A FAST AND ACCURATE TREATMENT PLANNING METHOD FOR BORON NEUTRON-CAPTURE THERAPY

Background and purpose: The aim of this study was to test the applicab ility of conventional semi-empirical algorithms for the treatment plan ning of boron neutron capture therapy (BNCT). Materials and methods: B eam data of a clinical epithermal BNCT beam obtained in a large cuboid water phantom were introduced into a commercial treatment planning sy stem (TPS). For the calculation of thermal neutron fluence distributio ns, the Gaussian pencil beam model of the electron beam treatment plan ning algorithm was used. A simple photon beam algorithm was used for t he calculation of the gamma-ray and fast neutron dose distribution. Th e calculated dose and fluence distributions in the central plane of an anthropomorphic head phantom were compared with measurements for vari ous field sizes. The calculation time was less than 1 min. Results: At the normalization point in the head phantom, the absolute dose and fl uence values agreed within the measurement uncertainty of approximatel y 2-3% (1 SD) with those at the same depth in a cuboid phantom of appr oximately the same size. Excellent agreement of within 2-3% (1 SD) was obtained between measured and calculated relative fluence and dose va lues on the central beam axis and at most off-axis positions in the he ad phantom. At positions near the phantom boundaries, generally in low dose regions, local differences of approximately 30% were observed. C onclusions: A fast and accurate treatment planning method has been dev eloped 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. (C) 1998 Elsevier Science I reland Ltd.