RBE andw_Rvalues of Auger emitters and low-range beta emitters with particular reference to tritium

Abstract

An apparent disparity exists between RBE (relative biological effectiveness) values for low-range beta and Auger emitters, and the current value for their radiation weighting factor (w(R)). This paper presents evidence that the current w(R) value of unity for these nuclides is inconsistent with most RBE evidence and should be increased by a factor of two to three. It recommends that the ICRP should clearly state that the most appropriate RBE value for these nuclides, and not the w(R) value, should be used in specific dose calculations, retrospective dose estimations and epidemiological studies. The ICRP should also publish guidance as to the methods and data sources that could be used for these RBE values.

Radiation-Induced Thyroid Stunning: Differential Effects of 123I, 131I, 99mTc, and 211At on Iodide Transport and NIS mRNA Expression in Cultured Thyroid Cells

“…Low-energy electrons (E # 50 keV) such as Auger electrons and a-particles ionize matter more densely than do photons or conventional electrons with higher energy, resulting in higher RBE. Auger electrons have RBE values of 1.5-40 depending on the electron energy and the location of the radionuclide, because of the limited range of these particles (25). Likewise, reported RBE values for the a-particle emitter 211 At vary between 1.5 and 25 for different tissues, experimental conditions, and endpoints (26)(27)(28)(29)(30)(31)(32)(33).…”

Commentary: childhood cancer near nuclear power stations

“…The uncertainties from each model have to be combined to gain an idea of the overall uncertainty in the final dose estimate [44]. Further uncertainties are introduced by unconservative radiation weighting factors and tissue weighting factors in official models [45]. The cumulative uncertainty in dose estimates could be very large as recognised by the report of the UK Government's CERRIE Committee [46].…”

Integrating Informative Priors from Experimental Research with Bayesian Methods

“…We consider tritium and gamma doses independently in units of Gray (Gy). 19 Estimated annual whole-body dose values in Sieverts (Sv)—the sum of gamma, tritium, and neutron doses—are available for all employment years; 6% of these records were estimated using a “nearby” method, previously described in Richardson et al 16 Annual whole-body dose estimates were utilized to derive annual tritium dose estimates for those person-years with missing information regarding the contribution of tritium to their cumulative annual whole-body dose. In total, there are 56.2 Gy of individual, annual tritium dose records, of which 4.3 Gy (7.7%) were estimated through use of a job-exposure matrix.…”