The Monte Carlo modelling of in vivo x-ray fluorescence measurement of lead in tissue.
A Monte Carlo model has been developed, using the EGS4 code, to model the in vivo x-ray fluorescence (XRF) measurement of Pb in non-superficial bone/tissue. Unlike previous work in this field the current model incorporates a correction for Doppler broadening of the Compton scatter peak due to the electron momentum distribution of the medium (tissue/water) in which the photons are Compton scattered by convolving the Compton peak of the Monte Carlo generated spectrum with a modified Compton profile for water. This correction improves the agreement between the measured spectral shape obtained using an experimental in vivo x-ray fluorescence Pb analyser with a 109Cd/180 degrees source/geometry combination, measuring a bone phantom at depth in water and the generated spectral shape obtained from the equivalent Monte Carlo model. The model enables improved estimates to be made of the spectral background beneath the Pb Kalpha1 and Kalpha2 x-ray peaks compared with estimates based on simpler models that assume that Compton interactions are with 'free' electrons and hence permits better optimization of in vivo analyser system design.
Wallace
J D
JD
Centre for Medical and Health Physics, Queensland University of Technology, Queensland, Australia.
D000465:Algorithms; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D003198:Computer Simulation; D003238:Connective Tissue / Q000378:metabolism*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D006801:Humans; D007854:Lead / Q000032:analysis*; D007855:Lead Poisoning / Q000175:diagnosis*; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D013052:Spectrometry, X-Ray Emission / Q000295:instrumentation / Q000379:methods*
D007854:Lead