Three-field technique for breast treatment using a rotatable half-beam block

Abstract

A new three-field technique for the radiation therapy of breast cancer has been developed. Two opposing tangential fields treat the breast, chest wall, and ipsilateral internal mammary lymph nodes. The third, an anterior field, treats the axilla and supraclavicular area. The objective of the technique is to make the posterior geometric edges of the tangential fields coplanar, and also to make their cephalad geometric edges and the caudad geometric edge of the supraclavicular field coplanar. To effect the matching of fields, the technique utilizes a rotatable half-beam shielding block. To simplify the simulation procedure, an exact mathematical solution is given for the required treatment set-up parameters.