Ac. James et A. Birchall, NEW ICRP LUNG DOSIMETRY AND ITS RISK IMPLICATIONS FOR ALPHA-EMITTERS, Radiation protection dosimetry, 60(4), 1995, pp. 321-326
Citations number
NO
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging","Nuclear Sciences & Tecnology
This paper follows on from Dr Bair's description of the new ICRP lung
model, by illustrating its practical application to the calculation of
dose coefficients for different forms of long-lived, alpha-emitting a
erosols of plutonium and uranium. At the other end of the dosimetric s
pectrum, the dosimetry of the short-lived, alpha-emitting progeny of r
adon are examined. The conclusion is that, when applied to radon proge
ny exposures, the new ICRP lung dosimetry provides an opportunity to e
xamine more critically the risk factors that are currently assumed for
alpha radiation doses received by lung tissues. The results of large
scale studies of lung cancer in uranium miners indicate that one Worki
ng Level Month (WLM) of exposure to radon progeny is equivalent in ter
ms of lifetime lung cancer risk to approximately 5 mSv of effective do
se. The currently recommended risk factors include the radiation weigh
ting factor (W-R(alpha)), the total detriment per sievert at high dose
rate (DE(H)), the dose and dose rare effectiveness factor (DDREF), an
d the lung-tissue weighting factor (W-T(lung)). However, consideration
of the uncertainties involved in calculating the effective dose per u
nit exposure using the new lung model with the currently recommended r
isk factors shows that it is very unlikely to be as low as 5 mSv per W
LM. The most likely estimate is threefold higher, about 15 mSv per WLM
. Can this argument be used to provide a more realistic value of a com
posite risk weighting factor for all alpha emitters in the lungs? If s
o, the appropriate lung cancer risk factor, say Omega = (WRWTlung)-W-a
lpha(DE(H))(DDREF) would be about 0.05 per Gy. The value published by
Dr Bair in 1976 from his classic study in dogs was 0.06 per Gy!