The complication probability factor: a method for selection of radiation treatment plans.

The problem of selecting the best radiation treatment plan from several that may offer subtle differences has been considered. A method is introduced in which the concept of a complication probability factor (CPF) can be used to quantify the relative merits of such treatment plans. The CPF is a variant of integral dose and consists of a weighted volume of irradiated normal tissue which may relate to radiation-related complications. Treatment plans for irradiation of a pelvic tumour volume using parallel opposed, 360 deg rotational and four-field techniques with X-ray beams of 4, 8, 22, and 45 MV have been analyzed to demonstrate the utility of the method. This analysis suggests that complex radiation delivery techniques may offer a substantial improvement in dose distribution characteristics, while higher beam energies are relatively less advantageous.