Prompt Gamma In Vivo Neutron Activation Analysis (prompt-γ IVNAA), has been known as the most appropriate method for the measurement amount of body elements; and its main applications in nuclear medicine, are the measurement of small-mass body elements e.g. chlorine and potassium, or body certain elements which are unique constituents of body components e.g. nitrogen in protein and calcium in skeleton. For this aim, a prompt-γ IVNAA facility has been installed at Monash Medical Centre (MMC) Melbourne Australia, for the measurement of TBPr (Total Body Protein) in adults (Stroud et al, 1990; Borovnicar et al, 1991) and then applied to measure simultaneously TBN (Total Body Nitrogen) and TBCl (Total Body Chlorine) in children for diagnosis of CF (Cystic Fibrosis) disease (Borovnicar, 1996). This facility includes a paraffin-wax block (40cm × 40cm × 60cm) mingled with boric acid (%5 3 3 H BO by weight). A collimator within this block makes an inverted, rectangular pyramidal void cast with aperture measuring 40cm (length) × 20cm (width) at a level of bed. A 0.2 GBq 252Cf neutron source is positioned at the apex of this inverted pyramid. The Aluminium bed is located 50cm above the source as the trunk of patient exposure the neutron directly in vicinity of aperture of pyramid. Two pairs of NaI(Tl) detectors, located on both sides of the scanning bed, to detect the prompt gamma rays induced from the capture of neutrons by atomic nuclei in the body.

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