Date Approved

8-12-2026

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

School of Interdisciplinary Health

First Advisor

Kelly LaBant

Second Advisor

Ryan Malmin

Third Advisor

Kristen Vu

Academic Year

2025/2026

Abstract

Purpose: This study compared cone-based stereotactic radiosurgery (SRS) and single-isocenter volumetric modulated arc therapy (VMAT) for multiple (7) intracranial targets to evaluate differences in target coverage, conformality, dose falloff, and normal brain exposure.

Methods: A phantom-based study was performed using progressively increasing configurations of 10-mm spherical targets, from one to seven targets. Cone-based SRS and VMAT plans were evaluated using D99, CI100, CI50, gradient index (GI), maximum dose, V12Gy, and V5Gy.

Results: Both planning techniques achieved similar target coverage. Cone based SRS produced a steeper dose gradient, with a mean GI of 2.99 compared with 4.66 for VMAT (p = 0.0156). Cone plans also demonstrated higher maximum target doses (p = 0.0156). VMAT produced greater low dose normal brain exposure measured by V5Gy (p = 0.0313). VMAT demonstrated improved conformity, with a mean CI100 of 1.10 compared with 1.63 for cones (p = 0.0156). No significant differences were observed for D99, V12Gy, or CI50.

Conclusion: Both cone and VMAT SRS planning provided effective target coverage but demonstrated different dosimetric advantages. Cone based SRS achieved a sharper dose falloff and reduced low dose to the brain exposure while VMAT displayed better conformality. These results suggest that technique selection should be based on the specific dosimetric and clinical priorities of each case.

Download

Share

COinS