ViewRay Experience. Sasa Mutic, Ph.D. Washington University School of Medicine

Transcription

1 ViewRay Experience Sasa Mutic, Ph.D. Washington University School of Medicine

2 You can observe a lot, just by watching -Yogi Berra

3 Does organ motion matter? A slide often used to illustrate RT capabilities

4 Does organ motion matter?

5 Outline of Presentation ViewRay System Commissioning Work Some Early Cases Adaptive Radiotherapy Implementation

6 Learning Objectives Describe overall design of the ViewRay System Describe early clinical observations Describe work for implementation of ART on the ViewRay system

7 ViewRay 0.345T MRI 3 Co-60 heads (~550 iso) 3 fully divergent MLCs (minimized penumbra) Large imaging FOV (50 cm) and Tx volume (27cmx27cm) Conformal RT and\or IMRT Integrated planning system Monte Carlo dose calculation Fast optimization and calculation (9 field plan ~ 30 sec) Continuous MR Therapy Control

8 ViewRay

9 Implementation Strategy Routine clinical instrument from the first use No limitations of any kind Easily reproducible process Can implement at other institutions Staged in three steps (all with same goals as above) MR-IGRT (similar to CBCT-IGRT) MRTC - MR Treatment Control (a.k.a. MR Gating) On couch ART (Adaptive Radiation Therapy)

10 First MR-IGRT Treatment January 15, 2014

11 ViewRay Imaging Split Supercon 28 cm gap, T, 14.7 MHz 50 cm DSV, warm bore 1.05 m Split Gradient 28 cm gap, 5 mm former in gap, slew 200 mt/m/ms, 18 mt/m peak, 30 kw heat removal Isocenter matched to RT Iso (2mm) Body coil & surface coils -thin uniformly attenuating, electronics out of the beam Washington University Evaluation FDA testing and acceptance testing (manuscript in preparation) Clinical comparison of onboard MR and CT (manuscript submitted) Requirements from AAPM, ACR, NEMA, & IEC

12 Imaging System Evaluation Clinical study comparing 0.35T MR and CBCT Washington University Study Noelle, C. et. al., manuscript submitted

13 What else can we see with MR? Radiation Damage - Edema Washington University Study

14 Imaging system evaluation Clinical study comparing 0.35T MR and CBCT Onboard MR Onboard CT

15 Treatment Planning System Evaluation Dedicated TPS Integrated from prescription though delivery and adaptive therapy (including on couch optimization and planning) Supports only Monte Carlo based calculation with and without magnetic field effects Beam numbers in increments of 3 (3 heads) Planning on CT or MR or fusion of both Washington University Evaluation FDA related testing and acceptance testing (manuscript in preparation) Clinical plan comparison studies (manuscript in preparation) AAPM & ACR

16 Treatment Planning System Evaluation

17 Deformed CT Original MR 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))

18 Treatment Planning System Evaluation ViewRay (solid DVH) Clinical (dashed DVH) SKIN RECTUM BLADDER PTV ViewRay: 60 Co IMRT Clinical plan: 18 MV IMRT

19 Treatment Planning System Evaluation ViewRay (solid DVH) Clinical (dashed DVH) HEART R. LUNG PTV Clinical plan: 3D conformal using non-coplanar 6 MV beams. ViewRay: 60 Co coplanar IMRT

20 Treatment Planning System Evaluation ViewRay (solid DVH) Clinical (dashed DVH) CORD R. PAROTID L. PAROTID PTV ViewRay: 60 Co IMRT Clinical plan: Definitive 6 MV IMRT

21 Delivery Evaluation Conventional: IGRT machine with three heads and all related geometric and dosimetric concerns (TG142, TG51, etc.) Novel: On couch dose prediction, re-optimization and calculation MR Controlled Treatment MRTC (real-time accounting for target position and shape) 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.

22 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

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24 CIRS Gating Phantom Intended for evaluating gating functions; tracking, beam gating, and latency

25 ViewRay QA Phantom Torso coils Inserts for ion chambers Film Chamber MRI fluid filled

26 ViewRay QA Phantom MRI and CT Visibility MRI on CT MRI

27 ViewRay Plan Adaptation ViewRay imaging system is ready to support online (or offline) ART Workflow Image patient ~ 1-2 min Deformable registration, propagation, contouring ~ 1-15 min Plan generation/optimization ~ 1 min QC, QA and approval ~ 3 min Treatment delivery ~ normal Enablement of online (on-couch) ART within 15 min

28 No Margin vs. Margin Plans Standard Auto-contour + adapt Manual contour + adapt Margin 5-7mm 2mm 0mm Bladder V65Gy 36% 25% 12% Rectum V65Gy 16% 9% 6% Rectum V40Gy 36% 29% 24%

29 Steps No Adaptation (min) Results Auto Contouring and plan adaptation (min) Real-time Contour editing and plan adaptation (min) Imaging Auto-contouring Find Shifts Edit Contour Predict Dose Dose Evaluation Re-optimization Plan Evaluation Total ~2 ~12-15 ~ 25

30 ViewRay Plan Adaptation QC and QA tasks* 1. Verification of contour delineations of target and organs-at-risk (OARs) 2. Plan integrity check 3. Plan quality check 4. 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.

31 Plan Integrity Check (WIP) Prescription Rx, site and laterality Patient setup and imaging orientation, couch removal, VR table add-on, image slice thickness, FOV Target definition CTV, PTV margin and expansion ROI naming, gaps, laterality, OAR overlapping, completeness, density override, consistency between Pinnacle and VR Isocenter and POI Plan # of beam, beam angles, # of segments, per segment beam-on time, segment size, beam-eye view against PTV, total beam-on time Dose calculation algorithm selection, parameters, matrix size and resolution, electron density per structure Plan optimization optimization parameters, normalization Plan quality planning objective check based on DVH and rules

32 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 Prescription Isocenter Daily imaging parameters Major beam parameters Dose DVH ROI position and volumes Plan quality (using planqc tool)

33 Monte Carlo Independent Dose Calculation for ViewRay (WIP) Independent Monte Carlo ~ 1 min Clinical Plan

34 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

35 Thank you!

36 References 1. 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, The ViewRay system: MR guided and controlled radiotherapy, S. Mutic and J.F. Dempsey, Accepted for publication, Seminars in Radiation Oncology, 2014.