The radiation doses absorbed by major organs of males and females were studied from three types of dental X-ray devices. The absorbed doses from cone-beam computed tomography (CBCT), panoramic and intraoral X-ray machines were in the range of 0.23–1314.85 μGy, and were observed to be high in organs and tissues located in or adjacent to the irradiated area, there were discrepancies in organ doses between male and female. Thyroid, salivary gland, eye lens and brain were the organs that received higher absorbed doses. The organ absorbed doses were considerably lower than the diagnostic reference level for dental radiography in China. The calculated effective radiation doses for males and females were 56.63, 8.15, 2.56 μSv and 55.18, 8.99, 2.39 μSv, respectively, when using CBCT, the panoramic X-ray machine and intraoral X-ray machine. The effective radiation dose caused by CBCT was much higher than those of panoramic and intraoral X-ray machines.

Naturally occurring beryllium-7 ( 7 Be) and lead-210 ( 210 Pb) serve as powerful tracers in atmospheric studies. In this study, 7 Be and 210 Pb were simultaneously measured in atmospheric aerosols and deposition samples for an entire year (from January to December 2017) in Shenzhen, South China. The activity concentrations of the airborne 7 Be and 210 Pb ranged from 0.33 to 9.42 mBq m -3 (averaging 3.23 mBq m -3 ) and from 0.59 to 4.72 mBq m -3 (averaging 1.58 mBq m -3 ), respectively, and were observed to be high during the winter but low during the summer. Moreover, the relatively high 210 Pb concentration was probably due to the elevated level of radon in this region's soil. The deposition fluxes of the 7 Be and 210 Pb were found to range from 0.25 to 3.04 Bq m -2 day -1 (averaging 1.57 Bq m -2 day -1 ) and from 0.34 to 1.31 Bq m -2 day -1 (averaging 0.73 Bq m -2 day -1 ), respectively. The temporal trends of these fluxes were largely influenced by rainfall and the origin and pathway of air masses, as well as by atmospheric circulation. Based on their concentrations in the aerosols and their deposition fluxes, the average deposition velocities of 7 Be and 210 Pb were calculated to be 0.83 and 0.62 cm s -1 , respectively. The deposition velocities of both radionuclides correlated well with the amount of rainfall, indicating that precipitation plays a crucial role in removing 7 Be and 210 Pb from the air. The activity size distributions of these nuclides combined with the characteristic meteorological conditions in this region resulted in high deposition velocities during summer and low ones during winter.

This study aims to measure the radiation doses and estimate the associated lifetime attributable risks (LARs) of cancer incidence resulted from gemstone spectral imaging (GSI) and conventional polychromatic imaging (CPI) in computed tomography (CT) examinations. Organ doses were measured using an adult phantom and thermoluminescent dosimeters. Four scans, including head CT, thorax CT, abdomen CT and pelvis CT, were performed on the phantom. LARs of cancer incidence were estimated for Chinese population and US population. The effective doses of thorax CT was the highest. With CPI, it was 7.94 mSv for females, and 7.74 mSv for males. With GSI, it was 6.81 mSv for females, and 7.69 mSv for males. With GSI, the corresponding LARs for males and females aged 20-70 years were less than 0.062% and 0.154%, respectively. With CPI, these values were less than 0.074% and less than 0.171%, respectively. The LARs decreased in both US population and Chinese population when exposed age increased, with thorax scan causing the highest risk. GSI does not increased radiation exposure or cancer risk compared to CPI. These findings may allow the application of GSI in patients referred for CT.