[Volume effect models in radiation therapy].

Abstract

In radiation therapy, it is clearly recognized that the isoeffect dose of normal tissue decreases with the increase of the area or the volume of tissue irradiated, so that a marked change in therapeutic ratio occurs when large tumor is treated. This relationship has been called "volume effect" and several models such as power law relationship, volume dose histogram and integral probability have been developed to quantify the effect. Although the delivery of these models are based on clinical data, there is a wide variation between models and each model can be applied under restricted conditions. In order to develop reliable volume effect model theoretically and empirically, further studies with enough and suitable clinical data will be required.