Biokinetic functions


As mentioned in the overview, for most of the elements more isotopes are included in IDEAplus as compared to the previous IDEA versions and for most of these isotopes more physical/chemical forms are considered. This results in a large number of biokinetic functions for each isotope.


In the case of H-3 we have a scheme as shown in the table to the left. For the inhalation pathway there are two physical forms (aerosols and gas or vapor, respectively). For aerosols there are the standard absorption types F, M, and S. In addition, there are aerosols of biogenic organic compounds which cannot be allocated to the standard absorption types. For proper allocation of the respective biokinetic functions, IDEAplus defines up to three special aerosol inhalation absorption types H1, H2, and H3 (in the case of hydrogen there is only one special aerosol inhalation absorption type H1, but there are other elements with up to three such types). For gas or vapor there are the standard absorption type V and three special gas/vapor inhalation absorption types V1, V2, and V3. For most of the gases or vapors (tritiated methane, tritiated water, tritium gas) the GI absorption is not relevant and thus there is no fA coefficient. All other gases and vapors are allocated to the special gas/vapor inhalation absorption type V3 which is assumed to have the same behavior as type F material.


The next screenshot shows the transscription of this scheme into the terminology of IDEAplus. The column “Mat” contains detailed information about the physical and chemical specification which will be displayed when moving the curser across the respective line (here: type M Aerosols of H-3)


When selecting a parameter combination from the second column, a window opens showing the biokinetic functions which are available for the selected parameter combination (see next screenshot: inhalation of type M Aerosols of H-3 with 5 µm AMAD). The left column in the window shows the time after intake in days or in fractions of a day, respectively. This time grid corresponds to the time scale of the OIR DataViewer, the first grid point of which being one hour after intake.


The heading of the window is the same for all radionuclides and contains all retention and excretion functions which could be relevant for in vivo or in vitro measurements of any radionuclide, i.e.for in vivo measurements the retention functions for


  • whole body
  • thyroid
  • lungs
  • liver
  • skeleton

and for in vitro measurements the excretion functions for


  • urine
  • faeces

Please note that there is a qualitative difference between the time reference of the retention and excretion functions. The retention functions describe the activity content in the respective organ or tissue as a function of time in terms of Bq per Bq intake whereas the excretion functions describe the average daily excretion as a function of time in terms of Bq/d per Bq intake. So, the excretion function value for a certain time corresponds to the integrated activity excretion during the 24 hours before the respective time whereas the retention function value corresponds to the activity content at the respective time.


Because of this qualitative difference, the excretion functions are defined only for full days whereas the retention functions are defined also for any fraction of a day.









Prof. Dr.-Ing. Hans Richard Doerfel

IDEA System GmbH, Am Burgweg 4, D-76227 Karlsruhe, Germany.