Date Approved

8-1-2024

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

Health Professions

First Advisor

Sarah Johnson

Academic Year

2023/2024

Abstract

Purpose: This study compares the dosimetric effectiveness of HyperArc and Volumetric Modulated Arc Therapy (VMAT) techniques in treating primary glioblastoma multiforme (GBM) tumors.

Methods: A retrospective analysis was conducted on ten patients from MyMichigan Health, Radiation Oncology department with primary GBM tumors. Patients were treated with HyperArc on Varian TrueBeam systems. VMAT plans were generated for comparison using identical optimization parameters, except for the Normal Tissue Objective (NTO). Dosimetric factors, including dose distribution, target coverage conformity, and dose to critical structures, were evaluated. Statistical analysis was performed using the Wilcoxon Signed-Rank Test to compare the two techniques.

Results: HyperArc showed a steeper dose fall-off and better dose conformity compared to VMAT. The R50 (p = 0.0215) and 50% volume (p = 0.0215) metrics were statistically significant, with HyperArc demonstrating a mean R50 of 2.08 and a range of 0.27, while VMAT had a mean of 2.22 and a range of 0.42. Although other dosimetric measures were comparable, trends indicated lower doses to the brainstem and hippocampus with HyperArc plans.

Conclusions: HyperArc offers superior dosimetric advantages over VMAT in the treatment of primary GBM tumors, particularly in dose conformity and dose fall-off. While further research with larger patient samples is needed to confirm these findings and understand their clinical importance, HyperArc shows signs of enhancing treatment precision and potentially improving patient outcomes.

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