Abstract
SU-E-T-564: Multi-Helix Rotating Shield Brachytherapy for Cervical Cancer
Medical physics (Lancaster), Vol.42(6), pp.3465-3465
06/15/2015
DOI: 10.1118/1.4924926
Abstract
Purpose: To present a novel and practical brachytherapy technique, called multi-helix rotating shield brachytherapy (H-RSBT), for the precise positioning of a partial shield in a curved applicator. H-RSBT enables RSBT delivery using only translational motion of the radiation source/shield combination. H-RSBT overcomes the challenges associated with previously proposed RSBT approaches based on a serial (S-RSBT) step-and-shoot delivery technique, which required independent translational and rotational motion. Methods: A Fletcher-type applicator, compatible with the combination of a Xoft Axxent™ electronic brachytherapy source and a 0.5 mm thick tungsten shield, is proposed. The wall of the applicator contains six evenly-spaced helical keyways that rigidly define the emission direction of the shield as a function of depth. The shield contains three protruding keys and is attached to the source such that it rotates freely. S-RSBT and H-RSBT treatment plans with 180° and 45° azimuthal emission angles were generated for five cervical cancer patients representative of a wide range of high-risk clinical target volume (HR-CTV) shapes and applicator positions. The number of beamlets used in the treatment planning process was nearly constant for S-RSBT and H-RSBT by using dwell positions separated by 5 and 1.7 mm, respectively, and emission directions separated by 22.5° and 60°, respectively. For all the treatment plans the EQD2 of the HR-CTV was escalated until the EQD{sub 2cc} tolerance of either the bladder, rectum, or sigmoid colon was reached. Results: Treatment times for H-RSBT tended to be shorter than for S-RSBT, with changes of −38.47% to 1.12% with an average of −8.34%. The HR-CTV D{sub 90} changed by −8.81% to 2.08% with an average of −2.46%. Conclusion: H-RSBT is a mechanically feasible technique in the curved applicators needed for cervical cancer brachytherapy. S-RSBT and H-RSBT dose distributions were clinically equivalent for all patients considered, with the H-RSBT deliveries tending to be faster. Ryan Flynn has ownership interest in pxAlpha, LLC, which is a startup company developing a rotating shield brachytherapy system.
Details
- Title: Subtitle
- SU-E-T-564: Multi-Helix Rotating Shield Brachytherapy for Cervical Cancer
- Creators
- H Dadkhah - University of Iowa Hospitals and ClinicsX Wu - University of IowaR Flynn - University of IowaY Kim - University of Iowa
- Resource Type
- Abstract
- Publication Details
- Medical physics (Lancaster), Vol.42(6), pp.3465-3465
- DOI
- 10.1118/1.4924926
- ISSN
- 0094-2405
- eISSN
- 2473-4209
- Language
- English
- Date published
- 06/15/2015
- Academic Unit
- Neurology; Community and Behavioral Health; Radiation Oncology
- Record Identifier
- 9984315655202771
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