Dosimetric performance of HyperArc and VMAT techniques using full or ipsilateral arcs for unilateral temporal lobe tumor radiotherapy

Abstract

Objective

To assess the dosimetric performance of HyperArc and volumetric modulated arc radiotherapy (VMAT) techniques, using either full or ipsilateral arcs, for the radiotherapy of unilateral temporal lobe tumor, in order to quantify and analyze differences among these planning approaches using various dosimetric parameters.

Methods

This retrospective study reviewed 30 patients with unilateral temporal lobe tumors treated with radiotherapy in the Department of Radiation Oncology, Shenzhen People's Hospital from August 2020 to December 2023. Using the Eclipse treatment plan system with the Truebeam machine model, HyperArc and VMAT plans were designed with full or ipsilateral arcs, respectively Dosimetric parameters for the planning target volume (PTV) and organs at risk (OARs) were computed and analyzed. Additionally, the monitor units (MU) of four types of plans were calculated for consideration of rays utilization and delivery efficiency.

Results

HyperArc demonstrated superior dosimetric performance for PTV and OARs compared to VMAT (P ​< ​0.05), with exceptions noted for the low dose volume (V_{5 Gy}) of the healthy brain and mean dose of ipsilateral cochlea. Ipsilateral arcs and full arcs showed similar efficacy in sparing OARs adjacent to PTV. Furthermore, full arcs improved PTV conformity compared with ipsilateral arcs (P ​< ​0.05), while ipsilateral arcs reduced the dose to contralateral OARs, mean dose and the middle-to-low dose volume of the healthy brain (P ​< ​0.05). Regarding MU, HyperArc (full) plans exhibited the minimum values among the four plan types, with overall MU for HyperArc plans being less than those for VMAT.

Conclusions

This study not only highlights the outstanding performance of the HyperArc technique with respect to VMAT but also underscores the advantages of employing ipsilateral arcs over full arcs in the radiotherapy of unilateral temporal lobe tumor. Additionally, the HyperArc technique demonstrated higher efficiency of ray utilization and delivery. The findings of this study can aid in selecting appropriate techniques and guiding arcs arrangements for the radiotherapy of unilateral temporal lobe tumor.