Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK

three detectors are used. Two detectors are located on both side of subject’s head: in Figure
2.3.10 they are depicted according to a lateral prospective. The third detector is located under
the subject’s head and therefore not visible.
Both detecting systems were calibrated, for their own measurement positions, using
the whole USTUR phantom to evaluate the efficiency factors in case of activity distribution in
the skeleton. Furthermore both detecting systems were calibrated using LLNL phantom to
evaluate the efficiency factor in case of activity distribution in lungs, liver and lymph nodes.
For such calibration issue, efficiency factors relating to different chest wall thickness were
evaluated using the different overlays available for the LLNL phantom.
As phoswich is even used for measurement of activity in head, efficiency factors for
activity distribution in lungs, liver and lymph nodes were evaluated using the LLNL phantom
to evaluate their contribution for measurements performed on head. In this case, owing to
their low contributions, only a LLNL phantom overlay was used (29 mm, one of the two
central values).
The efficiency factors of the detecting systems for 59.5 keV energy peak of 241 Am are
given in Table 2.3.3 and Table 2.3.4 under different measurements positions of detectors
(MP) and activity distribution (AD) of the radionuclide in the body. For LLNL phantom
efficiency factors relate to overlays with 50%/50% fat/muscle ratio.
HPGe
Measurement position
1 2
Figure 2.3.10 The measurement positions (MP) of HPGe and phoswich detectors in respect
of the subject.
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Phoswich
Measurement position
Head Lungs Liver Knee