A simple technique was developed for using an imaging plate (IP) to estimate the individual concentrations of radon progeny in the air. The objective of this technique is to survey concentrations in high-humidity environments, such as caves, utility mains, and underground facilities. An IP called BAS-III, which performs well in extremely humid environments, was selected. The sampling flow rate was 65 liters per minute by a 47 mm-dia. glass-fiber filter (GF/F), and the grab sampling time was determined to be 5-10 minutes. One minute after the air sampling, the surface of the filter was attached directly to the IP in a prepared cassette. This was repeated six times for 10 minutes, for a total exposure of 60 minutes. Six values of Photo-Stimulated Luminescence (PSL) indicating the decay curve of the radon progeny sampled on the filter were analyzed. In environments with extremely high concentrations of radon, more accurate measurements can be obtained by making a simple distinction between PSL values for α and β rays. The lower detection limit for the equilibrium equivalent concentration (EEC) of radon was estimated to be about 20 Bqm-3. This system can be successfully adopted in humid areas.
Radon-222 (222Rn) is a good indicator for analyzing the speed at which surface water infiltrates the ground and reaches groundwater. Preferential flow, which is very fast, is expected to occur when the ground surface is inundated. Piston flow, which is very slow, is expected to occur when the ground surface is not inundated but is only sprinkled with water such as during a light rainfall. We hypothesized that preferential flow would reduce the222Rn concentration in groundwater but that piston flow would not ; our study verified this hypothesis experimentally. We then measured222Rn concentrations in groundwater for one year in lowland and upland locations.222Rn concentrations in groundwater decreased at the lowland site, where the ground surface was inundated by irrigation and heavy rainfall, while222Rn concentrations in groundwater did not decrease at the upland site, where the ground surface was not inundated.
Cerebral blood flow (CBF) measured with two different products of N-Isopropyl-4-lodoamphetamine (123I) Hydrochloride Autoradiography (IOF and IMP) was compared within 9 subjects without cerebrovascular disorders or other brain diseases (3 men, 6 women) . Qualitative assessments of CBF were not different within the products in all subjects, but quantitative value was slightly different in some subjects.