Dosimetric comparison between manual and inverse optimization methods in high-dose-rate intracavitary/ interstitial cervical cancer brachytherapy for two treatment planning systems.

Abstract

Purpose: To compare manual treatment planning with two inverse planning methods from two different treatment planning systems for high-dose-rate cervical cancer brachytherapy.

Material and methods: Thirty-one consecutive patients were included. Three treatment plans were created: manual, hybrid inverse treatment planning (HIPO), and RayStation Brachy (RSB), using Oncentra TPS for manual and HIPO, and RayStation TPS for RSB. Dose volume parameters, dwell time in intrauterine tandem, ovoids, and interstitial needles as well as Paddick, COIN, and dwell time inhomogeneity index, were evaluated.

Results: Compared with manual planning, HIPO plans resulted in a higher dose to targets while reducing the dose to organs at risk. It reduced the total treatment time and increased the loading in interstitial needles. RSB plans resulted in a similar dose to targets and organs at risk and a similar total treatment time, but a better homogeneity of dose distribution. All dosimetric indices were increased with inverse optimization.

Conclusions: Both inverse planning methods are able to produce dosimetrically acceptable plans, with an increase of target coverage and better homogeneity. RSB provides higher doses and better homogeneity than HIPO.