Gamma and Beta Absorbed Dose Conversion Coefficients in the Range from 10 keV to 10 MeV for Accidental Exposures From Point Sources Placed in Clothing in Proximity to the Body.

Retrospective dose assessment following acute radiation exposures during radiological incidents can be difficult and inaccurate due to the large uncertainties associated with dose estimation. However, rapid and accurate dose assessment is critical following an incident so that appropriate treatment can be provided to the patient as early as possible. Incident dose assessment relies heavily on biological dosimetry with corresponding large uncertainties for inhomogeneous exposures, resulting from the estimates of whole-body doses, while the assessment of absorbed doses to individual tissues might actually be more appropriate for acute radiation exposures. Incident exposure scenarios for orphan sources placed in a breast or back pants pocket were modeled using the International Commission on Radiological Protection computational reference male and female and the Monte Carlo N-particle code MCNP6 to compute absorbed dose conversion coefficients for organs of interest for monoenergetic photon and beta sources. The absorbed dose conversion coefficients are intended for use in conjunction with source information to rapidly estimate absorbed doses to organs of interest from radiological sources in one of the two pocket geometries. Absorbed dose conversion coefficients also have been calculated specifically for Co, Cs, and Ir. Those absorbed dose conversion coefficients were applied to data from a radiological incident in Yanango, Peru, for comparison with published dose assessments; the results agree within 20%. The conversion coefficients are expected to provide an accurate tool for assessing doses for the modeled geometries, provided uncertainties due to the exact source-body geometry and exposure time are considered.