133Xe Gas concentration during the examinations of the lung ventilating scintigraphy using 133Xe for three cases, was measured continuously by the flow type ionization chamber to estimate effective dose equivalent to the operator. The air flow distribution of the examination room was also measured for reference to examining the behavior of 133Xe gas. The air around the patient lingers for few minutes or more. Based on the derived air concentration (DAC) in ICRP Publication 30, effective dose equivalent to the operator per examination was estimated to be 0.1-1.0μSv, which was lower than expected.
