Comparison of Dosimetric Gains Provided by Intensity-Modulated Radiotherapy, Volume-Modulated Arc Therapy, and Helical Tomotherapy for High-Grade Glioma.

Pei Liu,Jidong Hong,Weibing Zhou,Ludi Ou,Gui Liu,Wen Chen,Rui Wei,Yangqing Sun,Guihua Wang,Qian Zeng,Qiongxuan Xie

doi:10.1155/2020/4258989

Abstract

Purpose Because of the poor prognosis for high-grade glioma (HGG) patients, it is important to increase the dose of the tumor to improve the efficacy while minimizing the dose of organs at risk (OARs). Thus, we evaluated the potential dosimetric gains of helical tomotherapy (HT) versus intensity-modulated radiotherapy (IMRT) or volume-modulated arc therapy (VMAT) for high-grade glioma (HGG). Methods A total of 42 HGG patients were retrospectively selected who had undergone helical tomotherapy; then, IMRT and VMAT plans were generated and optimized for comparison after contouring crucial neuronal structures for neurogenesis and neurocognitive function. IMRT and VMAT were optimized with the Eclipse treatment planning system (TPS) (Version 11.0.31) and HT using TomoTherapy Hi-Art Software (Version 2.0.7) (Accuray, Madison, WI, USA). All three techniques were optimized for simultaneously delivering 60 Gy to planning target volume (PTV) 1 and 50-54 Gy to PTV2. We also analyzed the homogeneity index (HI) and conformity index (CI) of PTVs and organ at risk (OAR) sparing. Results There was no significant difference in the PTV coverage among IMRT, VMAT, or HT. As for the HI, HT plans (PTV1 HI: 0.09 ± 0.03, PTV2 HI: 0.17 ± 0.05) had the best homogeneity when compared to IMRT plans (PTV1 HI: 0.10 ± 0.04, PTV2 HI: 0.18 ± 0.04) and VMAT plans (PTV1 HI: 0.11 ± 0.03, PTV2 HI: 0.20 ± 0.03). The CI value of HT (PTV1 CI: 0.98 ± 0.03, PTV2: 0.98 ± 0.05) was closest to the optimal value. Except for the IMRT and VMAT groups, there were statistically significant differences between the other two groups of the CI values in both PTV1 and PTV2. The other comparison values were statistically significant except for the optic nerve, and VMAT had the best sparing of the optic chiasm. The mean and max doses of OARs declined significantly in HT. Conclusions For high-grade glioma patients, HT had superior outcomes in terms of PTV coverage and OAR sparing as compared with IMRT/VMAT.

Highlights

Gliomas are tumors that originate from glial cells and have high morbidity, high recurrence, and poor prognosis
This study is aimed at evaluating the potential dosimetric gains of helical tomotherapy (HT) versus intensitymodulated radiotherapy (IMRT) or volume-modulated arc therapy (VMAT) for high-grade glioma (HGG)
The coverage of all three planned planning target volume (PTV) was assessed by comparing the target volumes receiving 95% of the prescribed dose (V95%)

Summary

Introduction

Gliomas are tumors that originate from glial cells and have high morbidity, high recurrence, and poor prognosis. One study showed that gliomas represent 47.1% of primary malignant brain and other central nervous system tumors, of which glioblastoma is the main type of gliomas, accounting for approximately 56.1% of cases [1]. The treatment process includes surgery, followed by radiotherapy with or without temozolomide chemotherapy [2]. Due to the biological characteristics of the tumor at the site and the limitations of the anatomical site, most tumors require radiation therapy after surgery. Radiotherapy (RT) occupies an integral role in treating gliomas [3, 4], and survival is significantly reduced in glioblastoma patients if RT is not initiated within the 6 weeks after complete resection of the tumor [5].

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