| Treatment vault shielding for a flattening filter-free medical linear accelerator. | |
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MedLine Citation:
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PMID: 19190359 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The requirements for shielding a treatment vault with a Varian Clinac 2100 medical linear accelerator operated both with and without the flattening filter were assessed. Basic shielding parameters, such as primary beam tenth-value layers (TVLs), patient scatter fractions, and wall scatter fractions, were calculated using Monte Carlo simulations of 6, 10 and 18 MV beams. Relative integral target current requirements were determined from treatment planning studies of several disease sites with, and without, the flattening filter. The flattened beam shielding data were compared to data published in NCRP Report No. 151, and the unflattened beam shielding data were presented relative to the NCRP data. Finally, the shielding requirements for a typical treatment vault were determined for a single-energy (6 MV) linac and a dual-energy (6 MV/18 MV) linac. With the exception of large-angle patient scatter fractions and wall scatter fractions, the vault shielding parameters were reduced when the flattening filter was removed. Much of this reduction was consistent with the reduced average energy of the FFF beams. Primary beam TVLs were reduced by 12%, on average, and small-angle scatter fractions were reduced by up to 30%. Head leakage was markedly reduced because less integral target current was required to deliver the target dose. For the treatment vault examined in the current study, removal of the flattening filter reduced the required thickness of the primary and secondary barriers by 10-20%, corresponding to 18 m(3) less concrete to shield the single-energy linac and 36 m(3) less concrete to shield the dual-energy linac. Thus, a shielding advantage was found when the linac was operated without the flattening filter. This translates into a reduction in occupational exposure and/or the cost and space of shielding. |
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Authors:
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Stephen F Kry; Rebecca M Howell; Jerimy Polf; Radhe Mohan; Oleg N Vassiliev |
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Publication Detail:
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Type: Journal Article Date: 2009-02-03 |
Journal Detail:
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Title: Physics in medicine and biology Volume: 54 ISSN: 0031-9155 ISO Abbreviation: Phys Med Biol Publication Date: 2009 Mar |
Date Detail:
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Created Date: 2009-02-10 Completed Date: 2009-06-03 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0401220 Medline TA: Phys Med Biol Country: England |
Other Details:
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Languages: eng Pagination: 1265-73 Citation Subset: IM |
Affiliation:
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Department of Radiation Physics, The University of Texas M.D Anderson Cancer Center, Houston, TX, USA. sfkry@mdanderson.org |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Humans Particle Accelerators* Radiation Protection / methods* Radiotherapy Planning, Computer-Assisted* Scattering, Radiation |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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