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Design and evaluation of electron beam energy degraders for breast boost irradiation

Cited 4 time in Web of Science Cited 4 time in Scopus
Authors
Park, Jong In; Ha, Sung Whan; Kim, Jung-in; Lee, Hyunseok; Lee, Jaegi; Kim, Il Han; Ye, Sung-Joon
Issue Date
2016-08-31
Publisher
BioMed Central
Citation
Radiation Oncology, 11(1):112
Keywords
Electron energy degraderBreast boost irradiationMonte Carlo simulationLinear accelerator
Abstract
Background
For breast cancer patients who require electron boost energies between 6 and 9 MeV, an energy degraders (ED) in the 9 MeV beamline was specially designed and manufactured to increase the skin dose of 6 MeV and to reduce the penetration depth of 9 MeV beams.

Methods
We used Monte Carlo (MC) techniques as a guide in the design of ED for use with linear accelerators. In order to satisfy percent depth dose (PDD) characteristics and dose profile uniformity in water, the shape and thickness of Lucite® ED in the 9 MeV beamline was iteratively optimized and then manufactured. The ED geometry consists of a truncated cone attached on top of a plane plate, with total central thickness of 1.0 cm. The ED was placed on the lower most scraper of the electron applicator. The PDDs, profiles, and output factors were measured in water to validate the MC-based design.

Results
Skin doses with the EDs increased by 8–9 %, compared to those of the 9 MeV beam. The outputs with the EDs were 0.882 and 0.972 for 10 × 10 and 15 × 15 cm2 cones, respectively, as compared to that of a conventional 9 MeV beam for a 10 × 10 cm2 cone. The X-ray contamination remained less than 1.5 %. In-vivo measurements were also performed for three breast boost patients and showed close agreement with expected values.

Conclusions
The optimally designed ED in the 9 MeV beamline provides breast conserving patients with a new energy option of 7 MeV for boost of the shallow tumor bed. It would be an alternative to bolus and thus eliminate inconvenience and concern about the daily variation of bolus setup.
Language
English
URI
http://hdl.handle.net/10371/109836
DOI
https://doi.org/10.1186/s13014-016-0686-7
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Graduate School of Convergence Science and Technology (융합과학기술대학원)Dept. of Transdisciplinary Studies(융합과학부)Journal Papers (저널논문_융합과학부)
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