Date Approved

8-5-2025

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

School of Interdisciplinary Health

First Advisor

Lee Culp

Academic Year

2024/2025

Abstract

Purpose

Spinal metastases are a common complication of advanced cancer, often requiring palliative radiation therapy. This study compares two dynamic conformal arc (DCA) based techniques for thoracic spine metastases: a single arc plan generated using EZFluence and a hybrid technique combining DCA with a posterior-anterior (PA) static field. The goal was to evaluate dosimetric differences in target coverage and organ-at-risk (OAR) sparing.

Methods

Ten thoracic spine computed tomography (CT) datasets from The Cancer Imaging Archive were retrospectively planned with both techniques using Eclipse v16.0. Each plan prescribed 3000 cGy in 10 fractions to a planning target volume (PTV) encompassing T5–T9 spine. Dose-volume histogram (DVH) metrics were collected for the PTV, spinal cord, lungs, heart, and esophagus. Appropriate statistical tests, including paired t-tests and sign tests, were utilized to analyze the data.

Results

EZFluence plans demonstrated significantly lower maximum doses to almost all OARs, including spinal cord (mean max 3134.9cGy vs. 3198.4cGy, p = 0.0002) and heart (mean max 1913.27cGy vs. 2577.55cGy, p = 0.0020). The hybrid plans achieved slightly improved PTV maximum dose coverage, but at the expense of higher OAR doses. EZFluence plans also showed superior dose uniformity and consistent normalization due to automated fluence optimization.

Conclusion

While both techniques are clinically viable, EZFluence-generated DCA plans provided better OAR sparing and more consistent dosimetric outcomes, making them preferable for routine palliative spine treatments. Further clinical studies are recommended to validate these findings in larger patient populations.

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