LET<sub>d</sub> Optimization Verification With an SOI Microdosimeter.

Pan, V A; Tran, L T; Madden, T; Clasie, B; Kooy, H; Rosenfeld, A B; Depauw, N · Int J Radiat Oncol Biol Phys · 2024

basic_science · Level V

Where this comes from

Abstract

A first of its kind experimental verification of dose-averaged linear energy transfer (LET<sub>d</sub>) optimized treatment plans for proton therapy has been carried out using a silicon-on-insulator microdosimeter at the Massachusetts General Hospital (MGH), Boston, USA. Three clinical treatment plans of a typical ependymoma structure set were designed using the standard clinical approach, the proposed protocol approach, and a one-field approach. The plans were then reoptimized to reduce the LET<sub>d</sub>-weighted dose in the brain stem. All six plans were delivered in a solid water phantom and the experimental y<sub>D</sub>‾ measured. After LET<sub>d</sub> optimization, a reduction in y<sub>D</sub>‾ was found within the brain stem by an average of 12%, 19%, and 4% for the clinical, protocol, and one-field plans, respectively, while maintaining adequate coverage of the tumor structure. The experimental LET<sub>d</sub>-weighted doses were in agreement with the treatment planning system calculations and Monte Carlo simulations and reinforced the improvement of the optimization. This work demonstrates the first experimental verification of the clinical implementation of LET<sub>d</sub> optimization for patient treatment with proton therapy.

Medical subject headings