Date Approved
8-5-2025
Graduate Degree Type
Project
Degree Name
Medical Dosimetry (M.S.)
Degree Program
School of Interdisciplinary Health
First Advisor
Sarah Johnson
Second Advisor
Michael Huberts
Third Advisor
Kristen Vu
Academic Year
2024/2025
Abstract
Importance Minimizing radiation dose to the heart, particularly the left anterior descending coronary artery (LAD), is essential in left-sided partial breast irradiation (PBI). Flattening filter-free (FFF) beam configurations may improve organ-at-risk (OAR) sparing and treatment efficiency.
Objective To compare dosimetric outcomes between 10 MV flattening filter (FF) and 10 MV flattening filter-free (FFF) VMAT plans in patients receiving accelerated partial breast irradiation (APBI), focusing on LAD dose sparing.
Design, Setting, and Participants This retrospective dosimetric study included 10 patients with early-stage, left-sided breast cancer. Each patient had two VMAT plans generated using identical geometry and constraints in Eclipse v16.01: one with 10 MV-FF beams and one with 10 MV-FFF beams.
Interventions Two VMAT plans per patient were created, delivering 30 Gy in 5 fractions using deep inspiratory breath-hold (DIBH). One plan used 10 MV-FF beams, the other 10 MV-FFF.
Main Outcomes and Measures Primary outcome was mean LAD dose. Secondary endpoints included dose metrics for the heart, lungs, and uninvolved ipsilateral breast. Statistical analysis was conducted using the Wilcoxon signed-rank test (P < .05).
Results Both plans met target coverage and OAR constraints. A significant reduction in the volume of uninvolved ipsilateral breast receiving ≥1500 cGy (V15 Gy) was observed with 10 MV-FFF (24.0% vs 26.0%, P = .049). No significant differences in LAD, heart, or lung doses were found, though minor trends favored FFF.
Conclusions and Relevance Both techniques are clinically viable. The small reduction in non-target breast dose with FFF may offer cosmetic or long-term benefits, but LAD sparing was not significantly improved. Further study in larger populations is warranted.
ScholarWorks Citation
Beliew, Jillian, "Comparison of 10 MV Flattening Filter and Flattening Filter-Free Volumetric Modulated Art Therapy (VMAT) Radiation Plans in Partial Breast Irradiation: Evaluating Dose Sparing to the Left Anterior Descending Coronary Artery" (2025). Culminating Experience Projects. 644.
https://scholarworks.gvsu.edu/gradprojects/644
