A fast and accurate treatment planning method for boron neutron capture therapy

Abstract

Background and purpose: The aim of this study was to test the applicability of conventional semi-empirical algorithms for the treatment planning of boron neutron capture therapy (BNCT). Materials and methods: Beam data of a clinical epithermal BNCT beam obtained in a large cuboid water phantom were introduced into a commercial treatment planning system (TPS). For the calculation of thermal neutron fluence distributions, the Gaussian pencil beam model of the electron beam treatment planning algorithm was used. A simple photon beam algorithm was used for the calculation of the gamma-ray and fast neutron dose distribution. The calculated dose and fluence distributions in the central plane of an anthropomorphic head phantom were compared with measurements for various field sizes. The calculation time was less than 1 min. Results: At the normalization point in the head phantom, the absolute dose and fluence values agreed within the measurement uncertainty of approximately 2–3% (1 SD) with those at the same depth in a cuboid phantom of approximately the same size. Excellent agreement of within 2–3% (1 SD) was obtained between measured and calculated relative fluence and dose values on the central beam axis and at most off-axis positions in the head phantom. At positions near the phantom boundaries, generally in low dose regions, local differences of approximately 30% were observed. Conclusions: A fast and accurate treatment planning method has been developed for BNCT. This is the first treatment planning method that may allow the same interactive optimization procedures for BNCT as applied clinically for conventional radiotherapy.