[The optimized dosage specific for different organs with regard to late effect].

Clinical and experimental evidence indicates that the optimized dosage may be different from organ to organ. In an effort to find an optimized dosage for laryngeal cancer treated in our department, the NSD-TDF concept and linear-quadratic (LQ) model were employed. The dose-fractionations using 2.5 Gy per fraction gave better results in terms of local control and complications than those using bigger fraction size and shorter treatment period. It is generally agreed that the maxillary cancer is best managed by combined radiation and surgery with or without chemotherapy. When irradiation is given in 16 fractions over 4 weeks, the local control and survival were decreased with increasing total dose, suggesting the presence of the supra-lethal dose phenomenon which was first mentioned by the Manchester group. The optimized dosage for carcinoma of the uterine cervix is more complicated, because both the external irradiation and intracavitary irradiation are combined for this disease. Our clinical data indicated that the optimal fractionation is: 50 Gy of total pelvic irradiation with the last 10-15 Gy given using a central shielding followed by RALS treatment delivering 30 Gy in 6 fractions at point A.