Calculation of effective Enhanced Dynamic Wedge Factors from Segmented Treatment Tables for symmetric and asymmetric photon beams
نویسندگان
چکیده
Purpose: A method for determination of effective transmission factors of the Varian Enhanced Dynamic Wedge (EDW) is investigated. Methods and Material: The model assumes that the EDW factor equals the fraction of monitor units delivered to the geometrical center of the beam. This ”MU fraction approximation” is verified by comparing its predictions with measurements of a series of symmetric and asymmetric fields at a Clinac 2300C/D with 6 MV and 18 MV photon beams. Results: Calculated and measured EDW factors agree typically within 1 %. Mean deviations are found to be less than 0.3 % for 6 MV and 0.2 % for 18 MV photons. Conclusion: Although the model is based on simplified assumptions, its accuracy is comparable with more complicated algorithms and quite sufficient for clinical use.
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