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 treatment 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 Axxent™ 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.
|Advisor:||Flynn, Ryan T.|
|Commitee:||Bayouth, John E., Flynn, Ryan T., Kim, Yusung, Reinhardt, Joseph M.|
|School:||The University of Iowa|
|School Location:||United States -- Iowa|
|Source:||MAI 51/02M(E), Masters Abstracts International|
|Subjects:||Biomedical engineering, Medical imaging, Oncology|
|Keywords:||Cervical cancer, Electronic brachytherapy, GEC-ESTRO, RS-IMBT|
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