This paper presents the direct comparison between measurements and Monte Carlo ion chamber simulations employing the EGSnrc Monte Carlo code.
Surrounding 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 60Co 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.