Measurements and EGSnrc Monte Carlo Simulations for Thimble Ion Chambers with Various Metal Caps at 60Co Beams

摘要

This paper presents the direct comparison between measurements and Monte Carlo ion chamber simulations employing the EGSnrc Monte Carlo codeSurrounding metal caps for a 1 cm3 ionization chamber (PTW30015) were varied both, in measurements and simulations. Absorbing caps made of iron, copper and aluminum alloy were manufactured each with wall thickness between 2 and 30 mm. As a radiation source, a Siemens Gammatron S ~(60)Co machine was used. Normalized dose values were compared and changes to the cross-sections used in the Monte Carlo simulations investigated.Results agreed within the range of the measurement uncertainties of -0.5%. Still, variations in photon cross-sections lead to significant changes in the results, highlighting the need of accurate input data for this type of investigation.