Program Information
Non-Scanning Dosimetric Data Analysis of 113 Units of Elekta VersaHD LINAC
M Ji , M Ji*, Elekta, Inc, St. Louis, MO
Presentations
TU-L-GePD-J(B)-3 (Tuesday, August 1, 2017) 1:15 PM - 1:45 PM Room: Joint Imaging-Therapy ePoster Lounge - B
Purpose: To analyze the non-scanning data of output factors and collimator scatter factors of Elekta VersaHD LINACs, to determine the descriptive statistics characteristics of the factors of different energies photon beams.
Methods: The non-scanning data of output factors in water (Scp), collimator scatter factors in air (Sc) of open and wedge fields of Elekta VersaHD LINACs submitted worldwide for beam modeling from 05/27/2014 to 02/13/2017 were collected. The Scp for square fields measured at 10cm depth, 90cm source-to-surface distance (SSD), the Sc for square and rectangular fields measured at 100cm SSD, for flattened 6MV, 10MV, 15MV, and flattening filter-free 6FFF and 10FFF energies were analyzed with R software. The wedge factors in water of 10x10cm field (WF10) for 60 degree wedge measured at 10cm depth, 90cm SSD, of 6MV, 10MV, 15MV were analyzed too.
Results: The data sets included data from 112 LINACs. For open fields, the data counts were 112, 111, 58, 102 and 84 of 6MV, 10MV, 15MV, 6FFF and 10FFF, respectively. For wedge fields the counts were 100, 96 and 53 of 6MV, 10MV and 15MV, respectively. The descriptive statistic information of Scp and Sc for open and wedge fields was summarized. For all energies, the open fields Scp of 1x1cm2 and 40x40cm2 had large variations. For wedge fields, the Scp and Sc of 40x30 cm2 had large variations. The analysis showed that for a certain energy, measured WF10 values difference could be up to 7% from the mean value.
Conclusion: This work presents the descriptive statistics information of non-scanning dosimetry data of Elekta VersaHD 6MV, 10MV, 15MV, 6FFF and 10FFF photon beams, which can be used as references when physicists collect the data. Physicists should be cautious when getting data of small fields and wedge fields.
Funding Support, Disclosures, and Conflict of Interest: I am working for Elekta, Inc.
Contact Email: