Sci—Thur PM: Planning & Delivery — 02: Treatment planning workflow for very high‐energy electron beam radiotherapy

Abstract

Purpose:To develop treatment planning workflow for rapid radiotherapy delivered with very‐high energy electron (VHEE) scanning beam.Methods:VHEE radiotherapy treatment planning was performed by linking Monte Carlo (MC) dose calculations with inverse optimization in a research version of RayStation. In order to study a number of treatment parameters, a Matlab graphical user interface (GUI) for calculation of VHEE beamlet dose was developed. Through the GUI, EGSnrc MC simulations were run for a number of beam energies, number of beams, beamlet spot and grid sizes, and machine bore sizes. VHEE plans for a pediatric patient with a 4.3 cm3 brain target optimized with spot‐scanning algorithm in RayStation were compared to the clinically delivered 6 MV VMAT plan.Results and Discussion:VHEE beam energy had the largest effect on the quality of dose distributions. For the same target dose, the mean doses to critical organs decreased by 10–15% when planned with 100 MeV compared to 60 MeV. VHEE plans calculated with 36 beams outperformed plans calculated with 13 and 17 beams. While beamlet spacing and bore size had a small effect on VHEE dose distributions, 0.1‐3mm beamlet sizes resulted in identical dose distributions. Critical organ doses were by up to 70% lower in the best VHEE plan compared to the clinical 6 MV VMAT plan.Conclusions:We have developed a GUI for MC beamlet generation for treatment planning of VHEE radiotherapy. We have demonstrated that pediatric VHEE plans resulted in significant critical organ dose sparing compared to the clinical VMAT plan.