Date Approved
7-27-2026
Graduate Degree Type
Project
Degree Name
Medical Dosimetry (M.S.)
Degree Program
School of Interdisciplinary Health
First Advisor
Vicente Ornelas
Second Advisor
Kristen Vu
Third Advisor
J.C. Barrett
Academic Year
2025/2026
Abstract
Accurate dose delivery at the chest wall-supraclavicular (CW-SCV) junction remains an important challenge in breast irradiation, especially when multileaf collimator (MLC) leaves are intentionally opened beyond the collimator jaws to improve junction coverage. This study evaluated the dosimetric accuracy of the Varian Eclipse treatment planning system (TPS) at the CW-SCV junction using the Anisotropic Analytical Algorithm (AAA) and Acuros XB calculation algorithms with mono-isocentric and dual-isocentric treatment techniques. A prospective phantom-based study was performed using a solid water phantom and a Varian TrueBeam linear accelerator. Twenty-four unique three-dimensional conformal treatment plan configurations were created using combinations of beam energy (6 MV, 10 MV, and 15 MV), dose calculation algorithm, isocenter technique, and MLC configuration. Each plan was delivered 12 consecutive times, and ion chamber measurements were compared with Eclipse-calculated dose values. Statistical analysis was performed using repeated-measures mixed-model ANOVA. Significant main effects were observed for beam energy, dose calculation algorithm, isocenter technique, and MLC configuration (all p < 0.0001). Acuros XB demonstrated closer agreement with measured dose than AAA, and mono-isocentric plans showed smaller discrepancies than dual-isocentric plans. Open MLC configurations generally produced smaller dose differences than corresponding closed configurations, while the largest discrepancies were observed with 10 MV beam energy plans. These findings demonstrate that Eclipse dose agreement at the CW-SCV junction is influenced by beam energy, calculation algorithm, isocenter technique, and MLC positioning behind the jaws. This study provides the first direct evaluation of Eclipse dose modeling accuracy in this clinically relevant but previously unstudied treatment scenario and may help guide treatment planning decisions in breast radiotherapy.
ScholarWorks Citation
Rogers, Amy, "Study on the accuracy of Varian Eclipse MLC modeling when MLCs are open beyond the jaw in Breast Cancer Patient Planning using AAA and Acuros with both dual-isocentric technique and mono-isocentric technique." (2026). Masters Projects. 703.
https://scholarworks.gvsu.edu/gradprojects/703
