Deriving detector-specific correction factors for rectangular small fields using a scintillator detector.

Deriving detector-specific correction factors for rectangular small fields using a scintillator detector.
J Appl Clin Med Phys. 2016 Nov 08;17(6):6433
Authors: Qin Y, Zhong H, Wen N, Snyder K, Huang Y, Chetty IJ
Abstract
The goal of this study was to investigate small field output factors (OFs) for flat-tening filter-free (FFF) beams on a dedicated stereotactic linear accelerator-based system. From this data, the collimator exchange effect was quantified, and detector-specific correction factors were generated. Output factors for 16 jaw-collimated small fields (from 0.5 to 2 cm) were measured using five different detectors including an ion chamber (CC01), a stereotactic field diode (SFD), a diode detector (Edge), Gafchromic film (EBT3), and a plastic scintillator detector (PSD, W1). Chamber, diodes, and PSD measurements were performed in a Wellhofer water tank, while films were irradiated in solid water at 100 cm source-to-surface distance and 10 cm depth. The collimator exchange effect was quantified for rectangular fields. Monte Carlo (MC) simulations of the measured configurations were also performed using the EGSnrc/DOSXYZnrc code. Output factors measured by the PSD and verified against film and MC calculations were chosen as the benchmark measurements. Compared with plastic scintillator detector (PSD), the small volume ion chamber (CC01) underestimated output factors by an average of -1.0% ± 4.9% (max. = -11.7% for 0.5 × 0.5 c...

Source: Journal of Applied Clinical Medical Physics - November 7, 2016 Category: Physics Authors: Qin Y, Zhong H, Wen N, Snyder K, Huang Y, Chetty IJ Tags: J Appl Clin Med Phys Source Type: research