The results of a study on the optimization of external irradiation of prostatic cancer are discussed. The study was performed with the aid of an automatic water phantom, an automatic densitometer, and a computerized treatment planning system using an anthropometric phantom Alderson. The following parameters were studied: Dose gradient, the size of areas of selected isodoses, and the shape of the 90% isodose. At present, we consider that the twosector biaxial arc technique characterized by an arc angle of 120 degrees, a distance of the arc axes of 3 cm, employing a 20 MeV X-ray of a linear accelerator is the optimal technique for target irradiation of carcinomas of the prostate.

Research Institute of Clinical and Experimental Oncology Brno Czechoslovakia