Answer to Question #4034 Submitted to "Ask the Experts"

Category: Doses and Dose Calculations — Basic dose information, dose quantities, units

The following question was answered by an expert in the appropriate field:

Is it possible to convert from amount of a radiolabeled substance (e.g., ¹⁴C) in Bq to effective dose (Sv) (and vice versa)? Or should this be determined experimentally?

Every radiolabeled substance will have a unique metabolic behavior in the body. This behavior, including the areas in the body where the material concentrates and at what rate it clears from these regions and from the body in general, must be known to estimate radiation doses to the various body organs. The effective dose is then calculated by multiplying these individual organ doses by assigned risk weighting factors. So there is no direct conversion that can be known beforehand, and, yes, some experimental data are needed. Sometimes these data will exist in a literature article somewhere. If not, new data must be collected.

Michael G. Stabin, PhD, CHP

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