JP2017209159A - Moving object tracking device and radiation irradiation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving object tracking device and a radiation irradiation system capable of further reducing a burden on an operator in moving object tracking.SOLUTION: A moving object tracking device 38 includes imaging X-ray generation devices 23A and 23B for imaging a marker 29, X-ray measurement instruments 24A and 24B, and a moving object tracking control device 41 for finding a position of the marker 29 from a captured image. The moving object tracking control device 41 finds the position of the marker 29 based on the information on the position on the captured image of the marker 29 identified when a radiation therapeutic plan is made.SELECTED DRAWING: Figure 8A

Description

  The present invention relates to a radiation irradiation system that treats a diseased part such as a tumor by irradiating radiation, such as a particle beam, and a moving body tracking apparatus suitable for such a radiation irradiation system.

  As an example of a moving body pursuit irradiation device that can automatically calculate the position of a tumor moving around in the trunk in real time and can ensure substantially necessary accuracy without depending on the absolute accuracy of the mechanical system, Patent Literature 1 includes an imaging device that simultaneously captures tumor markers embedded in the vicinity of a tumor from first and second directions to obtain first and second captured images, and digitized first and second captured images. Template matching is performed at a real-time level with a predetermined frame rate by applying a template image of a tumor marker registered in advance to the image of the tumor marker. Based on the first and second imaging conversion matrices, An image input recognition processing unit that calculates the first and second two-dimensional coordinates, and a central processing unit that calculates the three-dimensional coordinates of the tumor marker based on the calculated first and second two-dimensional coordinates; The calculated moving body tracking irradiation apparatus having an irradiation control unit that controls the treatment beam irradiation linac based on three-dimensional coordinates of the tumor marker is described.

Japanese Patent No. 3053389

  A method of irradiating a patient with cancer or the like with radiation such as particle beam or X-ray is known. Particle beams include proton beams and carbon beams. A radiation 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 for forming a dose distribution in a radiation irradiation system, a scanning irradiation method in which a fine particle beam is scanned with an electromagnet to form a dose distribution is becoming widespread.

  By the way, when a target such as a tumor moves by respiration or the like, accurate irradiation of particle beams becomes difficult. Therefore, gate irradiation in which a particle beam is irradiated only when the target is in a predetermined range (gate range) has been realized in recent years.

  Patent Document 1 described above describes a method called moving body tracking irradiation in which gate irradiation is performed based on the position of a marker embedded in the vicinity of an affected area. A 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 moving body tracking irradiation, gate irradiation is performed based on the position of a tracking target such as a marker embedded in the vicinity of an affected part or a target itself. The position of a tracking target such as a marker is measured using an image captured by 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 for comparing a captured image 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 at which the two lines connecting the position on the X-ray measuring device where the tracking target appears and the imaging X-ray generator are closest is regarded as the position where the tracking target exists. In the template matching, the captured image and the template image are compared, and the similarity such as normalized cross-correlation is evaluated as a matching score.

  Here, Patent Document 1 described above describes a method of reducing the amount of calculation for marker position determination by setting a search region and performing template matching only within the search region. However, a method for recognizing a marker from a state in which the marker is not recognized has not been studied.

  For this reason, the operator manually sets the search area in a state where the marker is not recognized. However, 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 apparatus and a radiation irradiation system capable of shortening a treatment time in moving body tracking.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present invention includes a plurality of means for solving the above-described problems. To give an example, an X-ray imaging apparatus that captures a plurality of tracking targets, a captured image captured by the X-ray imaging apparatus, And a control device that obtains the positions of the plurality of tracking targets based on the positional information of the plurality of tracking targets specified on the captured image captured when creating the treatment plan by radiation.

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

It is a whole block diagram of a proton beam irradiation system. It is a conceptual diagram with which a moving body tracking device acquires a captured 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 illustrating a display portion of an X-ray captured image of a console when setting a marker search region in the first embodiment. It is a figure which shows the change display part of the matching score of a console at the time of setting the search area | region of the marker in Example 1. FIG. It is a figure which shows the change display part of the common perpendicular | vertical length of a console at the time of setting the search area | region of the marker in Example 1. FIG. FIG. 6 is a diagram illustrating a display portion of an X-ray captured image of a console when setting a marker search region in the first embodiment. It is a figure which shows the change display part of the matching score of a console at the time of setting the search area | region of the marker in Example 1. FIG. It is a figure which shows the change display part of the common perpendicular | vertical length of a console at the time of setting the search area | region of the marker in Example 1. FIG. FIG. 6 is a diagram illustrating a display portion of an X-ray captured image of a console when setting a marker search region in the first embodiment. It is a figure which shows the change display part of the matching score of a console at the time of setting the search area | region of the marker in Example 1. FIG. It is a figure which shows the change display part of the common perpendicular | vertical length of a console at the time of setting the search area | region of the marker in Example 1. FIG. FIG. 6 is a diagram illustrating a display portion of an X-ray captured image of a console when setting a marker search region in the first embodiment. It is a figure which shows the change display part of the matching score of a console at the time of setting the search area | region of the marker in Example 1. FIG. It is a figure which shows the change display part of the common perpendicular | vertical length of a console at the time of setting the search area | region of the marker in Example 1. FIG. FIG. 3 is a conceptual diagram illustrating a console screen according to the first embodiment. FIG. 6 is a conceptual diagram illustrating a parameter setting screen used for marker search in the first embodiment. FIG. 10 is a conceptual diagram illustrating a method of setting a marker search area in the second embodiment. It is a figure which shows the distance of the planned position of a marker in Example 2, and a detection position.

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

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

  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 beam irradiation system will be described as an example with reference to FIG.

  As shown in FIG. 1, a proton beam irradiation system that is one embodiment 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. A proton beam irradiation apparatus 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 accelerator 18, a high-frequency output device 19, and an output 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, protons generated from the ion source 12 are accelerated in the previous stage by the linac 13 and enter 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 the direction is changed by the deflecting 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 the proton beam reaches a desired position in a plane perpendicular to the beam axis at the target position. The dose monitor measures the amount of proton beam irradiated. 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 the target in the irradiation object 26. In addition, when treating patients, such as cancer, the irradiation object 26 represents a patient and a target represents a tumor etc.

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

  The irradiation controller 40 is connected to the proton beam generator 10, the beam transport system 20, the irradiation nozzle 22, the moving object tracking controller 41, the couch 27, the storage device 42, the console 43, and the like. Devices such as the transport system 20 and the irradiation nozzle 22 are controlled.

  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 apparatus includes an imaging X-ray generator 23 </ b> A and an X-ray measuring device 24 </ b> A that capture an image of a marker (tracking target) 29 in the irradiation target 26. The second X-ray imaging apparatus includes an imaging X-ray generator 23B that captures an image captured by the marker 29 and an X-ray measuring device 24B.

  The first X-ray imaging apparatus and the second X-ray imaging apparatus are installed so that the respective X-ray paths intersect each other. The two pairs of imaging X-ray generators 23A and 23B and the X-ray measuring devices 24A and 24B are preferably installed in directions orthogonal to each other, but 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 are not necessarily arranged inside the gantry 25, and may be arranged at fixed places such as a ceiling and 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 can be irradiated 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 generation device 23 </ b> A, and performs 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. Further, the marker 29 is imaged by irradiating the marker 29 with X-rays generated from the imaging X-ray generator 23B and measuring the two-dimensional dose distribution of the X-rays that have passed through the marker 29 with 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 object 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. In addition, it is determined whether or not the obtained target position is in a gate range (irradiation permission range) designated in advance, and if it is determined that the target position is in the gate range, a gate-on signal is sent to the irradiation control device. 40 is transmitted to allow emission. On the other hand, if it is determined that the target position is not within the gate range, a gate-off signal is transmitted and emission is not permitted. In the irradiation control device 40, the emission of the proton beam is controlled based on the gate-on signal and the gate-off signal generated by the moving object 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, for example, 30 Hz. The acquired captured image includes a marker 29 embedded in the body. In this embodiment, the position of the marker 29 in the irradiation target 26 is specified by template matching with a template image of the marker 29 prepared in advance. Since searching for the entire range of the captured image requires time, the marker 29 can be searched only within a predetermined size range (hereinafter also referred to as a search region) centered on the position of the marker 29 in the previous captured image. Search for a location.

  FIG. 3 shows the line 28A connecting the position of the marker 29 detected by 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 generation of the imaging X-ray. 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 practice, the two lines 28A and 28B are usually in a twisted relationship without crossing each other due to the effects of template matching accuracy and installation errors of the X-ray imaging apparatus. A common perpendicular line can be drawn at the position where the two lines 28A and 28B in the twisted relationship are closest to each other. This common perpendicular is called a common perpendicular. The midpoint 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 becomes long. If the length of the common perpendicular 30 exceeds a preset threshold value, it is highly likely that the marker 29 cannot be detected accurately, and the moving body tracking control device 41 does not matter even when 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 the irradiation of the proton beam.

  The moving object tracking control device 41 according to the present embodiment is characterized in that the marker 29 is detected when starting imaging with respect to the plurality of markers 29.

  In the conventional method, as described above, a method for recognizing the marker 29 from a state where the marker 29 is not recognized has not been studied. Therefore, when the operator manually sets the search area when the marker 29 is not recognized, a method in which the operator designates the search area using an input device such as a mouse is assumed.

  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 is considered based on the planned position of the marker 29 on the captured image. Here, the planned position refers to the position of the marker 29 specified at the time of treatment planning. In moving body tracking irradiation, it is conceivable that the reference position is irradiated with 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 a 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 apparatuses, the moving object tracking control apparatus 41 sets a 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 comparative example above, the present embodiment targets the case where there are a plurality of markers 29. In this 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, and 29-3 on the captured image before the imaging is started.

  First, a method for specifying a planned position on a captured image will be described. When the proton beam is irradiated, the position of the isocenter on the treatment planning CT image is determined by the treatment planning apparatus. 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, a planned position when the 3D CT image is converted into a 2D image is obtained. When the direction of irradiating the imaging X-ray is determined using the two pairs of X-ray imaging apparatuses, 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. Similarly, for the markers 29-2 and 29-3, the planned positions on the captured image are obtained.

Assume that the markers 29-1, 29-2, and 29-3 periodically move as indicated by a locus 33 in FIG. 6A. When the imaging is started, the moving body tracking control device 41 searches the search areas 35-1, 35- having a predetermined size around the planned positions P ₁ , P ₂ , P ₃ with respect to the image immediately after the imaging is started. 2 and 35-3 are set. Thus, the marker position can be searched 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 start of imaging. In this embodiment, it is assumed that all markers are outside the search area at the start of imaging. The search for the marker 29 is repeatedly executed until any of the markers 29 enters the corresponding search area 35 and can be recognized. Whether or not marker recognition is possible is determined by setting a reference value for the matching score or the common perpendicular length. When determining using the matching score, a reference is set in advance, and if the matching score exceeds the value, it is determined that the marker has been recognized. When the common perpendicular length is used, a reference is set in advance, and it is determined that the marker 29 can be recognized if the common perpendicular length is less than the value. It is also possible to use the judgment criterion that both the matching score and the common perpendicular length satisfy the criterion.

For explanation, assuming that the captured image of FIG. 6A is the nth image from the start of imaging, the center positions of the search areas 35-1, 35-2, and 35-3 are Sn _{, 1} , _{Sn, 2} , _{Sn, 3} , respectively. To do. In FIG. 6A, since any marker 29 is outside the search area 35, the matching score is lower than the reference value as shown in FIG. 6B, and the common perpendicular length is longer 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 n-th captured image shown in FIG. 6A, the moving object tracking control device 41 sets the search area 35 around the planned position for the n + 1-th captured image. To do.

As shown in FIG. 7A, in the (n + 1) -th captured image, the matching score exceeds the reference value as shown in FIG. As shown, the common perpendicular length is below the reference value. Since the criteria of the matching score and the common perpendicular length are satisfied, it is determined that the marker 29-1 is recognized at the detection position Qn _{+ 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 + 2th captured image. As described above, since the marker 29-1 is recognized in the (n + 1) th captured image, the moving body tracking control device 41 sets the detection position Q _{n + 1,1} in the previous frame in the search area 35-1 of the marker 29-1. Install in the center. Regarding the markers 29-2 and 29-3, the moving body tracking control device 41 is centered on a position obtained by adding a difference between the planned position and the detected position of the marker 29-1 as a correction amount with respect to the planned position of each marker. Search areas 35-2 and 35-3 are set.

Specifically, the moving body tracking control device 41 has a center position 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. The areas indicated by the dotted lines in FIG. 8A are search areas 35-1A, 35-2A, and 35-3A set with the planned position as the center. For this reason, in the case of the marker 29-2, the search area 35-2A set around the planned position cannot be recognized by the n + 2th captured image, but the difference between the planned position and the detected position of the marker 29-1 is calculated. It is possible to recognize in the search area 35-2 set around the position added as the correction amount. Note that with the marker 29-3, the search region 35-3A set with the planned position as the center can be recognized by the n + 2th captured image. At this time, as shown in FIG. 8B, the matching score exceeds the reference value for all markers, and as shown in FIG. 8C, the common perpendicular length is below for all markers.

FIG. 9A shows the captured image of the (n + 3) th sheet. Since the markers 29-1, 29-2, and 29-3 can be recognized in the previous frame, the search centers S _{n + 3,1} , S _{n + 3,2} , and S _{n + 3, 3} The marker positions in the previous image are set, and search areas 35-1, 35-2, and 35-3 having predetermined sizes around the position are set.

  The size of the search area 35 may be changed before and after the marker 29 is recognized. For example, the search area 35-1 may be set smaller after the recognition than before the marker 29-1. By changing the size of the search area, the time for searching for a marker can be shortened and the treatment time can be shortened.

  It is also possible to combine the setting of the search area 35 based on the planned position of this 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 sets the marker within the designated search area 35 for the captured image of several frames from the time when the operator designates the search area 35. When each of the images 29 is searched and not recognized, a search area 35 is set around the planned position for the subsequent captured images, and the search is performed.

  Alternatively, for example, the marker 29-1 designates the search area 35-1 by the operator, and the moving body tracking control device 41 sets the search areas 35-2 and 35-3 for the other markers 29-2 and 29-3, respectively. Anyway.

  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 the preset time. If not obtained, imaging by the imaging X-ray generator 23A and the X-ray measuring device 24A, and the imaging X-ray generator 23B and the X-ray measuring device 24B are stopped.

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

  Further, when the marker 29 is traced and irradiated with a proton beam, even if the marker 29 is unsuccessfully recognized for some reason, the time required for re-recognizing the marker 29 is reduced by this 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 marker 29-1 has been successfully recognized for any one of the matching score, the common perpendicular length, and the distance between the detected marker position and the planned position by an operator input. A reference value for determining whether or not is set. When the matching score is used, the matching score is monitored while the marker 29-1 is recognized and tracked, and it is determined that the recognition is successful when the matching score has a result larger than the reference value. When the common perpendicular length is used, the common perpendicular length is monitored while the marker 29-1 is recognized and tracked, 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 the distance between the detected marker position and the planned position is used, the distance between the detected marker position and the planned position while the marker 29-1 is recognized and tracked is monitored and detected. It is determined that the recognition is successful when the distance between the determined marker position and the planned position is smaller than the reference value. For example, two values may be used in combination of a matching score and a common perpendicular length. In this case, it is determined that the recognition is successful when the matching score is larger than the reference value and the common perpendicular length is smaller than the reference value. More preferably, it is preferable to determine whether or not recognition is successful using all reference values for the matching score, the common perpendicular length, and the distance between the detected marker position and the planned position. In this case, it is determined that recognition is successful when the matching score is greater 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. .

  Further, when it is determined that the marker 29-1 has failed to be recognized using these determination criteria during tracking of the marker 29-1, the moving body tracking control device 41 searches the search area 35 around the planned position. Set -1. The subsequent method up to marker recognition is the same as the method at the start of imaging.

  The proton beam irradiation system of the above-described embodiment employs an irradiation method called a spot scanning method. The spot scanning method is a method of irradiating an irradiation spot (hereinafter also referred to as a spot) arranged on a target with a thin proton beam to form a dose distribution according to the shape of the target. Proton rays are characterized by the loss of energy within the body, with the energy loss maximizing immediately 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. The dose distribution shape in the direction perpendicular to the beam axis formed by the proton beam is generally a normal distribution. The position where the dose distribution in the direction perpendicular to the beam axis is formed can be adjusted by scanning the proton beam with a scanning electromagnet. A uniform dose distribution can be formed over the entire target by combining energy changes and scanning with a scanning magnet.

  Returning to FIG. 1, irradiation parameters for irradiation created by the treatment planning device are stored in the storage device 42, and the irradiation control device 40 receives necessary information from the storage device 42 before 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 signals acquired from the irradiation control device 40 and the moving body tracking control device 41. The information to be displayed includes information relating to the tracking state of the captured image and the marker 29. FIG. 7 shows an example of a screen related to the captured image displayed on the console 43 and the tracking status of the marker 29.

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

  Further, the console 43 receives 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 object tracking control device 41. The input information includes parameters necessary for moving body tracking. As shown in FIG. 11, an input screen for parameters necessary 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 (the group consisting of the imaging X-ray generator 23A and the X-ray measuring device 24A) as a marker position determination criterion setting item as shown in FIG. Reference value, reference value of matching score of X-ray imaging device B (a set consisting of imaging X-ray generator 23B and X-ray measuring device 24B), common perpendicular length reference value, search area 35 size, and standby time .

  Next, a procedure for irradiating a proton beam will be described.

  First, the irradiation object 26 is fixed on the couch 27. Thereafter, the couch 27 is moved to move the irradiation target 26 to a previously planned position. At this time, it is confirmed that the irradiation target 26 has moved to a previously planned position by capturing a captured image using an X-ray imaging apparatus.

  When the irradiation preparation button on the console 43 is pressed by the operator, 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 gantry 25 rotates, the operator presses the imaging start button 50 from the console 43 to cause the moving object tracking control device 41 to start X-ray imaging.

  In this embodiment, immediately after the start of imaging, the search area 35 is set using 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 for searching 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.

  The operator confirms the start of tracking on the two captured images corresponding to the two X-ray imaging apparatuses, 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, a gate-on signal is transmitted from the moving object tracking control device 41 to the irradiation control device 40. If the operator does not track the intended marker 29 as confirmed 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 energy to be irradiated first based on the energy information read from the storage device.

  Specifically, the irradiation control device 40 controls the ion source 12 and the linac 13, accelerates the protons generated from the ion source 12 to the previous stage by the linac 13, 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 circulating around the synchrotron 11 is accelerated by the high frequency from the high frequency accelerator 18. The irradiation controller 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 irradiated first 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 first irradiated spot position.

  After these settings are completed, if the irradiation control device 40 receives the gate-on signal from the moving object tracking control device 41, the emission of the proton beam is started. If a gate-off signal is received, the process waits until a 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 and starts emitting a proton beam. When a high frequency is applied to the high frequency emission device 19, a part of the proton beam that circulates in the synchrotron 11 passes through the emission deflector 17, passes through the beam transport system 20, and reaches the irradiation nozzle 22. The proton beam that has reached the irradiation nozzle 22 is scanned by a scanning electromagnet, passes through a dose monitor and a position monitor, reaches the target of the irradiation object 26, and forms a dose distribution. The irradiation amount for each spot is registered in the spot information read from the storage device 42. When the irradiation amount measured by the dose monitor reaches the value registered in the spot information, the irradiation control device 40 controls the high frequency for emission. Stop the proton beam. After emission of the proton beam, the irradiation control device 40 calculates the arrival position of the proton beam from the proton beam position information measured by the position monitor, and confirms that it matches the position registered in the spot information.

  In order to irradiate the next spot, the irradiation controller 40 sets the excitation amount of the scanning electromagnet so that the proton beam reaches the next spot position registered in the spot information. If the gate-on signal is continuously received after the setting is completed, the irradiation control device 40 controls the emission high frequency and starts emitting the proton beam. If a gate-off signal has been received, the process waits until a gate-on signal is received. When a gate-off signal is received during the irradiation of a certain spot, the proton beam is continuously emitted until the irradiation of the spot being irradiated is completed.

  When the irradiation of the spot is repeated and the irradiation of all the spots irradiated with the first energy is completed, the irradiation control device 40 controls the synchrotron 11 to decelerate the proton beam and starts the preparation for the irradiation with the proton beam of the next energy. . As in the case of the first energy, the irradiation control device 40 controls the ion source 12 and the linac 13 to cause the proton beam to enter the synchrotron 11, and controls the synchrotron 11 to protons up 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 operation is repeated and irradiation of all the spots is completed, an irradiation completion signal is transmitted from the irradiation control device 40 to the moving object tracking control device 41. Receiving the irradiation completion signal, the moving body tracking control device 41 controls the imaging X-ray generators 23A and 23B to stop X-ray imaging.

  When the target is irradiated 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 the present embodiment will be described.

  Embodiment 1 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 body. In a proton beam irradiation system provided with a tracking device 38, imaging X-ray generators 23A and 23B for imaging the marker 29, X-ray measuring devices 24A and 24B, and creation of a treatment plan using the captured images and proton beams A moving body tracking device 38 including a moving body tracking control device 41 that obtains the position of the marker 29 based on information on the position of the marker 29 that is sometimes identified on the captured image is provided.

  Thereby, even if the operator does not set the search area, the search area is set based on the position on the captured image of the plurality of markers 29 specified at the time of creating the treatment plan, and the search is quickly started. Treatment time can be shortened. Also, the search area setting operation by the operator can be omitted, and the burden on the operator can be reduced as compared with the conventional case.

  The moving object tracking control device 41 sets a search area 35 for searching for the position of the marker 29 based on the planned position information, and searches for the marker 29 in the set search area 35 to obtain the position. Since the search in the region where the marker 29 is assumed to exist without the operator setting the search region is started, 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.

  Furthermore, after the position of the marker 29 is recognized, the moving body tracking control device 41 sets the search area 35 to be searched later based on the recognized position of the marker 29, thereby continuing the search with high accuracy. can do.

  In addition, the console 43 for inputting an area for searching for the position of the marker 29 is provided. When the moving body tracking control apparatus 41 does not recognize a plurality of markers 29 within a predetermined time in the input search area 35, the following is performed. By searching for the marker 29 based on the planned position information, it is possible to combine the specification of the search area 35 by the operator and the setting of the search area 35 using the planned position, and further reduce the time until the marker 29 is recognized. It becomes possible to do.

  Furthermore, 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, and more than necessary. Can be prevented from being irradiated with imaging X-rays, and the burden on a patient, an apparatus, and the like can be reduced.

  Patent Document 1 discloses a method for tracking a plurality of markers. However, a method for associating a plurality of recognized markers with markers 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 does not recognize the marker based on the position of the recognized marker 29. By correcting the search area 35 for searching for the position of 29, the search area for the marker that has not been recognized is corrected using the information on the detection position of the already recognized marker, and all the markers are recognized. It becomes possible to shorten the time.

In the above example, the case where the markers 29-2 and 29-3 are recognized at the same time has been described as an example. However, the markers 29-1 and 29-2 are recognized and the marker 29- is recognized in the (n + 1) th captured image. for state 3 is not _{recognized, S n + 2,3 = P 3} + a search region 35-3 of the marker _{29-3 (Q n + 1,1 -P 1} ) / 2 + (Q n + 1,2 -P 2) / It can be calculated and corrected by a method such as 2.

  The moving body tracking control device 41 obtains the distance between the position of the marker 29 obtained while recognizing the marker 29 and the position on the captured image of the marker 29 specified at the time of creating the treatment plan, and the distance is predetermined. If the marker 29 is determined to be less than the reference value, it is possible to search for the marker 29 with higher accuracy, reduce the possibility of missing 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. .

  In addition, the moving body tracking device 38 outputs a signal permitting the emission of the proton beam to the irradiation control device 40 when the position of the marker 29 is within the range specified in advance, thereby to the target in the irradiation target 26. Proton beam irradiation accuracy can be increased.

<Example 2>
A moving object tracking device and a radiation irradiation system according to a second embodiment of the present invention will be described with reference to FIGS. The same components as those in FIGS. 1 to 11 are denoted by the same reference numerals, and description thereof is omitted.

  The difference between the moving object tracking device and the radiation irradiation system of the present embodiment and the first embodiment is that when there are a plurality of markers 29, any marker 29 is detected without setting a search area for searching for the marker position. 29 is specified based on the information on the planned position.

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

  Therefore, in the moving body tracking control device 41 of the present embodiment, the association of which marker 29 is the plurality of markers 29 is performed using information on 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 planned positions 1, 2, and 3 are recognized at detection 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 detection position of each marker.

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

  Other configurations and operations are substantially the same configurations and operations as the moving object tracking device and the radiation irradiation system of the first embodiment described above, and the details are omitted.

  In the second embodiment of the moving body tracking device and the radiation irradiation system of the present invention, substantially the same effect as that of the first embodiment of the moving body tracking device and the radiation irradiation system described above can be obtained.

  Further, the moving body tracking control device 41 identifies the marker 29 among the plurality of markers 29 based on the information on the planned position, with respect to the plurality of markers 29, Even when there are a plurality of markers, marker tracking can be started without depending on the skill level of the operator.

<Others>
In addition, this invention is not limited to said Example, Various modifications are included. The above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Moreover, it is also possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, in the above-described embodiment, the case where the target is imaged using two X-ray imaging apparatuses has been described as an example, but the number of X-ray imaging apparatuses is not necessarily two. For example, the captured image to be tracked may be captured from two different directions by moving one X-ray imaging apparatus.

  Moreover, although the case where gate irradiation was implemented based on the position of the spherical marker 29 was demonstrated to the example in the above-mentioned Example, the shape of the marker 29 may be coil shape. Further, 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.

  The irradiation method may be tracking irradiation that tracks the irradiation position 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 in accordance with the movement of the target, and the X-ray irradiation position is changed in accordance with the movement of the target. Even in the case of a particle beam, tracking irradiation can be performed by adjusting the excitation amount of the scanning electromagnet according to the target position.

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

  Furthermore, although the proton beam irradiation system was demonstrated to the example in the above-mentioned Example, the radiation irradiation system of this invention is with respect to the system which irradiates particle beams other than proton beams, such as a carbon beam, X-rays, an electron beam. Can be applied similarly. For example, when X-rays are used, the radiation irradiation apparatus includes an X-ray generation apparatus, a beam transport system, and an irradiation nozzle.

  In the case of a particle beam irradiation apparatus, the present invention is similarly applied to a raster scanning method and a line scanning method for irradiating a fine particle beam without stopping the particle beam, in addition to the spot scanning method described in the above-described embodiment. can do. 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 forms a dose distribution that matches the shape of the target using a collimator or bolus after expanding the particle beam distribution. 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 electromagnet 17 ... Deflection electromagnet 18 ... High frequency acceleration device 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 ... Lines 29, 29-1, 29-2, 29-3 ... Marker (tracking target) )
30 ... Common perpendicular 33 ... Trajectories 35, 35-1, 35-1A, 35-2, 35-2A, 35-3, 35-3A ... Search area 38 ... Moving object tracking device 40 ... Irradiation control device 41 ... Moving object tracking control Device 42 ... Storage device 43 ... Console 50 ... Imaging start button 51 ... Gate start button 61 ... Captured image A
62 ... Captured image B
63 ... Matching score change display part 64 of the captured image A ... Matching score change display part 65 of the captured image B ... Common perpendicular length change display part

Claims (12)

An X-ray imaging apparatus for imaging a plurality of tracking targets;
Control for obtaining the positions of the plurality of tracking targets based on the captured image captured by the X-ray imaging apparatus and the positional information of the plurality of tracking targets specified on the captured image captured when the radiation treatment plan is created. A moving body tracking device. The moving body tracking device according to claim 1,
The control device sets an area for searching for the position of the tracking object based on the position information, and obtains the positions of the plurality of tracking objects by searching the tracking object in the area. Motion tracking device. The moving body tracking device according to claim 2,
The moving object tracking device, wherein the control device corrects the region of the tracking target that is not recognized based on a position of the tracking target that has been previously recognized with respect to the plurality of tracking targets. The moving body tracking device according to claim 2 or 3,
After the position of the tracking target is recognized, the control device corrects the area based on the recognized position of the tracking target. The moving body tracking device according to claim 1,
For the plurality of tracking objects, the control device identifies which of the plurality of tracking objects is the recognized tracking object based on the position information. Motion tracking device. The moving body tracking device according to any one of claims 2 to 4,
Comprising an input device for receiving an input of the area;
The control device corrects the region based on the position information when at least one of the plurality of tracking targets is not recognized within a predetermined time in the input region. Tracking device. The moving body tracking device according to any one of claims 1 to 6,
The moving object tracking apparatus, wherein when at least one of the plurality of tracking targets is not recognized within a predetermined time, the control apparatus stops imaging by the X-ray imaging apparatus. The moving body tracking device according to any one of claims 1 to 7,
The control device obtains a 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 when creating the treatment plan, and this distance is a predetermined value. A moving body tracking device, wherein if it is below a reference value, it is determined that the tracking target is recognized. The moving body tracking device according to any one of claims 1 to 8,
The X-ray imaging apparatus picks up an image of the tracking target from two different directions. The moving body tracking device according to any one of claims 1 to 9,
The tracking target is a marker for identifying a target, the target, or a high-density region. A radiation irradiation device for irradiating the target with radiation;
An irradiation control device for controlling the radiation irradiation device;
The moving body tracking device according to claim 1,
The irradiation control device controls radiation based on a signal generated by the moving object tracking device. The radiation irradiation system according to claim 11.
The radiation irradiation system, wherein the moving object tracking device outputs a signal permitting radiation emission to the irradiation control device when the position of the tracking target is within a range specified in advance.

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