SU-E-T-289: On the Use of a Diode Array for the Commissioning of Dynamically-Wedged Asymmetric Fields Generated by Varian EDW's in the Pinnacle Treatment Planning System

Medical Physics
M AhmadR Nath

Abstract

To present a validation study of enhanced dynamic wedges (EDWs) implemented into Pinnacle3 treatment planning system (TPS) using a diode array, Monte Carlo (MC) simulation, and measurements. Modeling of EDW dose distribution in the Pinnacle3 TPS is based on a combination of open-field beam data and the Varian 'Golden Segmented Treatment Table' (GSTT) unique to each photon beam. To validate the EDW models, dose profiles of 6- and 10-MV photon beams from a Clinac 2100C/D were measured in virtual water at depths from near- surface to 30 cm for a wide range of asymmetric field sizes and wedge angles using the Profiler-2 diode array system. The EDW output factors for asymmetric fields were measured in solid water using a small-volume cylindrical ionization chamber placed at a depth of 10 cm on the central axis. In addition, absolute doses on central axis at depths of 5, 10, 15 and 20 cm were measured in virtual water using a small-volume cylindrical chamber for comparison with the collapsed-cone convolution (CCC) calculations. The 6- and 10-MV photon beams emerging from the treatment head of the Clinac 2100C/D were fully simulated using the Monte Carlo code BEAMnrc and DOSXYZnrc. This code was used to calculate the central-axis perc...Continue Reading

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