Comparison of the IPSA and HIPO algorithms for interstitial tongue high-dose-rate brachytherapy.

Chang Heon Choi,Jung-In Kim,So-Yeon Park,Jin-Ho Kim,Jong Min Park,Hong-Gyun Wu,Alan D Hutson

doi:10.1371/journal.pone.0205229

Abstract

PurposeThis study aimed to compare the inverse planning simulated annealing (IPSA) stochastic algorithm with the hybrid inverse planning and optimization (HIPO) algorithm for interstitial tongue high-dose-rate (HDR) brachytherapy.MethodsTwenty patients who received radiotherapy for tongue cancer using interstitial HDR brachytherapy were retrospectively selected for this study. Oncentra Brachy v. 4.3 was used for IPSA and HIPO planning. Four to eight fixed catheter configurations were determined according to the target shape. During the optimization process, predetermined constrain values were used for each IPSA and HIPO plan. The dosimetric parameters and dwell time were analyzed to evaluate the performances of the plans.ResultsThe total dwell time using IPSA was 4 seconds longer than that of HIPO. The number of active positions per catheter for the IPSA plans were approximately 2.5 fewer than those of the HIPO plans. The dose-volumetric parameters related to the clinical target volume with IPSA were lower than those with HIPO. In terms of the dose-volumetric parameters related to normal tissue, HIPO tended to associate with slightly higher values than IPSA, without statistical significance. After GrO, the target coverages were satisfied to clinical goal for all patients. The total dwell times was approximately increased by 10%.ConclusionsThe IPSA and HIPO dose optimization algorithms generate similar dosimetric results. In terms of the dwell time, HIPO appears to be more beneficial.

Highlights

High-dose-rate (HDR) brachytherapy has been established as an effective treatment method for early-stage tongue cancer [1,2,3]
The dose-volumetric parameters related to the clinical target volume with inverse planning simulated annealing (IPSA) were lower than those with hybrid inverse planning and optimization (HIPO)
In terms of the dose-volumetric parameters related to normal tissue, HIPO tended to associate with slightly higher values than IPSA, without statistical significance

Summary

Introduction

High-dose-rate (HDR) brachytherapy has been established as an effective treatment method for early-stage tongue cancer [1,2,3]. Brachytherapy provides a high localized dose of radiation to the tumor and reduces the volume of irradiated normal tissues, with rapid dose fall-off [7,8,9]. The tumor control can be improved and the probability of side effects (i.e., xerostomia and soft tissue fibrosis) can be reduced [9,10,11,12]. Treatment planning is performed by optimizing the source dwell positions and dwell times needed to cover the target with the prescription dose while reducing the dose to the normal tissues based on CT imaging [13], thereby enabling the generation of more accurate treatment plans. Iterative forward planning is a time-consuming and laborious process, owing to the numerous different combinations of dwell times and positions for optimal planning [14]

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Conclusion