Dosimetric study on radiotherapy for brain metastasis / 实用医学杂志

ABSTRACT

Objective To investigate the feasibility of sequential intensity-modulated radiotherapy (sIMRT)and simultaneously integrated boost intensity-modulated radiotherapy(SIB-IMRT)in the radiotherapy of brain metastasis,the dosimetric difference of target volumes and organs at risk(OARs). Methods Twenty pa-tients diagnosed as brain metastasis were randomly selected,with SIB-IMRT and sIMRT programs developed for each patient. Dosimetric differences between target areas and OARs were compared between the two radiotherapy protocols. Results Compared with sIMRT,SIB-IMRT had no significant difference in the average irradiation dose of the brainstem[(42.69 ± 2.18)Gy vs.(41.98 ± 0.96)Gy]and homogeneity index(HI)(1.46 ± 0.04 vs.1.42 ± 0.13)of P-CTV(P > 0.05). However,SIB-IMRT plan achieved higher than sIMRT in the conformation index (CI)(0.68 ± 0.05 vs. 0.44 ± 0.04)and HI(1.03 ± 0.01 vs. 1.06 ± 0.01)of P-GTV. Meanwhile,both maximum exposure dose of OARs and CI of P-CTV(0.68 ± 0.05 vs.0.44 ± 0.04)of SIB-IMRT were significant in comparison with sIMRT(P<0.05).Conclusions Both radiotherapies can meet target coverage and dose requirements.Com-pared to sIMRT technique,SIB-IMRT technique can decrease effectively the exposure dose of surrounding organs, and can give the tumor target more uniform physical dose conformation.