Date Approved

7-31-2023

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

Allied Health Sciences

First Advisor

Jessica Fountain

Academic Year

2022/2023

Abstract

Abstract

Introduction

The main purpose of this study was to determine whether there was a significant difference between the dose distributions when comparing static-IMRT and VMAT plans for patients with large left sided lumpectomy cavities located near the chest wall while utilizing DIBH. Thorough planning and statistical analysis was performed to determine whether there was a clear advantage for either treatment technique to better benefit patient outcomes.

Methods

Ten female patients with large left sided lumpectomy cavities were selected to be retrospectively planned using both static-IMRT and VMAT plans. Each patient fell within the ASTRO eligibility criteria for APBI treatments. Each plan was optimized to meet the OAR and target coverage constraints described in the Florence Trail. Findings were input into SAS institute’s statistical analysis software where a repeated measures ANCOVA test was performed.

Results

All variables were found to be non-statistically significant, with the exception of the maximum dose to the PTV. The mean PTV dose maximum was found to be on average approximately 7cGy higher for VMAT plans when compared to its static-IMRT counterpart. This corresponds to a 0.09% - 3.9% increase in max dose between plans respectively.

Conclusion

The overall dosimetric difference between static-IMRT and VMAT plans for this study group shows minimal differences that could be evaluated upon physician preference. Both methods offer comparable target coverage and OAR sparing while effectively treating the patient. Patient specific factors and overall ease of treatment with VMAT may eclipse the mostly non-significant differences between planning methods.

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