Guidance on Selection of Radiation Type

Importance of Internal Dosimetry Model Used to Estimate Dose

For example, for some alpha-emitting radionuclides (such as plutonium and americium), older internal dosimetry models developed by the International Commission on Radiological Protection (ICRP) and documented in ICRP Publication 30 assume that deposition occurs at only a few sites (bone, liver, gonads, and, in cases of inhalation, the respiratory tract), and doses to other organs or tissues, which are not irradiated by alpha particles, are much lower than doses at sites of deposition. However, the newer internal dosimetry models for these radionuclides, as documented in ICRP Publication 67, also assume that a fraction of the activity absorbed into blood is deposited in soft tissues throughout the body, and this results in higher doses from alpha particles in organs or tissues other than the primary sites of deposition. The ICRP's newer internal dosimetry models are documented in ICRP Publications 67, 69, and 71.