Characterization of low-LET radiation fields for irradiation of biological samples using recombination chamber

Abstract

Irradiation of biological samples for biological dosimetry and radiobiological studies should be performed in well characterized radiation fields. The reference quantity for gamma and X-ray radiations is usually kerma in air, deter-mined with ionization chamber. The paper presents an example of characterization performed for X-rays using a thin-walled, reference ionization chamber. Standard procedure was completed with determination of Recombination Index of Radiation Quality (RIQ), determined with recombination chamber. Irradiations were performed at special stand supporting standard test tubes, which are commonly used in bio-logical dosimetry for blood samples. The influence of all elements of the supporting stand was carefully determined and taken into account in calculations of tissue kerma in blood. The RIQ values reflect microdosimetric parameters of the radiation. The measurements performed for unfiltered X-rays of different energies resulted in markedly higher values of RIQ, comparing to those measured for 137Cs or 60Co gamma radiation fields.