Source of Support: None, Conflict of Interest: None
Tangential radiotherapy portals' with cobalt-60 gamma radiations are widely used in the management of post- operative breast cancer. The treatment planning and dosimetry are complex because of the obliquity and irregular contours. A method followed at our centre makes use of selected percentiles covering the tumour volumes for various preselected inter-field separations. Equivalent field concept is used for the half-blocked portals. Comparison with computerised plans and phantom measurements validate the outlined concept.