ESTRO 2022 - Abstract Book

S792

Abstract book

ESTRO 2022

Materials and Methods The QA platform is composed of a web interface, servers and computation scripts, and is capable to automatically launch simulations, and to identify and report dosimetric inconsistencies. It uses MCsquare as independent Monte Carlo dose calculation engine. Two workflows are defined inside the automatic plan QA: TPS plan QA and Log plan QA. The former is a secondary dose calculation of the TPS plan, the latter is based on plan reconstruction from delivery log files and subsequent dose calculation. For both workflows a dosimetric analysis is performed by comparing its result to the planned TPS dose by means of gamma analysis (2 mm, 2 %). This end-to-end automatized procedure was implemented clinically and performed for plans of all sites and indications. In case of a failed gamma analysis check, the m-QA was performed. In order to assure the quality of the spot recording and plan reconstruction, a machine QA for delivery log files is performed daily. Data on the performance and efficiency of these workflows over two years was collected and analyzed. The monthly in- room time saved due to this procedure was also estimated by the minimum time gain of 30 minutes per plan.

Figure 1. Scheme of the current automated QA platform for pre-treatment PSQA.

Results The automatic workflow performed a total of 2369 plan evaluations over the last 23 months, for which gamma analysis checks failed for 3.7% and 2.1% for TPS plan QA and Log plan QA, respectively. All the plans for which one gamma analysis check failed, passed the subsequent standard m-QA. The in-room time designated for PSQA decreased by an average of 23 hours per month.

Figure 2. Monthly number of plans processed and estimation for in-room time spared per month.

Conclusion The implementation on an automated QA platform based on independent Monte Carlo dose re-computation and plan reconstruction of delivery log files lead to a substantial decrease of in-room time required for PSQA. Besides its implementation for pre-treatment PSQA, we envision its application for fraction-wise dose reconstruction and accumulation evaluation during treatment.

PD-0899 Magnetic field of a proton pencil beam as range verification method: The impact of secondaries

M. Rädler 1 , G. Buizza 2 , P. Palaniappan 1 , C. Gianoli 1 , G. Baroni 2 , C. Paganelli 2 , K. Parodi 1 , M. Riboldi 1

1 Ludwig Maximilian University of Munich, Department of Medical Physics, Garching b. München, Germany; 2 Politecnico di Milano, Department of Electronics, Information and Bioengineering, Milano, Italy