Prone position breast irradiation.

Abstract

PURPOSE: An alternative technique for irradiating the breast following breast conserving surgery is described. METHODS AND MATERIALS: The technique utilizes the prone position and has been developed to improve the dose distribution within the breast and reduce the volume of normal tissues irradiated during whole breast treatment. Improvements in the dosimetry of breast irradiation are obtained through the optimization of the shape of the breast and result in a reduction in the magnitude of high-dose regions and isodose gradients at the base of the breast. RESULTS: The high dose region at the base of the breast, without lung correction, generally ranges from 116-118% for large breasted women treated in the supine position. These high dose regions are reduced to 102-103% for the same women treated in the prone position. Irradiation of the heart, lungs, chest wall and contralateral breast are minimized with this technique. The improvements appear to benefit women with large breasts, pendulous breasts, large separations and/or irregularly shaped chest contours. CONCLUSION: The prone position technique takes advantage of the reproducibility characteristics of the supine position technique and combines them with the homogeneity and normal tissue-sparing characteristics of the lateral decubitus position technique. Prone position breast irradiation appears to be a simple and effective alternative to irradiation of the breast in the conventional supine position when the supine position is likely to result in unacceptable dose inhomogeneity or significant doses to normal tissues.