Method for reducing scatter radiation dose to the contralateral breast during tangential breast irradiation therapy.

Abstract

To reduce scatter dose to the contralateral breast during tangential breast irradiation therapy. The authors used a 4-mm-thick commercially available vinyl-coated flexible lead shield that contains a compound of vinyl resin and lead powder of 1-mm-equivalent lead density. Contralateral scatter dose was measured at 5 cm outside the geometric field edge and along the field axis, with and without use of block trays and different wedges. On the skin, contralateral scatter dose from the medial tangential beam was reduced from about 15% to about 5% of the therapeutic dose delivered to the treated breast. The bulk of scatter dose was absorbed within the first 2 cm of breast tissue. Reduction in unwanted scatter dose to the contralateral breast is in accord with the philosophy of keeping radiation exposure as low as reasonably achievable and might be of most benefit for young patients.