Modeling of beam customization devices in the pencil beam splitting algorithm for heavy charged particle radiotherapy

TL;DR

This paper introduces a novel computational model for accurately simulating beam customization devices in heavy charged particle radiotherapy, improving dose calculation precision in complex treatment setups.

Contribution

It presents a new model that handles beam size growth and device structures in pencil-beam algorithms, enhancing treatment planning accuracy.

Findings

Penumbra sizes matched experimental data within submillimeter accuracy.

The model effectively simulates complex collimator structures.

Dose calculations aligned well with measured data.

Abstract

A broad-beam-delivery system for heavy-charged-particle radiotherapy often employs multiple collimators and a range-compensating filter, which potentially offer complex beam customization. In treatment planning, it is however difficult for a conventional pencil-beam algorithm to deal with these structures due to beam-size growth during transport. This study aims to resolve the problem with a novel computational model. The pencil beams are initially defined at the range compensating filter with angular-acceptance correction for the upstream collimators followed by the range compensation effects. They are individually transported with possible splitting near the downstream collimator edges to deal with its fine structure. The dose distribution for a carbon-ion beam was calculated and compared with existing experimental data. The penumbra sizes of various collimator edges agreed between them to a submillimeter level. This beam-customization model will complete an accurate and efficient dose-calculation algorithm for treatment planning with heavy charged particles.