Semester of Graduation

Summer 2026

Degree

Master of Science (MS)

Department

Physics and Astronomy

Document Type

Thesis

Abstract

Purpose: The purpose of this work was to commission and validate the electron treatment planning system ElectronRT (eRT) (.decimal, Sanford, FL) for clinical use following the recommendations outlined in the American Association of Physicists in Medicine (AAPM) Medical Physics Practice Guideline (MPPG) 5.b (2022). The system’s ability to accurately calculate electron dose distributions was evaluated under normal and oblique beam incidence, varying field sizes and source-to-surface distances (SSDs), and irregular surface geometries.

Methods: The eRT beam model was configured using commissioning data from an Elekta Infinity linear accelerator at Mary Bird Perkins Cancer Center (MBPCC). Validation measurements were performed for seven clinical electron energies (7–20 MeV) using a scanning water tank system. Percent depth doses (PDDs), lateral profiles, and 2D dose distributions were compared between measured and TPS-calculated data at standard (100 cm) and extended (110 cm) SSDs. Oblique incidence (30°) and a stepped-surface geometry were used to assess performance under extreme calculation geometries. Agreement was evaluated using gamma analysis (3%/3 mm, 10% low-dose threshold).

Results: eRT demonstrated strong agreement with measurement under normal incidence, oblique incidence, and incidence on a stepped surface, with gamma pass rates exceeding 95% for each of those geometries across all tested energies, field sizes, and SSDs, and in many cases approaching 100%. Calculated Monitor Units (MU) and absolute dose were generally (5/7) within 0.5% (maximum 0.6%) of the expected values at reference calibration conditions for each energy and most (103/112) within 1% (maximum 1.5%) across the wide range of tested field sizes and SSDs.

Conclusions: The eRT treatment planning system was successfully commissioned and validated in accordance with AAPM MPPG 5.b guidelines and demonstrated clinically acceptable accuracy for electron dose calculations across a range of treatment conditions. While minor discrepancies were observed in specific scenarios, overall agreement supports clinical implementation of eRT.

Date

5-26-2026

Committee Chair

Andrew McGuffey

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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