1991 Volume 47 Issue 11 Pages 1916-1924
Assessment was made of the three-dimensional dose distribution of open-field (O-F) beams in 54 patients with breast cancer treated by tangential breast irradiation (TBI). A new irradiation technique was developed for attaining optimum dose distribution of TBI. The treatment planning for the TBI was performed using a CT-simulator. Dose distribution was by the modified equivalent tissue maximum ratio method and normalized with respect to isocenter CT slices. For O-F beams, dose homogeneity was found to be determined by the anatomy of breast, tissue depth on central beam axis and length of the lung included in a tangential field. When tissue depth was greater than 11cm, a "hot spot" in excess of 110% of the isocenter dose could always be detected on the lateral chest wall, sternum, and near the apex of the breast. The area dose of a "hot spot" increased by the SINGLE-WEDGE-FIELD irradiation technique using a single-wedge filter for tangential beams, but decreased by the TWIN-WEDGE-FIELD (T-W-F) irradiation technique when using a twin-wedge filter. The present technique concluded the best method for treating TBI in breast cancer patients.
