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

counts
0 59.5
Figure 2.3.12 The spectrum acquired with the phoswich detecting system positioned on the
lung of the contaminated subject. The full energy peak is given by 241 Am (59.5
keV).
The measurements provided a first set of raw data given by the impulses counted by
each detector of the phoswich and HPGe detecting systems in each measurement position
geometry, i.e. lung, liver knee and heand for the phoswich and positions 1 and 2 for the HPGe
detectors. The results of the measurements are given in Table 2.3.7 and Table 2.3.8.
The counts values in Table 2.3.7 and Table 2.3.8 were converted to activity (Bequerel)
of 241 Am by means of a weighted multiple linear regression [139] using the efficiency factors
given in Table 2.3.3 and Table 2.3.4. Such efficiency factors were corrected for the actual
chest wall thickness according by linear interpolation. The subject’s actual chest wall
thickness was evaluated by means of the following expression:
CWT[cm] = 4.57 •
Weight[kg]
Height[cm]
+ 0.44
69
energy [keV]
equation 2.3.14
Such expression was evaluated on the basis of different empirical formula [140, 141,
142, 143] available in literature to calculate the chest wall thickness on the basis of the weight
and height of a subject. Such empirical curves were used to evaluate the chest wall thickness
for a group of seven subjects with different values of weight and height. The average of the
calculated chest wall thickness values were then fitted and the expression given in equation
2.3.14 was finally obtained.
The final results relating to the activity in the main organs with respect to the adopted
measurement geometry are given in Table 2.3.9.