Comparison of two inverse planning algorithms for cervical cancer brachytherapy.

Hui Yan,Manni Huang,Xi Yang,Jing Zuo,Yingjie Xu,Jusheng An,Jiayun Chen,Jianrong Dai,Qi Fu

doi:10.1002/acm2.13195

Abstract

PurposeTo compare two inverse planning algorithms, the hybrid inverse planning optimization (HIPO) algorithm and the inverse planning simulated annealing (IPSA) algorithm, for cervical cancer brachytherapy and provide suggestions for their usage.Material and methodsThis study consisted of 24 cervical cancer patients treated with CT image‐based high‐dose‐rate brachytherapy using various combinations of tandem/ovoid applicator and interstitial needles. For fixed catheter configurations, plans were retrospectively optimized with two methods: IPSA and HIPO. The dosimetric parameters with respect to target coverage, localization of high dose volume (LHDV), conformal index (COIN), and sparing of organs at risk (OARs) were evaluated. A plan assessment method which combines a graphical analysis and a scoring index was used to compare the quality of two plans for each case. The characteristics of dwell time distributions of the two plans were also analyzed in detail.ResultsBoth IPSA and HIPO can produce clinically acceptable treatment plans. The rectum D2cc was slightly lower for HIPO as compared to IPSA (P = 0.002). All other dosimetric parameters for targets and OARs were not significantly different between the two algorithms. The generated radar plots and scores intuitively presented the plan properties and enabled to reflect the clinical priorities for the treatment plans. Significant different characteristics were observed between the dwell time distributions generated by IPSA and HIPO.ConclusionsBoth algorithms could generate high‐quality treatment plans, but their performances were slightly different in terms of each specific patient. The clinical decision on the optimal plan for each patient can be made quickly and consistently with the help of the plan assessment method. Besides, the characteristics of dwell time distribution were suggested to be taken into account during plan selection. Compared to IPSA, the dwell time distributions generated by HIPO may be closer to clinical preference.

Highlights

Brachytherapy (BT) is an essential part of radiotherapy for locally-advanced cervical cancer (LACC)
The rectum D2cc was slightly lower for hybrid inverse planning optimization (HIPO) as compared to inverse planning simulated annealing (IPSA) (p=0.002)
Different characteristics were observed between the dwell time distributions generated by IPSA and HIPO

Summary

Introduction

Brachytherapy (BT) is an essential part of radiotherapy for locally-advanced cervical cancer (LACC). The conventional treatment planning approach is to manually activate source positions and manually adjust dwell times for better target coverage and sparing of organs at risk (OARs). This is an iterative forward planning method which requires an experienced planner to spend a lot of time changing the dwell weights constantly until an optimal solution is met. Over the last two decades, inverse planning has been more applied to BT [2] It is based on mathematical optimization algorithms, which was commonly used in external beam radiotherapy (EBRT). The principle of an inverse planning optimization algorithm is to search for the minimum value of an aggregate objective function based on a set of predefined dose objectives. Compared with forward planning, inverse planning has advantages including less planning time, better reproducibility, higher target coverage and lower dose to OARs [3,4,5,6]

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Discussion

Conclusion