Date Approved


Graduate Degree Type


Degree Name

Medical Dosimetry (M.S.)

Degree Program

Diagnostic & Treatment Sciences

First Advisor

Kristen Vu

Academic Year



Introduction: External beam radiation therapy for the treatment of prostate cancer is associated with side effects that result from ancillary dose to the neighboring bladder and rectum. Devices including hydrogel spacers have been developed and implemented in order to help spare dose to organs at risk (OAR) during these treatments, with primary focus on limiting dose to the rectum due to its greater radiosensitivity over the bladder. The hydrogel spacer may also be engaged in the improvement of bladder dose limitation by optimizing dose the space it creates in the treatment region.

Methods: This study is a retrospective dosimetric analysis of 10 early-stage subjects with prostate cancer. Two radiation therapy plans were created for each patient. The test plan allowed high doses in the hydrogel spacer rather than limiting dose to the spacer as normal tissue.

Results: The results indicated that allowing high doses into the hydrogel spacer did not yield statistically significant lower doses to the bladder compared to limiting dose to the spacer as normal tissue.

Conclusion: Expanding the margins where higher doses are directed is not beneficial in sparing multiple at risk organs in external beam radiation therapy treatments for prostate cancer.