By a News Reporter-Staff News Editor at Computer Weekly News -- Research findings on Oncology are discussed in a new report. According to news reporting out of London, United Kingdom, by VerticalNews editors, research stated, "To investigate the variability of the global gamma index (gamma) analysis in various commercial IMRT/VMAT QA systems and to assess the impact of measurement with low resolution detector arrays on gamma. Five commercial QA systems (PTW 2D-Array, Scandidos Delta4, SunNuclear ArcCHECK, Varian EPID, and Gafchromic EBT2 film) were investigated."
Our news journalists obtained a quote from the research from National Physical Laboratory, "The response of gamma analysis to deliberately introduced errors in pelvis and head & neck IMRT and RapidArc ™ plans was evaluated in each system. A theoretical gamma was calculated in each commercial QA system software (PTW Verisoft, Delta4 software, SNC Patient, Varian Portal Dosimetry and IBA OmniPro, respectively), using treatment planning system resolution virtual measurements and compared to an independent calculation. Error-induced plans were measured on a linear accelerator and were evaluated against the error-free dose distribution calculated using Varian Eclipse ™ in the relevant phantom CT scan. In all cases, global gamma was used with a 20% threshold relative to a point selected in a high dose and low gradient region. The gamma based on measurement was compared against the theoretical to evaluate the response of each system. There was statistically good agreement between the predicted gamma based on the virtual measurements from each software (concordance correlation coefficient, rho© > 0.92) relative to the independent prediction in all cases. For the actual measured data, the agreement with the predicted gamma reduces with tightening passing criteria and the variability between the different systems increases. This indicates that the detector array configuration and resolution have greater impact on the experimental calculation of gamma due to under-sampling of the dose distribution, blurring effects, noise, or a combination. It is important to understand the response and limitations of the gamma index analysis combined with the equipment in use."
According to the news editors, the research concluded: "For the same pass-rate criteria, different devices and software combinations exhibit varying levels of agreement with the predicted gamma analysis."
For more information on this research see: A comparison of the gamma index analysis in various commercial IMRT/VMAT QA systems. Radiotherapy and Oncology, 2013;109(3):370-376. Radiotherapy and Oncology can be contacted at: Elsevier Ireland Ltd, Elsevier House, Brookvale Plaza, East Park Shannon, Co, Clare, 00000, Ireland. (Elsevier - www.elsevier.com; Radiotherapy and Oncology - www.elsevier.com/wps/product/cws_home/506042)
Our news journalists report that additional information may be obtained by contacting M. Hussein, Natl Phys Lab, London, United Kingdom. Additional authors for this research include P. Rowshanfarzad, M.A. Ebert, A. Nisbet and C.H. Clark.
Keywords for this news article include: London, Europe, Oncology, Software, United Kingdom
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