Charles A Potter | PubMed Health

PubMed2005

Internal dosimetry: a review.

The field history and current status of internal dosimetry is reviewed in this article. Elements of the field that are reviewed include standards and models, derivation of dose coefficients and intake retention fractions, bioassay measurements, and intake and dose calculations. In addition, guidance is developed and provided as to the necessity of internal dosimetry for a particular facility or operation and methodology for implementing a program. A discussion of the purposes of internal dosimetry is included as well as recommendations for future development and direction.

Algorithms↗

PubMed2004

Internal dosimetry--a review.

The field history and current status of internal dosimetry is reviewed in this article. Elements of the field that are reviewed include standards and models, derivation of dose coefficients and intake retention fractions, bioassay measurements, and intake and dose calculations. In addition, guidance is developed and provided as to the necessity of internal dosimetry for a particular facility or operation and methodology for implementing a program. A discussion of the purposes of internal dosimetry is included as well as recommendations for future development and direction.

Algorithms↗

PubMed2004

Application of the ICRP clarification of the tritium metabolic model.

In 2001, the International Commission on Radiological Protection published a clarification to the model for tritium metabolism. This clarification described the use of the gastrointestinal tract model, respiratory tract model, and transfer compartment in calculations of tritium metabolism. This information was used to derive intake retention fractions for tritium and tritium compounds including tritiated water, organically bound tritium, and tritides. In addition, dose coefficients were derived for tritide compounds including general categories described by the ICRP and some specific compounds.

Humans↗

PubMed2002

Development of a routine 125I bioassay program for athyrotic individuals using a pseudo uptake retention function.

Individuals working in iodine production require bioassay to determine if intakes have occurred. This is both to determine dose received for regulatory purposes and to verify whether workplace controls limiting the spread of contamination are adequate. Thyroid monitoring is commonly used as a bioassay technique to detect isotopes of iodine. If an individual performing iodine processing does not have a thyroid gland, other means must be used to determine intake and infer dose. Data was obtained from a previously published thesis that attempted to verify a model for absorption and retention of iodine by athyrotic individuals. These data were reevaluated to determine a pseudo uptake retention function. This analysis does not attempt to identify a biokinetic model, only to describe excretion of iodine and calculate an intake. Once the pseudo uptake retention function was derived, it was combined with the standard respiratory and gastrointestinal tract models as an inhalation intake retention function. A periodic urine bioassay protocol has been designed using the intake retention function described above and a conservative dose coefficient derived using organ dose coefficients for reference man, excluding the thyroid, and the appropriate weighting factors.

Biological Assay↗

PubMed2002

Intake retention fractions developed from models used in the determination of dose coefficients developed for ICRP publication 68--particulate inhalation.

ICRP Publication 68 presents dose coefficients developed using systems of new models for the respiratory tract and metabolism of certain elements. The utility of these dose coefficients and associated models is limited without a method for calculating intake from bioassay results using the same models as in that publication. The calculation of a radionuclide intake requires values of expected fractions of the intake in bioassay samples collected at specific times after intake. The general system of models has been solved using a commercial software package and a method for solution of systems of first-order linear differential equations that uses eigenvectors and eigenvalues derived from the system of equations. The result of this work is a series of tables of fractions of acute inhalation intakes for different bioassay methods, times, and compound classes for intakes for those elements listed in ICRP Publication 68. The values in these tables can be used for intake calculations, development of bioassay frequencies, and development of action levels.

Administration, Inhalation↗