Quality assurance in radiation therapy: systematic evaluation of errors during the treatment execution.

A method to control the quality of the radiotherapy treatment during its execution has been developed. The method is based on a wide use of verification films in the practical routine of a centre together with a statistical analysis of the data obtained from them. The stepwise multiple regression analysis is applied in order to assess the influence, on the quality of the treatment, of a set of chosen factors with a certain clinical or technical significance. A test of the method is presented and the results are discussed.