Abstract
The principle of definitive radiotherapy is to control local lesions with doses up to the tolerated doses of irradiated normal tissues within radiation fields. When the therapeutic ratio is more than 1.0, lesions can be controlled without inducing adverse effects in normal tissues. However, when it is less than 1.0, lesions cannot be controlled with radiotherapy alone. The therapeutic ratio is much larger in boron neutron capture therapy (BNCT) for lesions where a sufficient amount of 10B can be selectively and homogenously delivered than any other radiotherapy modality. Thus, lesions can be controlled without any other adverse effect in normal tissues with BNCT. The key point for improving BNCT further is to develop a method to deliver neutrons to lesions as appropriately as possible and to deliver new 10B agents to lesions more selectively and homogeneously than at present.
