CyberKnife® Robotic Radiosurgery System CyberKnife Robotic Radiosurgery System ® Agenda Defining radiosurgery The right dose to the right place The right dose at the right time Targeting tumors that move with respiration System comparison overview Extracranial system utilization Defining Radiosurgery Defining Radiosurgery Radiosurgery and conventional radiotherapy are often confused Radiosurgery Radiotherapy Description Focused radiation delivered precisely to the target sparing surrounding normal tissue Large field radiation delivered to the target and surrounding normal tissue Typical Dose Per Treatment High dose Low dose (~ 6 to 25 Gy per treatment) (~ 2 Gy per treatment) Typical Treatment Duration 1 – 5 treatments 30 – 40 treatments These differences present specific challenges Safe delivery of radiosurgery requires treatment delivery techniques different than those used for radiotherapy The right dose to the right place The right dose to the right place Non-coplanar beam delivery is the proven approach for safe delivery of radiosurgery Demonstrated by more than 30 years of radiosurgical studies Enables greater dose conformality Enhances rapid dose fall-off Reduces potential for critical structure toxicity The right dose to the right place Intracranial Radiosurgery Image courtesy of Barrow Neurological Institute Image courtesy of Google images CyberKnife® System Conventional Radiotherapy Systems 208 beam non-coplanar treatment 6 beam coplanar treatment The right dose to the right place Prostate Radiosurgery Image courtesy of NCH Regional Cancer Institute Image courtesy of Google images CyberKnife® System Conventional Radiotherapy Systems 130 beam non-coplanar treatment 5 beam coplanar treatment The right dose to the right place Spine Radiosurgery Image courtesy of University of Pittsburgh Medical Center Image courtesy of Google images CyberKnife® System Conventional Radiotherapy Systems 103 beam non-coplanar treatment 7 beam coplanar treatment The right dose to the right place Dose Gradient and Conformality Ring Gantry System Conventional Gantry System Coplanar Radiosurgery Dose Gradient Varian Novalis Tx™ / Varian Trilogy™ / Elekta Coplanar Radiosurgery Dose Gradient Axesse® Tomotherapy Hi-ART® Non-Coplanar Radiosurgery Dose Gradient CyberKnife® Robotic Radiosurgery System Brown, William T., et al. Image-Guided Robotic Stereotactic Radiosurgery for Treatment of Lung Tumors. Robotic Radiosurgery Volume I. p 255-268. The right dose to the right place CyberKnife® Robotic Radiosurgery System Conventional Radiotherapy Systems Image courtesy of Google images Ring Gantry Radiotherapy Systems Image courtesy of Google images Image courtesy of Google images Robotic mobility enables beam delivery from a wide array of unique angles Motion constrained to clockwise / counterclockwise rotations Motion constrained to clockwise / counter-clockwise rotations Typical treatment includes hundreds of non-coplanar beams delivered in routine clinical practice Non-coplanar delivery creates collision potential with gantry and imaging system Always delivers beams in a single axial plane Almost exclusively delivers 5 to 7 beams in a single axial plane The right dose at the right time The right dose at the right time Tumors and patients can move during treatment delivery – even when immobilized Necessitates continual corrections for intra-fraction target motion Without this capability: The risk of missing the target increases Sub-optimal outcomes resulting from under-dosing the tumor Increased risk of healthy tissue / critical structure toxicity The right dose at the right time Intracranial Radiosurgery Immobilized intracranial targets can shift during treatment delivery Image courtesy of CIVCO Murphy MJ, Chang SD, Gibbs IC, Le QT, Hai J, Kim D, Martin DP, Adler JR Jr. Patterns of patient movement during frameless image-guided radiosurgery.. Int J Radiat Oncol Biol Phys. 2003 Apr 1;55(5):1400-8 The right dose at the right time Prostate Radiosurgery The prostate can shift during treatment delivery Kupelian P, et al. Multi-institutional clinical experience with the Calypso System in localization and continuous, real-time monitoring of the prostate gland during external radiotherapy. Int J Radiat Oncol Biol Phys. 2007 Mar 15;67(4):1088-98. Epub 2006 Dec 21 The right dose at the right time Spine Radiosurgery Immobilized spine tumors can shift during treatment delivery Immobilized Spine Intra-Fraction Target Motion Hoogeman, Mischa, ErasmusMC, Daniel den Hoed cancer Center, Rotterdam, The Netherlands The right dose at the right time Intra-Fraction Imaging Capabilities Immobilized Spine Intra-Fraction Target Motion Immobilized Spine Intra-Fraction Target Motion Immobilized Spine Intra-Fraction Target Motion IGRT / Cone Beam CT One pre-treatment image and correction Varian Trilogy™ / Tomotherapy Hi-ART® / Elekta Axesse® Image Capture Target Shift Correction Beam Delivery Conventional Orthogonal Image Guidance One image and correction prior to each delivered beam (5-7) Varian Novalis Tx™ Continual Image Guidance One image and correction prior to each delivered beam (>100) CyberKnife® Robotic Radiosurgery System Hoogeman, Mischa, ErasmusMC, Daniel den Hoed cancer Center, Rotterdam, The Netherlands The right dose at the right time CyberKnife® Robotic Radiosurgery System Conventional Radiotherapy Systems Image courtesy of Google images Image courtesy of Google images Ring Gantry Radiotherapy Systems Image courtesy of Google images Continual image guidance throughout the treatment kV CBCT image guidance limited to pretreatment set-up mV CT image guidance limited to pre-treatment set-up Automatic corrections for intra-fraction target movement All imaging capabilities often disabled with couch yaw rotations Intra-fraction target motion is not recognized Acquires images and corrects beam delivery approximately every 5-10 seconds of delivered dose Intra-fraction target motion is limited and infrequent - or most often not recognized Targeting tumors that move with respiration Targeting tumors that move with respiration Respiratory-induced motion of tumors causes significant targeting uncertainty Targeting tumors that move with respiration Respiratory-induced motion of tumors causes significant targeting uncertainty Conventional respiratory compensation techniques demand large planning margins Targeting tumors that move with respiration Respiratory-induced motion of tumors causes significant targeting uncertainty Conventional respiratory compensation techniques demand large planning margins Respiratory Gating Targeting tumors that move with respiration Respiratory-induced motion of tumors causes significant targeting uncertainty Conventional respiratory compensation techniques demand large planning margins Respiratory Gating Breath Holding Targeting tumors that move with respiration CyberKnife® System Dynamically track target motion throughout the respiratory cycle Continual beam delivery while the patient breathes freely Unprecedented targeting accuracy 0.75 mm targeting accuracy* Significantly smaller planning margins Maximizes surrounding healthy tissue preservation * Dietrich S, Taylor D, Chuang C, et al. The CyberKnife Synchrony Respiratory Tracking System: Evaluation of Systematic Targeting Uncertainty. Synchrony® Respiratory Tracking System clinical accuracy specification of 1.5 mm for moving targets. Targeting tumors that move with respiration Gross Tumor Volume (GTV) What the surgeon feels CTV GTV Clinical Target Volume (CTV) What the pathologist views Planning Target Volume (PTV) Margin added to accommodate for error due to motion compensation / tracking CyberKnife® Radiosurgery PTV CTV GTV aa Conventional Respiratory Compensation Techniques Targeting tumors that move with respiration CyberKnife® Radiosurgery Smaller additional margins to account for targeting errors Minimal normal tissue included in target volume CTV GTV CyberKnife® Radiosurgery Reduces risks of potential toxicity Conventional Respiratory Compensation Significant margin expansion to account for targeting errors Considerable normal tissue in target volume PTV CTV GTV aa Increases risks of potential toxicity Conventional Respiratory Compensation Techniques Targeting tumors that move with respiration Conventional Radiotherapy Systems Ring Gantry Radiotherapy Systems Dose delivered continuously throughout the breathing cycle Limited system mobility requires the beam to repeatedly turn on and off as the target moves through fixed crosshairs. Delivers high doses of radiation to the entire envelope of target motion – encompassing both healthy and cancerous tissues Requires 1.5 mm or less CTV to PTV margin expansion Requires 5 to 10 mm CTV to PTV margin expansion Requires 5 to 10 mm CTV to PTV margin expansion CyberKnife® Robotic Radiosurgery System Beams move in real-time with 3D target motion System Comparison Overview Delivery System Comparison CyberKnife® Robotic Radiosurgery System Total Targeting Accuracy < 1 millimeter for stationary tumors Applications Intracranial and Extracranial Image Guided Radiation Therapy Systems Conventional Radiation Therapy Systems (Varian Trilogy™, Elekta Axesse®), Tomotherapy Hi-ART®)) (Varian Clinac™, Elekta Synergy®) Dedicated Cobalt 60 Radiosurgery Systems 3 – 20 millimeters 5 – 20 millimeters < 1 millimeter Intracranial and Extracranial Intracranial and Extracranial Intracranial only (Elekta Gamma Knife®)) < 1.5 millimeters for moving tumors Limited spine capabilities (Perfexion™ only) Ability to Fractionate Unlimited Unlimited Unlimited Typically limited to a single fraction due to time, resource and pain constraints Image Guidance Continual image guidance throughout the treatment Limited to pre-treatment, patient set-up only Typically limited to MV portal imaging on a weekly basis None, relies exclusively on target’s fixed relative position to the stereotactic frame kV or mV cone-beam CT Frame mechanical accuracy may introduce 1.2-1.9 mm error* High resolution kV imaging Automatically track, detect and correct for tumor and patient movement Robotic mobility enables a large noncoplanar workspace capable of seamlessly delivering more than 1200 unique beam angles without treatment interruption or the need to manually reposition the patient Limited clockwise / counter-clockwise gantry mobility enables a single plane typically delivering 7 or less unique beam angles Moving Tumor Targeting Delivers tightly contoured beams synchronized precisely to tumor motion resulting in minimal healthy tissue exposure Stereotactic Frames No frames required Non-Coplanar Delivery Capabilities Limited clockwise / counter-clockwise gantry mobility enables a single plane typically delivering 7 or less unique beam angles Hemisphere with fixed collimators enables a non-coplanar workspace capable of delivering a maximum of 201 (190 Perfexion™) unique beam angles Utilizes gating / breath-holding techniques resulting in large contour margins and unnecessary healthy tissue exposure Utilizes gating / breath-holding techniques resulting in large contour margins and unnecessary healthy tissue exposure N/A Required in most Intracranial & Extracranial cases Immobilization devices used. Low dose per fraction reduces need for accuracy Requires invasive frames in all cases Additional planes can be achieved with manual couch yaw rotations, however without image guidance due to patient / OBI collisions resulting in less than ideal targeting accuracy. Further, the impractical nature of manual patient positioning has resulted in little or no clinical adoption * RJ Maciunas, RL Galloway Jr, JW Latimer. The application accuracy of stereotactic frames. Neurosurgery 35(4): 682–695, Oct 1994 CyberKnife® Robotic Radiosurgery System
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