Date Approved

8-9-2022

Graduate Degree Type

Project

Degree Name

Medical Dosimetry (M.S.)

Degree Program

Allied Health Sciences

First Advisor

Kristen Vu

Academic Year

2021/2022

Abstract

Introduction

Radiation therapy has been limited in the treatment of locally advanced pancreatic cancer. This is due to the dose tolerance to nearby organs at risk and breathing motion. Advancements in radiation treatment technology have now allowed pancreatic patients to be treated to higher doses in fewer fractions using stereotactic body radiotherapy treatment. With the use of MRI-guided treatments, using the ViewRay MRIdian linac, doses can be escalated using online adaptive treatment planning and real time tracking. However, there has yet to be an optimal breathhold technique investigated that can aid in this process.

Methods

Five patients that had been previously treated on the institutions ViewRay MRIdian linac to the pancreas were evaluated. A deep inspiration and end exhale plan were created for each patient using the ViewRay TPS. The treatment goals followed the SMART trial protocol guidelines. The prescription was 50 Gy treated in 5 f(x)s at least every other day. CTV goal coverage was 100% of the volume to 95% of the prescription dose and luminal OARs (stomach, duodenum, small intestine, and large intestine) to not exceed 33 Gy to 0.5 cc. A step and shoot intensity modulated radiation therapy technique was used.

Results

A nonparametric sign test was performed, and there was no statistically significant difference in the coverage of the CTV by the 95% isodose line. There was also no significant data found in the volume of the duodenum or stomach that received 33 Gy to 0.5 cc or the volume of the two organs within the zPTV_PRV30 planning ring.

Conclusion

An optimal gating technique was not discovered. A larger study group and further research is necessary to produce significant data.

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