The Problem of Auger Emitters for Radiological Protection

Doses and risks from uranium are not increased significantly by interactions with natural background photon radiation

“…A number of authors (for example, Hofer (55) ) discuss alternative dosimetry systems. Bingham et al (56) referred in particular to the scheme used by the American Association of Physicists in Medicine (57,58) , which recommends a radiation weighting factor of 20 for all Auger emitters for stochastic effects, for the proportion bound to DNA. Using this scheme, and assuming 100 % binding to DNA, Goddu et al (59) considered the example of doses delivered within the testes from the Auger emitting radionuclides, 67 Ga, 99m Tc and 125 I, and showed that conventional dosimetry would underestimate the self-dose by factors of 4, 2 and 8 times, respectively.…”

Modeling Dose Deposition and DNA Damage Due to Low-Energy β–Emitters

“…A number of authors (see Hofer, 1998) discuss alternative dosimetry systems. Bingham et al (2000) refer in particular to the scheme used by the American Association of Physicists in Medicine (AAPM) (Howell, 1992;Sastry, 1992) which recommends a w R of 20 for all Auger emitters for stochastic effects, for the proportion bound to DNA. Using this scheme, and assuming 100% binding to DNA, Goddu et al (1996) considered the example of doses delivered within the testes from 67 Ga, 99m Tc and 125 I, and showed that conventional dosimetry would underestimate this self-dose by factors of about 4, 2 and 8 times, respectively.…”

“…Tables and Figures Table 2C.1 Calculated ratio of dose to the nucleus 39 Table 2C.2 Occurrence and physical characteristics of Auger emitters (from Bingham et al, 2000; with addition of 137m Ba) 41 Table 3A.1 Second event probabilities for decay of 90 Sr and 132 Te 56 Table 4A.1 Infant leukaemia following the Chernobyl accident by birth cohort 82 Table 4A.2 Leukaemia incidence in young children (1-3 or 1-4 years of age) following the Chernobyl accident, by birth cohort 83 Table 4A.3 Leukaemia incidence in infants and children (0-14 years of age) following the Chernobyl accident, by dose category, in ECLIS (Parkin et al, 1996) 83 Table 4A.4 Infant leukaemia in Great Britain, by birth cohort (using the Petridou et al definition of periods of birth) and geographical region 86 Table 4A.5 Infant leukaemia in Great Britain, by birth cohort (using the CERRIE definition of periods of birth) and geographical region 87 Table 4A.6 Excess relative risks of infant leukaemia estimated in four birth cohort studies 88 Table 4B.1 Classification of calendar years by bone marrow dose equivalent for fetus or 1 year old and by testis dose equivalent for adult, as used by Darby et al (1992) 93 Table 4B.2 Relative risk of childhood leukaemia incidence in Nordic countries for categories of exposure to weapons fallout 95 Table 4B.3 Leukaemia death and registration rates per 100,000 persons per year in wet and dry regions of Great Britain, based on post-natal dose equivalent to red bone marrow (Haynes and Bentham, 1995) 96 Table 4C.1 Summary of results of the studies of Alexander et al (1990) and Lloyd et al (2002) 102 Figure 2.1 Possible dose-response curves describing the excess risk of stochastic health effects at low doses of radiation 19 Figure 4A.1 Rate of incidence of infant (<1 year of age) leukaemia in Great Britain by three periods of birth and by three areas of birth, categorised by the level of Chernobyl contamination (see Table 4A.4). Error bars show 95% confidence intervals on rates 85 Figure 4A.2 Rate of incidence of infant (<1 year of age) leukaemia in Great Britain by four periods of bir...…”

“…Tritiated DNA precursors represent a special case for which apparently greater RBE values may be observed, but this may be regarded as a property of the location of the emitting nuclide (ie within DNA) rather than an inherent property of the tritium beta particle. Auger electron emissions with their very low energies, very short ranges, multiple electrons and greater ionisation densities are also a special case in which high RBE values can be observed (>10), but again as a consequence of nuclide location -ie only if the Auger emitter is bound to, or is in close proximity to, DNA (Bingham et al, 2000). (See Annex 2C.…”

Main Text

“…(27) In the case of radionuclides such as 67 Ga, 111 In, 125 I, and 201 T1, administered in forms which result in their uptake in cell nuclei, the minor fraction of the energy carried by Auger electrons may have a disproportionately large effect, owing to their very short range in tissue (Stepanek et al, 1996;Bingham et al, 2000;Taylor, 2000c;Kassis, 2004). The assumption made here, that the absorbed dose is distributed uniformly within the cell, may therefore result in underestimation of the risk.…”