Date Approved

7-21-2025

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

Allied Health Sciences

First Advisor

Jacob Belardo

Second Advisor

Kristen Vu

Academic Year

2024/2025

Abstract

Non-coplanar beam arrangements have been used for many years in radiation treatment planning. Their use has been known to show an increase in target conformity and gradient index. However, by using non-coplanar beam arrangements, the treatment planning time as well as the treatment delivery time can increase. Despite the increase in treatment planning and delivery complexity and time, previous studies have shown a decrease in OAR doses resulting in a desire to use non-coplanar beams. Previous studies have looked at various body sites and target locations, though no research has been found specifically studying non-coplanar beam arrangement in multi-target treatment plans for inoperable non-small cell lung cancer patients.

This research aims to study the utility of non-coplanar beam arrangements for lung tissue sparing without sacrificing plan quality or target coverage in patients with multi-target inoperable non-small cell lung cancer on arm 2 of the NRG LU-008 clinical trial plan. 12 anonymized CT data sets of patients from an anonymized online database were downloaded and planned using the plan parameters provided in the NRG LU-008 arm 2 protocol. Each patient was planned with and without coplanar treatment arc geometry in accordance with the clinical trial OAR constraints and target prescriptions. Three EQD2 A/B = 3Gy composite plan dose summations were created in MIM for each patient: one composite with all coplanar arcs, one with non-coplanar arcs for the SBRT plan alone, and one with non-coplanar arcs for both plans. The composites were analyzed to study the change in dose to nearby OARs when adding non-coplanar beam arrangements.

Upon evaluation of the EQD2 composite plans optimized for 12 patients used in this sample population, the average maximum dose to the Lungs-IGTV, Brachial Plexus, and Heart contours decreased for the fully non coplanar EQD2 composite plans compared to strictly coplanar EQD2 composite plans. A paired student’s T test was performed to determine statistical significance for the changes to average OAR metrics and point doses. Our results indicate that for some patients, additional dose sparing is possible using non-coplanar arcs but that the utility of non-coplanar arcs for treating multi-target inoperable non-small cell lung cancer on the LU-008 arm 2 regiment, is not a statistically significant amount of dose reduction in lung tissue and other thoracic OAR anatomy.

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