ABSTRACT
Objective To compare and analyze the dosimetric discrepancy of combind intracavitary/interstitial brachytherapy using three different kinds of optimization method in locally advanced cervical cancer.Methods Totally 20 cases of locally advanced cervical cancer were selected and divided into three groups according to different optimization method which include manual optimization group (MO) based on graphical optimization,inverse planning simulated annealing (IPSA 1)based on simulated annealing optimization algorithm,IPSA 2 based on IPSA 1 with limitation on maximum dose of target.The dose volume histogram parameters of the targets (V200,V150,V100,D100,D90,HI) and the OARs(D0.1 cm3,D1 cm3 and D2 cm3) were analyzed.Results For CTV,compared with MO,there was no significantly statistical difference in D100between IPSA 1 and IPSA 2(P ＞ 0.05).However,V200,V150,V100 and HI for ISPA1 were better than for ISPA2 (t =-3.422-9.910,P ＜ 0.05).In addition,V100 and D100 in ISPA1 were better than in ISPA2 (t =7.238,5.032,P ＜0.05).For OARs,D0.1 cm3,D1 cm3 and D2 cm3 in rectum,bladder,sigmoid colon of both ISPA 1 and ISPA 2 were dramatically lower than those of MO (t =2.235 5.819,P ＜ 0.05),without significantly statistical difference found between ISPA1 and ISPA2.Conclusions For combined intracavitary/interstitial brachytherapy in locally advanced cervical cancer,all treatment plans based on three different kinds of optimization methods can meet the clinical need.Moreover,inverse optimization can ensure dose coverage over target and reduce maximum dose of rectum,bladder and sigmoid colon.
