w10 linac based mutic final - aapm
TRANSCRIPT
Outline of Presentation
⢠ViewRay System⢠Commissioning Work⢠Some Early Cases⢠Adaptive Radiotherapy Implementation
Learning Objectives
⢠Describe overall design of the ViewRay System⢠Describe early clinical observations⢠Describe work for implementation of ART on the
ViewRay system
ViewRay
⢠0.345T MRI⢠3 Co-60 heads â (~550 cGy/min @ iso)
⢠3 fully divergent MLCs (minimized penumbra)⢠Large imaging FOV (50 cm) and Tx volume (27cmx27cm)
⢠Conformal RT and\or IMRT⢠Integrated planning system
â Monte Carlo dose calculationâ Fast optimization and calculation (9 field plan ~ 30 sec)
⢠Continuous MR Therapy Control
⢠Routine clinical instrument from the first use⢠No limitations of any kind⢠Easily reproducible process
â Can implement at other institutions⢠Staged in three steps (all with same goals as above)
â MR-IGRT (similar to CBCT-IGRT)â MRTC - MR Treatment Control (a.k.a. MR Gating)â On couch ART (Adaptive Radiation Therapy)
Implementation Strategy
⢠ViewRay Imagingâ Split Supercon 28 cm gap, 0.345 T, 14.7 MHz 50 cm DSV, warm
bore 1.05 mâ Split Gradient 28 cm gap, 5 mm former in gap, slew 200
mT/m/ms, 18 mT/m peak, 30 kW heat removalâ Isocenter matched to RT Iso (2mm)â Body coil & surface coils -thin uniformly attenuating, electronics
out of the beam
⢠Washington University Evaluationâ FDA testing and acceptance testing (manuscript in preparation)â Clinical comparison of onboard MR and CT (manuscript
submitted)â Requirements from AAPM, ACR, NEMA, & IEC
Imaging System Evaluation
Noelle, C. et. al., manuscript submittedWashington University Study
Clinical study comparing 0.35T MR and CBCT
Treatment Planning System Evaluation⢠Dedicated TPS
â Integrated from prescription though delivery and adaptive therapy (including on couch optimization and planning)
â Supports only Monte Carlo based calculation with and without magnetic field effects
â Beam numbers in increments of 3 (3 heads)â Planning on CT or MR or fusion of both
⢠Washington University Evaluationâ FDA related testing and acceptance testing (manuscript in
preparation) â Clinical plan comparison studies (manuscript in preparation)â AAPM & ACR
Original MR
Deformed CT
Deformed Electron Density Map
Dose calculation on CT or MR (via bulk density correction or deformation of electron density maps (from particular patient or a generic one))
ViewRay: 60Co IMRT Clinical plan: 18 MV IMRT
SKINRECTUM BLADDER
PTV
ViewRay(solid DVH)
Clinical(dashed DVH)
Treatment Planning System Evaluation
Clinical plan: 3D conformal using non-coplanar 6 MV beams. ViewRay: 60Co coplanar IMRT
PTVR. LUNG
HEART
ViewRay(solid DVH)
Clinical(dashed DVH)
Treatment Planning System Evaluation
ViewRay: 60Co IMRT Clinical plan: Definitive 6 MV IMRT
ViewRay(solid DVH)
Clinical(dashed DVH)
PTVR. PAROTID
L. PAROTID
CORD
Treatment Planning System Evaluation
Delivery Evaluation
⢠Conventional:â IGRT machine with three heads and all related geometric and
dosimetric concerns (TG142, TG51, etc.)⢠Novel:
â On couch dose prediction, re-optimization and calculationâ MR Controlled Treatment MRTC (real-time accounting for
target position and shape)â Two headed mode (if there is a problem with one head)
⢠Phantom and simulated delivery with patient data studies⢠QA tolls and methods, immobilization, workflow, practicality, etc.
Profiler⢠MRI compatible solution from Sun Nuclear Corp. ⢠Intended machine QA.⢠Can measure beam consistency at various gantry
angles with the rotatable mount.
Rotatable mount for IC Profiler
ViewRay Plan Adaptation
⢠ViewRay imaging system is ready to support online (or offline) ART
⢠Workflowâ Image patient ~ 1-2 minâ Deformable registration, propagation, contouring ~ 1 - 15 minâ Plan generation/optimization ~ 1 minâ QC, QA and approval ~ 3 minâ Treatment delivery ~ normal
⢠Enablement of online (on-couch) ART within 15 min
No Margin vs. Margin Plans Standard Auto-contour +
adaptManual contour +
adaptMargin 5-7mm 2mm 0mmBladder V65Gy 36% 25% 12%Rectum V65Gy 16% 9% 6%Rectum V40Gy 36% 29% 24%
Results
Steps No Adaptation (min)
Auto Contouring and plan
adaptation(min)
Real-timeContour editing
and plan adaptation
(min)Imaging 1 1 1Auto-contouring 0 1 1Find Shifts 0.5 0.5 0.5Edit Contour 0 1 15Predict Dose 0 2 2Dose Evaluation 0 2 2Re-optimization 0 1 1Plan Evaluation 0 3 3Total ~2 ~12-15 ~ 25
ViewRay Plan Adaptation⢠QC and QA tasks*
1. Verification of contour delineations of target and organs-at-risk (OARs)
2. Plan integrity check3. Plan quality check4. Verification of dose calculation
⢠Normally these tasks would take hours, and measurement based QA cannot be done while patient is on the treatment table.
⢠Goal is to finish in 3 minutes, requiring QA\QC procedures not based on measurements
*Process-Based Quality Management for Clinical Implementation of Adaptive Radiotherapy, C. Noel, L. Santanam, P.J. Parikh, and S. Mutic, Submitted for publication Med Phys, 2014.
Plan Integrity Check (WIP)⢠Prescription â Rx, site and laterality⢠Patient setup and imaging â orientation, couch removal, VR table add-on, image
slice thickness, FOV⢠Target definition â CTV, PTV margin and expansion⢠ROI â naming, gaps, laterality, OAR overlapping, completeness, density override,
consistency between Pinnacle and VR⢠Isocenter and POI⢠Plan â # of beam, beam angles, # of segments, per segment beam-on time,
segment size, beam-eye view against PTV, total beam-on time⢠Dose calculation â algorithm selection, parameters, matrix size and resolution,
electron density per structure⢠Plan optimization â optimization parameters, normalization⢠Plan quality â planning objective check based on DVH and rules
Additional Fractional Check (WIP)⢠Purpose is to check the consistency between the re-optimized plan
and the original plan, and between treatment fractions⢠Consistencies of
â Prescriptionâ Isocenterâ Daily imaging parametersâ Major beam parametersâ Doseâ DVHâ ROI position and volumesâ Plan quality (using planQC tool)
Monte Carlo Independent Dose Calculation for ViewRay (WIP)
Independent Monte Carlo ~ 1 min Clinical Plan
Acknowledgements
⢠Olga Green, PhD⢠Rojano Kashani, PhD⢠Omar Wooten, PhD⢠Lakshmi Santanam, PhD⢠Harold Li, PhD⢠Tianyu Zhao, PhD⢠Vivian Rodriguez, PhD⢠Deshan Yang PhD⢠Kari Tanderup, PhD⢠Greg Kamal
⢠Yanle Hu, PhD⢠James Dempsey, PhD⢠Iwan Kawrakow, PhD⢠James Victoria, CMD⢠Tracy Hand, CMD⢠Camille Noel, PhD⢠Parag Parikh, MD⢠Jeff Olsen, MD⢠Many others at WashU and
ViewRay
References1. Process-Based Quality Management for Clinical Implementation of
Adaptive Radiotherapy, C. Noel, L. Santanam, P.J. Parikh, and S. Mutic, Submitted for publication, Med Phys, 2014.
2. The ViewRay system: MR guided and controlled radiotherapy, S. Mutic and J.F. Dempsey, Accepted for publication, Seminars in Radiation Oncology, 2014.