Date Approved
8-5-2025
Graduate Degree Type
Project
Degree Name
Medical Dosimetry (M.S.)
Degree Program
Health Professions
First Advisor
Sarah Johnson MS, CMD, R.T.(T)
Second Advisor
Kristen Vu M.S., CMD, RT(T)
Third Advisor
Raj Varadhan PhD, DABR, DABMP
Fourth Advisor
Sarah Way MS, DABR
Academic Year
2024/2025
Abstract
Objective: This study compares cone-based and volumetric modulated arc therapy (VMAT) stereotactic radiosurgery (SRS) planning for dual intracranial targets, examining the effects of target size, inter-target separation, and isocenter displacement on dosimetric outcomes. Methods: Plans were generated for spherical targets of 8.0 mm, 10.0 mm, and 12.0 mm diameters using both VMAT and cone-based techniques with single-isocenter configurations. Key metrics including maximum dose, volumes of normal brain receiving 12 Gy and 50% of the prescription dose (V12Gy, V50%), high-dose volume (V100%), gradient index, and target coverage were evaluated. Results: Cone-based plans demonstrated superior dose conformity and reduced normal tissue exposure across all target sizes, reflected by lower gradient index and smaller V12Gy and V50% volumes. VMAT plans achieved comparable or slightly improved target coverage but exhibited increased dose spill to surrounding brain tissue. Statistical analysis using Fisher’s Exact Test showed no significant association between planning technique and achieving full target coverage (p = 1.0). Conclusion: These findings suggest that while both techniques are effective for dual-target SRS, cones provide improved dose conformity and normal brain sparing.
ScholarWorks Citation
Angeli, Hannah, "Cone vs. VMAT SRS planning for dual targets: effects of target size, separation, and isocenter displacement" (2025). Culminating Experience Projects. 630.
https://scholarworks.gvsu.edu/gradprojects/630
