By a News Reporter-Staff News Editor at Health & Medicine Week -- Investigators publish new report on Therapeutics. According to news reporting out of Brisbane, Australia, by NewsRx editors, research stated, "Intensity modulated radiotherapy (IMRT) treatments require more beam-on time and produce more linac head leakage to deliver similar doses to conventional, unmodulated, radiotherapy treatments. It is necessary to take this increased leakage into account when evaluating the results of radiation surveys around bunkers that are, or will be, used for IMRT."
Our news journalists obtained a quote from the research from the Queensland University of Technology, "The recommended procedure of applying a monitor-unit based workload correction factor to secondary barrier survey measurements, to account for this increased leakage when evaluating radiation survey measurements around IMRT bunkers, can lead to potentially costly overestimation of the required barrier thickness. This study aims to provide initial guidance on the validity of reducing the value of the correction factor when applied to different radiation barriers (primary barriers, doors, maze walls, and other walls) by evaluating three different bunker designs. Radiation survey measurements of primary, scattered, and leakage radiation were obtained at each of five survey points around each of three different radiotherapy bunkers and the contribution of leakage to the total measured radiation dose at each point was evaluated. Measurements at each survey point were made with the linac gantry set to 12 equidistant positions from 0 to 330, to assess the effects of radiation beam direction on the results. For all three bunker designs, less than 0.5% of dose measured at and alongside the primary barriers, less than 25% of the dose measured outside the bunker doors and up to 100% of the dose measured outside other secondary barriers was found to be caused by linac head leakage. Results of this study suggest that IMRT workload corrections are unnecessary, for survey measurements made at and alongside primary barriers. Use of reduced IMRT workload correction factors is recommended when evaluating survey measurements around a bunker door, provided that a subset of the measurements used in this study are repeated for the bunker in question."
According to the news editors, the research concluded: "Reduction of the correction factor for other secondary bather survey measurements is not recommended unless the contribution from leakage is separately evaluated."
For more information on this research see: Correcting radiation survey data to account for increased leakage during intensity modulated radiotherapy treatments. Medical Physics, 2013;40(11):116-121. Medical Physics can be contacted at: Amer Assoc Physicists Medicine Amer Inst Physics, Ste 1 No 1, 2 Huntington Quadrangle, Melville, NY 11747-4502, USA. (American Association of Physicists in Medicine - www.aapm.org; Medical Physics - online.medphys.org/)
Our news journalists report that additional information may be obtained by contacting T. Kairn, Queensland University of Technology, Fac Sci & Engn, Brisbane, Qld 4000, Australia. Additional authors for this research include S.B. Crowe and J.V. Trapp (see also Therapeutics).
Keywords for this news article include: Brisbane, Therapeutics, Conformal Radiotherapy, Australia and New Zealand, Intensity-Modulated Radiotherapy
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