Document Type


Date of Degree

Summer 2012

Degree Name

MS (Master of Science)

Degree In

Biomedical Engineering

First Advisor

Flynn, Ryan T

First Committee Member

Flynn, Ryan T

Second Committee Member

Reinhardt, Joseph M

Third Committee Member

Bayouth, John E

Fourth Committee Member

Kim, Yusung


Purpose: To assess rotating shield brachytherapy (RSBT) delivered with the electronic brachytherapy (eBT) source comparing to intracavitary (IC) and intracavitary plus supplemental interstitial brachytherapy (IC+IS BT) delivered with a conventional 192Ir radioactive source.

Method and Materials: IC, IC+IS and RSBT treamtent plan were simulated for 5 patients with bulky (>40 cc) cervical cancer. One BT plan for each patient (fraction 1) guided by magnetic resonance imaging (MRI) was used in our treatment planning system (TPS). A bio- and MRI-compatible polycarbonate (Makrolon Rx3158) intrauterine applicator was simulated for IC and RSBT, and the Vienna applicator was simulated for IC+IS BT. 192Ir was used as the radiation source of IC and IC+IS BT, and the Xoft AxxentTM eBT source was used for RSBT. A 0.5 mm thick tungsten shield was used for RSBT with different azimuthal and zenith angles, which reduced radiation transmission through the shield to less than 0.1%. The total dose delivered was calculated as the external beam radiation therapy (EBRT) dose plus the BT dose delivered over five treatment fractions.

Results: RSBT and IC+IS BT had higher dose conformity in terms of the minimum dose to the hottest 90% (D90) of the high-risk clinical target volume (HR-CTV) than IC BT for all the patients. The advantage of RSBT over IC+IS BT was dependent on the shield emission angle, tumor shape and tandem applicator location. The delivery time of RSBT was increased as finer emission angle were selected.

Conclusions: RSBT is a less-invasive potential alternative to conventional IC and IC+IS BT for treating bulky cervical cancer. RSBT delivery times are clinically acceptable if proper emission angle is selected based on the tumor shape and tandem applicator location.


cervical cancer, Electronic brachytherapy, GEC-ESTRO, RS-IMBT


vii, 26 pages


Includes bibliographical references (pages 25-26).


Copyright 2012 Wenjun Yang