Date Approved
7-18-2025
Graduate Degree Type
Project
Degree Name
Medical Dosimetry (M.S.)
Degree Program
Allied Health Sciences
First Advisor
Addah Riebschleger, M.S., CMD
Second Advisor
Kristen Vu, M.S., CMD, RT(T)
Academic Year
2024/2025
Abstract
This study is aimed to compare two different planning constraints for post-lumpectomy whole breast radiation treatments to evaluate whether or not the mean dose to the contralateral breast can be significantly reduced while maintaining plan quality for treatment. A total of 10 patients who had first undergone a lumpectomy were included into this study. Each patient’s initial treatment plan was created using a conventional approach with a mean dose constraint of < 600 cGy (Plan A) and then was replanned using the Import High protocol of a mean dose constraint, aiming to further push for a mean dose < 150 cGy (Plan B) to the contralateral breast. Both of these plans were analyzed for PTV coverage and dose to the surrounding critical structures. The results have shown that the contralateral mean dose was significantly reduced from an average of 216.32 in Plan A to 126.53 cGy in Plan B. All while meeting the target coverage of > 95% isodose line. Statistical testing showed a significant difference between the two planning techniques of lowering the contralateral dose (p < 0.0001), and normality testing supported the validity of the data analysis. In addition to a substantial dose reduction to the contralateral breast, Plan B maintained equal or improved dose constraint to other surrounding critical organs at risk, including the heart, lungs, spinal cord, and thyroid. The Import High protocol demonstrated consistent outcomes across diverse patient anatomies. These findings suggest that by using the Import High mean dose constraint, it is possible to maintain plan quality while reducing dose to the contralateral breast. This approach may help reduce the risk of long-term side effects and improve the patient’s overall outcomes in whole breast radiation treatments.
ScholarWorks Citation
Nordby, Shannon J., "Comparing and Evaluating Contralateral Breast Dose Relative to Median PTV Tumor Bed Dose for Hypo-fractionated Breast Treatments Using Import High Dose Constraints." (2025). Culminating Experience Projects. 592.
https://scholarworks.gvsu.edu/gradprojects/592
