Study of commercial detector responses in non-equilibrium small photon fields of a 1000Â MU/min CyberKnife system

Perturbations due to volume averaging effect, active material effect and coating effect were investigated and quantified for five active detectors. Since these perturbations can cause opposite effects, wrong conclusions may be drawn regarding the radiological water-equivalence of detectors. Thus, we recommend performing such a study for each novel detector available on the market.