Dose volume histogram (DVH) analysis in boron neutron capture therapy

The volume of radiotherapy target tumor can be estimated by 3D images constructed by CT, MRI, etc., of which dose volume histogram (DVH) analysis gives the maximal, average and minimal doses for the therapy. Kyoto University Research Reactor (KUR) uses the planning system of Simulation Environment for Radiotherapy equipped with DVH analysis software (Idaho Natl. Technol. Inst., US), for planning of boron neutron capture therapy (BNCT), in which epithermal neutron beam is irradiated to tumors possessing boron compounds given previously. The purpose of the present study is to evaluate the DVH analysis in the therapy of recurrent head and neck cancers in KUR to improve the planning. Subjects are 14 cases of patients with those cancers after their standard treatments: 6 cases with one irradiation, 7 with two and 1 with three. Evaluation is done after BNCT. As a result, since the dose distribution in gross tumor volume is found heterogeneous (the dose difference between the maximum and minimum is large relative to the average), for increasing the therapeutic gain factor, intra-arterial administration of boron compound is recommended most desirable. (N.I.)