adon Dosimetry

Inhaled radon (222Rn) progeny are the most important source of irradiation of the human respiratory tract. Epidemiological studies of underground miners of uranium and other minerals have provided reasonably firm estimates of the risk of lung cancer associated with exposure to radon progeny. It is well established that the absorbed radon dose in the lung is mainly due to radon progeny, but not the radon gas itself. Therefore, long-term measurements of the concentrations of radon progeny or the equilibrium factor F, the size distribution of radon progeny and the unattached fraction fp of the potential alpha energy concentration are needed to accurately assess the health hazards contribution from radon progeny.
Resources
Book chapter: Nikezic, D., Yu, K.N., "Computer Simulation of Radon Measurements with Nuclear Track Detectors", 2007, in Computer Physics Research Trends, Ed. S. J. Bianco, (Nova Science Publishers: New York), p. 119-150. (download pdf version) (purchase book)
Book chapter: Yu, K.N., Nikezic, D., "Long-Term Measurements of Radon Progeny Concentrations with Solid State Nuclear Track Detectors", 2009, in Nuclear Track Detectors: Design, Methods and Applications, Eds. Maksim Sidorov and Oleg Ivanov, (Nova Science Publishers: New York) p. 107-131. (download pdf version) (purchase book)
Review paper: Yu, K.N., Lau, B.M.F., Nikezic, D., “Assessment of Environmental Radon Hazard Using Human Respiratory Tract Models", 2006, Journal of Hazardous Materials, 132, 98-110. (download pdf version).

Invited talk (22 ICNTS, Barcelona 2004): Yu, K.N., Nikezic, D., Ng, F.M.F., Leung, J.K.C., "Long-term Measurements of Radon Progeny Concentrations with Solid State Nuclear Track Detectors", 2005, Radiation Measurements, 40, 560-568. (download pdf version).

Invited talk (23 ICNTS, Beijing 2006): Yu, K.N., Leung, S.Y.Y., Nikezic, D., Leung, J.K.C., "Equilibrium factor determination using SSNTDs", 2008, Radiation Measurements, 43 (Suppl. 1), S357-S363. (download pdf version).

 

Long-term Measurements of Equilibrium Factor (F) and Unattached Fraction (fp)

 

Dosimetric Modeling

 

Microdosimetry

The most updated dosimetric lung model is the one published by the International Commission on Radiological Protection (ICRP) in their ICRP66 report. In their approach, the dose is calculated in the layers containing the sensitive cells by assuming that the dose values in the sensitive cells are the same as those in the layers. By using a micro-dosimetric approach in which the energy of alpha particles deposits only in the nuclei of sensitive cells, the DCC has been lowered by about one-third (from 15 mSv/WLM down to approximately 10 mSv/WLM). The most recent attempt was the consideration of killing of target cells through an effect-specific track length model. To focus on the relevant part of the absorbed dose in the cell nuclei, the absorbed dose, which causes cell-killing is discarded in the final calculations of the DCC. Following this approach, the calculated DCC has become 3.4 mSv WLM-1 which is very close to the epidemiologically derived value of ~4 mSv WLM-1.
  Publications
  • Nikezic, D., Yu, K.N., "Alpha hit frequency due to radon decay products in human lung cells", 2001, International Journal of Radiation Biology, 77, 559-565.
  • Nikezic, D., Yu, K.N., "Micro-dosimetric calculation of absorption fraction and the resulted dose conversion factor for radon progeny", 2001, Radiation and Environmental Biophysics, 40, 207-211.
  • Nikezic, D., Yu, K.N., "Distributions of Specific Energy in Sensitive Layers of Human Respiratory Tract", 2002, Radiation Research, 157, 92-98.
  • Nikezic, D., Yu, K.N., "Alpha particle lineal energy spectra for the human lung", 2002, International Journal of Radiation Biology, 78, 605-609.
  • Nikezic, D., Lau, B.M.F., Stevanovic, N., Yu, K.N., “Absorbed Dose in Target Cell Nuclei and Dose Conversion Coefficient of Radon Progeny in the Human Lung”, 2006, Journal of Environmental Radioactivity, 89, 18-29.
  • Lau, B.M.F., Nikezic, D., Yu, K.N., "Killing of target cells due to radon progeny in the human lung", 2006, Radiation Protection Dosimetry, 122, 534-536.
 

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Nuclear Radiation Unit
Department of Physics and Materials Science
City University of Hong Kong
Tat Chee Ave, Kowloon Tong, Hong Kong
Email: apnru@cityu.edu.hk

 

Page last modified on 17-Jan-2012

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