WO2010059349A1 - Objet de test pour la validation de suivi en présence de mouvement - Google Patents

Objet de test pour la validation de suivi en présence de mouvement Download PDF

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Publication number
WO2010059349A1
WO2010059349A1 PCT/US2009/062395 US2009062395W WO2010059349A1 WO 2010059349 A1 WO2010059349 A1 WO 2010059349A1 US 2009062395 W US2009062395 W US 2009062395W WO 2010059349 A1 WO2010059349 A1 WO 2010059349A1
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WIPO (PCT)
Prior art keywords
motion
target
radiation
cardiac
respiratory
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Application number
PCT/US2009/062395
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English (en)
Inventor
Edward Gardner
Thilaka Sumanaweera
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Cyberheart, Inc.
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Application filed by Cyberheart, Inc. filed Critical Cyberheart, Inc.
Publication of WO2010059349A1 publication Critical patent/WO2010059349A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
    • A61B5/319—Circuits for simulating ECG signals
    • 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
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1049—Monitoring, verifying, controlling systems and methods for verifying the position of the patient with respect to the radiation beam
    • 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
    • G09B23/286—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for medicine for scanning or photography techniques, e.g. X-rays, ultrasonics
    • 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
    • G09B23/288—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for medicine for artificial respiration or heart massage
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B2017/00681—Aspects not otherwise provided for
    • A61B2017/00694—Aspects not otherwise provided for with means correcting for movement of or for synchronisation with the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02—Operational features
    • A61B2560/0223—Operational features of calibration, e.g. protocols for calibrating sensors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/113—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb occurring during breathing
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/58—Testing, adjusting or calibrating thereof
    • A61B6/582—Calibration
    • A61B6/583—Calibration using calibration phantoms
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
    • 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
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1075—Monitoring, verifying, controlling systems and methods for testing, calibrating, or quality assurance of the radiation treatment apparatus
    • A61N2005/1076—Monitoring, verifying, controlling systems and methods for testing, calibrating, or quality assurance of the radiation treatment apparatus using a dummy object placed in the radiation field, e.g. phantom
    • 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
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1064—Monitoring, verifying, controlling systems and methods for adjusting radiation treatment in response to monitoring
    • A61N5/1065—Beam adjustment
    • A61N5/1067—Beam adjustment in real time, i.e. during treatment

Definitions

  • the present invention is generally related to medical devices, systems, and methods.
  • the present invention is in the field of quality assurance and verification for radiosurgery or radiation therapy planning.
  • Radiosurgery and radiotherapy are hampered by motion of the patient during dose delivery. This motion results in less dose delivered to the target structure and, potentially, more dose delivered to critical structures than desired. Patients can be immobilized to reduce inadvertent motion but breathing, cardiac motion, and bowel motions are involuntary and cannot be prevented during the treatment period.
  • a radiosurgery system has been developed (Accuray CyberKnife with Synchrony) that can detect breathing motion of the patient and move the radiation source to compensate for this motion. This system does not compensate for cardiac or other involuntary movements. Treatment plans can be created that take into account the reduction in precision produced by patient motion in order to predict the dose delivered to moving targets or critical structures.
  • Test objects have been developed that simulate movements due to respiration. Wong et al. [KH Wong, S DieterichJ Tang, K Cleary, Quantitative Measurement of CyberKnife Robotic Arm Steering, Technology in Cancer Research and Treatment, 6:589-
  • Both the Wong and the Accuray/CIRS test objects are designed to use a fiducial in the radiation detector that can be used for alignment with the radiation delivery system. This fiducial is automatically detected by an x-ray imaging subsystem. The radiation source is then moved based on the position of the fiducial.
  • the heart exhibits complicated motion due to contraction. This motion causes different parts of the heart to move in significantly different ways. Therefore, tracking fiducials that are not located on the target area can subject the treatment to some error. This may, however be acceptable if the treatment area is not conducive to the placement of fiducial markers.
  • the differential motion between the fiducial location and the treated location can be compensated in the treatment plan.
  • the test objects developed by Wong and CIRS/Accuray do not have any provision for differential motion between the fiducial and the radiation detector.
  • the present invention generally provides target motion simulator devices, systems, and methods for quality assurance and verification for radiosurgery or radiation therapy systems.
  • the invention is particularly well suited for simulating motion of moving targets, such as target tissues of the heart and tissue structures adjacent the heart, that move with the respiratory and cardiac or heartbeat motion.
  • the invention provides a target motion simulator system for use in verifying target tracking with a radiation therapy device.
  • the system comprises a radiation detection target coupled to a first motion actuator simulating a first motion of a first tissue and a fiducial coupled to a second motion actuator simulating a second motion of a second tissue offset from the first tissue, a component of the first motion having different frequency content than the second motion.
  • a synthetic physiological signal generator is synchronized with the component of the first motion, wherein an output signal from the generator, in combination with a sensed position of the fiducial, may be used by the radiation therapy device in tracking the target.
  • the invention provides a target motion simulator system for use in verifying target tracking with a radiation therapy device.
  • the system comprises a radiation detection target coupled to a first motion actuator simulating both a first respiratory motion and a first cardiac motion of a first tissue and a fiducial coupled to a second motion actuator simulating a second respiratory motion of a second tissue offset from the first tissue.
  • An electrocardiogram (EKG) output signal generator is synchronized with the first cardiac motion, wherein an EKG output signal from the EKG signal generator, in combination with a sensed fiducial position signal, may be used by the radiation therapy device in tracking the target.
  • the target motion simulator system may further comprise an internal fiducial coupled to a third motion actuator simulating both the first respiratory motion and a second cardiac motion.
  • the internal fiducial may comprise a deformable heart shell around the target or proximate the target, or a portion of a catheter.
  • the target motion simulator system may further comprise a radiation-sensitive collateral tissue structure model coupled to a fourth motion actuator simulating both the first respiratory motion and a third cardiac motion.
  • the invention provides a target motion simulator system for simulating motion of a target having both respiratory and cardiac motion for use in verifying target tracking with a radiation therapy device.
  • the system comprises an internal chest simulator coupled to a first respiratory motion actuator simulating internal chest respiratory motion with a radiation detection target coupled to the internal chest simulator with a first cardiac motion actuator simulating a first cardiac motion.
  • the target movement includes both internal chest respiratory motion and first cardiac motion.
  • An external skin simulator is coupled to a second respiratory motion actuator simulating external skin respiratory motion with an external fiducial coupled to the external skin simulator.
  • An electrocardiogram (EKG) output signal generator synchronized with the first cardiac motion, wherein an EKG output signal from the EKG signal generator may be used by the radiation therapy device in tracking the target.
  • the invention comprises a method of using a target motion simulator system having both respiratory and cardiac motion for use in verifying target tracking with a radiation therapy device.
  • the method comprises moving a radiation detection target with both a first respiratory motion and a first cardiac motion and moving a fiducial with a second respiratory motion.
  • An electrocardiogram (EKG) output signal is simulated and synchronized with the first cardiac motion.
  • the radiation detection target is tracked with the radiation therapy device using input from the EKG output signal and the external fiducial movement and fires a radiation dose from the radiation therapy device at the target.
  • the method of using a target motion simulator further comprises moving an internal fiducial with the first respiratory motion and a second cardiac motion and tracking the internal fiducial with the radiation therapy device, wherein the radiation therapy device uses input from the internal fiducial movement in tracking the radiation detection target.
  • the method of using a target motion simulator further comprises moving a model of a radiation-sensitive collateral tissue structure with both the first respiratory motion and a third cardiac motion, tracking the radiation-sensitive collateral tissue structure with the radiation therapy device and determining radiation received by radiation-sensitive collateral tissue structure.
  • the invention comprises a method of using a target motion simulator system having both respiratory and cardiac motion for use in verifying target tracking with a radiation therapy device.
  • the method comprises moving an internal chest simulator simulating an internal chest respiratory motion, moving a radiation detection target coupled to the internal chest simulator simulating a first cardiac motion, and moving an external fiducial coupled to an external skin simulator simulating external skin respiratory motion.
  • Simulating an electrocardiogram (EKG) output signal synchronized with the first cardiac motion and tracking the radiation detection target and external fiducial with the radiation therapy device using input from the EKG output signal and the external fiducial movement, and firing a radiation from the radiation therapy device at the target.
  • EKG electrocardiogram
  • the method of using a target motion simulator further comprises determining radiation received by the target.
  • the method of using a target motion simulator further comprises moving an internal fiducial coupled to the internal chest simulator simulating a second cardiac motion and tracking the internal fiducial with the radiation therapy device, wherein the radiation therapy device uses input from the internal fiducial movement in tracking the radiation detection target.
  • the method of using a target motion simulator further comprises moving a radiation-sensitive collateral tissue structure coupled to the internal chest simulator simulating a third cardiac motion, tracking the radiation-sensitive collateral tissue structure with the radiation therapy device and determining radiation received by the radiation- sensitive collateral tissue structure.
  • the invention provides a simulator system for simulating motion of a target for use in verifying target tracking with a radiation therapy device.
  • the system comprises a movable primary actuator stage with a radiation detection target coupled to the primary actuator stage with a first movable secondary actuator stage, a combination of movement from the primary actuator stage and first secondary actuator stage simulating both a first respiratory motion and a first cardiac motion.
  • a fiducial is coupled to the primary actuator stage with a second movable secondary actuator stage, a combination of movement from the primary actuator stage and second secondary actuator stage simulating a second respiratory motion, and an electrocardiogram (EKG) output signal synchronized with the first cardiac motion, wherein the EKG output signal may be used by the radiation therapy device in tracking the target.
  • EKG electrocardiogram
  • FIG. 1 is an exemplary CyberRnife stereotactic radiosurgery system for use in embodiments of the invention.
  • FIG. IA is a graph showing exemplary data from the anterior/posterior motion of a point at the cavotricuspid isthmus inside the right atrium of a pig heart.
  • FIG. 2 is a graph similar to Fig. IA showing timing for acquiring a time-sequence of 11 X-ray image pairs over 1 respiratory cycle at a common cardiac phase, ⁇ .
  • FIG. 3 is an illustration of an EKG waveform showing exemplary phases where a time-sequence of CT volumes are acquired.
  • FIG. 4 is an illustration of MxN X-rays, LED signals and ECG signals as acquired over 1 respiratory cycle for use, for example, in an intra-operative motion prediction and validation model.
  • FIG. 5 A shows one embodiment of the target motion simulator system including a first actuator moving a radiation detection target and a second actuator moving an external fiducial.
  • FIG. 5B shows another embodiment of the target motion simulator system of FIG. 5A further including a third actuator moving an internal fiducial.
  • FIG. 6 shows another embodiment of the target motion simulator system.
  • FIG. 7 shows the optical measurement of motion imparted to the radiation detector target by the actuator (blue) in comparison with a measured motion of a structure in the heart that was used as input (red).
  • FIG. 8A shows the data collected for a stationary radiation detector.
  • FIG. 8B shows the measurement when the radiation detector is moved to mimic the motion of the cavotricuspid isthmus.
  • FIG. 9 shows another embodiment of the target motion simulator system.
  • FIG. 10 shows the workflow of the simulated treatment process.
  • the present invention generally provides target motion simulator devices, systems, and methods for quality assurance and verification for radiosurgery or radiation therapy systems.
  • the invention is particularly well suited for simulating motion of moving targets, such as target tissues of the heart and tissue structures adjacent the heart, that move with the respiratory and cardiac or heartbeat motion.
  • the cardiac motion is typically considerably faster than the respiration motion and the invention uses simulations of both motions in the target motion.
  • the target motion simulator may be correlated to a heart signal sensor such as an electrocardiogram (ECG) or (EKG), with the EKG output signal being used by the radiation therapy device in tracking the target. Multiple models may be employed, including separation of the target motion into a cardiac motion and a respiration motion.
  • the target motion may be correlated to both cardiac and respiratory motion.
  • Internal and external fiducials may be used, with each fiducial being moved with either respiratory motion, cardiac motion, or both.
  • a radiation-sensitive collateral tissue structure or critical structure may also be simulated having respiratory motion, cardiac motion, or both.
  • Suitable system components may comprise:
  • a linear accelerator capable of generating a series of X-ray beams
  • a tracking system for tracking the target during treatment in case the target changes shape or moves between the time of, for example, an initial tracking X-ray of a pre-treatment computed tomography (CT) exam and the time of treatment, and/or during treatment due to respiration, patient-induced gross anatomical movement, and the like;
  • CT computed tomography
  • a couch capable of positioning the target (patient) independent of the mechanism described in #2 above.
  • the above 5 items may correspond to: ⁇ A 6 MeV X-band X-ray Linac
  • a patient registration system consisting of: o Two ceiling-mounted diagnostic X-ray sources o Two amorphous silicon image detectors mounted on the floor.
  • two orthogonal X-rays are taken and registered with the CT data by cross-correlating the X-rays with simulated X-rays generated by CT data, called digitally reconstructed radiographs (DRR).
  • DRR digitally reconstructed radiographs
  • the tracking system may include several light-emitting diodes (LEDs) mounted on the patent's skin to provide additional information at a rate faster than what X-rays alone provide.
  • LEDs light-emitting diodes
  • Radiosurgery system 10 has a single source of radiation, which moves about relative to a patient.
  • Radiosurgery system 10 includes a lightweight linear accelerator 12 mounted to a highly maneuverable robotic arm 14.
  • An image guidance system 16 uses image registration techniques to determine the treatment site coordinates with respect to linear accelerator 12, and transmits the target coordinates to robot arm 14 which then directs a radiation beam to the treatment site. When the target moves, system 10 detects the change and corrects the beam.
  • system 10 makes use of robot arm 14 and linear accelerator 12 under computer control.
  • Image guidance system 16 includes diagnostic x-ray sources 18 and image detectors 20, this imaging hardware comprising two diagnostics fluoroscopes. These fluoroscopes provide a frame of reference for locating the patient's anatomy, which, in turn, has a known relationship to the reference frame of robot arm 14 and linear accelerator 12.
  • a target and its surrounding tissue are first imaged using CT, resulting in a volume of data.
  • the target volume is then delineated in this CT volume and a desired dose to the target is prescribed.
  • Delicate or other tissue structures of concern in the vicinity of the target are also delineated and may be assigned a maximum desired dose that can be deposited at these structures.
  • a computer program then receives the location and the shape of the target and the critical structures, the prescribed doses and the geometric configuration of the radiation delivery system and computes (a) the position and orientation of the beams to be fired and (b) a contour diagram showing dose received by all voxels in the CT volume.
  • the radiation oncologist then reviews this data to see if the target is receiving the right dose and if structures in the vicinity receive too much dose. He or she may modify the boundaries of the target and the critical structures, along with dose received by them, to reach an acceptable treatment plan.
  • the target can be first registered with the coordinate system of the treatment delivery system by using the patient registration system.
  • the treatment delivery system may also receive the beam positions and orientations from the treatment planning stage. It then positions and orients the Linac and fires the beams towards the target.
  • a preferred robot manipulator may be capable of positioning and orienting the Linac so that it follows the target due to breathing. Since Fluoroscopic imaging may be disadvantageous for the entire duration of the radiation delivery (optionally about 2 hours or more) because it subjects the patient to extra radiation, the tracking system may first build an intra-operative correlation model between the motion of the skin of the patient recorded by the imaging of external light emitting diodes (LEDs) mounted to the skin of the patient and any fiducials implanted in the vicinity of the target and seen in the X-rays. (The tumor itself need not be visible in the X-rays).
  • LEDs external light emitting diodes
  • Tracking of the LEDs using one or more cameras oriented toward the skin of the patient can then be used to determine data regarding the respiration cycle and the positions of tissues that move with the respiration cycle. More specifically, intra-operative correlation models can be built by taking a series of X-ray images in quick succession for one or more breathing cycles and at the same time, recording the position of the skin using the signals from the LEDs. Following this, the LED signals alone may be used for at least a portion of the tracking. X-rays may be intermittently acquired to verify the validity of the correlation model. If the model is no longer sufficiently valid, a fresh model is generated by following the same procedure as before.
  • Targets in the heart pose two challenges for radiation delivery systems:
  • Implantation of fiducials in the heart muscle can be difficult and/or disadvantageous.
  • the heart itself beats fairly rapidly (for example, roughly at a rate of 1 beat every second), and some parts of the heart move more than the other parts due to this beating. In addition, the heart as a whole may also move due to respiration.
  • FIG. IA graphically shows the anterior/posterior motion of a point at the cavotricuspid isthmus inside the right atrium of a pig heart. As can be seen, the motion has two components: a slow varying breathing component and a rapidly varying cardiac component.
  • Case 1 No (or Negligible) Cardiac Component; With Significant Respiratory Component
  • the target in the heart muscle has only a respiratory component and not a cardiac component.
  • Targets in the left atrium near the pulmonary veins may fall into this category.
  • the steps may include:
  • N I l.
  • Other examples include parts of the esophagus, the trachea, the bronchial tree, the lungs, the ribs, the diaphragm, the clavicles, the right atrium, the left atrium, the right ventricle, the left ventricle, inferior vena cava, superior vena cava, ascending aorta, descending aorta, pulmonary veins, pulmonary arteries, the heart/lung border and the blood pool.
  • Any artificial landmarks such as one or more fiducials inserted in to the esophagus, the trachea, the bronchial tree, or a catheter placed inside the heart.
  • pre-process X-rays, CT volume or DRRs using techniques such as: Filtering (thresholding, gradient detection, curvature detection, edge enhancement, image enhancement, spatial frequency-based adaptive processing).
  • mapping such as windowing, nonlinear mapping
  • Histogram equalization Spatial windowing, such as region-of-interest
  • both X-ray images and LED signals can be acquired using either prospectively or retrospectively gating.
  • the ECG waveform may be analyzed by a system module and X-ray images and LED signals can be acquired when the cardiac phase ⁇ arrives in time.
  • the X-ray images, LED signals and ECG samples are continuously acquired and saved with their respective time stamps. Later a separate module compares the time stamps of X-ray images and LED signals to the time stamps of the ECG samples to sort them into the appropriate cardiac phase.
  • ⁇ (j) may be acquired in Step 1 and X-rays and LED signals in Step 2 may also be acquired at any one of the cardiac phases, ⁇ (j)-
  • the registration in Step 3 will then be done by using CT and X-ray images corresponding to the same cardiac phase, ⁇ (j)-
  • the target in the heart muscle has both a respiratory component and a cardiac component. Targets in the ventricles near the valves fall into this category.
  • a high speed CT scanner such as 64-slice Siemens SOMOTOM Definition to acquire CT volumes quickly, e.g. one volume in 83 ms. Contrast agents may be used.
  • FIG. 4 shows this scenario, schematically showing M cardiac phases during which a total of M x N X-rays.
  • the X-ray acquisition can be prospectively or retrospectively to either or both respiratory and ECG cycles.
  • pre-process X-rays, CT volume or DRRs using techniques such as: c. Filtering (thresholding, gradient detection, curvature detection, edge enhancement, image enhancement, spatial frequency-based adaptive processing). d. Segmentation e. Mapping, such as windowing, nonlinear mapping f. Histogram equalization g. Spatial windowing, such as region-of-interest h. Higher order processing, such as connectivity model i. Temporal processing, such as filtering, convolution, differentiation, integration, motion analysis and optical flow.
  • the present invention discloses a target motion simulator system that utilizes actuators to impart motion to the various components of the target motion simulator system, such as a radiation detection target, one or more f ⁇ ducials, radiation-sensitive collateral tissue or critical structure, or other components.
  • the actuators may simulate individual motion, such as respiratory or cardiac motion, or may simulate a combination of motions, such as both respiratory and cardiac motion.
  • the actuators used for cardiac motion should be capable of motion similar to heart structures, for example speeds up to 5cm/s and accelerations up to 20 cm/s 2 . In order to achieve these speeds and accelerations, the radiation detector target mass must be minimized.
  • Prior art test objects have used a structure or shell around the radiation detector in order to provide build up of absorbed dose in the tissue.
  • the actuators used in the target motion simulator system may be driven to simulate or match general physiologic position measurements or may simulate individual subjects.
  • FIG. 5 A shows one embodiment of the target motion simulator system 100 for use in verifying target tracking with a radiation therapy device, such as with the CyberKnife stereotactic radiosurgery system 10 in FIG. 1.
  • the target motion simulator system 100 uses separate actuators for moving the components, including a first actuator 105 moving a radiation detection target 110 and a second actuator 115 moving an external fiducial 120.
  • the radiation detection target 110 may include sensors and/or film to detect radiation hits and amounts, and may be a ball cube phantom.
  • the actuators may be mounted on separate bases or a common base.
  • the actuators can move with different, synchronized motions that are chosen to simulate the motions of structures in the heart due to respiratory and cardiac motion.
  • the first actuator 105 may simulate both a respiratory motion and a cardiac motion for the target 110.
  • the second actuator 115 may simulate respiratory motion at another tissue site of the external fiducial 120, such as the chest surface.
  • the motion of the second actuator 115 may be detected through the use of an LED 120 as the second fiducial.
  • the respiratory motion and cardiac motion may be the same for each component, or they may be different, simulating movement of different locations within a body.
  • the separate actuators are used to move the radiation detector targets and fiducial(s) so that differential motion can be imparted identical to the differential motion of the anatomic fiducial and target locations within a person.
  • An EKG signal generator 150 is used to provide an EKG output signal E 155 that can be input to the radiation therapy device, such as the CyberKnife system.
  • FIG. 5B shows another embodiment of the target motion simulator system 100 of FIG. 5A having a third actuator 125 used to mimic the motion of an internal fiducial 130, for example, a portion of a catheter, radiation-sensitive collateral tissue or critical structure.
  • the motion of the third actuator 125 may include respiratory motion, cardiac motion or both motions at the internal fiducial site.
  • FIG. 6 shows another embodiment of the target motion simulator system 200 having two platforms, Pi 205 and P 2 210.
  • the platform Pi 205 powered by the actuator Ri 215, moves according to a respiratory motion internal to the chest, possibly at the heart.
  • the platform P 2 210 powered by the actuator R 2 220, moves according to a respiratory motion at the chest (external) of the patient.
  • An external fiducial 225 such as a synchrony tracking IR sensor, is mounted on P 2 210.
  • Mounted on the platform Pi 205 are two cardiac actuators, Ci 230 and C 2 235, providing cardiac motion.
  • the actuator Ci 230 provides the cardiac motion at a radiation detection target T 240, while the actuator C 2 235 provides cardiac motion of an internal fiducial, such as motion/deformation of a shell of the heart, S 245.
  • An EKG signal generator 250 provides an EKG output signal E 255 that can be used by the CyberKnife system in tracking the target.
  • a radiation-sensitive collateral tissue or critical structure C 250 coupled to platform Pi 205 with cardiac actuator C3 255 providing cardiac motion. Shown in broken line is target T 240a, fiducial S 245 a, and critical structure C 250a at a different point in time.
  • the Synchrony IR sensors will be mounted on this platform. a. Degrees of freedom - initially perhaps 2 (anterior/posterior and superior/inferior translations) b. Accuracy of phantom position during motion
  • the shell of the heart (S): The shell mimics the heart muscle/lung interface of the heart. In CT this interface should be visible and in X-rays and in DRRs, this interface should be visible as the cardiac silhouette. The silhouette will be used to track the motion during treatment. Ideally, the shell should move/deform periodically during the EKG cycle.
  • the cardiac motion of S can be programmed using C 2 , while the respiratory motion can be programmed using R 1 .
  • a. Degree of freedom Initially the shape can be a blob that has no symmetry, that can oscillate back and forth around an axis.
  • the shell includes any surrogate anatomical structures that can be tracked in X-rays, such as pulmonary veins, pulmonary arteries, trachea and bronchi, aorta, and any other structures in the heart.
  • the target (T) The target moves its own composite waveform containing both cardiac motion and the respiration.
  • the cardiac motion of T can be programmed using C 1
  • the respiratory motion can be programmed using R 1 .
  • Ability to insert dosimetry film c. Spherical casing to avoid edge artifacts impacting tracking algorithms
  • EKG out The phantom will generate a simulated EKG waveform synchronized with the cardiac motion that will serve as an input to the CyberHeart module.
  • Dosimetry film The target should be able to hold a stack of dosimetry film in a manner similar to existing ball cube phantom targets used to evaluate CK dose delivery. Bang gel may also be used.
  • the phantom should be able to withstand the scatter radiation from the CyberRnife beam (6 MeV).
  • the target area should be able to withstand the radiation from the direct beam.
  • CT scan-ability The phantom should be able to undergo 4D gated cardiac CT and not introduce artifacts affecting tracking algorithms..
  • X-ray imageability The phantom should be able to undergo CyberKnife X-ray imaging and not introduce artifacts affecting tracking algorithms. 10. Size and weight: The phantom should be able to sit on the CyberKnife couch with the target positioned in the vicinity of room iso-center, as well has the couch of CT scanners. The smaller and the lighter the better.
  • the phantom will be used by the customers. It should have undergone some product testing, although not to the same level as a clinical product. 12. Host: A PC should be able to interface with the phantom to control it.
  • Application Programming Interface An application programming interface should be provided to control the phantom using the actuators, R 1 , R 2 , Ci and C 2 .
  • actuators can also carry any waveform, be it cardiac motion or respiratory motion or a combination of both.
  • Motion can be provided using electric, pneumatic or hydraulic actuators.
  • the shapes of the shell S 245, the target T 240 and critical structure C 250 can also be deforming over a physiologic cycle.
  • This test object is able to move faster in order to accurately follow the motion of the heart. In order to do this, the mass of the detector is reduced by removing shells that allow for absorbed dose build up.
  • Dose modeling is used to determine dose without the use of significant mass around the radiation detector. • This test object is able to move an object that will be used for tracking (the fiducial) and the radiation detector differently in order to determine the error introduced by tracking an object other than the ultimate target.
  • FIG. 7 shows the optical measurement of motion imparted to the radiation detector target by the actuator (blue) in comparison with a measured motion of a structure in the heart that was used as input (red).
  • the results show that the motion imparted to the radiation detector target (ball cube) accurately follows the driving waveform and is quite accurate for real motion of the heart.
  • the position measurements also include high-frequency noise that is not tracked by the system.
  • FIGs. 8 A and 8B show radiation measurements (red) compared to predictions from Accuray MuliPlanTM.
  • the graph in FIG. 8A shows the data collected for a stationary radiation detector.
  • the graph in FIG. 8B shows the measurement when the radiation detector is moved to mimic the motion of the cavotricuspid isthmus. The prediction is much more accurate for the stationary detector than for the moving detector. This result supports compromising the detection accuracy in order to preserve motion accuracy.
  • a fiducial can be given different motion from the radiation detection target by attaching the fiducial and radiation detection target to different parts of a system that has redundant movement stages, such as shown in FIG. 9. Moving such a radiation detection target requires that the mass of the different stages be minimized in order to allow rapid motion.
  • FIG. 9 shows another embodiment of the target motion simulator system 200 for use in verifying target tracking with a radiation therapy device.
  • the target motion simulator system 200 uses a primary actuator 205 moving a radiation detection target 210, a secondary actuators actuator 215 and an external fiducial 220.
  • the secondary actuators actuator 215 moves the fiducial 220 with additional motion.
  • the actuators can move with different, synchronized motions that are chosen to simulate the motions of structures in the heart due to respiratory and cardiac motion.
  • the primary actuator 205 may simulate both a respiratory motion and a cardiac motion for the target 210.
  • the secondary actuator 215 may simulate respiratory and cardiac motion at another tissue site of the internal fiducial 220, such as the coronary sinus.
  • the motion of the second actuator 215 may be detected through the use of an imaging system component of the treatment system detecting the fiducial 220.
  • the respiratory motion and cardiac motion may be the same for each component, or they may be different, simulating movement of different locations within a body.
  • the separate actuators are used to move the radiation detector targets and fiducial(s) so that differential motion can be imparted identical to the differential motion of the anatomic fiducial and target locations within a person.
  • An EKG signal generator 250 is used to provide an EKG output signal E 255 that can be input to the radiation therapy device, such as the CyberRnife system.
  • Additional secondary actuators may be used to mimic the motion of an internal or external fiducial, for example, an external chest motion, radiation-sensitive collateral tissue or critical structure.
  • a relatively simple treatment flowchart 300 can represent steps used for simulating motion of a target having both respiratory and cardiac motion for use in verifying target tracking with a radiation therapy device, according to embodiments of the present invention.
  • the radiation detection target and fiducials are imaged 305, typically using a remote imaging modality such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasound imaging, X-ray imaging, optical coherence tomography, a combination of these or other imaging modalities, and/or the like.
  • CT computed tomography
  • MRI magnetic resonance imaging
  • ultrasound imaging X-ray imaging
  • optical coherence tomography optical coherence tomography
  • the imaging used in many embodiments may include a time sequence of three dimensional tissue volumes, with the time sequence typically spanning one or more cycles (such as a cardiac or heartbeat cycle, a respiration or breathing cycle, and/or the like).
  • a plan 310 will be prepared for simulating treatment of the radiation detection target, with the plan typically comprising a series of radiation beam trajectories which intersect within the radiation detection target.
  • the radiation dose within the radiation detection target should be at least sufficient to provide the desired effect if it were actual target tissue.
  • Embodiments of the invention may employ the 3-D volumes acquired in the imaging step 305 during the planning 310, with some embodiments making use of the motion model represented by the time sequence of 3-D tissue volumes so as to more accurately identify exposure of radiation outside of the radiation detection target, within radiation-sensitive collateral tissue models, inside the target, and the like.
  • Planned timing of some or all of a series of radiation beams may be established based on the a synthetic physiological signal generator simulating a cardiac cycle, respiration cycle, and/or the like so as to generate the desired dosages within the radiation detection target, so as to minimize or inhibit radiation exposure to radiation-sensitive collateral tissue, and/or to provide desired gradients between the radiation detection target and radiation-sensitive collateral tissue.
  • the order of the planned radiation beams may be altered and/or the trajectories of the radiation beams may be calculated in response to the motion of the model volume.
  • the simulated treatment 315 can be implemented.
  • the simulated treatment will often make use of a processor to direct movement of a robotic structure supporting a radiation beam source, along with registration, validation, and/or tracking modules which enhance accuracy of the treatment.
  • Tracking may employ the motion model developed during imaging 305, and/or may also employ a separate intraoperative motion model.
  • the treatment 315 step and the associated hardware may use a sensor and/or input for physiological wave forms such as synthetic physiological signal generator synchronized with the radiation detection target and fiducials for use in such tracking.

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Abstract

L'invention porte sur un système simulateur de mouvement cible pour utilisation dans la vérification d'un suivi de cible par un dispositif de radiothérapie. Le système comprend une cible de détection de rayonnement couplée à un premier actionneur de mouvement simulant un premier mouvement d'un premier tissu et une référence couplée à un second actionneur de mouvement simulant un second mouvement d'un second tissu décalé du premier tissu, le composant du premier mouvement étant asynchrone vis-à-vis du second mouvement. Un générateur de signal physiologique synthétique est synchronisé avec le composant du premier mouvement, un signal de sortie provenant du générateur pouvant être utilisé en association avec une position détectée du repère par le dispositif de radiothérapie dans le suivi de la cible.
PCT/US2009/062395 2008-11-21 2009-10-28 Objet de test pour la validation de suivi en présence de mouvement WO2010059349A1 (fr)

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