A clinically practical electron cone for the treatment of head and neck cancer.

Abstract

The purpose of the work was to develop a practical electron cone and to compare its dosimetry with that of the conventional applicator collimation system. The electron cone consists of the upper part of a manufacturer-supplied electron applicator and an institution-built rectangular extension tube which produces a 12 cm x 6 cm field at 100 cm SSD while maintaining an air gap of 5 cm between the patient. The compact size of the cone allows electron irradiation without having to reposition the patient after photon treatment. The radiation field is very similar to that of a standard 15 cm x 15 cm applicator with a 12 cm x 6 cm field restricting insert. Radiation leakage at the surface of the special cone is typically less than 1% of the useful beam at dmax. During 12 years of clinical use the special cone proved itself very practical in the treatment of more than 300 patients. An electron cone practical for clinical use with dosimetry comparable to the conventional applicator was developed.