WO2019198765A1 - Robotic mobile body phantom system - Google Patents
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- WO2019198765A1 WO2019198765A1 PCT/JP2019/015667 JP2019015667W WO2019198765A1 WO 2019198765 A1 WO2019198765 A1 WO 2019198765A1 JP 2019015667 W JP2019015667 W JP 2019015667W WO 2019198765 A1 WO2019198765 A1 WO 2019198765A1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N5/00—Radiation therapy
- A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
- G09B23/28—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for medicine
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- the present invention relates to a robot moving body phantom system, and more particularly, to a robot moving body phantom system that includes a robot manipulator, a moving body tracking device, and a phantom, and verifies a treatment plan for radiation therapy.
- Radiotherapy is mainly three-dimensional radiation therapy in which CT (Computed Tomography) images are used to three-dimensionally grasp the anatomical structure and tumor position of the human body.
- CT Computer Planar Tomography
- radiotherapy for tumors involving respiratory movement such as the chest and abdomen needs to be performed including the entire region where the tumor moves by respiratory motion.
- radiation therapy has a problem that although radiation concentration on the tumor is increased, extra radiation is also administered to surrounding normal tissues, and side effects due to radiation are increased.
- intensity modulation as a radiation therapy technology that can irradiate the tumor intensively while combining the multiple beams formed by the multileaf diaphragm to increase and decrease the radiation and reduce the dose to normal tissue Radiation therapy is known.
- intensity-modulated radiation therapy is administered to a site with respiratory movement, a dose of radiation that is completely different from the scheduled dose is administered, resulting in problems such as reduced tumor control rate and increased side effects on normal tissues. is there.
- moving body tracking radiotherapy is performed using a moving body tracking device (SyncTraX TM , Shimadzu Corporation), which is one of four-dimensional radiotherapy.
- SynTraX TM moving body tracking device
- Patent Document 1 discloses a metal placed in the vicinity of a tumor under a bronchoscope or under CT or ultrasonic guidance by performing pattern recognition image processing on a bi-directional X-ray fluoroscopic image.
- a moving body tracking device capable of calculating a three-dimensional position coordinate of a marker in real time and tracking a metal marker (tumor) moving by respiratory movement.
- the X-ray fluoroscopic position of the moving body tracking device can be selected from three directions, and the metal marker can be tracked without being restricted by the irradiation angle (independent of gantry and couch angle) of the medical linear accelerator. Is possible.
- the moving body tracking radiotherapy is a treatment in which the radiation is irradiated only when the three-dimensional position of the metal marker calculated in real time using the moving body tracking apparatus reaches a certain position, and the moving body tracking apparatus and the medical linear accelerator are used. It becomes possible to carry out treatment by combining.
- a patient-specific fixture is created and CT imaging for treatment planning is performed.
- a treatment plan for simulating on the computer the direction and dose of radiation is performed.
- the visibility of the metal marker placed on the patient is confirmed using the moving body tracking device, and the fluoroscopic position used in the treatment is determined.
- the three-dimensional coordinates of the metal marker moved by respiration are recorded as a log. Thereafter, in order to evaluate the validity of the treatment plan on the simulation, the quality of the treatment plan is assured.
- Patent Document 2 discloses that a radiation phantom having a radiation absorption rate equivalent to that of a human body and simulated as a water equivalent tissue is measured with a dosimeter inserted into the phantom.
- a quality assurance procedure is disclosed that verifies that there is no difference between a given radiation dose and a calculated value at the time of treatment planning. When the accuracy of radiotherapy is ensured by this quality assurance, treatment is started for the patient.
- the quality assurance of the current moving body tracking radiotherapy is based on the one-axis coordinate data with the three-dimensional coordinates of the metal marker acquired by using the moving body tracking device as disclosed in Patent Document 1.
- a phantom as disclosed in Document 2 is driven by one axis. For this reason, there is no device using a phantom that reproduces the movement of a tumor that moves three-dimensionally due to the respiration of the human body, and the quality of moving body tracking radiotherapy cannot be assured with high accuracy.
- the present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a degree of freedom capable of three-dimensional translational motion to reproduce actual tumor motion, and is used for quality assurance of radiotherapy. It is an object of the present invention to provide a moving phantom system having a following accuracy.
- a robot moving body phantom system includes a robot manipulator having a three-dimensional translational freedom degree, a robot control device for controlling the robot manipulator, a robot manipulator fixed to the tip of the human body,
- the robot controller includes a phantom having an equivalent radiation absorption rate and a moving body tracking device that measures a change in the marker position of the patient placed in the vicinity of the tumor in real time.
- a target trajectory generating unit that generates a target trajectory of the robot manipulator, and controlling the robot manipulator so that the marker position in the phantom follows the target trajectory.
- the robot moving body phantom system according to the present invention can improve the accuracy of quality assurance for radiation therapy.
- the effect described here is not necessarily limited, and may be any effect described in the present technology.
- FIG. 1 It is a schematic diagram which shows the coordinate system of the robot moving body phantom system which concerns on 1st Embodiment of this invention
- (A) shows the treatment apparatus coordinate system of a medical linear accelerator
- (B) shows the working coordinate system of a robot manipulator. Show. It is a graph which shows the lung tumor locus
- a moving phantom system is known as such a device.
- the moving body phantom system is a phantom drive device that simulates changes in the position of a tumor in a patient's body in real time, a water equivalent phantom having a radiation absorption rate equivalent to that of a living tissue (human body), a dosimeter, and a radiation sensitive film.
- It is a quality assurance system for radiation therapy that is composed of a combination of
- a marker to be position-measured by the moving body tracking device is embedded, and a dosimeter or a radiation sensitive film is installed as necessary.
- the phantom drive device moves the water equivalent phantom with the tumor movement trajectory at the time of rest of the patient recorded in advance as a target value. While monitoring this operation in the same way as during treatment, radiation is performed according to the treatment plan, and the dose is measured by a dosimeter to confirm whether the irradiation dose determined in the treatment plan can be administered.
- the above moving body phantom system is capable of linear reciprocating motion with one degree of freedom, and a large follow-up error of about several millimeters occurs transiently.
- the movement of the tumor in the body is a movement in a three-dimensional space, which can be reproduced, and a moving body phantom system that can suppress the three-dimensional tracking error of the whole time to about 1 mm for high-precision radiotherapy is desired.
- a stepping motor and a 6-axis robot manipulator are used to simulate the deformation of the rib cage due to breathing and to simulate the movement of the tumor in the rib cage.
- What built the moving body phantom system for radiation therapy is known.
- the three-dimensional target trajectory used for evaluating the tracking accuracy of the tumor trajectory is a sine wave.
- the particularity and difficulty of problem setting when using a robot manipulator in a moving phantom system is that the target trajectory is periodic to a large marker, but the amplitude and phase, and in some cases the waveform shape itself varies, This point is not mentioned in this moving phantom system.
- a phantom drive device using an XYZ table configured by combining a direct acting actuator has been developed.
- the tumor trajectory tracking performance was evaluated by ⁇ + 2 ⁇ value of 3D error signal, and it was reported that it was within 0.8mm for 20 cases of lung cancer, liver cancer and pancreatic cancer.
- the performance evaluation of the phantom drive device is performed using the following accuracy with respect to the tumor motion trajectory of the cancer patient measured in advance as an index. As will be described later, although the tumor movement has a large difference between cases, the present inventors also decided to evaluate the performance using the above values as a standard.
- the present inventors constructed a robot moving body phantom system using an industrial small 6-axis robot manipulator system (MZ07-01, Fujikoshi Co., Ltd.).
- Table 1 shows an outline of the specifications of the selected robot manipulator as an example.
- the degree of freedom of motion required as a robot moving body phantom is only three-dimensional translational freedom (translational 3 degrees of freedom), but a total of 6 water equivalent phantoms and fixing jigs are fixed to the tip of the robot manipulator. Since it has a mass of 7 kg, the model was selected in consideration of the loadable mass at the tip guaranteed by the robot manipulator.
- the motion required for the robot manipulator is only a translational motion, it cannot be denied that the rotary joint type robot manipulator is disadvantageous in terms of mechanism and control over the positioning device based on the linear motion actuator.
- a robot manipulator When a robot manipulator is used at a normal production site, it can be programmed using the attached teaching device or special software, whether it is point-to-point position control or following a continuous trajectory. As long as it is used for the same work in the same place, it is not necessary to change the trajectory and motion once programmed. However, when the robot manipulator is used as a phantom driving device for a moving phantom, the tumor trajectory to be followed by the phantom is different for each patient, and high-precision tracking is required over the entire time during operation.
- FIG. 1 is a schematic diagram showing a coordinate system of the robot moving body phantom system according to the first embodiment of the present invention.
- FIG. 1 (A) shows how to determine the coordinate system of the medical linear accelerator 10 used during measurement and treatment of the tumor position in quality assurance
- FIG. 1 (B) shows the work coordinates used for the work plan of the robot manipulator. Indicates system settings.
- a radiation treatment / measurement system is formed by the medical linear accelerator 10 and the bed 11 and an origin ic (iso-center) of the treatment apparatus coordinate system is provided.
- the robot manipulator 12 has a water equivalent phantom 13 attached to the tip, and the rear end is set at the origin O of the work coordinate system.
- the robot manipulator 12 When the robot moving body phantom system is used in combination with the radiation therapy / measurement system of FIG. 1A, the robot manipulator 12 is placed on the bed 11 visible in front of FIG. Is fixed so as to coincide with the y-axis direction of the medical linear accelerator 10 which is a treatment apparatus. For this reason, when the coordinate data of the tumor trajectory measured in the therapeutic apparatus coordinate system is passed to the robot moving body phantom system, coordinate conversion is necessary.
- the three-dimensional trajectory data and the operation result of the robot manipulator 12 shown in this specification are all expressed in the work coordinate system of the robot manipulator 12 in FIG. 1B.
- the plot is created by parallel translation so that it overlaps the origin ic of the system.
- FIGS. 2 to 5 are graphs showing lung tumor trajectories in the X-axis, Y-axis, and Z-axis directions of four lung cancer patients A to D measured by the moving body tracking apparatus according to the first embodiment of the present invention. is there.
- the waveforms shown in FIGS. 2 to 5 show the lung tumor trajectories of the patients A to D taken up as target trajectories in the accuracy verification of the robot moving body phantom system of this embodiment.
- a lung tumor it shows a behavior in which a vibration of a high frequency component caused by the pulsation of an adjacent heart is superimposed on a slow vibration of a period of about 4 s called respiratory movement. It can be seen that there are very large individual differences. It is also important to reflect the fluctuation of the rhythmic movement of the living body and to be a periodic signal in a strict sense.
- FIG. 6 is a schematic diagram showing the configuration of the robot moving body phantom system according to the first embodiment of the present invention.
- the robot moving body phantom system 60 includes a robot manipulator 61, a robot control device 62, a teaching pendant 63, and an external controller 64. Further, a water equivalent phantom 65 is attached to the arm tip of the robot manipulator 61.
- the robot control device 62 has a target trajectory generation unit 66 that converts a three-dimensional motion trajectory of a patient tumor measured in advance using a moving body tracking device into a target trajectory for the robot manipulator 61 and outputs the target trajectory.
- a target trajectory generation unit 66 that converts a three-dimensional motion trajectory of a patient tumor measured in advance using a moving body tracking device into a target trajectory for the robot manipulator 61 and outputs the target trajectory.
- it has a “sampling period conversion” function for interpolating the measurement result of the time interval by the moving body tracking device and holding the information of the marker position of the patient and up-sampling.
- the robot moving body phantom system 60 is configured to cause the marker position in the water equivalent phantom 65 fixed to the tip of the robot manipulator 61 to follow the target trajectory generated by the robot target trajectory generating unit 66 with high accuracy. Has been.
- the robot moving body phantom system 60 that satisfies the required accuracy of the clinical site is constructed by using the follow-up mode of the external controller 64 provided in the robot control device 62 of the selected robot manipulator 61.
- the “sampling cycle conversion” function is not limited to the case where the external controller 64 has, but may include other configurations such as the robot control device 62.
- the robot controller 62 includes a motor driver for driving each axis of the robot manipulator 61 and an encoder signal processing circuit.
- the robot control device 62 includes a lower system that performs servo compensation control by a two-degree-of-freedom controller at each axis level, a host system that realizes a response to an operation using the teaching pendant 63 by an operator, and a teaching reproduction function. , Has a hierarchical structure. The lower system and the upper system operate while constantly transmitting and receiving data (information signals) necessary for control and operation by the communication means.
- the host system of the robot control device 62 performs TCP (Transmission Control Protocol) data communication with the external controller 64 at a fixed period of 5 ms.
- the external controller 64 can command the target trajectory of the end effector to the robot controller 62 in real time.
- the robot controller 62 is configured to perform control based on the target trajectory information given from the external controller 64 and to feed back information such as the current tip position / posture as a result to the external controller 64.
- Table 2 below shows information exchanged between the robot controller 62 and the external controller 64.
- the selected robot manipulator 61 achieves ⁇ 0.02 mm in position repeatability (based on JIS B 8342) according to control by the robot controller 62.
- the tracking performance required for use as the robot moving body phantom system 60 is not a repetitive positioning to a fixed point but a high-accuracy tracking in real time to a target trajectory that cannot be explicitly described as a function of time.
- the robot moving body phantom system 60 of the present embodiment is used as a quality assurance tool in a clinical field, it is considered difficult to entrust the user of the system to adjust the control operation of the robot manipulator 61 in order to improve the trajectory tracking accuracy.
- the target trajectory is less regular and is a tumor trajectory that varies greatly from patient to patient.
- a method for online correction of the tip position target trajectory to be given to the robot manipulator 61 using the patient's tumor position trajectory measured by the moving body tracking device as a starting point is proposed, and parameter readjustment for each patient's tumor trajectory is proposed. It was decided to construct a robot moving body phantom system 60 that does not need to be used.
- FIG. 7 is a schematic diagram showing the moving body tracking device 80 installed together with the medical linear accelerator 81 according to the first embodiment of the present invention.
- the moving body tracking device 80 of this embodiment includes color image receiving devices 84 and 85 corresponding to the two X-ray sources 82 and 83.
- a bed 86 on which a patient to be treated is placed is installed at a position facing the medical linear accelerator 81.
- the coordinate values in the images are specified using a template matching technique, and the coordinate values of the markers in the therapeutic apparatus coordinate system are output.
- the color image receiving devices 84 and 85 corresponding to the X-ray sources 82 and 83 are arranged at positions where the medical linear accelerator 81 intersects, as shown in FIG.
- two X-ray sources 82b and 83 are arranged on the left side of the paper surface of FIG. 7B, and two color image receiving devices 84b and 85 corresponding to the right side of the paper surface of FIG. 7B.
- two X-ray sources 82 and 83b are arranged on the right side of the paper surface of FIG. 7B, and two color image receiving devices 84 and 85b corresponding to the left side of the paper surface of FIG. 7B.
- the moving object tracking device 80 ensures that the localization error of the marker position is within 0.8 mm.
- the moving body tracking device 80 has the ability to measure and output the tracking result of the marker position placed near the tumor in a period of about 33 ms in order to track the position of the mobile tumor.
- the external controller 64 is configured to feed the target value to the robot controller 62 at intervals of 5 ms. Therefore, for driving the robot manipulator 61, it is necessary to generate a target value time series for the robot manipulator with shorter time intervals from the time series of the measurement result log file of the moving body tracking device 80.
- this target trajectory generation as a method of determining a target value between sample points of the measurement result of the moving object tracking device 80, four methods are shown below using FIG.
- FIG. 8 is a diagram for explaining a method for determining a target value between sample points of the measurement result of the moving object tracking device according to the first embodiment of the present invention.
- FIG. 8S is a process common to any method for determining a target value of this embodiment.
- A) A process of reading time information corresponding to patient marker position information measured by, for example, SyncTraX TM. is there.
- the measurement of the moving body tracking device according to the present embodiment is not limited to the case of measuring with SyncTraX TM .
- FIG. 8 [8] The method shown in FIG. 8 [1] is the most basic method, and is a method of maintaining the current value until the target coordinate value is updated.
- FIG. 8 [1] after the step of FIG. 8 [S] a), b) the latest marker position information is held until the next sampling time, and c) the locus of the marker position information held in the previous step is a sampling period of 5 ms. Upsample with.
- FIG. 8 [2] is a method of prefetching the marker position at the next sampling time.
- b) the marker position at the next sampling time is pre-read and held, and c) the marker position trajectory held in the previous process is sampled at a sampling period of 5 ms. Upsampling.
- the method of FIG. 8 [2] is the same as the method of FIG. 8 [1] in that a constant value is maintained within one hour interval, but the target value is obtained by prefetching the value of one sample ahead of the moving body tracking device 80 log. Is set to reduce the influence of the transient response operation of the robot controller 62 on the error.
- the method shown in FIG. 8 [3] is simply a linear interpolation method that interpolates between two adjacent coordinates with a line segment.
- 8 [3] after the step of FIG. 8 [S] a), b) coordinate data is interpolated with line segments, and c) the locus of the coordinate data interpolated in the previous step is upsampled at a sampling period of 5 ms.
- FIG. 8 [4] is a method of interpolating coordinate data with a cubic spline function.
- the coordinate data is interpolated with a cubic spline function
- the locus of the coordinate data interpolated in the previous step is upsampled at a sampling period of 5 ms.
- the method shown in FIG. 8 [4] is an interpolation method that guarantees continuity of speed and acceleration at the connection point of time based on the idea that the speed and acceleration indicating the motion of a biological tissue such as a tumor are continuous. .
- the target trajectory calculation data corresponding to one hour section of the moving object tracking device 80 log file is 12 coefficients of these three polynomials.
- the process of generating the coefficient set of (Equation 1) from the moving object tracking device 80 log file is executed by creating a mlab script of MATLAB (Mathworks).
- MATLAB MATLAB
- the polynomial coefficient generation from the moving body tracking device 80 log described in the first embodiment is a process necessary for instructing the robot moving body phantom system 60 of the tumor trajectory data of the patient to be treated, and the moving body tracking device 80. It does not change the data contained in the logs. However, if the target trajectory is simply fed from the external controller 64 to the robot controller 62 using the method shown in FIG. Therefore, in the second embodiment, on the premise of the configuration of the robot moving body phantom system 60 shown in FIG. 6, target trajectory correction using target trajectory correction and tracking error information for constructing a system with higher tracking accuracy. The online re-interpolation method will be described.
- the robot moving body phantom system 60 uses network communication for data exchange between the subsystems, and a delay may occur due to the communication between the systems. Since the data delay in the transfer of the amount related to the control directly leads to the deterioration of the tracking accuracy, the robot moving body phantom system 60 that requires high tracking accuracy in real time needs to reduce the influence of this delay.
- the acceleration term takes a pulse-like non-zero value in one sample after the connection point of the sampling period conversion, but becomes zero in other steps, and the robot becomes zero. Not only does it cause vibration of the manipulator 61, but also the effect of the correction is not sufficiently exhibited. Assuming that the transfer characteristic from the speed target value to the speed target can be approximated as a first order lag for the speed control system of the robot manipulator 61, the acceleration changes like the impulse response of the first order lag system.
- the acceleration value at the time is attenuated according to the following (Equation 3-2).
- the correction target value of each axis defined in the above (Equation 2) is determined only from the tumor motion trajectory observed by the moving body tracking device 80, and a tracking error that occurs when the robot manipulator 61 is actually moved. It is not a correction that takes into account. Therefore, using the position information of the tip of the robot manipulator 61 fed back from the robot controller 62 to the external controller 64, an additional feedback correction using the tracking error information is performed on the target value given to the robot controller 62.
- the current value of the tip position / posture of the robot manipulator 61 is fed back to the external controller.
- the interpolation work for generating the target value to be sent to the robot controller 62 at a cycle of 5 ms is performed again to regenerate the interpolation trajectory.
- the above-described tracking error is added to the coordinate value of the interpolation start point that has already become past data, and the target coordinate value to be sent to the robot controller 62 in the future is increased or decreased according to the sign of the error. I do.
- the calculation algorithm of dynamic re-interpolation is shown below. Since the same processing is independently performed for all of the X axis, the Y axis, and the Z axis, the calculation procedure for the X axis will be described here representatively. Assuming that the time interval for performing the re-interpolation is the kth time interval t ⁇ [Tst [k], Tst [k + 1]) of the moving object tracking device log, as described above, before correction in this interval. The target value is determined by a cubic polynomial of the following (Equation 4).
- xk (t) ax [k] + bx [k] (t-Tst [k]) + cx [k] (t-Tst [k]) 2 + dx [k] (t-Tst [k]) 3 (Formula 4)
- x (i) k (t) ax [k, i] + bx [k, i] (t-Tst [k]) + cx [k, i] (t-Tst [k]) 2 + Dx [k, i] (t-Tst [k]) 3 (Expression 5)
- Equation 7 requests that the target value at the end time of this section matches the initial value of the target value in the next section.
- the above (Equation 8) and (Equation 9) are conditional expressions for ensuring the continuity of velocity and acceleration at the connection point, which is a feature of cubic spline interpolation. In this section, the method shown here is used. Even if the target value generation polynomial is changed to the above (Equation 5), the continuity of position, velocity and acceleration is maintained.
- FIG. 9 is a graph showing the operation of this algorithm in the case of linear interpolation by the control device according to the second embodiment of the present invention.
- 9A shows the next target value sent to the robot controller
- FIG. 9B shows the current position of the tip calculated by the encoder information of the robot
- FIG. 9C shows the pre-correction value.
- Next target trajectory and the next target value sent to the robot controller shows the current position of the new tip calculated by the robot encoder
- FIG. 9E shows the target trajectory before and after correction.
- FIG. 10 is a schematic diagram showing the introduction of an additional feedback loop using the external controller according to the second embodiment of the present invention.
- a feedback control system is formed between the robot manipulator 61 and the robot control device 62 of the present embodiment.
- the external controller 64 of the present embodiment includes a target trajectory generation unit 66, a target trajectory correction unit 111, and a target trajectory regeneration unit 112.
- the target trajectory generation unit 66 can include a position acquisition unit 201 that acquires a three-dimensional motion trajectory of the patient's marker position, and an angle calculation unit 202 that calculates the rotation angle of the marker that acquired the three-dimensional motion trajectory. .
- the target trajectory of the robot manipulator 61 is generated by performing a process of calculating the rotation angle of the tumor by the angle calculation unit 202 based on the acquired marker position.
- FIG. 11 is a diagram illustrating an example of a calculation method used when the angle calculation unit 202 determines the rotation angle of a tumor.
- FIG. 11A shows a state when the moving object tracking device 80 detects the positions of the three markers m 1 , m 2 , and m 3 at time k ⁇ 1.
- FIG. 11B shows a state when the same three marker positions are detected at the next time k.
- FIG. 12 is an image example in which the conductor tracking device 80 captures a plurality of markers that are actually embedded. It is assumed that the change in position of the markers m 1 , m 2 , and m 3 is sufficiently represented only by the three-dimensional position change of the tumor centroid position and the rotation in the three-dimensional space.
- the rotation angle of the tumor between the two images can be defined using an angle such as roll, pitch, yaw or Euler angle.
- FIG. 13 is an example of the tumor rotation angle obtained by the method according to the present invention. The rotation angle in the previous three-dimensional space is used between each vector v 1 , v 2 , n k ⁇ 1 at time k ⁇ 1 and the corresponding vector v ′ 1 , v ′ 2 , n k at time k.
- a simultaneous transformation matrix defined using a rotation matrix R defined by a vector ⁇ representing a three-dimensional position change of a tumor center of gravity determined by using the position acquisition unit 201 Using Therefore, the rotation matrix R can be determined numerically and uniquely from these three equations, and the target trajectory of the rotation angle of the phantom fixed to the hand of the robot can be generated from the determined rotation matrix. it can.
- the previous rotational transformation matrix is expressed using column vectors r1, r2, and r3.
- the number of unknowns increases due to the introduction of a, b, and c. In this case, the change between the times k ⁇ 1 and k of the vector from m2 to m3 may be used.
- the target trajectory correction unit 111 has a function of correcting the robot target trajectory using the speed or acceleration of the motion trajectory of the robot manipulator 61 defined by interpolating the trajectory output as a result of the tumor position tracking of the moving body tracking device 80.
- the target trajectory correction unit 111 includes a position correction unit 203 that corrects the three-dimensional coordinate position of the robot manipulator 61 and an angle correction unit 204 that corrects the rotation angle of the robot manipulator 61 that corrected the three-dimensional coordinate position. it can.
- the position correction unit 203 corrects the three-dimensional coordinate position of the robot manipulator 61
- the angle correction unit 204 corrects the robot manipulator 61 based on the corrected three-dimensional coordinate position.
- the target trajectory of the robot manipulator 61 is corrected by performing a process of calculating the rotation angle.
- the target trajectory regeneration unit 112 has a function of calculating the tracking error of the target trajectory at each control sampling time from the control results for the target trajectory given from the target trajectory generation unit 66 and transmitting the information to the target trajectory correction unit 111.
- the target trajectory correcting unit 111 regenerates the target trajectory by performing interpolation in real time during control by adding the received tracking error of the target trajectory to the target value information at the start point of the interpolation section corresponding to the time.
- the external controller 64 of this embodiment information on the target trajectory of the work coordinate system generated by interpolation by the target trajectory generating unit 66 is transmitted to the target trajectory correcting unit 111 and the target trajectory regenerating unit 112. Thereafter, the target trajectory correction unit 111 performs delay correction using the velocity and acceleration, and the target trajectory regeneration unit 112 performs correction by feedback re-storage. Then, the information of the corrected target value is transmitted to the robot manipulator 61.
- FIG. 14 is a schematic diagram showing an installation example of a robot manipulator according to an embodiment of the present invention.
- the robot manipulator 61 in FIG. 14 is fixed to a fixed base 121, and a water equivalent phantom 65 is attached to the tip of the arm.
- FIG. 15 is a schematic diagram showing an installation example of a robot manipulator according to another embodiment of the present invention.
- the robot manipulator 61 shown in FIG. 15 is fixed to a bed 86 as shown in FIG. 8A with a fixture 131, and a water equivalent phantom 65 is attached to the tip of the arm.
- the experiment was performed using two robot manipulators 61 in two different environments.
- the first environment is a laboratory having a concrete floor.
- the robot manipulator 61 is installed and fixed according to the specification of the manufacturer.
- the information on the tip position of the robot manipulator 61 obtained in this environment is only the tip position calculated by the robot controller 62 from the encoder information and fed back to the external controller 64.
- the second environment is a clinical environment where patients are actually being treated.
- a measurement value using the moving body tracking device 80 is also obtained.
- the robot manipulator 61 is fixed to a bed 86 of a medical linear accelerator 81 with a fixture 131, and a vibration-absorbing urethane foam is placed between the bed and the bed base. Installed and experimented.
- Table 3 shows the results of calculating the mean square error value and the value of ⁇ + 2 ⁇ with respect to the target tumor trajectory from the results of experiments conducted in the laboratory.
- the error in this case is calculated as the difference between the value before correction of the target value sent from the external controller 64 to the robot controller 62 in a certain sample period and the marker position returned from the robot controller 62 in the next sample period. ing.
- network communication is used for data exchange between the external controller 64 and the robot controller 62 and within the robot controller 62, and there is a delay associated therewith, and the delay is caused by the network buffer.
- the error calculated here is not an accurate error at a certain sample time.
- the statistical error index value calculated using the actual value of the robot control device 62 is large, the statistical error index value evaluated using the moving body tracking device 80 is also large. Become.
- the feedback re-interpolation method exhibits a large error reduction effect as compared to the case where the robot manipulator 61 is driven by the sampling period conversion alone, but the effect is small compared to the error reduction amount when the delay compensation is used.
- delay compensation and feedback re-interpolation are used in combination, it was confirmed that the result was degraded in this environment, although it was very small. However, the difference is within the range of the error of repeated positioning to a fixed point guaranteed by the robot manipulator 61 used.
- Table 4 below shows the result of processing the error from the tumor position target trajectory before correction in the above case.
- Table 5 below shows the result of statistical processing of the error between the marker position measurement result of the moving body tracking device 80 and the tumor target position before correction.
- FIG. 16 shows a graph in which the tumor trajectory in FIG. 5 is set as a target value and the time change of the three-dimensional error is plotted for the three target value generation schemes in Table 5.
- Table 5 which is an error using the measurement result using the moving body tracking device 80
- Table 5 which is an error using the measurement result using the moving body tracking device 80
- the best value of ⁇ + 2 ⁇ is about 0.2 mm to 0.25 mm in cases A, B, and D with large tumor movement, and about 0.06 mm in case C with small movement. It is getting bigger.
- three of the four examples using cubic spline interpolation resulted in the minimum ⁇ + 2 ⁇ value.
- the delay compensation and the dynamic re-interpolation are used together, the result becomes worse, which is the same as the analysis using the position output of the robot controller 62.
- the marker position output by the robot control device 62 is relative position information from the work coordinate origin O on the fixed base 121 of the robot manipulator 61, whereas the measurement result of the moving body tracking device 80 is a medical linear accelerator.
- This is an absolute coordinate value in a coordinate system fixed in a room determined with respect to the origin ic of 81. If the work coordinate origin O of the robot manipulator 61 does not move on the coordinate system of the medical linear accelerator 81, the difference between the two measurement values is caused by the difference between the measurement systems. In this case, it is an error that can occur in three-dimensional position measurement using a stereo X-ray image by the moving object tracking device 80. Template matching is used for capturing a marker in an X-ray fluoroscopic image, and an error may occur in the calculation of the marker centroid position in the process.
- the robot manipulator 61 is fixed to the bed 86 of the medical linear accelerator 81. It stays. In the preliminary experiment, the bed and the robot manipulator sometimes vibrated in such a size that they could be clearly confirmed by visual observation. Therefore, the vibration was reduced as described above. As a result, there is no vibration that can be visually recognized, but it is considered that fine vibration that cannot be visually confirmed remains, and the measured value in the moving object tracking device 80 can also capture the vibration. This is considered to be a large factor as the reason why the value becomes larger than the error value at 62.
- the robot moving body phantom system 60 of the above embodiment is used for quality assurance of radiotherapy, it is a value when the moving body tracking device 80 is used as an evaluation of the influence on the quality.
- the best value of ⁇ + 2 ⁇ was less than 0.8 mm in all four cases, indicating that the robot moving body phantom system 60 is good. Accuracy is shown.
- the water equivalent phantom 65 is treated while actually measuring the position of the marker in the phantom using the moving body tracking device 80.
- treatments that irradiate radiation when a tumor that exhibits respiratory movement which is generally referred to as ambush irradiation, comes near a specified range of a pre-planned location, in the actual treatment, markers placed near the tumor are planned. It is a protocol that administers radiation when it enters the inside of a cube with a side of 4 mm centering on the position.
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Abstract
[Problem] To provide a mobile phantom system which can move with three translational degrees of freedom for reproducing an actual tumor movement and which has tracking accuracy that can be utilized to guarantee the quality of radiation therapy. [Solution] A robotic mobile body phantom system (60) includes: a robotic manipulator (61) that has three translational degrees of freedom; a robot control device (62) that controls the robot manipulator (61); a phantom (65) that is fixed to a distal end of the robot manipulator (61) and has a radiation absorptivity that is the same as that of a human body; and a mobile body tracking device (80) that measures, in real time, changes in a marker position of a patient placed near a tumor. The robot mobile body phantom system (60) is characterized in that the robot control device (62) includes a target trajectory generation unit (66) that generates a target trajectory for the robot manipulator (61) from a three-dimensional movement path of the marker position of the patient, and controls the robot manipulator (61) such that the marker position in the phantom (65) follows the target trajectory.
Description
本発明は、ロボット動体ファントムシステムに関し、より詳細には、ロボットマニピュレータ、動体追跡装置およびファントムを備え、放射線治療の治療計画を検証するロボット動体ファントムシステムに関する。
The present invention relates to a robot moving body phantom system, and more particularly, to a robot moving body phantom system that includes a robot manipulator, a moving body tracking device, and a phantom, and verifies a treatment plan for radiation therapy.
超高齢化社会の到来により、悪性新生物(がん)を治療する場合は、低侵襲な治療が選択されるようになり、放射線治療のニーズが非常に高まっている。放射線治療は、コンピュータなどの技術の進歩により目覚ましい発展を遂げ、がん治療の3本柱の一つに位置づけられている。この放射線治療は、腫瘍の完全根治にのみ使用されるのではなく、腫瘍による痛みを軽減する緩和目的においても使用される。
With the advent of a super-aging society, when a malignant neoplasm (cancer) is treated, a minimally invasive treatment has been selected, and the need for radiation therapy has been greatly increased. Radiation therapy has made remarkable progress due to advances in technology such as computers and is positioned as one of the three pillars of cancer treatment. This radiation therapy is not only used for the complete cure of the tumor, but also for palliative purposes to reduce the pain caused by the tumor.
現在の放射線治療は、CT(Computed Tomography) 画像を用い、人体の解剖学的構造と腫瘍位置を3次元的に把握して治療を行う3次元放射線治療が主流である。しかし、胸部や腹部など呼吸性移動を伴う腫瘍に対する放射線治療は、腫瘍が呼吸運動によって動く領域全てを含めて治療を行う必要がある。そのため、放射線治療には、腫瘍への放射線集中性は高まるものの、周囲の正常組織にも余分な放射線投与が行われ、放射線による副作用が増加するという問題がある。
Current radiation therapy is mainly three-dimensional radiation therapy in which CT (Computed Tomography) images are used to three-dimensionally grasp the anatomical structure and tumor position of the human body. However, radiotherapy for tumors involving respiratory movement such as the chest and abdomen needs to be performed including the entire region where the tumor moves by respiratory motion. For this reason, radiation therapy has a problem that although radiation concentration on the tumor is increased, extra radiation is also administered to surrounding normal tissues, and side effects due to radiation are increased.
さらに、コンピュータの助けを借りて、多葉絞りで形成された複数のビームを組み合わせることで放射線に強弱をつけ、正常組織へ線量低減させながら、腫瘍に集中的に照射できる放射線治療技術として強度変調放射線治療が知られている。強度変調放射線治療は、呼吸性移動を伴う部位へその治療を施行すると、予定とは全く異なった放射線量を投与することになり、腫瘍の制御率の低下や正常組織に対する副作用が増加する問題がある。
Furthermore, with the help of a computer, intensity modulation as a radiation therapy technology that can irradiate the tumor intensively while combining the multiple beams formed by the multileaf diaphragm to increase and decrease the radiation and reduce the dose to normal tissue Radiation therapy is known. When intensity-modulated radiation therapy is administered to a site with respiratory movement, a dose of radiation that is completely different from the scheduled dose is administered, resulting in problems such as reduced tumor control rate and increased side effects on normal tissues. is there.
これらの問題を解決するため、近年、放射線治療は、3次元空間に時間要素を加えた4次元化に向けた研究開発が進んでおり、臨床への展開が期待されている。臨床現場では、4次元放射線治療の一つである動体追跡装置(SyncTraXTM,島津製作所)を用いた動体追跡放射線治療を行っている。
In order to solve these problems, in recent years, research and development for radiotherapy has been progressing toward four-dimensionalization in which a time element is added to a three-dimensional space, and clinical development is expected. In clinical practice, moving body tracking radiotherapy is performed using a moving body tracking device (SyncTraX ™ , Shimadzu Corporation), which is one of four-dimensional radiotherapy.
このような動体追跡装置の一例として、特許文献1には、2方向のX線透視画像をパターン認識画像処理することで、気管支鏡下またはCTもしくは超音波ガイド下で腫瘍付近に留置された金属マーカの3次元位置座標をリアルタイムに算出し、呼吸性移動によって動く金属マーカ(腫瘍)を追跡することが可能な動体追跡装置が開示されている。動体追跡装置のX線透視位置は、3方向から選択することができ、医療用直線加速器の照射角度(ガントリ、カウチ角度に依存せず)に制約を受けることなく、金属マーカの追跡をすることが可能である。動体追跡放射線治療は、動体追跡装置を用いてリアルタイムに算出される金属マーカの3次元位置が、ある位置に来たときのみ放射線が照射される治療であり、動体追跡装置および医療用直線加速器を組み合わせることで治療実施可能となる。
As an example of such a moving body tracking device, Patent Document 1 discloses a metal placed in the vicinity of a tumor under a bronchoscope or under CT or ultrasonic guidance by performing pattern recognition image processing on a bi-directional X-ray fluoroscopic image. There is disclosed a moving body tracking device capable of calculating a three-dimensional position coordinate of a marker in real time and tracking a metal marker (tumor) moving by respiratory movement. The X-ray fluoroscopic position of the moving body tracking device can be selected from three directions, and the metal marker can be tracked without being restricted by the irradiation angle (independent of gantry and couch angle) of the medical linear accelerator. Is possible. The moving body tracking radiotherapy is a treatment in which the radiation is irradiated only when the three-dimensional position of the metal marker calculated in real time using the moving body tracking apparatus reaches a certain position, and the moving body tracking apparatus and the medical linear accelerator are used. It becomes possible to carry out treatment by combining.
動体追跡放射線治療では、医師の診察後、患者専用の固定具を作成し、治療計画用CT撮影を行う。そのCT画像の解剖学的情報を基に、放射線を照射する方向や照射量をコンピュータ上でシミュレーションする治療計画を行う。治療計画が完了すると、動体追跡装置を使用して、患者に留置された金属マーカの視認性を確認し、治療で使用するX線透視位置を決定する。この時、呼吸によって動いた金属マーカの3次元座標をログとして記録する。その後、シミュレーション上の治療計画の妥当性を評価するため、治療計画の品質保証を行う。
In moving body tracking radiotherapy, after examination by a doctor, a patient-specific fixture is created and CT imaging for treatment planning is performed. Based on the anatomical information of the CT image, a treatment plan for simulating on the computer the direction and dose of radiation is performed. When the treatment plan is completed, the visibility of the metal marker placed on the patient is confirmed using the moving body tracking device, and the fluoroscopic position used in the treatment is determined. At this time, the three-dimensional coordinates of the metal marker moved by respiration are recorded as a log. Thereafter, in order to evaluate the validity of the treatment plan on the simulation, the quality of the treatment plan is assured.
治療計画に基づく放射線治療の一例として、特許文献2には、人体と同等の放射線吸収率を有し、水等価組織として模擬したファントムに対して施行し、ファントム内に挿入された線量計で測定された放射線量と治療計画時の計算値に相違がないことを検証する品質保証の手順が開示されている。この品質保証により、放射線治療の精度が担保されると、患者に対して治療が開始される。
As an example of radiation therapy based on a treatment plan, Patent Document 2 discloses that a radiation phantom having a radiation absorption rate equivalent to that of a human body and simulated as a water equivalent tissue is measured with a dosimeter inserted into the phantom. A quality assurance procedure is disclosed that verifies that there is no difference between a given radiation dose and a calculated value at the time of treatment planning. When the accuracy of radiotherapy is ensured by this quality assurance, treatment is started for the patient.
しかしながら、現在の動体追跡放射線治療の品質保証は、特許文献1に開示されているような動体追跡装置を利用して取得した金属マーカの3次元座標のある1軸の座標データを基に、特許文献2に開示されているようなファントムを1軸駆動させて行っている。そのため、人体の呼吸により3次元的に動く腫瘍の動きを再現するファントムを用いた装置等が存在せず、高精度に動体追跡放射線治療の品質保証ができていないのが現状である。
However, the quality assurance of the current moving body tracking radiotherapy is based on the one-axis coordinate data with the three-dimensional coordinates of the metal marker acquired by using the moving body tracking device as disclosed in Patent Document 1. A phantom as disclosed in Document 2 is driven by one axis. For this reason, there is no device using a phantom that reproduces the movement of a tumor that moves three-dimensionally due to the respiration of the human body, and the quality of moving body tracking radiotherapy cannot be assured with high accuracy.
本発明は、上記従来の問題点に鑑みてなされたものであり、その目的は、実際の腫瘍運動を再現するため3次元の並進運動が可能な自由度を持ち、放射線治療の品質保証に活用できる追従精度を有する動体ファントムシステムを提供することにある。
The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a degree of freedom capable of three-dimensional translational motion to reproduce actual tumor motion, and is used for quality assurance of radiotherapy. It is an object of the present invention to provide a moving phantom system having a following accuracy.
上記課題を解決するために本発明に係るロボット動体ファントムシステムは、3次元の並進運動自由度を有するロボットマニピュレータと、ロボットマニピュレータを制御するロボット制御装置と、ロボットマニピュレータの先端に固定され、人体と同等の放射線吸収率を有するファントムと、腫瘍付近に留置された患者のマーカ位置の変化を実時間で測定する動体追跡装置と、を備え、ロボット制御装置は、患者のマーカ位置の3次元運動軌跡からロボットマニピュレータの目標軌道を生成する目標軌道生成部を有し、ファントム内のマーカ位置が目標軌道に追従するようにロボットマニピュレータを制御することを特徴とする。
In order to solve the above-described problems, a robot moving body phantom system according to the present invention includes a robot manipulator having a three-dimensional translational freedom degree, a robot control device for controlling the robot manipulator, a robot manipulator fixed to the tip of the human body, The robot controller includes a phantom having an equivalent radiation absorption rate and a moving body tracking device that measures a change in the marker position of the patient placed in the vicinity of the tumor in real time. And a target trajectory generating unit that generates a target trajectory of the robot manipulator, and controlling the robot manipulator so that the marker position in the phantom follows the target trajectory.
本発明に係るロボット動体ファントムシステムによれば、放射線治療の品質保証の精度を高めることができる。なお、ここに記載された効果は、必ずしも限定されるものではなく、本技術中に記載されたいずれかの効果であってもよい。
The robot moving body phantom system according to the present invention can improve the accuracy of quality assurance for radiation therapy. In addition, the effect described here is not necessarily limited, and may be any effect described in the present technology.
<1.第1実施形態>
まず、本発明の第1実施形態に係るロボット動体ファントムシステムの構成について、図1~図6を用いて説明する。なお、本発明の実施形態は、以下に示す実施形態に限られず、いずれかの実施形態を組み合わせることもできる。また、以下に示す実施形態では、動体ファントムとして「水等価ファントム」を用いているが、これに限らず「水等価」以外のファントムを用いてもよい。 <1. First Embodiment>
First, the configuration of the robot moving body phantom system according to the first embodiment of the present invention will be described with reference to FIGS. In addition, embodiment of this invention is not restricted to embodiment shown below, Any embodiment can also be combined. In the embodiment described below, the “water equivalent phantom” is used as the moving object phantom, but the present invention is not limited to this, and a phantom other than “water equivalent” may be used.
まず、本発明の第1実施形態に係るロボット動体ファントムシステムの構成について、図1~図6を用いて説明する。なお、本発明の実施形態は、以下に示す実施形態に限られず、いずれかの実施形態を組み合わせることもできる。また、以下に示す実施形態では、動体ファントムとして「水等価ファントム」を用いているが、これに限らず「水等価」以外のファントムを用いてもよい。 <1. First Embodiment>
First, the configuration of the robot moving body phantom system according to the first embodiment of the present invention will be described with reference to FIGS. In addition, embodiment of this invention is not restricted to embodiment shown below, Any embodiment can also be combined. In the embodiment described below, the “water equivalent phantom” is used as the moving object phantom, but the present invention is not limited to this, and a phantom other than “water equivalent” may be used.
<2-1.動体ファントムシステムの概要>
放射線治療において、呼吸や心拍などの影響を受けて移動する腫瘍(マーカ)の動きを再現するデバイスは、動体追跡放射線治療や動体追尾照射などの移動腫瘍に対する放射線治療の品質保証を行う上で重要である。このようなデバイスとして、動体ファントムシステムが知られている。ここで動体ファントムシステムとは、患者の体内における腫瘍位置の変化を実時間で模擬するファントム駆動装置と、生体組織(人体)と同等の放射線吸収率を有する水等価ファントムおよび線量計や放射線感応フィルムの組み合わせで構成される、放射線治療用の品質保証システムである。 <2-1. Overview of the moving phantom system>
In radiotherapy, a device that reproduces the movement of a tumor (marker) that moves under the influence of respiration and heartbeat is important for quality assurance of radiotherapy for moving tumors such as moving body tracking radiotherapy and moving body tracking irradiation. It is. A moving phantom system is known as such a device. Here, the moving body phantom system is a phantom drive device that simulates changes in the position of a tumor in a patient's body in real time, a water equivalent phantom having a radiation absorption rate equivalent to that of a living tissue (human body), a dosimeter, and a radiation sensitive film. It is a quality assurance system for radiation therapy that is composed of a combination of
放射線治療において、呼吸や心拍などの影響を受けて移動する腫瘍(マーカ)の動きを再現するデバイスは、動体追跡放射線治療や動体追尾照射などの移動腫瘍に対する放射線治療の品質保証を行う上で重要である。このようなデバイスとして、動体ファントムシステムが知られている。ここで動体ファントムシステムとは、患者の体内における腫瘍位置の変化を実時間で模擬するファントム駆動装置と、生体組織(人体)と同等の放射線吸収率を有する水等価ファントムおよび線量計や放射線感応フィルムの組み合わせで構成される、放射線治療用の品質保証システムである。 <2-1. Overview of the moving phantom system>
In radiotherapy, a device that reproduces the movement of a tumor (marker) that moves under the influence of respiration and heartbeat is important for quality assurance of radiotherapy for moving tumors such as moving body tracking radiotherapy and moving body tracking irradiation. It is. A moving phantom system is known as such a device. Here, the moving body phantom system is a phantom drive device that simulates changes in the position of a tumor in a patient's body in real time, a water equivalent phantom having a radiation absorption rate equivalent to that of a living tissue (human body), a dosimeter, and a radiation sensitive film. It is a quality assurance system for radiation therapy that is composed of a combination of
ファントム駆動装置上に設置された水等価ファントムには、動体追跡装置で位置測定対象となるマーカが埋め込まれるとともに線量計もしくは放射線感応フィルムなどが必要に応じて設置される。ファントム駆動装置は、あらかじめ記録された患者の安静時における腫瘍移動軌跡を目標値として水等価ファントムを動かす。この動作を治療時と同様にモニタリングしながら治療計画に沿った放射線照射を行うとともに、線量を線量計によって計測し、治療計画で定められた照射線量を投与できているかを確認する。
In the water equivalent phantom installed on the phantom drive device, a marker to be position-measured by the moving body tracking device is embedded, and a dosimeter or a radiation sensitive film is installed as necessary. The phantom drive device moves the water equivalent phantom with the tumor movement trajectory at the time of rest of the patient recorded in advance as a target value. While monitoring this operation in the same way as during treatment, radiation is performed according to the treatment plan, and the dose is measured by a dosimeter to confirm whether the irradiation dose determined in the treatment plan can be administered.
現在、上記動体ファントムシステムは、1自由度の直線往復運動が可能なもので、かつ過渡的に数mm程度の大きな追従誤差が発生することが知られている。体内での腫瘍の動きは3次元空間での運動であり、それを再現できること、また高精度放射線治療のため全時間の3次元追従誤差が1mm 程度に抑えられる動体ファントムシステムが望まれている。
Currently, it is known that the above moving body phantom system is capable of linear reciprocating motion with one degree of freedom, and a large follow-up error of about several millimeters occurs transiently. The movement of the tumor in the body is a movement in a three-dimensional space, which can be reproduced, and a moving body phantom system that can suppress the three-dimensional tracking error of the whole time to about 1 mm for high-precision radiotherapy is desired.
ロボットマニピュレータおよびそれに類する位置決め装置を利用した動体ファントムシステムの構成に関して、ステッピングモータと6軸のロボットマニピュレータを利用し、胸郭の呼吸による変形を模擬しつつ、かつ胸郭内での腫瘍の動きを模擬する放射線治療のための動体ファントムシステムを構築したものが知られている。しかし、この動体ファントムシステムは、ロボットマニピュレータの先端に固定されるのが粒子線の検出器であることに加え、腫瘍軌跡への追従精度評価のために用いられている3次元目標軌道が正弦波のみで、追従精度向上が比較的容易であると考えられる目標値に対する誤差評価しかなされていない。動体ファントムシステムにロボットマニピュレータを利用する場合の問題設定の特殊性と困難は、目標軌道が大マーカに周期的ではあるものの振幅や位相、場合によっては波形形状そのものも変動するという状況にあるが、この動体ファントムシステムではその点には触れられていない。
Concerning the configuration of a moving phantom system using a robot manipulator and similar positioning device, a stepping motor and a 6-axis robot manipulator are used to simulate the deformation of the rib cage due to breathing and to simulate the movement of the tumor in the rib cage. What built the moving body phantom system for radiation therapy is known. However, in this moving body phantom system, in addition to the particle beam detector fixed to the tip of the robot manipulator, the three-dimensional target trajectory used for evaluating the tracking accuracy of the tumor trajectory is a sine wave. Thus, only error evaluation with respect to a target value that is considered to be relatively easy to improve the tracking accuracy is performed. The particularity and difficulty of problem setting when using a robot manipulator in a moving phantom system is that the target trajectory is periodic to a large marker, but the amplitude and phase, and in some cases the waveform shape itself varies, This point is not mentioned in this moving phantom system.
一方、直動型アクチュエータを組み合わせて構成したXYZテーブルによるファントム駆動装置が開発されている。このファントム駆動装置によると、その腫瘍軌道追従性能を3次元誤差信号のμ+2σ値で評価した結果が、肺がん、肝臓がんおよび膵臓がんの計20症例について0.8mm以内であったことが報告されている。上記ファントム駆動装置の性能評価は、事前に測定されたがん患者の腫瘍運動軌跡に対する追従精度を指標として行われている。後述するように、腫瘍の運動は症例間の差が大きいが、本発明者らも上記値を一つの目安として性能評価を行うこととした。
On the other hand, a phantom drive device using an XYZ table configured by combining a direct acting actuator has been developed. According to this phantom drive device, the tumor trajectory tracking performance was evaluated by μ + 2σ value of 3D error signal, and it was reported that it was within 0.8mm for 20 cases of lung cancer, liver cancer and pancreatic cancer. Has been. The performance evaluation of the phantom drive device is performed using the following accuracy with respect to the tumor motion trajectory of the cancer patient measured in advance as an index. As will be described later, although the tumor movement has a large difference between cases, the present inventors also decided to evaluate the performance using the above values as a standard.
そこで、本発明者らは、産業用の小型6軸ロボットマニピュレータシステム(MZ07-01,株式会社不二越)を用いたロボット動体ファントムシステムの構築を行った。表1に、一例として、選択したロボットマニピュレータの仕様の概要を示す。
Therefore, the present inventors constructed a robot moving body phantom system using an industrial small 6-axis robot manipulator system (MZ07-01, Fujikoshi Co., Ltd.). Table 1 shows an outline of the specifications of the selected robot manipulator as an example.
ロボット動体ファントムとして要求される運動自由度は、3次元の並進運動自由度(並進3自由度)のみであるが、ロボットマニピュレータの先端に固定する水等価ファントムと固定用の治具が合計6.7kgの質量を有するため、ロボットマニピュレータに保証されている先端の可搬質量を考慮して機種選定を行った。ロボットマニピュレータに要求される運動が並進運動のみである場合、回転関節型のロボットマニピュレータは、直動アクチュエータに基づく位置決め装置に対して機構的、制御的に不利であることは否めない。ところが、本明細書では、ロボットマニピュレータに与える目標軌道の補正方法を提案し、姿勢によりアクチュエータに掛かる負荷が大きく変化する回転関節型のロボットマニピュレータを用いても、患者の腫瘍軌道に対する追従性能が臨床現場の要求精度を満たすことができるロボット動体ファントムシステムを提案している。
The degree of freedom of motion required as a robot moving body phantom is only three-dimensional translational freedom (translational 3 degrees of freedom), but a total of 6 water equivalent phantoms and fixing jigs are fixed to the tip of the robot manipulator. Since it has a mass of 7 kg, the model was selected in consideration of the loadable mass at the tip guaranteed by the robot manipulator. When the motion required for the robot manipulator is only a translational motion, it cannot be denied that the rotary joint type robot manipulator is disadvantageous in terms of mechanism and control over the positioning device based on the linear motion actuator. However, in this specification, we proposed a method for correcting the target trajectory given to the robot manipulator, and the follow-up performance to the tumor trajectory of the patient is clinical even when using a rotary joint type robot manipulator in which the load on the actuator changes greatly depending on the posture. We have proposed a robot moving body phantom system that can meet the accuracy requirements of the site.
<2-2.ロボット動体ファントムシステムの構成例>
ロボットマニピュレータを通常の生産現場において利用する場合、その動作は、point to pointの位置制御であれ連続軌跡への追従であれ、付属の教示装置や専用ソフトウェアなどを利用してプログラムすることが可能で、同じ場所で同一作業のために利用される限りにおいては、一度プログラムされた軌道と動作を変更する必要はない。しかし、ロボットマニピュレータを動体ファントムのファントム駆動装置として利用する場合には、ファントムが追従すべき腫瘍軌跡は患者ごとに異なり、かつ動作中の全時間で高精度な追従が求められる。 <2-2. Configuration example of a robot moving body phantom system>
When a robot manipulator is used at a normal production site, it can be programmed using the attached teaching device or special software, whether it is point-to-point position control or following a continuous trajectory. As long as it is used for the same work in the same place, it is not necessary to change the trajectory and motion once programmed. However, when the robot manipulator is used as a phantom driving device for a moving phantom, the tumor trajectory to be followed by the phantom is different for each patient, and high-precision tracking is required over the entire time during operation.
ロボットマニピュレータを通常の生産現場において利用する場合、その動作は、point to pointの位置制御であれ連続軌跡への追従であれ、付属の教示装置や専用ソフトウェアなどを利用してプログラムすることが可能で、同じ場所で同一作業のために利用される限りにおいては、一度プログラムされた軌道と動作を変更する必要はない。しかし、ロボットマニピュレータを動体ファントムのファントム駆動装置として利用する場合には、ファントムが追従すべき腫瘍軌跡は患者ごとに異なり、かつ動作中の全時間で高精度な追従が求められる。 <2-2. Configuration example of a robot moving body phantom system>
When a robot manipulator is used at a normal production site, it can be programmed using the attached teaching device or special software, whether it is point-to-point position control or following a continuous trajectory. As long as it is used for the same work in the same place, it is not necessary to change the trajectory and motion once programmed. However, when the robot manipulator is used as a phantom driving device for a moving phantom, the tumor trajectory to be followed by the phantom is different for each patient, and high-precision tracking is required over the entire time during operation.
図1は、本発明の第1実施形態に係るロボット動体ファントムシステムの座標系を示す模式図である。図1(A)は、品質保証における腫瘍位置の測定と治療時に用いられる医療用直線加速器10の座標系の取り方を示し、図1(B)は、ロボットマニピュレータの作業計画に使われる作業座標系の設定を示す。図1(A)において、医療用直線加速器10および寝台11で放射線治療・計測システムを形成し、治療装置座標系の原点ic(iso-center)が設けられている。図1(B)において、ロボットマニピュレータ12は、先端に水等価ファントム13を取り付け、後端が作業座標系の原点Oに設置されている。
FIG. 1 is a schematic diagram showing a coordinate system of the robot moving body phantom system according to the first embodiment of the present invention. FIG. 1 (A) shows how to determine the coordinate system of the medical linear accelerator 10 used during measurement and treatment of the tumor position in quality assurance, and FIG. 1 (B) shows the work coordinates used for the work plan of the robot manipulator. Indicates system settings. In FIG. 1A, a radiation treatment / measurement system is formed by the medical linear accelerator 10 and the bed 11 and an origin ic (iso-center) of the treatment apparatus coordinate system is provided. In FIG. 1B, the robot manipulator 12 has a water equivalent phantom 13 attached to the tip, and the rear end is set at the origin O of the work coordinate system.
ロボット動体ファントムシステムを図1(A)の放射線治療・計測システムと組み合わせて用いる場合、ロボットマニピュレータ12は、図1(A)の手前に見えている寝台11上に、ロボットマニピュレータ12のX軸方向が、治療装置である医療用直線加速器10のy軸方向と一致するように固定される。このため、治療装置座標系で計測された腫瘍軌跡の座標データをロボット動体ファントムシステムに渡す際には座標変換が必要である。本明細書で示す3次元の軌跡データとロボットマニピュレータ12との動作結果は、全て図1(B)のロボットマニピュレータ12の作業座標系で表現されたものであるが、その原点Oが治療装置座標系の原点icと重なるように平行移動してplotを作成している。
When the robot moving body phantom system is used in combination with the radiation therapy / measurement system of FIG. 1A, the robot manipulator 12 is placed on the bed 11 visible in front of FIG. Is fixed so as to coincide with the y-axis direction of the medical linear accelerator 10 which is a treatment apparatus. For this reason, when the coordinate data of the tumor trajectory measured in the therapeutic apparatus coordinate system is passed to the robot moving body phantom system, coordinate conversion is necessary. The three-dimensional trajectory data and the operation result of the robot manipulator 12 shown in this specification are all expressed in the work coordinate system of the robot manipulator 12 in FIG. 1B. The plot is created by parallel translation so that it overlaps the origin ic of the system.
図2~図5は、本発明の第1実施形態に係る動体追跡装置により測定された、4名の肺がん患者A~DのX軸、Y軸およびZ軸方向の肺腫瘍軌跡を示すグラフである。図2~図5に表された波形は、本実施形態のロボット動体ファントムシステムの精度検証で目標軌道として取り上げた患者A~Dの肺腫瘍軌跡を示している。肺腫瘍の場合、呼吸性移動と呼ばれる周期4s程度のゆっくりした振動に、隣接する心臓の拍動に起因する高い周波数成分の振動が重畳したような挙動を示すが、その振幅や重なりの度合いには非常に大きな個人差があることがわかる。また、生体のリズム運動の揺らぎを反映し、厳密な意味での周期信号にはまずなり得ないという事実も重要である。
2 to 5 are graphs showing lung tumor trajectories in the X-axis, Y-axis, and Z-axis directions of four lung cancer patients A to D measured by the moving body tracking apparatus according to the first embodiment of the present invention. is there. The waveforms shown in FIGS. 2 to 5 show the lung tumor trajectories of the patients A to D taken up as target trajectories in the accuracy verification of the robot moving body phantom system of this embodiment. In the case of a lung tumor, it shows a behavior in which a vibration of a high frequency component caused by the pulsation of an adjacent heart is superimposed on a slow vibration of a period of about 4 s called respiratory movement. It can be seen that there are very large individual differences. It is also important to reflect the fluctuation of the rhythmic movement of the living body and to be a periodic signal in a strict sense.
<2-3.ロボット制御システムの構成例>
図6は、本発明の第1実施形態に係るロボット動体ファントムシステムの構成を示す模式図である。ロボット動体ファントムシステム60は、ロボットマニピュレータ61、ロボット制御装置62、ティーチングペンダント63、および外部コントローラ64を備えている。さらに、ロボットマニピュレータ61のアーム先端には、水等価ファントム65が取り付けられている。 <2-3. Robot control system configuration example>
FIG. 6 is a schematic diagram showing the configuration of the robot moving body phantom system according to the first embodiment of the present invention. The robot movingbody phantom system 60 includes a robot manipulator 61, a robot control device 62, a teaching pendant 63, and an external controller 64. Further, a water equivalent phantom 65 is attached to the arm tip of the robot manipulator 61.
図6は、本発明の第1実施形態に係るロボット動体ファントムシステムの構成を示す模式図である。ロボット動体ファントムシステム60は、ロボットマニピュレータ61、ロボット制御装置62、ティーチングペンダント63、および外部コントローラ64を備えている。さらに、ロボットマニピュレータ61のアーム先端には、水等価ファントム65が取り付けられている。 <2-3. Robot control system configuration example>
FIG. 6 is a schematic diagram showing the configuration of the robot moving body phantom system according to the first embodiment of the present invention. The robot moving
ロボット制御装置62は、動体追跡装置を用いて事前に測定された患者腫瘍の3次元運動軌跡をロボットマニピュレータ61のための目標軌道に変換して出力する目標軌道生成部66を有している。外部コントローラ64は、動体追跡装置の腫瘍位置追跡の時間間隔とロボット制御装置62によるロボットマニピュレータ61の目標軌道との追従動作の制御周期を一致させるために、患者のマーカ位置の情報を保持するか、または動体追跡装置による時間間隔の計測結果を補間し患者のマーカ位置の情報を保持してアップサンプリングする「サンプリング周期変換」機能を有する。このように、ロボット動体ファントムシステム60は、ロボットマニピュレータ61の先端に固定された水等価ファントム65内のマーカ位置をロボット目標軌道生成部66により生成された目標軌道に高精度に追従動作させるよう構成されている。
The robot control device 62 has a target trajectory generation unit 66 that converts a three-dimensional motion trajectory of a patient tumor measured in advance using a moving body tracking device into a target trajectory for the robot manipulator 61 and outputs the target trajectory. Does the external controller 64 hold the information on the marker position of the patient in order to make the control period of the tracking operation of the robot manipulator 61 follow the time interval of tracking the tumor position of the moving body tracking device and the robot manipulator 61? Alternatively, it has a “sampling period conversion” function for interpolating the measurement result of the time interval by the moving body tracking device and holding the information of the marker position of the patient and up-sampling. As described above, the robot moving body phantom system 60 is configured to cause the marker position in the water equivalent phantom 65 fixed to the tip of the robot manipulator 61 to follow the target trajectory generated by the robot target trajectory generating unit 66 with high accuracy. Has been.
本実施形態では、選択したロボットマニピュレータ61のロボット制御装置62が備える外部コントローラ64の追従モードを利用して、臨床現場の要求精度を満たすロボット動体ファントムシステム60を構築している。なお、「サンプリング周期変換」機能は、外部コントローラ64が有する場合に限らず、ロボット制御装置62等の他の構成が有していてもよい。
In this embodiment, the robot moving body phantom system 60 that satisfies the required accuracy of the clinical site is constructed by using the follow-up mode of the external controller 64 provided in the robot control device 62 of the selected robot manipulator 61. Note that the “sampling cycle conversion” function is not limited to the case where the external controller 64 has, but may include other configurations such as the robot control device 62.
ロボット制御装置62は、ロボットマニピュレータ61の各軸を駆動するモータのドライバとエンコーダ信号の処理回路を含む。ロボット制御装置62は、各軸レベルの2自由度制御器によりサーボ補償制御を行う下位システムと、作業者によるティーチングペンダント63を用いた操作への応答と、教示再生の機能を実現する上位システムと、の階層構造を取っている。下位システムと上位システムは、通信手段で制御および動作に必要なデータ(情報信号)を常時、送受信しながら動作している。
The robot controller 62 includes a motor driver for driving each axis of the robot manipulator 61 and an encoder signal processing circuit. The robot control device 62 includes a lower system that performs servo compensation control by a two-degree-of-freedom controller at each axis level, a host system that realizes a response to an operation using the teaching pendant 63 by an operator, and a teaching reproduction function. , Has a hierarchical structure. The lower system and the upper system operate while constantly transmitting and receiving data (information signals) necessary for control and operation by the communication means.
外部コントローラ64の追従モードでは、ロボット制御装置62の上位システムが外部コントローラ64と一定周期5msでTCP(Transmission Control Protocol)のデータ通信を行う。外部コントローラ64は、ロボット制御装置62に対してエンドエフェクタの目標軌道を実時間で指令することができる。
In the follow-up mode of the external controller 64, the host system of the robot control device 62 performs TCP (Transmission Control Protocol) data communication with the external controller 64 at a fixed period of 5 ms. The external controller 64 can command the target trajectory of the end effector to the robot controller 62 in real time.
一方、ロボット制御装置62は、外部コントローラ64より与えられた目標軌道情報に基づき制御を行い、その結果である現在の先端位置・姿勢などの情報を外部コントローラ64へフィードバックするように構成されている。以下の表2は、これらのロボット制御装置62と外部コントローラ64との間でやり取りされる情報を示している。
On the other hand, the robot controller 62 is configured to perform control based on the target trajectory information given from the external controller 64 and to feed back information such as the current tip position / posture as a result to the external controller 64. . Table 2 below shows information exchanged between the robot controller 62 and the external controller 64.
選択したロボットマニピュレータ61は、表1に示したように、ロボット制御装置62での制御により位置繰り返し精度(JIS B 8342 準拠)で±0.02mmを達成している。しかし、ロボット動体ファントムシステム60として用いる場合に求められる追従性能は、固定点への反復位置決めではなく、時間の関数として陽に記述できない目標軌道への実時間での高精度追従である。
As shown in Table 1, the selected robot manipulator 61 achieves ± 0.02 mm in position repeatability (based on JIS B 8342) according to control by the robot controller 62. However, the tracking performance required for use as the robot moving body phantom system 60 is not a repetitive positioning to a fixed point but a high-accuracy tracking in real time to a target trajectory that cannot be explicitly described as a function of time.
本実施形態のロボット動体ファントムシステム60を品質保証の道具として臨床の現場で用いる場合、軌道追従精度の向上のためシステムの使用者にロボットマニピュレータ61の制御動作の調整をゆだねることは難しいと考えられる。加えて目標軌道は規則性に乏しく、患者ごとに大きく異なる腫瘍軌道である。
When the robot moving body phantom system 60 of the present embodiment is used as a quality assurance tool in a clinical field, it is considered difficult to entrust the user of the system to adjust the control operation of the robot manipulator 61 in order to improve the trajectory tracking accuracy. . In addition, the target trajectory is less regular and is a tumor trajectory that varies greatly from patient to patient.
そこで本実施形態では、動体追跡装置で計測された患者の腫瘍位置軌跡を出発点として、ロボットマニピュレータ61に与える先端位置目標軌道をオンライン補正する方法を提案し、患者の腫瘍軌跡ごとのパラメータ再調整が不要なロボット動体ファントムシステム60の構築を図ることとした。
Therefore, in the present embodiment, a method for online correction of the tip position target trajectory to be given to the robot manipulator 61 using the patient's tumor position trajectory measured by the moving body tracking device as a starting point is proposed, and parameter readjustment for each patient's tumor trajectory is proposed. It was decided to construct a robot moving body phantom system 60 that does not need to be used.
<3. 目標軌道の補正による追従誤差低減>
次に、目標軌道の補正による追従誤差低減について、図7~図10を用いて説明する。 <3. Tracking error reduction by correcting the target trajectory>
Next, tracking error reduction by correcting the target trajectory will be described with reference to FIGS.
次に、目標軌道の補正による追従誤差低減について、図7~図10を用いて説明する。 <3. Tracking error reduction by correcting the target trajectory>
Next, tracking error reduction by correcting the target trajectory will be described with reference to FIGS.
<3-1.腫瘍移動軌跡の測定>
ここでは、ロボット動体ファントムシステム60にとっての目標軌道となる、患者の腫瘍軌跡データの取得について説明する。本発明者らは、上述のとおりマーカの動体追跡装置を利用し、臨床現場のプロセスの中でこの測定を行っている。 <3-1. Measurement of tumor trajectory>
Here, acquisition of tumor trajectory data of a patient, which is a target trajectory for the robot movingbody phantom system 60, will be described. As described above, the present inventors make use of the marker moving body tracking device and perform this measurement in the clinical process.
ここでは、ロボット動体ファントムシステム60にとっての目標軌道となる、患者の腫瘍軌跡データの取得について説明する。本発明者らは、上述のとおりマーカの動体追跡装置を利用し、臨床現場のプロセスの中でこの測定を行っている。 <3-1. Measurement of tumor trajectory>
Here, acquisition of tumor trajectory data of a patient, which is a target trajectory for the robot moving
図7は、本発明の第1実施形態に係る医療用直線加速器81とともに設置された動体追跡装置80を示す模式図である。図7(A)に示すように、本実施形態の動体追跡装置80は、2つのX線源82、83に対応するカラー受像装置84、85を備えている。医療用直線加速器81と対向する位置には、治療対象の患者を載せる寝台86が設置されている。2枚のステレオ画像内に捕らえられたマーカは、テンプレートマッチングの技法を用いて画像内の座標値が特定され、治療装置座標系におけるマーカの座標値が出力される。
FIG. 7 is a schematic diagram showing the moving body tracking device 80 installed together with the medical linear accelerator 81 according to the first embodiment of the present invention. As shown in FIG. 7A, the moving body tracking device 80 of this embodiment includes color image receiving devices 84 and 85 corresponding to the two X-ray sources 82 and 83. A bed 86 on which a patient to be treated is placed is installed at a position facing the medical linear accelerator 81. For the markers captured in the two stereo images, the coordinate values in the images are specified using a template matching technique, and the coordinate values of the markers in the therapeutic apparatus coordinate system are output.
また、図7(B) に示すように、X線源82、83とカラー受像装置84、85には3とおりの異なる空間的な組み合わせが可能となっており、腫瘍部位と、治療のために移動させる寝台86とガントリに干渉しない組み合わせを選択して利用するようになっている。
In addition, as shown in FIG. 7B, three different spatial combinations are possible for the X-ray sources 82 and 83 and the color image receiving devices 84 and 85, and for the tumor site and for treatment. A combination that does not interfere with the bed 86 to be moved and the gantry is selected and used.
パターン1は、図7(A)に示すように、X線源82、83と対応するカラー受像装置84、85が医療用直線加速器81を挟んで交差する位置に配置されている。パターン2は、図7(B)の紙面に向かって左側に2つのX線源82b、83が配置され、図7(B)の紙面に向かって右側に対応する2つのカラー受像装置84b、85が各X線の交差する位置に配置されている。パターン3は、図7(B)の紙面に向かって右側に2つのX線源82、83bが配置され、図7(B)の紙面に向かって左側に対応する2つのカラー受像装置84、85bが各X線の交差する位置に配置されている。
7A, the color image receiving devices 84 and 85 corresponding to the X-ray sources 82 and 83 are arranged at positions where the medical linear accelerator 81 intersects, as shown in FIG. In the pattern 2, two X-ray sources 82b and 83 are arranged on the left side of the paper surface of FIG. 7B, and two color image receiving devices 84b and 85 corresponding to the right side of the paper surface of FIG. 7B. Are arranged at positions where the X-rays intersect. In the pattern 3, two X-ray sources 82 and 83b are arranged on the right side of the paper surface of FIG. 7B, and two color image receiving devices 84 and 85b corresponding to the left side of the paper surface of FIG. 7B. Are arranged at positions where the X-rays intersect.
しかし、いずれの場合でもテンプレートマッチングによるステレオ座標計測を行うという原理に変わりはない。動体追跡装置80では、マーカ位置の定位誤差が0.8mm 以内であることを保証している。
However, in any case, the principle of performing stereo coordinate measurement by template matching remains the same. The moving object tracking device 80 ensures that the localization error of the marker position is within 0.8 mm.
<3-2.腫瘍移動軌跡の生成>
本実施形態の動体追跡装置80は、移動性腫瘍の位置を追跡するため、腫瘍付近に留置されたマーカ位置の追跡結果を33ms前後の周期で計測出力する能力を有する。一方、ロボット動体ファントムシステム60の構成では、外部コントローラ64は5ms間隔で目標値をロボット制御装置62にフィードするように構成されている。そのため、ロボットマニピュレータ61の駆動には、動体追跡装置80の計測結果ログファイルの時系列から、より短い時間間隔のロボットマニピュレータ用目標値時系列を生成する必要がある。この目標軌道生成において、動体追跡装置80の測定結果のサンプル点間における目標値を定める方法として、図8を用いて以下に4とおりの方法を示す。 <3-2. Generation of tumor trajectory>
The movingbody tracking device 80 according to the present embodiment has the ability to measure and output the tracking result of the marker position placed near the tumor in a period of about 33 ms in order to track the position of the mobile tumor. On the other hand, in the configuration of the robot moving body phantom system 60, the external controller 64 is configured to feed the target value to the robot controller 62 at intervals of 5 ms. Therefore, for driving the robot manipulator 61, it is necessary to generate a target value time series for the robot manipulator with shorter time intervals from the time series of the measurement result log file of the moving body tracking device 80. In this target trajectory generation, as a method of determining a target value between sample points of the measurement result of the moving object tracking device 80, four methods are shown below using FIG.
本実施形態の動体追跡装置80は、移動性腫瘍の位置を追跡するため、腫瘍付近に留置されたマーカ位置の追跡結果を33ms前後の周期で計測出力する能力を有する。一方、ロボット動体ファントムシステム60の構成では、外部コントローラ64は5ms間隔で目標値をロボット制御装置62にフィードするように構成されている。そのため、ロボットマニピュレータ61の駆動には、動体追跡装置80の計測結果ログファイルの時系列から、より短い時間間隔のロボットマニピュレータ用目標値時系列を生成する必要がある。この目標軌道生成において、動体追跡装置80の測定結果のサンプル点間における目標値を定める方法として、図8を用いて以下に4とおりの方法を示す。 <3-2. Generation of tumor trajectory>
The moving
図8は、本発明の第1実施形態に係る動体追跡装置の測定結果のサンプル点間における目標値を定める方法を説明する図である。図8[S]は、本実施形態のいずれの目標値を定める方法にも共通する工程で、a)例えば、SyncTraXTMで計測された患者のマーカ位置情報と対応する時間情報を読み出す、工程である。なお、本実施形態に係る動体追跡装置の測定は、SyncTraXTMで計測する場合に限られない。
FIG. 8 is a diagram for explaining a method for determining a target value between sample points of the measurement result of the moving object tracking device according to the first embodiment of the present invention. FIG. 8S is a process common to any method for determining a target value of this embodiment. A) A process of reading time information corresponding to patient marker position information measured by, for example, SyncTraX TM. is there. In addition, the measurement of the moving body tracking device according to the present embodiment is not limited to the case of measuring with SyncTraX ™ .
図8[1] の方法は、最も基本的な方法で、目標座標値が更新されるまで現在の値を維持する方法である。図8[1]では、図8[S]a)の工程後に、b)最新のマーカ位置情報を次のサンプリング時刻まで保持し、c)前工程で保持したマーカ位置情報の軌跡をサンプリング周期5msでアップサンプリングする。
[8] The method shown in FIG. 8 [1] is the most basic method, and is a method of maintaining the current value until the target coordinate value is updated. In FIG. 8 [1], after the step of FIG. 8 [S] a), b) the latest marker position information is held until the next sampling time, and c) the locus of the marker position information held in the previous step is a sampling period of 5 ms. Upsample with.
図8[2]の方法は、次のサンプリング時刻のマーカ位置を先読みする方法である。図8[2]では、図8[S]a)の工程後に、b)次のサンプリング時刻のマーカ位置を先読みして保持し、c)前工程で保持したマーカ位置の軌跡をサンプリング周期5msでアップサンプリングする。図8[2]の方法は、1時間区間内で一定値を保つことは図8[1]の方法と同一であるが、動体追跡装置80ログの1サンプル先の値を先取りして目標値と設定することで、ロボット制御装置62の過渡応答動作が誤差に与える影響を小さくすることを狙ったものである。
8 [2] is a method of prefetching the marker position at the next sampling time. In FIG. 8 [2], after the step of FIG. 8 [S] a), b) the marker position at the next sampling time is pre-read and held, and c) the marker position trajectory held in the previous process is sampled at a sampling period of 5 ms. Upsampling. The method of FIG. 8 [2] is the same as the method of FIG. 8 [1] in that a constant value is maintained within one hour interval, but the target value is obtained by prefetching the value of one sample ahead of the moving body tracking device 80 log. Is set to reduce the influence of the transient response operation of the robot controller 62 on the error.
図8[3]の方法は、単純に、隣り合う2つの座標間を線分で補間する直線補間の方法である。図8[3]では、図8[S]a)の工程後に、b)座標データを線分で補間し、c)前工程で補間した座標データの軌跡をサンプリング周期5msでアップサンプリングする。
The method shown in FIG. 8 [3] is simply a linear interpolation method that interpolates between two adjacent coordinates with a line segment. 8 [3], after the step of FIG. 8 [S] a), b) coordinate data is interpolated with line segments, and c) the locus of the coordinate data interpolated in the previous step is upsampled at a sampling period of 5 ms.
図8[4]の方法は、座標データを3次スプライン関数で補間する方法である。図8[4]では、図8[S]a)の工程後に、b)座標データを3次スプライン関数で補間し、c)前工程で補間した座標データの軌跡をサンプリング周期5msでアップサンプリングする。図8[4]の方法は、腫瘍などの生体組織の運動を示す速度および加速度は連続であるとの考え方に基づいて、時間の接続点における速度と加速度の連続性を保証する補間方法である。
8 [4] is a method of interpolating coordinate data with a cubic spline function. In FIG. 8 [4], after the step of FIG. 8 [S] a), b) the coordinate data is interpolated with a cubic spline function, and c) the locus of the coordinate data interpolated in the previous step is upsampled at a sampling period of 5 ms. . The method shown in FIG. 8 [4] is an interpolation method that guarantees continuity of speed and acceleration at the connection point of time based on the idea that the speed and acceleration indicating the motion of a biological tissue such as a tumor are continuous. .
最終的に生成される軌道は、図8[1]~[4]の4とおりのどの方法を用いたとしても動体追跡装置80ログファイル上のk(k=0,1,・・・,N-1) 番目の時間区間に属する時間変数t∈[Tst[k],Tst[k+1]) を用いて、以下の(式1)で表される。
The final generated trajectory is k (k = 0, 1,..., N on the movingobject tracking device 80 log file, regardless of which of the four methods shown in FIGS. 8 [1] to [4]. −1) Using the time variable t∈ [Tst [k], Tst [k + 1]) belonging to the first time interval, it is expressed by the following (formula 1).
The final generated trajectory is k (k = 0, 1,..., N on the moving
このように、tについての3次多項式で表すことができることから、動体追跡装置80ログファイルの1時間区間に対応する目標軌道計算用データは、これら3つの多項式の係数12個となる。
Thus, since it can be expressed by a third-order polynomial for t, the target trajectory calculation data corresponding to one hour section of the moving object tracking device 80 log file is 12 coefficients of these three polynomials.
基本的に1サンプル区間の長さは、Tst[k+1]-Tst[k]=0.033sである。しかし、多少の揺らぎがあることに加え、ごくまれではあるが動体追跡装置80の画像処理の工程でマーカの認識に失敗した場合に当該区間でデータが欠落する。データが欠落した場合は、次に取得できたマーカ位置と時刻を用いて計算する。動体追跡装置80ログファイルから(式1)の係数集合を生成する処理は、MATLAB(Mathworks)のmスクリプトを作成して実行する。以上により、目標軌道を時間の関数として表現できるようになるので、これを用いて以下で詳述する外部コントローラ64上での実時間での目標軌道の補正や、追従誤差改善のための処理が実行可能となる。
Basically, the length of one sample section is Tst [k + 1] −Tst [k] = 0.033s. However, in addition to some fluctuations, in rare cases, when marker recognition fails in the image processing process of the moving object tracking device 80, data is lost in the section. When data is missing, calculation is performed using the marker position and time obtained next. The process of generating the coefficient set of (Equation 1) from the moving object tracking device 80 log file is executed by creating a mlab script of MATLAB (Mathworks). As described above, since the target trajectory can be expressed as a function of time, processing for correcting the target trajectory in real time and improving the tracking error on the external controller 64 described in detail below using this can be performed. It becomes executable.
<4.第2実施形態>
次に、本発明の第2実施形態に係るロボット動体ファントムシステムについて説明する。 <4. Second Embodiment>
Next, a robot moving body phantom system according to a second embodiment of the present invention will be described.
次に、本発明の第2実施形態に係るロボット動体ファントムシステムについて説明する。 <4. Second Embodiment>
Next, a robot moving body phantom system according to a second embodiment of the present invention will be described.
<4-1.目標軌道の通信遅延低減補正とオンライン再補間>
第1実施形態で説明した、動体追跡装置80ログからの多項式係数生成は、治療対象となる患者の腫瘍軌跡データをロボット動体ファントムシステム60に指令するために必要な処理であり、動体追跡装置80のログに含まれるデータを変更するものではない。しかし、図8[1]の方法を利用して外部コントローラ64からロボット制御装置62に目標軌道を単純フィードしただけでは、求められる臨床現場の要求精度は満足しにくい。そこで第2実施形態では、図6で示したロボット動体ファントムシステム60の構成を前提として、より追従精度が高いシステムを構築するための、目標軌道の補正および追従誤差の情報を用いた目標軌道のオンライン再補間法について説明する。 <4-1. Communication delay reduction correction and online re-interpolation of target trajectory>
The polynomial coefficient generation from the movingbody tracking device 80 log described in the first embodiment is a process necessary for instructing the robot moving body phantom system 60 of the tumor trajectory data of the patient to be treated, and the moving body tracking device 80. It does not change the data contained in the logs. However, if the target trajectory is simply fed from the external controller 64 to the robot controller 62 using the method shown in FIG. Therefore, in the second embodiment, on the premise of the configuration of the robot moving body phantom system 60 shown in FIG. 6, target trajectory correction using target trajectory correction and tracking error information for constructing a system with higher tracking accuracy. The online re-interpolation method will be described.
第1実施形態で説明した、動体追跡装置80ログからの多項式係数生成は、治療対象となる患者の腫瘍軌跡データをロボット動体ファントムシステム60に指令するために必要な処理であり、動体追跡装置80のログに含まれるデータを変更するものではない。しかし、図8[1]の方法を利用して外部コントローラ64からロボット制御装置62に目標軌道を単純フィードしただけでは、求められる臨床現場の要求精度は満足しにくい。そこで第2実施形態では、図6で示したロボット動体ファントムシステム60の構成を前提として、より追従精度が高いシステムを構築するための、目標軌道の補正および追従誤差の情報を用いた目標軌道のオンライン再補間法について説明する。 <4-1. Communication delay reduction correction and online re-interpolation of target trajectory>
The polynomial coefficient generation from the moving
<4-2.通信遅延影響の低減を目的とした目標軌道の補正>
図6中に記入されているが、ロボット動体ファントムシステム60では各サブシステム間のデータ授受にネットワーク通信を利用しており、各システム間の通信が原因で遅延が発生しうる。制御に関する量の授受におけるデータの遅延は、追従精度の悪化に直結するため、実時間で高い追従精度が要求されるロボット動体ファントムシステム60は、この遅延の影響を軽減することが必要である。 <4-2. Target trajectory correction to reduce communication delay effects>
As shown in FIG. 6, the robot movingbody phantom system 60 uses network communication for data exchange between the subsystems, and a delay may occur due to the communication between the systems. Since the data delay in the transfer of the amount related to the control directly leads to the deterioration of the tracking accuracy, the robot moving body phantom system 60 that requires high tracking accuracy in real time needs to reduce the influence of this delay.
図6中に記入されているが、ロボット動体ファントムシステム60では各サブシステム間のデータ授受にネットワーク通信を利用しており、各システム間の通信が原因で遅延が発生しうる。制御に関する量の授受におけるデータの遅延は、追従精度の悪化に直結するため、実時間で高い追従精度が要求されるロボット動体ファントムシステム60は、この遅延の影響を軽減することが必要である。 <4-2. Target trajectory correction to reduce communication delay effects>
As shown in FIG. 6, the robot moving
そこで、この補償を意図して、(式1) のxk(t)、yk(t)、zk(t)に対し、Tr=0.005sを用いて、補正量
を以下の(式2)により算出して目標値を拡張する。
Therefore, with the intention of this compensation, the correction amount is set using Tr = 0.005 s for xk (t), yk (t), and zk (t) in (Equation 1).
Is calculated by the following (Equation 2) to extend the target value.
を以下の(式2)により算出して目標値を拡張する。
Therefore, with the intention of this compensation, the correction amount is set using Tr = 0.005 s for xk (t), yk (t), and zk (t) in (Equation 1).
Is calculated by the following (Equation 2) to extend the target value.
ただし,(式2)に含まれる定数αx、αy、αz、βx、βy、βzは、正値となるように選択した。なお、動体追跡装置80からロボット制御装置62の短時間間隔の目標値系列を生成する工程で、動体追跡装置80ログの一時間区間内で一定値を保つ図8[1]および[2]の方法については、区間内で速度と加速度の変化がないことから、実験評価においてはこの補正の適用対象外としている。
However, the constants αx, αy, αz, βx, βy, βz included in (Equation 2) were selected to be positive values. It should be noted that in the step of generating the target value series at short time intervals of the robot control device 62 from the moving body tracking device 80, the constant values in one time section of the moving body tracking device 80 log are maintained as shown in FIG. 8 [1] and [2]. As for the method, since there is no change in speed and acceleration in the section, this correction is not applied in the experimental evaluation.
図8[3]のように直線補間を行った場合、加速度項はサンプリング周期変換の接続点後の1サンプルでパルス状の0でない値を取るが、その他のステップでは0となってしまい、ロボットマニピュレータ61の振動を誘起する原因となるだけでなく補正の効果も十分に表れない。ロボットマニピュレータ61の速度制御系について、速度目標値から速度目標までの伝達特性が一次遅れとして近似できると仮定すると、加速度は一次遅れシステムのインパルス応答のように変化する。
When linear interpolation is performed as shown in FIG. 8 [3], the acceleration term takes a pulse-like non-zero value in one sample after the connection point of the sampling period conversion, but becomes zero in other steps, and the robot becomes zero. Not only does it cause vibration of the manipulator 61, but also the effect of the correction is not sufficiently exhibited. Assuming that the transfer characteristic from the speed target value to the speed target can be approximated as a first order lag for the speed control system of the robot manipulator 61, the acceleration changes like the impulse response of the first order lag system.
その伝達関数が1/(Ts+1)(T>0)と表せる場合、加速度信号α(t)を一定時間間隔Tr>0ごとに観察すれば、α(t)は、以下の(式3-1) に従って減衰する。
α((i+1)Tr)=γ・α(i・Tr)(γ=e-Tr/T) ・・・(式3-1) When the transfer function can be expressed as 1 / (Ts + 1) (T> 0), if the acceleration signal α (t) is observed at regular time intervals Tr> 0, α (t) can be expressed by the following equation (3-1): ) To decay.
α ((i + 1) Tr) = γ · α (i · Tr) (γ = e −Tr / T ) (Formula 3-1)
α((i+1)Tr)=γ・α(i・Tr)(γ=e-Tr/T) ・・・(式3-1) When the transfer function can be expressed as 1 / (Ts + 1) (T> 0), if the acceleration signal α (t) is observed at regular time intervals Tr> 0, α (t) can be expressed by the following equation (3-1): ) To decay.
α ((i + 1) Tr) = γ · α (i · Tr) (γ = e −Tr / T ) (Formula 3-1)
そこで、直線補間の場合、区間最初に算出される0でないx軸の加速度値をαkとして,区間t∈[Tst[k],Tst[k+1])中の時刻ti=i・Tr(i=1,2,・・・) なる時刻における加速度の値を、以下の(式3-2) に従って減衰させている。
Therefore, in the case of linear interpolation, the acceleration value of the non-zero x axis calculated at the beginning of the section is αk, and the time ti = i · Tr (i in the section t∈ [Tst [k], Tst [k + 1]) = 1,2,...) The acceleration value at the time is attenuated according to the following (Equation 3-2).
Therefore, in the case of linear interpolation, the acceleration value of the non-zero x axis calculated at the beginning of the section is αk, and the time ti = i · Tr (i in the section t∈ [Tst [k], Tst [k + 1]) = 1,2,...) The acceleration value at the time is attenuated according to the following (Equation 3-2).
y軸およびz軸についても、上記x軸の処理と同様に処理することができる。なお、γの値は実験を重ねる中で試行錯誤的に調整し、γ=0.9を用いているが、他の値を用いてもよい。
The y-axis and z-axis can be processed in the same manner as the above x-axis processing. Note that the value of γ is adjusted by trial and error while repeating experiments, and γ = 0.9 is used, but other values may be used.
<4-3.動的再補間によるフィードバック目標値補正>
次に、図9および図10を用いて、ロボット制御装置62内の追従誤差情報を利用した動的再補間によるフィードバック目標値補正について説明する。 <4-3. Feedback target value correction by dynamic re-interpolation>
Next, feedback target value correction by dynamic re-interpolation using tracking error information in therobot control device 62 will be described with reference to FIGS. 9 and 10.
次に、図9および図10を用いて、ロボット制御装置62内の追従誤差情報を利用した動的再補間によるフィードバック目標値補正について説明する。 <4-3. Feedback target value correction by dynamic re-interpolation>
Next, feedback target value correction by dynamic re-interpolation using tracking error information in the
上記(式2)で定義された各軸の補正目標値は、動体追跡装置80で観測された腫瘍運動軌跡のみから決定されるもので、ロボットマニピュレータ61を実際に動かしたときに発生する追従誤差を考慮した補正とはなっていない。そこで、ロボット制御装置62から外部コントローラ64にフィードバックされるロボットマニピュレータ61の先端位置情報を用いて、ロボット制御装置62に与える目標値に追従誤差情報を利用した追加のフィードバック補正を行う。
The correction target value of each axis defined in the above (Equation 2) is determined only from the tumor motion trajectory observed by the moving body tracking device 80, and a tracking error that occurs when the robot manipulator 61 is actually moved. It is not a correction that takes into account. Therefore, using the position information of the tip of the robot manipulator 61 fed back from the robot controller 62 to the external controller 64, an additional feedback correction using the tracking error information is performed on the target value given to the robot controller 62.
上述のとおり、ロボット制御装置62の外部コントローラ64追従モードでは、ロボットマニピュレータ61の先端位置・姿勢の現在値が外部コントローラにフィードバックされる。この両者の差である追従誤差の値を用い、5ms周期でロボット制御装置62に送出する目標値を生成するための補間作業をやり直し、補間軌道を再生成する。具体的には、すでに過去のデータとなった補間の始点の座標値に上述の追従誤差を加算して、誤差の符号に応じて今後ロボット制御装置62に送出される目標座標値を増減する補正を行う。
As described above, in the external controller 64 following mode of the robot controller 62, the current value of the tip position / posture of the robot manipulator 61 is fed back to the external controller. Using the value of the tracking error that is the difference between the two, the interpolation work for generating the target value to be sent to the robot controller 62 at a cycle of 5 ms is performed again to regenerate the interpolation trajectory. Specifically, the above-described tracking error is added to the coordinate value of the interpolation start point that has already become past data, and the target coordinate value to be sent to the robot controller 62 in the future is increased or decreased according to the sign of the error. I do.
ここで、動的再補間の計算アルゴリズムを以下に示す。X軸、Y軸およびZ軸の全ての軸に同一の処理を独立に行うので、ここでは代表してX軸に対する計算手順を説明する。今、再補間を実施する時間区間を動体追跡装置ログのk番目の時間区間t∈[Tst[k],Tst[k+1])であるとすると、上述のとおり、この区間での補正前目標値は、以下の(式4)の3次多項式で決定される。
xk(t)=ax[k]+bx[k](t-Tst[k])+cx[k](t-Tst[k])2+dx[k](t-Tst[k])3・・・(式4) Here, the calculation algorithm of dynamic re-interpolation is shown below. Since the same processing is independently performed for all of the X axis, the Y axis, and the Z axis, the calculation procedure for the X axis will be described here representatively. Assuming that the time interval for performing the re-interpolation is the kth time interval tε [Tst [k], Tst [k + 1]) of the moving object tracking device log, as described above, before correction in this interval. The target value is determined by a cubic polynomial of the following (Equation 4).
xk (t) = ax [k] + bx [k] (t-Tst [k]) + cx [k] (t-Tst [k]) 2 + dx [k] (t-Tst [k]) 3 (Formula 4)
xk(t)=ax[k]+bx[k](t-Tst[k])+cx[k](t-Tst[k])2+dx[k](t-Tst[k])3・・・(式4) Here, the calculation algorithm of dynamic re-interpolation is shown below. Since the same processing is independently performed for all of the X axis, the Y axis, and the Z axis, the calculation procedure for the X axis will be described here representatively. Assuming that the time interval for performing the re-interpolation is the kth time interval tε [Tst [k], Tst [k + 1]) of the moving object tracking device log, as described above, before correction in this interval. The target value is determined by a cubic polynomial of the following (Equation 4).
xk (t) = ax [k] + bx [k] (t-Tst [k]) + cx [k] (t-Tst [k]) 2 + dx [k] (t-Tst [k]) 3 (Formula 4)
この時間区間内での外部コントローラ64のサンプル番号をi (i=1、2、・・・) で表すことにし、ロボット制御装置62より外部コントローラ64にフィードバックされるX軸の現在位置から、例えば、ステップiにおいてex[i]なる誤差が観測されたとする。このとき、この区間内でのみ有効な、(式4)に替わる目標軌道生成式は、以下の(式5)により表される。
x(i)k(t)=ax[k,i]+bx[k,i](t-Tst[k])+cx[k,i](t-Tst[k])2
+dx[k,i](t-Tst[k])3 ・・・(式5) The sample number of theexternal controller 64 in this time interval is represented by i (i = 1, 2,...). From the current position of the X axis fed back to the external controller 64 from the robot controller 62, for example, Suppose that an error ex [i] is observed in step i. At this time, a target trajectory generation formula that is valid only in this section and is substituted for (Formula 4) is expressed by the following (Formula 5).
x (i) k (t) = ax [k, i] + bx [k, i] (t-Tst [k]) + cx [k, i] (t-Tst [k]) 2
+ Dx [k, i] (t-Tst [k]) 3 (Expression 5)
x(i)k(t)=ax[k,i]+bx[k,i](t-Tst[k])+cx[k,i](t-Tst[k])2
+dx[k,i](t-Tst[k])3 ・・・(式5) The sample number of the
x (i) k (t) = ax [k, i] + bx [k, i] (t-Tst [k]) + cx [k, i] (t-Tst [k]) 2
+ Dx [k, i] (t-Tst [k]) 3 (Expression 5)
そして、(式5)が以下の拘束条件を全て満足するように係数ax[k,i]~dx[k,i]を定める。
Then, coefficients ax [k, i] to dx [k, i] are determined so that (Equation 5) satisfies all the following constraint conditions.
Then, coefficients ax [k, i] to dx [k, i] are determined so that (Equation 5) satisfies all the following constraint conditions.
上記(式7)は、この区間の終端時刻における目標値の値が次区間の目標値の初期値に一致することを要請する。上記(式8)および(式9)は、3次スプライン補間の特徴である接続点における速度と加速度の連続性を担保するための条件式であり、ここで示した方法を用いてこの区間での目標値生成多項式を上記(式5)に変更したとしても、位置、速度および加速度の連続性は維持されることになる。
(Equation 7) requests that the target value at the end time of this section matches the initial value of the target value in the next section. The above (Equation 8) and (Equation 9) are conditional expressions for ensuring the continuity of velocity and acceleration at the connection point, which is a feature of cubic spline interpolation. In this section, the method shown here is used. Even if the target value generation polynomial is changed to the above (Equation 5), the continuity of position, velocity and acceleration is maintained.
ここで、
として、(式5)の係数は、(式6)と以下の(式10) により定められるので、これらの式をオンラインで計算することで再補間実施後の補間多項式を求めることができる。
here,
Since the coefficient of (Expression 5) is determined by (Expression 6) and the following (Expression 10), an interpolation polynomial after re-interpolation can be obtained by calculating these expressions online.
として、(式5)の係数は、(式6)と以下の(式10) により定められるので、これらの式をオンラインで計算することで再補間実施後の補間多項式を求めることができる。
here,
Since the coefficient of (Expression 5) is determined by (Expression 6) and the following (Expression 10), an interpolation polynomial after re-interpolation can be obtained by calculating these expressions online.
図9は、本発明の第2実施形態に係る制御装置による直線補間の場合の本アルゴリズムの動作を示すグラフである。図9(A)は、ロボットコントローラに送られる次の目標値を表し、図9(B)は、ロボットのエンコーダ情報で計算される先端の現在位置を表し、図9(C)は、修正前の目標軌道およびロボットコントローラに送られる次の目標値を表す。続いて、図9(D)は、ロボットのエンコーダで計算される新しい先端の現在位置を表し、図9(E)は、修正前の目標軌道および修正後の目標軌道を表す。
FIG. 9 is a graph showing the operation of this algorithm in the case of linear interpolation by the control device according to the second embodiment of the present invention. 9A shows the next target value sent to the robot controller, FIG. 9B shows the current position of the tip calculated by the encoder information of the robot, and FIG. 9C shows the pre-correction value. Next target trajectory and the next target value sent to the robot controller. 9D shows the current position of the new tip calculated by the robot encoder, and FIG. 9E shows the target trajectory before and after correction.
目標値軌道を3次スプライン関数で定める場合も再補間の計算の考え方は、図9で示すアルゴリズムと全く同じである。なお、図8[1]および[2]に示す区間内で目標値を一定値とする場合については、(式6)と(式7)を同時に満たすことができない。この場合でも(式6)のみを用いて区間内で使用する目標値を増減させることは可能であるが、そのような設定でロボットマニピュレータ61を試験動作させた場合、激しい振動を誘発することがある。これは、目標値の変化が階段状で一時的に大きな偏差が発生することで、(式6)で加算されるex[i]の値も大きくなることが原因であると考えられる。試行動作の結果、この設定で実験を行うことは危険であると判断されたため、以下の評価実験では、一定目標値を利用する場合先の速度および加速度を利用した補正と同様適用の対象外としている。
When the target value trajectory is determined by a cubic spline function, the concept of re-interpolation calculation is exactly the same as the algorithm shown in FIG. In the case where the target value is set to a constant value within the section shown in FIGS. 8 [1] and [2], (Expression 6) and (Expression 7) cannot be satisfied at the same time. Even in this case, it is possible to increase or decrease the target value to be used in the section using only (Equation 6), but when the robot manipulator 61 is subjected to a test operation with such a setting, intense vibrations may be induced. is there. This is considered to be caused by the fact that the value of ex [i] added in (Equation 6) also increases because the target value changes stepwise and a large deviation occurs temporarily. As a result of the trial operation, it was determined that it was dangerous to conduct an experiment with this setting.Therefore, in the following evaluation experiment, if a fixed target value is used, it will be excluded from the same application as the correction using the previous speed and acceleration. Yes.
目標値軌道の動的再補間アルゴリズムを適用した結果得られる目標値と、速度および加速度を利用した上記(式2)で表される目標値補正を同時に用いた場合、外部コントローラ64からロボット制御装置62に送出される軌道指令値
は、以下の(式11)~(式13)で与えられる。
When the target value obtained as a result of applying the dynamic re-interpolation algorithm of the target value trajectory and the target value correction expressed by the above (Equation 2) using the speed and acceleration are used at the same time, the robot controller from theexternal controller 64 Orbit command value sent to 62
Is given by (Equation 11) to (Equation 13) below.
は、以下の(式11)~(式13)で与えられる。
When the target value obtained as a result of applying the dynamic re-interpolation algorithm of the target value trajectory and the target value correction expressed by the above (Equation 2) using the speed and acceleration are used at the same time, the robot controller from the
Is given by (Equation 11) to (Equation 13) below.
上記(式11)~(式13)は、ロボットマニピュレータ61とロボット制御装置62との間で出来上がっているフィードバック制御系の外側に、以下の図10に示すように追加のフィードバックループを導入することに相当する。
The above (Expression 11) to (Expression 13) are to introduce an additional feedback loop as shown in FIG. 10 below outside the feedback control system completed between the robot manipulator 61 and the robot controller 62. It corresponds to.
図10は、本発明の第2実施形態に係る外部コントローラを用いた追加のフィードバックループの導入を示す模式図である。本実施形態のロボットマニピュレータ61とロボット制御装置62との間では、フィードバック制御系が形成されている。また、本実施形態の外部コントローラ64は、目標軌道生成部66と、目標軌道補正部111と、目標軌道再生成部112と、を有している。目標軌道生成部66は、患者のマーカ位置の3次元運動軌跡を取得する位置取得部201と、3次元運動軌跡を取得したマーカの回転角度を算出する角度算出部202と、を備えることができる。腫瘍の回転角度も把握したい場合は、位置取得部201で患者の最低3つのマーカ位置の3次元運動軌跡を取得し続ける必要がある。そして、取得したマーカ位置に基づいて角度算出部202で腫瘍の回転角度を算出する処理を行うことにより、ロボットマニピュレータ61の目標軌道を生成する。
FIG. 10 is a schematic diagram showing the introduction of an additional feedback loop using the external controller according to the second embodiment of the present invention. A feedback control system is formed between the robot manipulator 61 and the robot control device 62 of the present embodiment. In addition, the external controller 64 of the present embodiment includes a target trajectory generation unit 66, a target trajectory correction unit 111, and a target trajectory regeneration unit 112. The target trajectory generation unit 66 can include a position acquisition unit 201 that acquires a three-dimensional motion trajectory of the patient's marker position, and an angle calculation unit 202 that calculates the rotation angle of the marker that acquired the three-dimensional motion trajectory. . When it is desired to grasp the rotation angle of the tumor, it is necessary to continuously acquire the three-dimensional motion trajectory of the patient at least three marker positions by the position acquisition unit 201. Then, the target trajectory of the robot manipulator 61 is generated by performing a process of calculating the rotation angle of the tumor by the angle calculation unit 202 based on the acquired marker position.
図11は、角度算出部202が腫瘍の回転角度を定める際の計算方法の一例を説明する図である。図11(a)は、動体追跡装置80が時刻k-1で3個のマーカm1,m2,m3の位置を検出した時の様子を示している。図11(b)は次の時刻kにおいて同じ3個のマーカ位置を検出した時の様子を示している。図12は、実際に複数埋め込まれたマーカを導体追跡装置80が捉えた画像例である。マーカm1,m2,m3の位置変化が、腫瘍重心位置の3次元位置変化と、3次元空間内の回転のみで十分表されると仮定する。この2枚の画像の間の腫瘍の回転角はロール・ピッチ・ヨーもしくはオイラー角などの角度を用いて定義できる。図13は本発明にかかる方法で求めた腫瘍回転角度の例である。時刻k-1における各ベクトルv1,v2,nk-1と、時刻kにおける対応するベクトルv’1,v’2,nkの間は、先の3次元空間内の回転角度を用いて定義される回転行列Rと、位置取得部201を用いて定められる腫瘍重心位置の3次元位置変化を表すベクトルδを用いて定義される同時変換行列
を用いて
と関係づけられるので、この3つの式から回転行列Rを数値的に一意に定めることができ、定まった回転行列からロボットの手先に固定されているファントムの回転角度の目標軌道を生成することができる。 FIG. 11 is a diagram illustrating an example of a calculation method used when theangle calculation unit 202 determines the rotation angle of a tumor. FIG. 11A shows a state when the moving object tracking device 80 detects the positions of the three markers m 1 , m 2 , and m 3 at time k−1. FIG. 11B shows a state when the same three marker positions are detected at the next time k. FIG. 12 is an image example in which the conductor tracking device 80 captures a plurality of markers that are actually embedded. It is assumed that the change in position of the markers m 1 , m 2 , and m 3 is sufficiently represented only by the three-dimensional position change of the tumor centroid position and the rotation in the three-dimensional space. The rotation angle of the tumor between the two images can be defined using an angle such as roll, pitch, yaw or Euler angle. FIG. 13 is an example of the tumor rotation angle obtained by the method according to the present invention. The rotation angle in the previous three-dimensional space is used between each vector v 1 , v 2 , n k−1 at time k−1 and the corresponding vector v ′ 1 , v ′ 2 , n k at time k. And a simultaneous transformation matrix defined using a rotation matrix R defined by a vector δ representing a three-dimensional position change of a tumor center of gravity determined by using the position acquisition unit 201
Using
Therefore, the rotation matrix R can be determined numerically and uniquely from these three equations, and the target trajectory of the rotation angle of the phantom fixed to the hand of the robot can be generated from the determined rotation matrix. it can.
を用いて
と関係づけられるので、この3つの式から回転行列Rを数値的に一意に定めることができ、定まった回転行列からロボットの手先に固定されているファントムの回転角度の目標軌道を生成することができる。 FIG. 11 is a diagram illustrating an example of a calculation method used when the
Using
Therefore, the rotation matrix R can be determined numerically and uniquely from these three equations, and the target trajectory of the rotation angle of the phantom fixed to the hand of the robot can be generated from the determined rotation matrix. it can.
実際の腫瘍の運動、特に肺腫瘍に関しては、患者の呼吸に伴い肺自体が拡張と収縮を繰り返す。この変形をより厳密に表現するには、先の回転変換行列を列ベクトルr1,r2,r3を用いて表現した
R=[r1,r2,r3]
に、座標軸方向の拡大、縮小を表すスカラ実数a,b,cを導入し
R=[ar1,br2,cr3]
と表現して、行列Rに加えてa,b,cを定めると良い。a,b,cを導入したことによって未知数が増えるが、その場合はm2からm3に至るベクトルの時刻k-1,k間の変化を利用すればよい。 For actual tumor movements, especially lung tumors, the lungs themselves repeatedly expand and contract as the patient breathes. In order to express this deformation more precisely, the previous rotational transformation matrix is expressed using column vectors r1, r2, and r3. R = [r1, r2, r3]
Introduces scalar real numbers a, b, c representing expansion and reduction in the coordinate axis direction, and R = [ar1, br2, cr3]
And a, b, and c may be determined in addition to the matrix R. The number of unknowns increases due to the introduction of a, b, and c. In this case, the change between the times k−1 and k of the vector from m2 to m3 may be used.
R=[r1,r2,r3]
に、座標軸方向の拡大、縮小を表すスカラ実数a,b,cを導入し
R=[ar1,br2,cr3]
と表現して、行列Rに加えてa,b,cを定めると良い。a,b,cを導入したことによって未知数が増えるが、その場合はm2からm3に至るベクトルの時刻k-1,k間の変化を利用すればよい。 For actual tumor movements, especially lung tumors, the lungs themselves repeatedly expand and contract as the patient breathes. In order to express this deformation more precisely, the previous rotational transformation matrix is expressed using column vectors r1, r2, and r3. R = [r1, r2, r3]
Introduces scalar real numbers a, b, c representing expansion and reduction in the coordinate axis direction, and R = [ar1, br2, cr3]
And a, b, and c may be determined in addition to the matrix R. The number of unknowns increases due to the introduction of a, b, and c. In this case, the change between the times k−1 and k of the vector from m2 to m3 may be used.
目標軌道補正部111は、動体追跡装置80の腫瘍位置追跡の結果出力された軌道を補間することによって規定されるロボットマニピュレータ61の運動軌跡の速度または加速度を用いてロボット目標軌道を補正する機能を有する。目標軌道補正部111は、ロボットマニピュレータ61の3次元座標位置を補正する位置補正部203と、3次元座標位置を補正したロボットマニピュレータ61の回転角度を補正する角度補正部204と、を備えることができる。回転角度も考慮してロボット目標軌道を補正する場合は、位置補正部203でロボットマニピュレータ61の3次元座標位置を補正し、補正した3次元座標位置に基づいて角度補正部204でロボットマニピュレータ61の回転角度を算出する処理を行うことにより、ロボットマニピュレータ61の目標軌道を補正する。
The target trajectory correction unit 111 has a function of correcting the robot target trajectory using the speed or acceleration of the motion trajectory of the robot manipulator 61 defined by interpolating the trajectory output as a result of the tumor position tracking of the moving body tracking device 80. Have. The target trajectory correction unit 111 includes a position correction unit 203 that corrects the three-dimensional coordinate position of the robot manipulator 61 and an angle correction unit 204 that corrects the rotation angle of the robot manipulator 61 that corrected the three-dimensional coordinate position. it can. When the robot target trajectory is corrected in consideration of the rotation angle, the position correction unit 203 corrects the three-dimensional coordinate position of the robot manipulator 61, and the angle correction unit 204 corrects the robot manipulator 61 based on the corrected three-dimensional coordinate position. The target trajectory of the robot manipulator 61 is corrected by performing a process of calculating the rotation angle.
目標軌道再生成部112は、目標軌道生成部66から与えられた目標軌道に対する制御実績から各制御サンプリング時点での目標軌道の追従誤差を算出してその情報を目標軌道補正部111に伝達する機能を有する。目標軌道補正部111は、受領した目標軌道の追従誤差を当該時間に対応する補間区間の始点の目標値情報に加算することで制御中に実時間で補間をやり直して目標軌道を再生成する機能を有する。
The target trajectory regeneration unit 112 has a function of calculating the tracking error of the target trajectory at each control sampling time from the control results for the target trajectory given from the target trajectory generation unit 66 and transmitting the information to the target trajectory correction unit 111. Have The target trajectory correcting unit 111 regenerates the target trajectory by performing interpolation in real time during control by adding the received tracking error of the target trajectory to the target value information at the start point of the interpolation section corresponding to the time. Have
本実施形態の外部コントローラ64内において、目標軌道生成部66で補間により生成された作業座標系の目標軌道の情報が、目標軌道補正部111および目標軌道再生成部112に伝達される。その後、目標軌道補正部111では、速度および加速度を用いた遅延補正がなされ、目標軌道再生成部112では、フィードバック再保管による補正がなされる。そして、各補正後の目標値の情報が、ロボットマニピュレータ61に伝達される。
In the external controller 64 of this embodiment, information on the target trajectory of the work coordinate system generated by interpolation by the target trajectory generating unit 66 is transmitted to the target trajectory correcting unit 111 and the target trajectory regenerating unit 112. Thereafter, the target trajectory correction unit 111 performs delay correction using the velocity and acceleration, and the target trajectory regeneration unit 112 performs correction by feedback re-storage. Then, the information of the corrected target value is transmitted to the robot manipulator 61.
<5.実施例>
次に、上記実施形態のロボット動体ファントムシステム60を用いた放射線治療の品質保証の実施例について、図14~図16を用いて説明する。 <5. Example>
Next, an example of quality assurance of radiation therapy using the robot movingbody phantom system 60 of the above embodiment will be described with reference to FIGS.
次に、上記実施形態のロボット動体ファントムシステム60を用いた放射線治療の品質保証の実施例について、図14~図16を用いて説明する。 <5. Example>
Next, an example of quality assurance of radiation therapy using the robot moving
図14は、本発明の一実施例に係るロボットマニピュレータの設置例を示す模式図である。図14のロボットマニピュレータ61は、固定台121に固定され、アームの先端に水等価ファントム65が取り付けられている。
FIG. 14 is a schematic diagram showing an installation example of a robot manipulator according to an embodiment of the present invention. The robot manipulator 61 in FIG. 14 is fixed to a fixed base 121, and a water equivalent phantom 65 is attached to the tip of the arm.
図15は、本発明の他の実施例に係るロボットマニピュレータの設置例を示す模式図である。図15のロボットマニピュレータ61は、図8(A)に示すような寝台86に固定具131で固定され、アームの先端に水等価ファントム65が取り付けられている。
FIG. 15 is a schematic diagram showing an installation example of a robot manipulator according to another embodiment of the present invention. The robot manipulator 61 shown in FIG. 15 is fixed to a bed 86 as shown in FIG. 8A with a fixture 131, and a water equivalent phantom 65 is attached to the tip of the arm.
<5-1.腫瘍軌跡への追従精度評価実験>
本実施例では、上記提案した目標軌道の補正法の効果を評価するため、ロボットマニピュレータ61の先端に実際に水等価ファントム65を固定した状態で、図2~図5で示した肺腫瘍軌跡4症例を目標軌道として開発した上記実施形態に係るロボット動体ファントムシステム60を駆動し、その追従精度を評価した。 <5-1. Experiment for evaluating the accuracy of tracking the tumor trajectory>
In this embodiment, in order to evaluate the effect of the proposed method for correcting the target trajectory, thelung tumor trajectory 4 shown in FIGS. 2 to 5 in a state where the water equivalent phantom 65 is actually fixed to the tip of the robot manipulator 61. The robot moving body phantom system 60 according to the above-described embodiment, which was developed with a case as a target trajectory, was driven and the following accuracy was evaluated.
本実施例では、上記提案した目標軌道の補正法の効果を評価するため、ロボットマニピュレータ61の先端に実際に水等価ファントム65を固定した状態で、図2~図5で示した肺腫瘍軌跡4症例を目標軌道として開発した上記実施形態に係るロボット動体ファントムシステム60を駆動し、その追従精度を評価した。 <5-1. Experiment for evaluating the accuracy of tracking the tumor trajectory>
In this embodiment, in order to evaluate the effect of the proposed method for correcting the target trajectory, the
本明細書で提案した手法では、33ms程度の時間間隔で得られている動体追跡装置80を用いた腫瘍軌跡の測定結果から、5ms周期でロボット制御装置62に供給する目標値を生成するサンプリング周期変換に4とおりの選択が可能である。(式2)で示される遅延補償を意図した補正の有無に2とおりの選択が可能である。(式4)~(式10)を用いて説明した、ロボット制御装置62で取得できる追従誤差を用いた目標軌道生成のための動的再補間適用の有無に2とおりの選択が可能である。したがって、全ての組み合わせは16とおりとなる。
In the method proposed in this specification, a sampling cycle for generating a target value to be supplied to the robot controller 62 at a cycle of 5 ms from a measurement result of a tumor trajectory using the moving body tracking device 80 obtained at a time interval of about 33 ms. There are four choices for conversion. Two types of selection are possible depending on whether or not correction is intended for delay compensation represented by (Equation 2). Two types of selection are possible depending on whether or not to apply dynamic re-interpolation for generating a target trajectory using a tracking error that can be acquired by the robot control device 62 described using (Expression 4) to (Expression 10). Therefore, there are 16 combinations.
しかしながら、上述したように、動体追跡装置80の1サンプリング周期内で一定の目標値を用いる場合については、軌道の速度・加速度が1サンプリング周期内で0となるので、遅延補償項が0となることに加え、(式6)と(式7)を同時に満たすこともできないので、フィードバック再補間も適用することができない。そこで、この評価では、全16とおりの組み合わせから、補正が機能しないか実現できない6とおりを除外した計10とおりの異なる組み合わせを対象として実験を行い、ロボットマニピュレータ61を利用したロボット動体ファントムシステム60の補正前目標軌道に対する追従精度を評価した。追従誤差は時系列データとして定まるが、そこから誤差のRMS値と、発生しうる最大誤差に関する指標であるμ+2σ値を計算してまとめた。
However, as described above, when a constant target value is used within one sampling period of the moving object tracking device 80, the velocity compensation and the acceleration of the orbit are zero within one sampling period, so the delay compensation term is zero. In addition, since (Equation 6) and (Equation 7) cannot be satisfied simultaneously, feedback re-interpolation cannot be applied. Therefore, in this evaluation, an experiment was conducted on a total of 10 different combinations excluding 6 combinations from which all 16 combinations could not be realized or not realized, and the robot moving body phantom system 60 using the robot manipulator 61 was tested. The tracking accuracy with respect to the target trajectory before correction was evaluated. The tracking error is determined as time series data, and the RMS value of the error and the μ + 2σ value, which is an index related to the maximum error that can occur, are calculated and compiled.
実験は2台のロボットマニピュレータ61を用いて、2つの異なる環境で行った。第一の環境は、コンクリート床を有する実験室で、図14に示すように、ロボットマニピュレータ61は、製造メーカの指定に従った設置固定がなされている。この環境で得られるロボットマニピュレータ61の先端位置の情報は、ロボット制御装置62がエンコーダ情報から計算して外部コントローラ64にフィードバックした先端位置のみとなる。
The experiment was performed using two robot manipulators 61 in two different environments. The first environment is a laboratory having a concrete floor. As shown in FIG. 14, the robot manipulator 61 is installed and fixed according to the specification of the manufacturer. The information on the tip position of the robot manipulator 61 obtained in this environment is only the tip position calculated by the robot controller 62 from the encoder information and fed back to the external controller 64.
第二の環境は、実際に患者の治療が行われている臨床環境である。ここでは、ロボット制御装置62による先端位置情報に加え、動体追跡装置80を用いた測定値も得られる。詳細は後述するが、臨床環境においては、図15に示すように、ロボットマニピュレータ61を医療用直線加速器81の寝台86に固定具131で固定し、かつ吸振ウレタンフォームを寝台と寝台基部の間に設置して実験した。
The second environment is a clinical environment where patients are actually being treated. Here, in addition to the tip position information by the robot control device 62, a measurement value using the moving body tracking device 80 is also obtained. Although details will be described later, in a clinical environment, as shown in FIG. 15, the robot manipulator 61 is fixed to a bed 86 of a medical linear accelerator 81 with a fixture 131, and a vibration-absorbing urethane foam is placed between the bed and the bed base. Installed and experimented.
<5-2.実験室における実験結果>
実験室で行った実験結果から、目標腫瘍軌跡に対する二乗平均誤差値とμ+2σの値を計算したものを、表3に示す。 <5-2. Experimental results in the laboratory>
Table 3 shows the results of calculating the mean square error value and the value of μ + 2σ with respect to the target tumor trajectory from the results of experiments conducted in the laboratory.
実験室で行った実験結果から、目標腫瘍軌跡に対する二乗平均誤差値とμ+2σの値を計算したものを、表3に示す。 <5-2. Experimental results in the laboratory>
Table 3 shows the results of calculating the mean square error value and the value of μ + 2σ with respect to the target tumor trajectory from the results of experiments conducted in the laboratory.
この場合の誤差は、外部コントローラ64からあるサンプル周期にロボット制御装置62に送出した目標値の補正前の値と、次のサンプル周期にロボット制御装置62から返送されるマーカ位置の差として計算している。上述したように、外部コントローラ64とロボット制御装置62との間、およびロボット制御装置62内のデータ授受にネットワーク通信が利用されており、それに伴う遅延があること、およびその遅延はネットワークのバッファの状態によりランダムに変化することを考えれば、ここで計算している誤差はあるサンプル時点における正確な誤差とはなっていない。ただし、以下の臨床環境での評価結果が示すように、ロボット制御装置62の実績値を用いて計算した統計誤差指標値が大きければ、動体追跡装置80を用いて評価した統計誤差指標値も大きくなる。
The error in this case is calculated as the difference between the value before correction of the target value sent from the external controller 64 to the robot controller 62 in a certain sample period and the marker position returned from the robot controller 62 in the next sample period. ing. As described above, network communication is used for data exchange between the external controller 64 and the robot controller 62 and within the robot controller 62, and there is a delay associated therewith, and the delay is caused by the network buffer. Considering that it changes randomly according to the state, the error calculated here is not an accurate error at a certain sample time. However, as shown in the evaluation results in the following clinical environment, if the statistical error index value calculated using the actual value of the robot control device 62 is large, the statistical error index value evaluated using the moving body tracking device 80 is also large. Become.
表3の数値より、上記で提案した通信遅延の低減を目的とした目標軌道の補正が極めて有効に作用していることが見て取れる。4症例全て、直線補間に遅延補償を組み合わせ、フィードバック再補間を用いないものが最も小さなμ+2σ値を与えていることがわかる。しかし、直線補間での結果を見比べると、遅延補償がある状態でフィードバック再補間を行う場合と行わない場合のμ+2σ 値の差は、症例Dを除いて表1に記載したこのロボットマニピュレータ61の静的反復位置決め精度である0.02mm以内となっており,偶発的に発生する誤差と区別できないレベルに収まっていることがわかる。
From the numerical values in Table 3, it can be seen that the correction of the target trajectory proposed above for the purpose of reducing the communication delay works extremely effectively. It can be seen that all four cases combined delay compensation with linear interpolation and did not use feedback re-interpolation gave the smallest μ + 2σ value. However, when comparing the results of linear interpolation, the difference between the values of μ + 2σ with and without feedback re-interpolation in the presence of delay compensation is the static of the robot manipulator 61 described in Table 1 except for case D. It can be seen that the repetitive positioning accuracy is within 0.02 mm, which is within a level indistinguishable from an accidental error.
一方、サンプリング周期変換に3次スプライン補間を用いた場合、μ+2σ値は直線補間に対して0.1mm以上悪化しており、今回の4症例について、実験室環境での実験では3次スプライン補間の使用が直線補間と比して誤差を大きくするよう作用していることがわかる。
On the other hand, when cubic spline interpolation is used for sampling period conversion, the value of μ + 2σ is deteriorated by 0.1 mm or more with respect to linear interpolation. It can be seen that the use acts to increase the error compared to linear interpolation.
フィードバック再補間の手法は、サンプリング周期変換単体でロボットマニピュレータ61を駆動した場合に比べれば大きな誤差低減効果を発揮するが、遅延補償を利用した場合の誤差低減量に比べれば効果が小さい。また遅延補償とフィードバック再補間を併用した場合、本環境では微小ではあるが結果の悪化を招くことも確認された。ただし、その差は、使用したロボットマニピュレータ61が保証する固定点への繰り返し位置決めの誤差に収まる程度のものである。
The feedback re-interpolation method exhibits a large error reduction effect as compared to the case where the robot manipulator 61 is driven by the sampling period conversion alone, but the effect is small compared to the error reduction amount when the delay compensation is used. In addition, when delay compensation and feedback re-interpolation are used in combination, it was confirmed that the result was degraded in this environment, although it was very small. However, the difference is within the range of the error of repeated positioning to a fixed point guaranteed by the robot manipulator 61 used.
<5-3.臨床環境における評価実験>
次に、病院の臨床設備を用い、動体追跡装置80も併用した評価実験を行った。実験の内容は実験室での実験と全く同一で、図2~図5に示した4症例の腫瘍軌跡に対して、実験室での実験と全く同じパラメータ値を用いてロボット動体ファントムシステム60を駆動した。臨床環境では、ロボットマニピュレータ61の動作結果として、ロボット制御装置62が出力する位置情報と、動体追跡装置80により得られる計測値の2つの計測結果が得られる。ロボット制御装置62が出力する位置情報を用いた場合の誤差の定義は上記と同様である。 <5-3. Evaluation experiment in clinical environment>
Next, an evaluation experiment was performed using clinical equipment of a hospital and also using the movingobject tracking device 80. The content of the experiment is exactly the same as the experiment in the laboratory. For the tumor trajectories of the four cases shown in FIGS. 2 to 5, the robot moving body phantom system 60 is set using the same parameter values as in the experiment in the laboratory. Driven. In the clinical environment, as the operation result of the robot manipulator 61, two measurement results are obtained, that is, position information output from the robot control device 62 and a measurement value obtained by the moving object tracking device 80. The definition of the error when the position information output from the robot controller 62 is used is the same as described above.
次に、病院の臨床設備を用い、動体追跡装置80も併用した評価実験を行った。実験の内容は実験室での実験と全く同一で、図2~図5に示した4症例の腫瘍軌跡に対して、実験室での実験と全く同じパラメータ値を用いてロボット動体ファントムシステム60を駆動した。臨床環境では、ロボットマニピュレータ61の動作結果として、ロボット制御装置62が出力する位置情報と、動体追跡装置80により得られる計測値の2つの計測結果が得られる。ロボット制御装置62が出力する位置情報を用いた場合の誤差の定義は上記と同様である。 <5-3. Evaluation experiment in clinical environment>
Next, an evaluation experiment was performed using clinical equipment of a hospital and also using the moving
以下の表4に、上記場合の補正前腫瘍位置目標軌道との誤差を処理した結果を示す。また、以下の表5に、動体追跡装置80のマーカ位置測定結果と補正前腫瘍目標位置との誤差を統計処理した結果を示す。
Table 4 below shows the result of processing the error from the tumor position target trajectory before correction in the above case. Table 5 below shows the result of statistical processing of the error between the marker position measurement result of the moving body tracking device 80 and the tumor target position before correction.
また、誤差評価の一例として、図5の腫瘍軌跡を目標値とし、表5中の3つの目標値生成スキームについて3次元誤差の時間変化をプロットしたグラフを図16に示す。
As an example of error evaluation, FIG. 16 shows a graph in which the tumor trajectory in FIG. 5 is set as a target value and the time change of the three-dimensional error is plotted for the three target value generation schemes in Table 5.
まず、実験室環境と同様ロボット制御装置62で得られる先端位置を用いた誤差解析の結果である表4で最小のμ+2σ値を与える組み合わせは、表3と同じで直線補間に基づき遅延補償項を入れたものとなっている。またその最小値も、表3のものとほぼ同等となっている。フィードバック再補間は単独で用いればある程度の誤差低減効果を発揮するが、遅延補償と組み合わせた場合大きくはないが結果の悪化を招く傾向も同一であった。
First, the combination that gives the minimum μ + 2σ value in Table 4, which is the result of error analysis using the tip position obtained by the robot controller 62 as in the laboratory environment, is the same as in Table 3, and the delay compensation term is based on linear interpolation. It is the one that was put. The minimum value is almost the same as that in Table 3. The feedback re-interpolation exhibits a certain degree of error reduction effect when used alone, but the tendency to deteriorate the result is the same when combined with delay compensation.
これに対して、動体追跡装置80を利用した測定結果を用いた誤差である表5では、異なる結果が得られている。まず、μ+2σの最良値が表3および表4と比較して、腫瘍の動きが大きいA、B、Dの症例で0.2mmから0.25mmほどで、動きが小さい症例Cで0.06mmほど大きくなっている。また、4例中3例で3次スプライン補間を用いたものが最小のμ+2σ値を与える結果となった。遅延補償と動的再補間を併用すると結果が悪くなる点は、ロボット制御装置62の位置出力を用いた解析と同じになった。
On the other hand, in Table 5 which is an error using the measurement result using the moving body tracking device 80, different results are obtained. First, in comparison with Tables 3 and 4, the best value of μ + 2σ is about 0.2 mm to 0.25 mm in cases A, B, and D with large tumor movement, and about 0.06 mm in case C with small movement. It is getting bigger. Further, three of the four examples using cubic spline interpolation resulted in the minimum μ + 2σ value. When the delay compensation and the dynamic re-interpolation are used together, the result becomes worse, which is the same as the analysis using the position output of the robot controller 62.
ロボット制御装置62が出力するマーカ位置は、ロボットマニピュレータ61の固定台121上にある作業座標原点Oからの相対位置情報であるのに対し、動体追跡装置80での計測結果は、医療用直線加速器81の原点icに対して定まる部屋内で固定された座標系での絶対座標値である。もしロボットマニピュレータ61の作業座標原点Oが医療用直線加速器81の座標系上で動かないのであれば、2つの測定値の差は測定系の差に起因するものとなる。今回の場合それは動体追跡装置80によるステレオX線画像を用いた3次元位置計測で発生しうる誤差である。X線透視画像内でのマーカ捕捉にはテンプレートマッチングを用いており、その過程でマーカ重心位置の算出に誤差が発生しうる。
The marker position output by the robot control device 62 is relative position information from the work coordinate origin O on the fixed base 121 of the robot manipulator 61, whereas the measurement result of the moving body tracking device 80 is a medical linear accelerator. This is an absolute coordinate value in a coordinate system fixed in a room determined with respect to the origin ic of 81. If the work coordinate origin O of the robot manipulator 61 does not move on the coordinate system of the medical linear accelerator 81, the difference between the two measurement values is caused by the difference between the measurement systems. In this case, it is an error that can occur in three-dimensional position measurement using a stereo X-ray image by the moving object tracking device 80. Template matching is used for capturing a marker in an X-ray fluoroscopic image, and an error may occur in the calculation of the marker centroid position in the process.
本実施例で利用したロボットマニピュレータ61には、その設置固定について、固定台121の固定のため、床にアンカーボルトを打つこと、ロボットマニピュレータ61の固定台121への固定については満足すべきボルト締め付けトルクの値が指示されている。
For the robot manipulator 61 used in the present embodiment, for fixing the fixing base 121, anchor bolts are hit on the floor in order to fix the fixing base 121, and the bolt tightening that is satisfactory for fixing the robot manipulator 61 to the fixing base 121 is satisfactory. Torque value is indicated.
一方、臨床環境ではアンカーボルトの設置は不可能で、かつ金属製の台座も放射線に悪影響を与えることから使用できなかったため、ロボットマニピュレータ61を医療用直線加速器81の寝台86に対して固定するにとどまっている。予備実験の過程で寝台とロボットマニピュレータが目視ではっきり確認できる大きさで振動した場合があったため、上述のとおり防振材を用いて振動の軽減化を図った。これにより目視でわかるほどの振動は無くなったが、目視では確認できない微細振動は残存していると考えられ、かつ動体追跡装置80での計測値はその振動も捉えることができるので、ロボット制御装置62での誤差値と比較して大きな値となることの理由として大きな要因であると考えられる。
On the other hand, in a clinical environment, anchor bolts cannot be installed, and a metal pedestal could not be used because it adversely affects radiation. Therefore, the robot manipulator 61 is fixed to the bed 86 of the medical linear accelerator 81. It stays. In the preliminary experiment, the bed and the robot manipulator sometimes vibrated in such a size that they could be clearly confirmed by visual observation. Therefore, the vibration was reduced as described above. As a result, there is no vibration that can be visually recognized, but it is considered that fine vibration that cannot be visually confirmed remains, and the measured value in the moving object tracking device 80 can also capture the vibration. This is considered to be a large factor as the reason why the value becomes larger than the error value at 62.
動体追跡装置80を利用した評価で、4症例中3症例において3次スプライン補間を用いた場合が最も高精度になったことも、この寝台86とロボットマニピュレータ61の振動で説明が可能であると考えられる。3次スプラインでは、補間の接続点における速度と加速度の連続性が担保されているため、ロボット制御装置62が生成する操作量の連続性も高いと思われるが、直線補間の場合接続点で速度と加速度がステップ状、インパルス状に変化をするため、スプライン補間に比べれば過渡的な振動を誘起しやすいと考えられる。
In the evaluation using the moving body tracking device 80, it can be explained by the vibration of the bed 86 and the robot manipulator 61 that the highest accuracy is obtained when cubic spline interpolation is used in 3 out of 4 cases. Conceivable. In the cubic spline, the continuity of the speed and acceleration at the connection point of interpolation is ensured, so it seems that the continuity of the operation amount generated by the robot controller 62 is high, but in the case of linear interpolation, the speed at the connection point The acceleration changes in steps and impulses, so it is considered that transient vibrations are more likely to be induced than in spline interpolation.
放射線治療の品質保証に上記実施形態のロボット動体ファントムシステム60を利用する場合、その品質に与える影響の評価として意味を持つのは動体追跡装置80を用いた場合の値である。その意味で、臨床環境での測定結果において、動体追跡装置80を用いた誤差解析の結果、4症例全てにおいて、μ+2σの最良値が0.8mm 未満となったことは、ロボット動体ファントムシステム60の良好な精度を示している。
When the robot moving body phantom system 60 of the above embodiment is used for quality assurance of radiotherapy, it is a value when the moving body tracking device 80 is used as an evaluation of the influence on the quality. In that sense, as a result of error analysis using the moving body tracking device 80 in the measurement results in the clinical environment, the best value of μ + 2σ was less than 0.8 mm in all four cases, indicating that the robot moving body phantom system 60 is good. Accuracy is shown.
呼吸性移動を示す腫瘍の放射線治療における品質保証では、動体追跡装置80を用いたファントム内マーカの位置計測を実際に行いながら水等価ファントム65に対して治療を施行する。一般に待ち伏せ照射と呼ばれる、呼吸性移動を示す腫瘍が事前に計画された位置の指定範囲近傍に来た際に放射線を照射する治療について、実際の治療では、腫瘍付近に留置されたマーカが、計画位置を中心とする一辺4mmの立方体内部に入ったことをもって放射線を投与するプロトコルになっている。μ+2σ<0.8という結果は、腫瘍軌跡が計画位置である立方体の中心にあるにもかかわらず、水等価ファントム65の位置決め誤差が原因で投与がなされないという状況がほぼ発生しないことを意味しており、ロボット動体ファントムシステム65を用いることで、品質保証の精度を向上させることができることを示す、意義のある結果である。
In the quality assurance in the radiotherapy of the tumor showing respiratory movement, the water equivalent phantom 65 is treated while actually measuring the position of the marker in the phantom using the moving body tracking device 80. For treatments that irradiate radiation when a tumor that exhibits respiratory movement, which is generally referred to as ambush irradiation, comes near a specified range of a pre-planned location, in the actual treatment, markers placed near the tumor are planned. It is a protocol that administers radiation when it enters the inside of a cube with a side of 4 mm centering on the position. The result of μ + 2σ <0.8 means that there is almost no situation where the administration is not performed due to the positioning error of the water equivalent phantom 65 even though the tumor trajectory is at the center of the cube which is the planned position. This is a meaningful result showing that the accuracy of quality assurance can be improved by using the robot moving body phantom system 65.
本実施例では、放射線治療の品質保証の精度向上を目的として、患者の体内における3次元の腫瘍運動軌跡に高い精度で追従することのできる、4Dロボット動体ファントムシステム60の構築を試みた。本実施例に示した結果からは、開発したロボット動体ファントムシステム60を臨床現場における品質保証に用いることができることがわかった。
In the present embodiment, for the purpose of improving the accuracy of quality assurance of radiotherapy, an attempt was made to construct a 4D robot moving body phantom system 60 that can follow a three-dimensional tumor motion trajectory in a patient's body with high accuracy. From the results shown in the present example, it was found that the developed robot moving body phantom system 60 can be used for quality assurance in clinical practice.
10 医療用直線加速器
11 寝台
12 ロボットマニュピレータ
13 水等価ファントム
60 ロボット動体ファントムシステム
61 ロボットマニュピレータ
62 ロボット制御装置
63 教示ペンダント
64 外部コントローラ
65 水等価ファントム
66 目標軌道生成部
80 動体追跡装置
81 医療用線形加速器
82、83、82b、83b X線源
84、85、84b、85b カラー受像装置
86 寝台
111 目標軌道補正部
112 目標軌道再生成部
121 固定台
131 固定具
201 位置取得部
202 角度算出部
203 位置補正部
204 角度補正部
ic 治療装置座標系の原点
O 作業座標系の原点 DESCRIPTION OFSYMBOLS 10 Medical linear accelerator 11 Bed 12 Robot manipulator 13 Water equivalent phantom 60 Robot moving body phantom system 61 Robot manipulator 62 Robot control device 63 Teaching pendant 64 External controller 65 Water equivalent phantom 66 Target track generation part 80 Moving body tracking apparatus 81 Medical linear accelerator 82, 83, 82b, 83b X-ray sources 84, 85, 84b, 85b Color image receiving device 86 Bed 111 Target trajectory correction unit 112 Target trajectory regeneration unit 121 Fixing base 131 Fixing tool 201 Position acquisition unit 202 Angle calculation unit 203 Position correction Unit 204 Angle correction unit ic The origin of the treatment apparatus coordinate system O The origin of the work coordinate system
11 寝台
12 ロボットマニュピレータ
13 水等価ファントム
60 ロボット動体ファントムシステム
61 ロボットマニュピレータ
62 ロボット制御装置
63 教示ペンダント
64 外部コントローラ
65 水等価ファントム
66 目標軌道生成部
80 動体追跡装置
81 医療用線形加速器
82、83、82b、83b X線源
84、85、84b、85b カラー受像装置
86 寝台
111 目標軌道補正部
112 目標軌道再生成部
121 固定台
131 固定具
201 位置取得部
202 角度算出部
203 位置補正部
204 角度補正部
ic 治療装置座標系の原点
O 作業座標系の原点 DESCRIPTION OF
Claims (8)
- 3次元の並進運動自由度を有するロボットマニピュレータと、該ロボットマニピュレータを制御するロボット制御装置と、該ロボットマニピュレータの先端に固定され、人体と同等の放射線吸収率を有するファントムと、腫瘍付近に留置された患者のマーカ位置の変化を実時間で測定する動体追跡装置と、を備え、
前記ロボット制御装置は、前記患者のマーカ位置の3次元運動軌跡から前記ロボットマニピュレータの目標軌道を生成する目標軌道生成部を有し、前記ファントム内のマーカ位置が前記目標軌道に追従するように前記ロボットマニピュレータを制御することを特徴とするロボット動体ファントムシステム。 A robot manipulator having a three-dimensional translational freedom degree, a robot control device for controlling the robot manipulator, a phantom fixed to the tip of the robot manipulator and having a radiation absorption rate equivalent to that of a human body, and placed near the tumor A moving body tracking device that measures a change in the marker position of the patient in real time,
The robot control device includes a target trajectory generation unit that generates a target trajectory of the robot manipulator from a three-dimensional motion trajectory of the marker position of the patient, and the marker position in the phantom follows the target trajectory. A robot moving phantom system characterized by controlling a robot manipulator. - 前記ロボット制御装置と情報信号の送受信を行う外部コントローラをさらに備え、
該外部コントローラは、前記患者のマーカ位置の情報を保持して該マーカ位置の軌跡をアップサンプリングすることにより、前記動体追跡装置の腫瘍位置追跡の時間間隔と前記目標軌道との追従動作の制御周期を一致させることを特徴とする請求項1に記載のロボット動体ファントムシステム。 An external controller that transmits and receives information signals to and from the robot controller;
The external controller holds information on the marker position of the patient and up-samples the locus of the marker position, thereby controlling the tracking period of the tracking position of the tumor tracking of the moving body tracking device and the target trajectory. The robot moving body phantom system according to claim 1, wherein: - 前記ロボット制御装置と情報信号の送受信を行う外部コントローラをさらに備え、
該外部コントローラは、前記時間間隔の計測結果を補間して前記マーカ位置の軌跡をアップサンプリングすることにより、前記動体追跡装置の腫瘍位置追跡の時間間隔と前記目標軌道との追従動作の制御周期を一致させることを特徴とする請求項1に記載のロボット動体ファントムシステム。 An external controller that transmits and receives information signals to and from the robot controller;
The external controller interpolates the measurement result of the time interval and upsamples the locus of the marker position, thereby setting a control period of the tracking operation between the time interval of the tumor tracking of the moving body tracking device and the target trajectory. The robot moving body phantom system according to claim 1, wherein the robot moving body phantom system is matched. - 前記目標軌道生成部は、前記患者のマーカ位置の3次元運動軌跡を取得する位置取得部と、3次元運動軌跡を取得したマーカが埋め込まれた腫瘍の回転角度を算出する角度算出部と、を備えることを特徴とする請求項1から3のいずれか一項に記載のロボット動体ファントムシステム。 The target trajectory generation unit includes a position acquisition unit that acquires a three-dimensional motion trajectory of the marker position of the patient, and an angle calculation unit that calculates a rotation angle of a tumor in which the marker that acquired the three-dimensional motion trajectory is embedded. The robot moving body phantom system as described in any one of Claim 1 to 3 characterized by the above-mentioned.
- 前記目標軌道を補正する目標軌道補正部をさらに有し、
該目標軌道補正部は、動体追跡装置の腫瘍位置追跡の結果出力された軌道を補間することによって規定されるロボットマニピュレータ運動軌跡の速度または加速度を用いてロボット目標軌道を補正することを特徴とする請求項1から4のいずれか一項に記載のロボット動体ファントムシステム。 A target trajectory correction unit for correcting the target trajectory;
The target trajectory correction unit corrects the robot target trajectory using the speed or acceleration of the robot manipulator motion trajectory defined by interpolating the trajectory output as a result of the tumor position tracking of the moving body tracking device. The robot moving body phantom system according to any one of claims 1 to 4. - 前記目標軌道を再生成する目標軌道再生成部をさらに有し、前記目標軌道生成部より与えられた前記目標軌道に対する制御実績から各制御サンプリング時点での目標軌道の追従誤差を算出してその情報を前記目標軌道再生成部に伝達し、
前記目標軌道再生成部は、受領した目標軌道の追従誤差を当該時間に対応する補間区間の始点の目標値情報に加算することで制御中に実時間で補間をやり直して目標軌道を再生成することを特徴とする請求項5に記載のロボット動体ファントムシステム。 A target trajectory regenerator that regenerates the target trajectory is further provided, and the tracking error of the target trajectory at each control sampling point is calculated from the control results for the target trajectory given by the target trajectory generator, and the information Is transmitted to the target trajectory regeneration unit,
The target trajectory regeneration unit regenerates the target trajectory by performing interpolation again in real time during control by adding the received tracking error of the target trajectory to the target value information at the start point of the interpolation section corresponding to the time. The robot moving body phantom system according to claim 5. - 前記目標軌道補正部は、前記ロボットマニピュレータの3次元座標位置を補正する位置補正部と、3次元座標位置を補正した前記ロボットマニピュレータの回転角度を補正する角度補正部と、を備えることを特徴とする請求項5または6に記載のロボット動体ファントムシステム。 The target trajectory correction unit includes a position correction unit that corrects a three-dimensional coordinate position of the robot manipulator, and an angle correction unit that corrects a rotation angle of the robot manipulator that corrects the three-dimensional coordinate position. The robot moving body phantom system according to claim 5 or 6.
- 前記ロボット制御装置と前記動体追跡装置とは、通信手段を用いて情報信号の送受信を行うことを特徴とする請求項1から7のいずれか一項に記載のロボット動体ファントムシステム。 The robot moving body phantom system according to any one of claims 1 to 7, wherein the robot control apparatus and the moving body tracking apparatus transmit and receive information signals using communication means.
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