Application of inverse planning simulated annealing in the treatment of cervical cancer with combined intracavitary and interstitial three-dimensional brachytherapy

Abstract

Objective To evaluate the effect of an inverse planning simulated annealing (IPSA) in the treatment of cervical cancer with combined intracavitary and interstitial three-dimensional brachytherapy. Methods A total of 60 patients with locally advanced cervical cancer who received both external beam radiotherapy and combined intracavitary and interstitial brachytherapy in our hospital from October 2016 to July 2018 were enrolled. Patients were divided into four groups with 15 patients each according to the number of needles applied (1, 2, 3, and 4 needles, respectively). Dosimetric distributions were optimized with both Graphical optimization (GRO) and IPSA. Paired t-test was applied to compare the dosimetric differences between plans optimized with GRO and IPSA. Results The D90 and V100 of IPSA plans were higher than those of GRO (t=-4.742, -4.823, P 0.05) was observed. There was also no significant difference in the D2 cm3 of bladder and rectum between IPSA and GRO (P>0.05). The difference of D90 between IPSA and GRO was increased as the number of implanted needles increased, which increased from 4 cGy to 14 cGy as the number of needle increased from 1 to 4. The difference of V100 between GRO and IPSA was also increased as the number of needle increased. Conclusions In the treatment of cervical cancer with combined intracavitary and interstitial three-dimensional brachytherapy, IPSA plan could improve the target coverage(D90, V100)without increasing the dose to the OARs and high dose region in the target compared with GRO. With the numbers of needles increased, the advantage of IPSA increased in terms of target coverage. Key words: Cervical cancer; Graphical optimization; Inverse planning simulated annealing; Three-dimensional brachytherapy; Interstitial brachytherapy