Is based on the radionuclide(s) involved (see tables)
Should occur in consultation with a professional who is knowledgeable about treating radiological injuries such as a hospital Radiation Safety Officer, nuclear medicine physician, radiation oncologist, and/or a toxicologist
Decrease radiation absorbed dose
Reduce the risk of future biological effects.
Many of the countermeasures listed in the table on REMM have an unfavorable risk-to-benefit ratio when used to treat persons having low levels of internal contamination.
Most authorities do not recommend treatment of internal contamination when the body burden is less than one annual limit of intake (ALI)8.
Treatment is strongly recommended when the body burden exceeds 10 ALI.
For internal contamination levels greater than 1 ALI and less than 10 ALI, clinical judgment dictates treatment of internal contamination.
According to NCRP, ALI is an operational quantity defined originally by ICRP as the level of intake of radionuclide activity that would irradiate a person to the annual limit set by the ICRP for occupational (workplace) exposure7.
Per NCRP, this number is usually considered to be 0.05 sievert (5 rem) effective dose and 0.5 sievert (50 rem) equivalent dose to any exposed tissue. This equivalent dose is thought to be not only below the threshold at which deterministic health effects occur but also low enough to limit the incidence of stochastic health effects.
The ALI concept assumes continuous low level uptake, as could happen with an occupational exposure. The ALI concept was developed to protect workers, not members of the general public.
ALI was never intended for use as a measure of intake for persons internally contaminated as a result of radiological or nuclear incidents and certainly not for members of the public during events such as accidents or terrorist incidents, when intake might occur over a very short period of time.
Nevertheless, the ALI concept has been used by some clinicians when considering when to initiate countermeasures for individual members of the public who have been internally contaminated with radioactive materials as a result of a terrorist incident or unintentional event (e.g., transportation accident).
Clinical Decision Guide (CDG)
NCRP has updated its guidance on the management of persons internally contaminated with radionuclides.1, 2, 3 This update supersedes previously published guidance from NCRP5 and introduces a new operational quantity - the Clinical Decision Guide (CDG) - to replace the ALI as a decision-making tool. CDG values represent thresholds for initiating treatment with medical countermeasures and take into account both the acute (deterministic) and chronic (stochastic) effects of internalized radionuclides. CDGs for children (0-18 years) and pregnant women are defined as one-fifth the derived adult value.
Limits for Intakes of Radionuclides by Workers (ICRP Publication 30), International Commission on Radiological Protection. (Note: ICRP Publication 30 includes 10 separate documents published between 1979 and 1988. All are listed on ICRP Publications, but online access may be limited to libraries with electronic subscriptions.)