Monitoring inhalation of thorium environmental radioactivity in humans with phoswich detector

Assessment of inhalation intake of thorium in humans is carried out by direct, indirect and thoron in breath measurement techniques. The assessment of thorium by direct method requires proper calibration of the detection system. In this paper we present the results of calibration of our detector systems for whole body/lung monitoring of humans for thorium. The thorax phantom developed by Japan Atomic Energy Research Institute, which is popularly known as JAERI phantom has been used for calibration with its thorium lung set. The measurement is carried out with (20.3 cm dia x 0.3 cm thick) and (20.3 cm dia x 1.27 cm thick) primary NaI(Tl) Phoswich detectors, and (20.3 cm dia x 10.2 cm thick) NaI(Tl) detector systems in different geometries. The calibration factors obtained with JAERI phantom have been compared for phoswich and NaI(Tl) detector. (author)