Study of radiation dose to the thyroid gland in different fractionated radiotherapies of intensity-modulated radiotherapy after radical mastectomy for breast cancer
Objective To explore the radiation dose to the thyroid gland in different fractionated radiotherapies (conventional fractionated and hypofractionated radiotherapy) of intensity-modulated radiotherapy (IMRT) after radical mastectomy for breast cancer,so as to provide reference for making radiotherapy plan after radical mastectomy. Methods 45 patients after radical mastectomy for breast cancer were selected as study subjects,all of whom were treated with conventional fractionated (irradiation dose of 50 Gy/25F,2.0 Gy/F) and hypofractionated (irradiation dose of 42 Gy/15F,2.8 Gy/F) intensity-modulated radiotherapy according to the uniform field of vision on radiation exposure,with the dose of radiotherapy in supraclavicular region of Dt 50 Gy/25F and the dose-limiting parameter for the thyroid gland of V40<45％. The dosimetry parameters[dose covering 5％ of the PTV (D5),dose covering 95％ of the PTV (D95),mean dose (Dmean),maximum dose (Dmax),minimum dose (Dmin),homogeneity index (HI),conformity index (CI)]of planning target volume (PTV) and thyroid dosimetry parameters[V5,V10,V20,V30,V40,V50,Dmax,Dmean,>30 Gy absolute value,<30 Gy absolute value]of different fractionated radiotherapies were compared. Results Patients with conventional radiotherapy had D5 of (5364.50±34.19) cGy,D95 of (4885.90±74.03) cGy,Dmax of (5634.70±86.56) cGy,Dmean of (5162.50±21.28) cGy,Dmin of (3293.20±70.64) cGy,HI of (1.10±0.02),and CI of (0.67±0.05),which were higher than (5167.20±38.85) cGy,(4727.60±70.55) cGy,(5418.70±72.53) cGy,(4978.00±28.06) cGy,(3230.20±50.87) cGy,(1.09±0.02),and (0.64±0.05) of patients with hypofractionated radiotherapy. The difference was statistically significant (P<0.05). V5 of patients with conventional radiotherapy was slightly higher than that of patients with hypofractionated radiotherapy,and V10,V20 and Dmax were slightly lower than those of patients with hypofractionated radiotherapy. The difference was not statistically significant (P>0.05). Patients with conventional radiotherapy had V30 of (34.71±12.40)％,V40 of (18.89±11.85)％,V50 of (3.51±0.93)％,Dmean of (2198.00±391.05) cGy and>30 Gy absolute value of (2.70±0.36) cm3,which were all significantly lower than (40.18±11.87)％,(28.42±12.78)％,(8.45±3.31)％,(2405.00±423.91) cGy,and (3.07±0.45) cm3 in patients with hypofractionated radiotherapy;<30 Gy absolute value of (5.49±0.83) cm3 in patients with conventional radiotherapy was higher than (4.81±0.03) cm3 in patients with hypofractionated radiotherapy;the difference was statistically significant (P<0.05). Conclusion Both conventional fractionated radiotherapy and hypofractionated radiotherapy can meet the requirements of radiotherapy after radical mastectomy. Conventional fractionated radiotherapy protects the thyroid better than hypofractionated radiotherapy.
Radical mastectomyFractionated radiotherapyRadiation dose to the thyroid glandPlanning target volume
万方数据
维普
