** To display S values, first select a model from the left panel, then
select a source and a radioisotope.
**

** The S values calculated refer only to the radionuclide under consideration,
so to evaluate the absorbed dose one must consider the decay and the S values of all
the daughters.
**

*S values* are calculated following the equation:
\[ S_{\left( Target \leftarrow Source \right)} =
\sum_i y_i E_i \Phi_{i \left( Target \leftarrow Source \right)} \]
where \( \Phi_{i \left( Target \leftarrow Source \right)} \) is the Specific Absorbed
Fraction (SAF, kg^{-1}) for radiation type i and \(y_i\), \(E_i\) are the yield
(Bq^{-1}.s^{-1}) and energy (J) of radiation type i, respectively.

A Python program performs the calculation for a selected set of parameters (model, source,
radioisotope).
From the selection and for each target, the Python script queries all corresponding SAFs
from the OpenDose database and the radioisotope decay data of ICRP publication 107
[1].
The SAFs are then averaged between all Monte Carlo codes and interpolated to each radiation
type energy of the selected radioisotope. Then, the interpolated SAFs are multiplied by the
yield and energy of this radiation type or interpolated over the beta spectrum. Finally,
every radiation type contribution is summed to give the *S value*.

The *S value* statistical uncertainty is estimated following the equation:
\[ \sigma \left( S_{\left( Target \leftarrow Source \right)} \right)^2 =
\sum_i \left( y_i E_i \sigma \left( \Phi_{i \left( Target \leftarrow Source \right)}
\right) \right)^2 \]
where \( \sigma \left( \Phi_{i \left( Target \leftarrow Source \right)} \right) \) is the
SAF statistical uncertainty (kg^{-1}) for radiation type i and \(y_i\), \(E_i\)
are the yield (Bq^{-1}.s^{-1}) and energy (J) of radiation type i,
respectively.

This section allows to get *S values* for 2 models, 141 sources, 172 targets and
1252 radioisotopes. An interactive chart shows *S values* for all targets per
particle type contribution, with their statistical uncertainties. A table at the bottom of
the page shows *S values* with their statistical uncertainties for all targets and
the mass of the target.
The data from the table can be easily downloaded in CSV format with a button placed on top
of it.

**Note:** the *S value* calculation involve a lot of operations and
requires ~50 ms per target, it is normal to wait a few seconds for the result page to
appear.