Dosimetry and treatment planning for boron neutron capture therapy

Abstract

Dosimetric techniques were developed for the determination of the various dose components in phantoms irradiated with an epithermal neutron beam for boron neutron capture therapy (BNCT). Using paired ionization chambers and activation foils, the accuracy (1 standard deviation, SD) in the determination of the absolute thermal neutron fluence, gamma‐ray dose and fast neutron dose amounted to 5%, 5%, and 18%, respectively. Methods were developed which assure an agreement between prescribed and actual obtained values of 1% (1 SD) for the absolute beam output and 5%–10% (1 SD) for the blood–boron concentration during irradiation. Clinical dosimetry studies were performed resulting in a set of reference beam data which are used for quality control, dosimetry intercomparisons and as input for a conventional semi‐empirical treatment planning system (TPS). Using these reference beam data and the electron and photon beam model of the TPS, the various dose components could be calculated fast and with a high accuracy in a homogeneous anthropomorphic head phantom. At the central axis, the agreement between measurements and calculations was within 2%–3% (1 SD). It is concluded that the accuracy in dosimetry, beam output monitoring, blood–boron monitoring and treatment planning is sufficient to start clinical studies of BNCT in Petten, The Netherlands.