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Can a Knowledge-Based Planning Solution Increase Inter-Operator Standardization of Head and Neck VMAT Treatment Plans?

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A Scaggion

A Scaggion1*, M Fusella1 , M Rossato1 , N Pivato1 , S Bacco1 , A Roggio1 , L Arana Pena2 and M Paiusco1 , (1) Veneto Institute of Oncology IOV - IRCCS, Padua, Italy, Padova, PD, (2) The Abdus Salam International Centre for Theoretical Physics, Trieste, TS


SU-I-GPD-T-326 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To evaluate the potential of a commercial knowledge-based planning (KBP) algorithm to standardize and improve the quality of the radiotherapy treatment. This study evaluates if the predicted DVH constraints generated by the KBP algorithm can reduce the inter-operator variability thus providing a better standard of quality.

Methods: We build a model for HN VMAT treatments using Varian RapidPlan with 69 previously treated patients. The model was validated through closed-loop and open-loop (10 patients) tests using Plan Quality Metric (PQM) score distributions generated by PlanIQ software (SunNuclear).Further five patients (each with two PTVs), not included in the training database, were anonymized and randomized. Seven operators, with different planning expertise, were asked to manually obtain a clinical VMAT plan (mVMAT) for each of these patients. Subsequently, each operator replied the planning procedure assisted by RapidPlan DVH predictions obtaining a second VMAT plan (rpVMAT). We evaluated the inter-operator variability in terms of PQM score.

Results: No net PQM improvements were find in the selected group of patients. mVMAT and rpVMAT plans resulted in similar target coverage while reduction in OAR sparing variability is achieved only occasionally. This suggest that the large variability of individual patient anatomy might dirve a large variability in planning solutions even when KBP assists the planners.

Conclusion: Using RapidPlan predictions in five HN patients does not reduce the overall inter-planner variability, while the overall plan quality remains the same.This study tries to provides a quantitative measure of the RapidPlan potential as an instrument to improve plan quality with a better standard outcome among operators. The main limitation is the small number of patient. Further work will include more patient to take into account the high variability of PTVs and OARs for these kind treatmens.

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