The Accuracy of Analytical Anisotropic Algorithm Version 8.9.17 on Wedge Factor and 2D Dose Distribution for Symmetric and Asymmetric Fields of Enhanced Dynamic Wedge
Keywords:
Enhanced dynamic wedge, Analytical anisotropic algorithm, 2D dose distribution, MapCheck, Wedge factorAbstract
Background: The technique of Enhanced Dynamic Wedge (EDW) was introduced to establish the wedge shape dose distribution. Prior to the application in clinical situations was required the verification of dose calculation to reproduce the EDW in treatment planning system (TPS).
Objective: To evaluate the accuracy of Anisotropic Analytical Algorithm (AAA) version 8.9.17 for the EDW in symmetric and asymmetric fields.
Methods: Comparison between measured and calculated Enhanced Dynamic Wedge Factors (EDWFs) and 2D dose distributions were investigated for 6 MV photon beam of 10o, 30o, and 60o EDW non field size 10x10 cm2, 15x15 cm2 and 20x20 cm2 for symmetric and asymmetric fields in wedge and non-wedge direction. The points of evaluation for EDWF were the central and off-axis for each situation.
Results: The percentage deviation between measured and calculated EDWFs was less than 1% for all geometries, both symmetric and asymmetric of EDW field. For the off-axis points, the maximum deviation was 1.22% for asymmetric field Y2 = 0 (in wedge direction) of field size 10x10 cm2 for EDW 60o. The comparison of 2D dose distributions using MapCHECK2 showed good agreement between measured and calculated with the AAA algorithm with a 100% passing rate for nearly all geometries of EDW fields. The minimum passing rate found in asymmetric field size 20x20 cm2 (X1 = 0 and Y2 = 0) of EDW 10o was 94.9%.
Conclusions: The results of this study confirm the accuracy of the AAA calculations in modeling the enhanced dynamic wedge both symmetric and asymmetric fields.
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