the moving body tracking control device 41 searches the images immediately after the imaging is started with the search positions 35-1, 35- with a predetermined size centered on the planned positions P ₁ , P ₂ , P ₃ . 2, 35-3 are set respectively. As a result, it is possible to search for the marker position from the image immediately after the start of imaging without manually setting the search range.

There is a case where any of the markers 29 is not inside the search area at the time of starting the imaging. In the present embodiment, it is assumed that all the markers are outside the search area at the start of imaging. The search for the marker 29 is repeatedly executed until one of the markers 29 enters the corresponding search area 35 and can be recognized. Whether or not the marker can be recognized is determined by setting a reference value for the matching score or the common perpendicular length. When making a judgment using the matching score, a criterion is set in advance, and if the matching score exceeds the value, it is judged that the marker can be recognized. When the common perpendicular length is used, a reference is set in advance, and if the common perpendicular length is shorter than that value, it is determined that the marker 29 can be recognized. Further, it is also possible to make the judgment criteria that both the matching score and the common perpendicular length satisfy the criteria.

For the sake of explanation, assuming that the imaged image of FIG. 6A is the nth image from the start of image capturing, the center positions of the search areas 35-1, 35-2, 35-3 are S _n,1 , S _n,2 , S _n,3 , respectively. To do. In FIG. 6A, since all the markers 29 are outside the search area 35, the matching scores are all lower than the reference value as shown in FIG. 6B, and the common perpendicular length is more than the reference value as shown in FIG. 6C.

FIG. 7A shows the (n+1)th captured image. Since no marker 29 is recognized in the nth captured image shown in FIG. 6A, the moving body tracking control device 41 sets the search area 35 centered on the planned position for the (n+1)th captured image. To do.

As shown in FIG. 7A, in the (n+1)th captured image, since the marker 29-1 has entered the search area 35-1, the matching score exceeds the reference value as shown in FIG. 7B, and in FIG. 7C. As shown, the common perpendicular length is below the standard value. Since the matching score and the common perpendicular length criterion are satisfied, it is determined that the marker 29-1 is recognized at the detection position Q _n+1,1 in the search area 35-1. At this time, the markers 29-2 and 29-3 are not yet recognized.

FIG. 8A shows the (n+2)th captured image. Since the marker 29-1 is recognized in the n+1th captured image as described above, the moving body tracking control device 41 determines that the search area 35-1 of the marker 29-1 is the detection position Q _n+1,1 in the previous frame. Install in the center. Regarding the markers 29-2 and 29-3, the moving body tracking control device 41 centers on the position where the difference between the planned position of the marker 29-1 and the detected position is added as a correction amount to the planned position of each marker. Search areas 35-2 and 35-3 are set.

Specifically, the moving body tracking control device 41 determines that the center positions S _n+2,2 =P ₂ +(Q _n+1,1 −P ₁ ), S _n+2,3 =P ₃ +(Q _n+1,1 −P ₁ ). Set. Areas indicated by dotted lines in FIG. 8A are search areas 35-1A, 35-2A, and 35-3A set around the planned position. Therefore, in the case of the marker 29-2, it is impossible to recognize in the n+2th captured image in the search area 35-2A that is set around the planned position, but the difference between the planned position and the detected position of the marker 29-1 is It can be recognized in the search area 35-2 centered on the position added as the correction amount. It should be noted that the marker 29-3 can be recognized by the n+2th captured image even in the search area 35-3A set around the planned position. At this time, as shown in FIG. 8B, the matching score is above the reference value for all markers, and as shown in FIG. 8C, the common perpendicular length is below all markers.

FIG. 9A shows the (n+3)th captured image. Since the markers 29-1, 29-2, 29-3 can be recognized in the previous frame, the search centers S _n+3,1 , S _n+3,2 , S _n+3,3 are detected in the subsequent frames. The marker positions in the previous image are set, and the search areas 35-1, 35-2, and 35-3 having a predetermined size centering on the position are set.

The size of the search area 35 may be changed before and after recognizing the marker 29. For example, the search area 35-1 may be set smaller after recognition than before recognition of the marker 29-1. By changing the size of the search region, it is possible to shorten the time for searching the marker and shorten the treatment time.

It is also possible to combine the setting of the search area 35 based on the planned position of the present embodiment and the designation of the search area 35 by the operator.

Specifically, when the operator designates the search area 35, the moving body tracking control device 41 causes the marker within the designated search area 35 for the captured images of several frames from the time when the operator designates the search area 35. When each of the 29 images is not recognized and is not recognized, the search region 35 is set around the planned position for the subsequent captured images, and the search is performed.

Alternatively, for example, the marker 29-1 specifies the search area 35-1 by the operator, and the other markers 29-2 and 29-3 are set by the moving body tracking control device 41 to set the search areas 35-2 and 35-3, respectively. You can

In addition, the moving body tracking control device 41 sets a standby time so as not to continue imaging for a long time in a state where the marker 29 is not recognized, and any position of the marker 29 is set during a preset time. If not obtained, the imaging by the imaging X-ray generator 23A and the X-ray measuring instrument 24A and the imaging X-ray generator 23B and the X-ray measuring instrument 24B is stopped.

An example of an input screen example for setting the above-mentioned parameters and reference values will be described later.

In addition, even if the marker 29 fails to be recognized for some reason while the marker 29 is being tracked and irradiated with a proton beam, the time for re-recognizing the marker 29 again can be shortened according to the present embodiment. It becomes possible. A specific method will be described below using the marker 29-1 as an example.

The moving body tracking control device 41 determines whether or not the recognition of the marker 29-1 has succeeded with respect to any of the matching score, the common perpendicular length, and the distance between the detected marker position and the planned position, depending on the operator's input. Set the reference value to determine whether or not. When using the matching score, the matching score is monitored while the marker 29-1 is recognized and tracked, and when the result of the matching score is larger than the reference value, it is determined that the recognition is successful. When the common perpendicular length is used, the common perpendicular length is monitored while recognizing and tracking the marker 29-1, and it is determined that the recognition is successful when the result of the common perpendicular length is smaller than the reference value. To do. When using the distance between the detected marker position and the planned position, the distance between the detected marker position and the planned position is monitored and detected while recognizing and tracking the marker 29-1. When the distance between the selected marker position and the planned position is smaller than the reference value, it is determined that the recognition is successful. Further, for example, two values may be used in combination of a matching score and a common perpendicular length. In this case, when the matching score is larger than the reference value and the common perpendicular length is smaller than the reference value, it is determined that the recognition is successful. More preferably, with respect to the matching score, the common perpendicular length, and the distance between the detected marker position and the planned position, it is preferable to use all the reference values to judge whether or not the recognition is successful. In this case, when the matching score is larger than the reference value and the common perpendicular length and the distance between the detected marker position and the planned position are smaller than the reference value, it is determined that the recognition is successful. ..

In addition, when it is determined that the marker 29-1 has not been recognized using these determination criteria during the tracking of the marker 29-1, the moving body tracking control device 41 focuses on the planned position and the search area 35. Set -1. The method up to the subsequent marker recognition is the same as the method at the start of imaging.

The proton beam irradiation system of this embodiment described above employs an irradiation method called a spot scanning method. The spot scanning method is a method in which an irradiation spot (hereinafter also referred to as a spot) arranged on a target is irradiated with a thin proton beam to form a dose distribution that matches the shape of the target. The proton beam has a characteristic that it advances while losing energy in the body, and the energy loss becomes maximum just before stopping. The shape of the dose distribution due to this energy loss is called a Bragg curve, and has a peak at the end of the range. The depth at which the proton beam forms a peak can be adjusted by changing the energy of the proton beam. Further, the dose distribution shape in the direction perpendicular to the beam axis formed by the proton beam is almost normal distribution. The position that forms the dose distribution in the direction perpendicular to the beam axis can be adjusted by scanning the proton beam with a scanning electromagnet. The combination of changing energy and scanning with a scanning electromagnet can form a uniform dose distribution over the target.

Returning to FIG. 1, the irradiation parameter for irradiation created by the treatment planning apparatus is stored in the storage device 42, and the irradiation control device 40 receives the necessary information from the storage device 42 before the irradiation.

The console 43 is connected to the irradiation control device 40 and the moving body tracking control device 41, and displays information on a monitor based on the signals acquired from the irradiation control device 40 and the moving body tracking control device 41. The information displayed includes the captured image and information about the tracking status of the marker 29. FIG. 7 shows an example of a screen regarding the captured image displayed on the console 43 and the tracking status of the marker 29.

As shown in FIG. 10, an imaging start button 50, a gate start button 51, a captured image A61 and a captured image B62 obtained from the two pairs of X-ray measuring instruments 24A and 24B are displayed on the screen of the console 43. .. Furthermore, the search area 35 and its center are displayed on the captured images A and B, respectively. Further, on the screen, the matching score change display portion 63 of the captured image A as shown in FIGS. 6A, 7A, 8A, and 9A, and the captured images as shown in FIGS. 6B, 7B, 8B, and 9B. A matching score change display portion 64 of B and a common perpendicular line length change display portion 65 as shown in FIGS. 6C, 7C, 8C, and 9C are displayed.

Further, the console 43 receives an input from an operator who operates the proton beam irradiation system, and transmits various control signals to the irradiation control device 40 and the moving body tracking control device 41. The input information includes parameters required for moving body tracking. As shown in FIG. 11, an input screen for parameters required for moving body tracking may be displayed on the console 43.

The parameters that can be input include the matching score of the X-ray imaging apparatus A (a set including the imaging X-ray generator 23A and the X-ray measuring instrument 24A) as a setting item of the marker position determination reference as shown in FIG. There are a reference value, a reference value of a matching score of the X-ray imaging apparatus B (a set including the imaging X-ray generator 23B and the X-ray measuring device 24B), a reference value of the common perpendicular line length, a size of the search region 35, and a waiting time. ..

Next, a procedure of irradiating with a proton beam will be described.

First, the irradiation target 26 is fixed on the couch 27. After that, the couch 27 is moved to move the irradiation target 26 to a position planned in advance. At this time, it is confirmed that the irradiation target 26 has moved to a position planned in advance by capturing a captured image using the X-ray imaging device.

When the operator presses the irradiation preparation button on the console 43, the irradiation control device 40 reads information on the gantry angle, energy and spot, and information on the planned position of the marker 29 from the storage device 42. In accordance with the read gantry angle information, the operator presses the gantry rotation button from the console 43 to rotate the gantry 25.

After the rotation of the gantry 25, the operator presses the imaging start button 50 from the console 43 to cause the moving body tracking control device 41 to start X-ray imaging.

In the present embodiment, the search area 35 is set immediately after the start of imaging using the information on the planned position of the marker 29 on the captured image, and the search for the marker 29 is started on each captured image. Template matching is used to search for the marker 29. In template matching, a position that best matches the pattern of a marker image registered in advance as a template image is searched for on the captured image.

After confirming the start of tracking on the two captured images corresponding to the two X-ray imaging apparatuses, the operator sets the gate range and presses the gate start button 51.

After the gate start button 51 is pressed, if the position of the marker 29 is within the gate range, the moving body tracking control device 41 sends a gate-on signal to the irradiation control device 40. If the operator does not track the intended marker 29 by checking it on the screen, the operator can correct it.

When the operator presses the irradiation start button on the console 43, the irradiation control device 40 accelerates the proton beam to the first irradiation energy based on the energy information read from the storage device 42.

Specifically, the irradiation control device 40 controls the ion source 12 and the linac 13, accelerates the protons generated by the ion source 12 by the linac 13 to the previous stage, and causes the protons to enter the synchrotron 11.

Next, the irradiation control device 40 controls the synchrotron 11 to accelerate the incident proton beam to the energy for first irradiation. The proton beam that orbits the synchrotron 11 is accelerated by the high frequency waves from the high frequency accelerator 18. The irradiation control device 40 controls the excitation amounts of the deflection electromagnet 21 and the quadrupole electromagnet of the beam transport system 20 so that the proton beam of the energy to be initially irradiated can reach the irradiation nozzle 22 from the synchrotron 11. Further, based on the spot information read from the storage device 42, the excitation amounts of the two scanning electromagnets are set so that the proton beam reaches the spot position to be irradiated first.

After these settings are completed, if the irradiation control device 40 receives the gate-on signal from the moving body tracking control device 41, the emission of the proton beam is started. If the gate-off signal has been received, it waits until the gate-on signal is received.

After receiving the gate-on signal, the irradiation control device 40 applies a high frequency to the high frequency emission device 19 to start the emission of the proton beam. When a high frequency is applied to the high frequency emission device 19, a part of the proton beam circulating in the synchrotron 11 passes through the emission deflector 17, the beam transport system 20, and reaches the irradiation nozzle 22. The proton beam that has reached the irradiation nozzle 22 is scanned by the scanning electromagnet, passes through the dose monitor and the position monitor, reaches the target of the irradiation target 26, and forms a dose distribution. The irradiation amount for each spot is registered in the spot information read from the storage device 42, and when the irradiation amount measured by the dose monitor reaches the value registered in the spot information, the irradiation control device 40 controls the extraction high frequency. Stops the emission of the proton beam. After the emission of the proton beam, the irradiation control device 40 calculates the arrival position of the proton beam from the position information of the proton beam measured by the position monitor, and confirms that it coincides with the position registered in the spot information.

Since the irradiation controller 40 irradiates the next spot, the excitation amount of the scanning electromagnet is set so that the proton beam reaches the next spot position registered in the spot information. After the setting is completed, if the gate-on signal is continuously received, the irradiation control device 40 controls the extraction high frequency to start the emission of the proton beam. If the gate-off signal is received, it waits until the gate-on signal is received. When the gate-off signal is received during the irradiation of a certain spot, the emission of the proton beam is continued until the irradiation of the spot during irradiation is completed.

When the irradiation of the spot is repeated and the irradiation of the spot irradiated with the first energy is completed, the irradiation control device 40 controls the synchrotron 11 to decelerate the proton beam and start the irradiation preparation of the proton beam of the next energy. .. The irradiation control device 40 controls the ion source 12 and the linac 13 to inject a proton beam into the synchrotron 11 as in the case of the first energy, and controls the synchrotron 11 to the second irradiation energy. Accelerate the line. The irradiation control device 40 controls the beam transport system 20 and the scanning electromagnet to irradiate the spot read from the storage device 42.

When the above operations are repeated and the irradiation of all the spots is completed, the irradiation control device 40 transmits an irradiation completion signal to the moving body tracking control device 41. Upon receiving the irradiation completion signal, the moving body tracking control device 41 controls the imaging X-ray generators 23A and 23B to stop the X-ray imaging.

When irradiating the target from a plurality of directions, after changing the angle of the gantry 25 and the position of the couch 27, the operator presses the irradiation preparation button and repeats the irradiation of the proton beam in the same manner.

Next, the effect of this embodiment will be described.

The first embodiment of the moving body tracking device 38 and the radiation irradiation system of the present invention described above includes a proton beam irradiation device for irradiating a target with a proton beam, an irradiation control device 40 for controlling the proton beam irradiation device, and a moving object. In the proton beam irradiation system including the tracking device 38, imaging X-ray generators 23A and 23B for imaging the marker 29, X-ray measuring devices 24A and 24B, and a treatment plan created by the captured image and the proton beam. A moving body tracking control device 38 is provided, which includes a moving body tracking control device 41 that obtains the position of the marker 29 based on the information on the position of the marker 29 that is specified on the captured image that is sometimes captured.

As a result, even if the operator does not set the search area, the search area is set based on the positions of the plurality of markers 29 identified at the time of creating the treatment plan on the captured image, and the search is quickly started. Treatment time can be shortened. Further, the work of setting the search area by the operator can be omitted, and the burden on the operator can be reduced as compared with the conventional case.

Further, since the moving body tracking control device 41 sets the search area 35 for searching the position of the marker 29 based on the information of the planned position, and searches for the marker 29 in the set search area 35, the position is obtained, Since the search is started in the region where the marker 29 is supposed to exist without the operator setting the search region, the marker 29 can be recognized more quickly, the treatment time can be shortened, and the burden on the operator can be reduced. It can be reduced more.

Further, after the position of the marker 29 is recognized, the moving body tracking control device 41 sets the search region 35 to be searched thereafter based on the position of the recognized marker 29, and continues the search with high accuracy. can do.

Further, the moving object tracking control device 41 is provided with a console 43 for inputting a region for searching the position of the marker 29, and when the moving body tracking control device 41 does not recognize a plurality of markers 29 within a predetermined time in the input search region 35, By searching the marker 29 based on the information of the planned position, the operator can specify the search area 35 and the setting of the search area 35 using the planned position, and further shorten the time until the marker 29 is recognized. It becomes possible to do.

Further, when the moving body tracking control device 41 does not recognize the positions of the plurality of markers 29 within a predetermined time, the moving body tracking control device 41 stops the imaging by the first X-ray imaging device and the second X-ray imaging device, so that it is unnecessary. It is possible to prevent the X-rays for imaging from being irradiated, and it is possible to reduce the burden on the patient, the device, and the like.

In addition, Patent Document 1 discloses a method of tracking a plurality of markers. However, a method of associating a plurality of recognized markers with a marker placed on a patient has not been studied. Therefore, there is a problem that it may take a long time if the operator manually associates the markers. On the other hand, when there are a plurality of markers 29 as in the present embodiment, after a certain marker 29 is recognized, the moving body tracking control device 41 determines that the marker 29 is not recognized based on the position of the recognized marker 29. By correcting the search area 35 for searching the positions of 29, by using the information of the detected positions of the already recognized markers, the search area for the unrecognized markers can be corrected to recognize all the markers. It is possible to shorten the time.

In the above example, the case where the markers 29-2 and 29-3 are simultaneously recognized has been described as an example, but the markers 29-1 and 29-2 are recognized and the marker 29- in the (n+1)th captured image. When 3 is not recognized, the search area 35-3 of the marker 29-3 is set to S _n+2,3 =P ₃ +(Q _n+1,1 −P ₁ )/2+(Q _n+1,2 −P ₂ )/ It can be calculated and corrected by the method such as 2.

Further, the moving body tracking control device 41 obtains the distance between the position of the obtained marker 29 and the position on the captured image of the marker 29 specified at the time of creating the treatment plan while recognizing the marker 29, and the distance is predetermined. By determining that the marker 29 is required if the value is equal to or less than the reference value, it is possible to search for the marker 29 with higher accuracy, reduce the possibility of losing the marker, and shorten the treatment time.

Furthermore, the first X-ray imaging apparatus and the second X-ray imaging apparatus can obtain the three-dimensional position of the marker 29 in the irradiation target 26 with high accuracy by imaging the marker 29 from two different directions. ..

Further, the moving body tracking device 38 outputs a signal for permitting the emission of the proton beam to the irradiation control device 40 when the position of the marker 29 is within the range designated in advance, so that the target inside the irradiation target 26 is output. The irradiation accuracy of the proton beam can be improved.

<Example 2>
A second embodiment of the moving body tracking device and the radiation irradiation system of the present invention will be described with reference to FIGS. 12 and 13. 1 to 11 are denoted by the same reference numerals, and the description thereof will be omitted.

The difference between the moving body tracking apparatus and the radiation irradiation system of the present embodiment and the first embodiment is that, when there are a plurality of markers 29, the detected marker 29 does not depend on which marker is detected without setting a search region for the marker position search. 29 is specified based on the information on the planned position.

First, the moving body tracking control device 41 performs a search for recognizing the marker 29. When the marker position is searched for in the entire captured image without setting the search area, the marker position can be searched immediately after the start of imaging. Here, when there are a plurality of markers, it is necessary to associate the recognized plurality of markers with the markers set on the patient. When the operator manually associates the markers, it may take a long time depending on the skill of the operator. If this operation can be omitted, the burden on the operator will be further reduced and the time will be shortened. Will be able to.

Therefore, in the moving body tracking control device 41 of the present embodiment, which marker 29 the plurality of markers 29 belong to is associated with each other by using the information of the planned position of each marker 29. This will be described with reference to FIG. FIG. 12 is an example of a captured image when there are three markers.

As shown in FIG. 12, three markers having the planned positions 1, 2, and 3 are recognized at the detected positions 1, 2, and 3, respectively. In the moving body tracking control device 41 of the present embodiment, the distance between the planned position and the detected position is used to associate the markers. FIG. 13 shows the distance between the planned position and the detected position of each marker.

The moving body tracking control device 41 obtains all the combinations of the distances between the planned position and the detected position of the three markers, and obtains the marker positions as the combinations associated with the combination having the smallest distance. In the case of FIG. 13, the detection position 1 is associated with the marker 29-1, the detection position 2 is associated with the marker 29-2, and the detection position 3 is associated with the marker 29-3.

The other configurations and operations are substantially the same as the configurations and operations of the moving body tracking device and the radiation irradiation system of the above-described first embodiment, and the details are omitted.

Also in the second embodiment of the moving body tracking device and the radiation irradiation system of the present invention, substantially the same effects as those in the first embodiment of the moving body tracking device and the radiation irradiation system described above can be obtained.

Further, for the plurality of markers 29, the moving body tracking control device 41 specifies which of the plurality of markers 29 the detected marker 29 is, based on the information of the planned position, Even when there are a plurality of markers, it is possible to start the marker tracking independent of the skill level of the operator.

<Other>
It should be noted that the present invention is not limited to the above-described embodiments, but includes various modifications. The above embodiments have been described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. It is also possible to add/delete/replace other configurations with respect to a part of the configurations of the respective embodiments.

For example, in the above-described embodiment, the case where the image of the target is picked up by using two X-ray image pickup devices has been described as an example, but the number of X-ray image pickup devices is not necessarily two. For example, the captured image of the tracking target may be captured from two different directions by moving one X-ray imaging device.

Further, in the above-described embodiment, the case where the gate irradiation is performed based on the position of the spherical marker 29 has been described as an example, but the shape of the marker 29 may be coiled. Although the case where the tracking target is the marker 29 has been described, the tracking target is not limited to the marker 29, and the target may be directly detected without using the marker 29. Alternatively, the tracking target can be a high-density region in the irradiation target 26, for example, a bone such as a rib.

Further, the irradiation method may be tracking irradiation in which the irradiation position is tracked based on the position of the marker 29 or the like instead of the gate irradiation. For example, in X-ray tracking irradiation, the orientation of the distribution forming X-ray generator is changed according to the movement of the target, and the X-ray irradiation position is changed according to the movement of the target. Even in the case of particle beam, tracking irradiation can be performed by adjusting the amount of excitation of the scanning electromagnet according to the target position.

Although imaging X-rays are also a type of radiation, they are not used for the purpose of forming a dose distribution. Therefore, in this specification, distribution forming radiation is used as a generic term for radiation other than imaging X-rays.

Furthermore, although the proton beam irradiation system has been described as an example in the above-described embodiments, the radiation irradiation system of the present invention can be applied to a system that irradiates a particle beam other than a proton beam such as a carbon beam, an X-ray, an electron beam, or the like. Can be similarly applied. For example, when X-rays are used, the radiation irradiation device is composed of an X-ray generation device, a beam transportation system, and an irradiation nozzle.

Further, in the case of a particle beam irradiation apparatus, the present invention is similarly applied to a raster scanning method or a line scanning method of irradiating a fine particle beam without stopping the particle beam, in addition to the spot scanning method described in the above embodiment. can do. Further, in addition to the scanning method, the present invention is also applied to an irradiation method such as a wobbler method or a double scatterer method that broadens the distribution of particle beams and then forms a dose distribution that matches the shape of the target by using a collimator or a bolus. can do.

In the case of a particle beam irradiation system, the particle beam generator may be a cyclotron in addition to the synchrotron 11 described in the above embodiment.

DESCRIPTION OF SYMBOLS 10... Proton beam generator 11... Synchrotron 12... Ion source 13... Linac 14... Deflection magnet 17... Deflection deflector 18... High frequency accelerator 19... High frequency emission device 20... Beam transport system 21... Deflection electromagnet 22... Irradiation nozzle 23A , 23B... Imaging X-ray generators 24A, 24B... X-ray measuring device 25... Gantry 26... Irradiation target 27... Couch 28A, 28B... Line 29, 29-1, 29-2, 29-3... Marker (tracking target) )
30... Common perpendicular 33... Locus 35, 35-1, 35-1A, 35-2, 35-2A, 35-3, 35-3A... Search area 38... Moving body tracking device 40... Irradiation control device 41... Moving body tracking control Device 42... Storage device 43... Console 50... Imaging start button 51... Gate start button 61... Imaging image A
62... Captured image B
63... Change display portion of matching score of captured image A 64... Change display portion of matching score of captured image B... Change display portion of common perpendicular length

Claims (9)

An X-ray imaging device for imaging a plurality of tracking targets;
Control for obtaining positions of the plurality of tracking targets based on a captured image captured by the X-ray imaging apparatus and position information of the plurality of tracking targets specified on the captured image captured when the treatment plan by radiation is created Equipped with a device,
The control device sets a region for searching the position of the tracking target based on the position information, and obtains the positions of the plurality of tracking targets by searching the tracking target in the region, and The moving body tracking device, wherein the area of the unrecognized tracking target is corrected based on the position of the tracking target previously recognized with respect to the tracking target. An X-ray imaging device for imaging a plurality of tracking targets;
Control for obtaining positions of the plurality of tracking targets based on a captured image captured by the X-ray imaging apparatus and position information of the plurality of tracking targets specified on the captured image captured when the treatment plan by radiation is created Equipped with a device,
The control device sets a region for searching the position of the tracking target based on the position information, and obtains the positions of the plurality of tracking targets by searching the tracking target in the region, and the tracking target after the position of the is recognized, the moving object tracking device, characterized in that modifying the region based on the tracked position is recognized. An X-ray imaging device for imaging a plurality of tracking targets;
Control for obtaining positions of the plurality of tracking targets based on a captured image captured by the X-ray imaging apparatus and position information of the plurality of tracking targets specified on the captured image captured when the treatment plan by radiation is created Device,
An input device that receives an input of a region for searching the position of the tracking target based on the position information ;
The control device obtains the positions of the plurality of tracking targets by searching for the tracking targets in the region, and at least one of the plurality of tracking targets within a predetermined time in the input region. A moving body tracking device, characterized in that when one is not recognized, the area is corrected based on the position information. The moving body tracking device according to any one of claims 1 to 3 ,
The moving body tracking device, wherein the control device stops imaging by the X-ray imaging device when at least one of the plurality of tracking targets is not recognized within a predetermined time. The moving body tracking device according to any one of claims 1 to 4 ,
The control device obtains the distance between the position of the tracking target obtained while recognizing the tracking target and the position on the captured image of the tracking target specified at the time of creating the treatment plan, and this distance is a predetermined value. A moving body tracking device, characterized in that it is determined that the tracking target is recognized if it is less than or equal to a reference value. The moving body tracking device according to any one of claims 1 to 5 ,
The moving body tracking device, wherein the X-ray imaging device images the tracking target from two different directions. The moving body tracking device according to any one of claims 1 to 6 ,
The tracking target is any one of a marker for identifying a target, the target, and a high-density region. A radiation irradiation device for irradiating the target with radiation,
An irradiation control device for controlling this radiation irradiation device,
And a moving object tracking apparatus according to any one of claims 1 to 7,
The irradiation control device controls the radiation based on a signal generated by the moving body tracking device. The radiation irradiation system according to claim 8 ,
The radiation irradiating system, wherein the moving body tracking device outputs a signal permitting emission of radiation to the irradiation control device when the position of the tracking target is within a range designated in advance.

Images