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Program Information

MRI-Guided Single-Session Simulation, Online Adaptation, and Treatment

P Hill

P Hill*, M Geurts, K Mittauer, J Bayouth, University of Wisconsin, Madison, WI


SU-F-J-110 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To develop a combined simulation and treatment workflow for MRI-guided radiation therapy using the ViewRay treatment planning and delivery system.

Methods: Several features of the ViewRay MRIdian planning and treatment workflows are used to simulate and treat patients that require emergent radiotherapy. A simple “pre-plan” is created on diagnostic imaging retrieved from radiology PACS, where conformal fields are created to target a volume defined by a physician based on review of the diagnostic images and chart notes. After initial consult in radiation oncology, the patient is brought to the treatment room, immobilized, and imaged in treatment position with a volumetric MR. While the patient rests on the table, the pre-plan is applied to the treatment planning MR and dose is calculated in the treatment geometry. After physician review, modification of the plan may include updating the target definition, redefining fields, or re-balancing beam weights. Once an acceptable treatment plan is finalized and approved, the patient is treated.

Results: Careful preparation and judicious choices in the online planning process allow conformal treatment plans to be created and delivered in a single, thirty-minute session. Several advantages have been identified using this process as compared to conventional urgent CT simulation and delivery. Efficiency gains are notable, as physicians appreciate the predictable time commitment and patient waiting time for treatment is decreased. MR guidance in a treatment position offers both enhanced contrast for target delineation and reduction of setup uncertainties. The MRIdian system tools designed for adaptive radiotherapy are particularly useful, enabling plan changes to be made in minutes. Finally the resulting plans, typically 6 conformal beams, are delivered as quickly as more conventional AP/PA beam arrangements with comparatively superior dose distributions.

Conclusion: The ViewRay treatment planning software and delivery system can accommodate a fast simulation and treatment workflow.

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