Longitudinal and transverse uniformity in clinical whole body counting by an improved technique.

A new technique using a single NaI(Tl) detector (9 cm x 6.3 cm) in two positions and based on the response curves of the detector has been described. Also a different approach to select the energy band was adopted which is helpful in reducing the dependence of counting efficiency on source depth. Various portions of the compton continuum were taken rather than confining to valley and photo-peak. For transverse uniformity it was found that the energy band which gave 50% normalized count rate at half depth would give a resultant flat response with least variation. For longitudinal uniformity the separation between the two positions of the detector need to be nearly equal to the full width at half maximum of the response curve. The response curve coupling technique described here is different from the commonly used technique of iso-response curves.