Field output correction factors of small static field for IBA razor nanochamber

Abstract

Purpose. The goal of this work is present results of field output factors (OF) using an IBA CC003 (Razor NanoChamber) and compare these results with PTW 60019 (MicroDiamond) and IBA Razor Diode. The experimental results for IBA CC003 were also compared with Monte Carlo (MC) Simulation, using Penelope and Ulysses programs. In addition, field output correction factors () for IBA CC003 were derived with three different methods: (1) using PTW 60019 and IBA Razor as reference detectors; (2) comparison between MC and experimental measurements; and (3) using only MC.Material and Methods. The beam collimation included in this study were (1) square field size between 10 × 10 and 0.5 × 0.5 cm2 defined by the MLC and jaws and (2) cones of different diameters. For IBA CC003 it was determined the polarity and ion collection efficiency correction factors in parallel and perpendicular orientation.Results. The results indicate (1) the variation of polarity effect with the field size is relevant for the determination of OF using IBA CC003, especially for parallel orientation; (2) there is no significant variation of the ion collection efficiency with the field size using IBA CC003 in parallel orientation; (3) OF differences between IBA CC003 and PTW 60019/IBA Razor, and experimental and MC results, increase with decreasing field size;The results indicate (1) using the first and second method, increase with decreasing field size, which can be related with the influence of the volume effect and (2) using the third method, decrease with decreasing field size, which can be explained by the perturbation effect.Conclusions. Our results demonstrate the need of applying for IBA CC003 for 1 cm, to compensate for volume averaging and perturbations effects.