Design of a non-docking intraoperative electron beam applicator system

A development of a non-docking system is described which enables collimation of an electron beam for intraoperative radiation therapy. This system, adapted to a linear accelerator (SATURNE 43-CGR MeV), has been designed to minimize the mechanical, electrical and tumor visualization problems associated with a docking system. A number of dosimetric considerations and technical innovations have been used in the design of this system. Among them are the central axis of the beam alignment with the axis of the cone via a laser system and the clamping method of the intraoperative cone to the treatment couch by a rigid system. This collimation system can be adapted for different makes of linear accelerator. The dose distribution in this new design system shows a better homogeneity in the patient's target volume and small (thus accessable) leakage radiation dose to tissues outside the intraoperative cone. The design concept and dosimetric characteristics of this novel applicator system are presented in this paper.