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Functional-Guided Radiotherapy Using Knowledge-Based Planning

A Faught

A Faught1*, L Schubert1 , L Olsen2 , J Zhang3 , E Castillo3 , R Castillo4 , T Guerrero3 , Y Vinogradskiy1 , (1) University of Colorado School of Medicine, Denver, CO, (2) Memorial Hospital, Colorado Springs, CO, (3) Beaumont Health System, Royal Oak, MI, (4) Univ Texas Medical Branch at Galveston, Galveston, TX


SU-H1-GePD-J(A)-6 (Sunday, July 30, 2017) 3:00 PM - 3:30 PM Room: Joint Imaging-Therapy ePoster Lounge - A

Purpose: 4DCT-ventilation is being used to calculate lung ventilation and novel implementations of functional-guided radiotherapy. The incorporation of functional information into the treatment planning process allows for preferential sparing of high-functioning lung with the goal of reducing toxicity events. There are two significant challenges when implementing functional radiotherapy: 1) the lack of knowledge of realistic patient specific dosimetric goals for functional lung sparing and 2) ensuring consistent treatment plans across multiple centers involved in clinical trials. Knowledge-based planning (KBP) is uniquely positioned to address these concerns by estimating achievable dose reductions to functional lung and improving plan quality and consistency. The purpose of our study was to develop a pilot KBP model to test the feasibility of use in functional-guided radiotherapy.

Methods: Using Varian’s knowledge-based planning package, RapidPlan, a model was created from 31 previously planned functional-guided lung patients. In addition to standard critical structures in lung radiotherapy, a functional contour delineating areas of high ventilation was included. The RapidPlan model was validated by comparing V20Gy and mean dose within the functional contour from 5 independent cases that were planned with and without RapidPlan. Absolute differences in the dose-function metrics are reported.

Results: A comparison of the average V20Gy and mean dose to the functional contour in the validation set demonstrated respective values of 14.9% and 9.8Gy for the non-RapidPlan plans and 14.1% and 9.5Gy for the plans using RapidPlan. Both dose-function metrics demonstrated a small improvement for plans utilizing RapidPlan.

Conclusion: Knowledge-based planning is especially valuable to new and emerging treatment planning strategies such as functional-guided radiotherapy. The dose predictions can guide treatment plan optimization with respect to areas of high function. KBP can improve plan quality and consistency within a department and even more so in ongoing multi-institutional clinical trials where consistent quality is of added importance.

Funding Support, Disclosures, and Conflict of Interest: R01CA200817 (AF,RC,EC,TG,YV), 1K01-CA-181292-01 (RC), Patent licensed to Varian Medical Systems US Patent 20120310615A1 (LO)

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