title: Voxel phantoms and Monte Carlo methods applied to in vivo measurements for simultaneous 241Am contamination in four body regions.
abstract: A Monte Carlo program, Visual Monte Carlo (VMC) in vivo, was written to simulate photon transport through an anthropomorphic phantom and to detect radiation emitted from the phantom. VMC in vivo uses a voxel phantom provided by Yale University and may be used to calibrate in vivo systems. This paper shows the application of VMC in vivo to the measurement of 241Am deposited simultaneously in the thoracic region, the bones, the liver and in the rest of the body. The percentages of 241Am in the four body regions were calculated using the biokinetic models established by the ICRP, for a single intake via inhalation. The four regions of the voxel phantom were then 'contaminated' in accordance with the calculated percentages. The calibration factor of the in vivo system was then obtained. This procedure was repeated for the radionuclide distributions obtained 5, 30, 120, 240 and 360 days after intake. VMC in vivo was also used to calculate the calibration factor of the in vivo system in which the radionuclide was assumed to be deposited only in the lung, as is normally done. The activities calculated with the radionuclide distributed in the four body regions as a factor of time, and the activities calculated with the radionuclide deposited in the lung only are compared.
authors.affiliation: Institute of Radiation Protection and Dosimetry, Av. Salvador Allende s/n, Recreio, Rio de Janeiro, CEP 22780-160, Brazil. john@ird.gov.br
authors.forename: J G
authors.initials: JG
authors.lastname: Hunt
authors.forename: B M
authors.initials: BM
authors.lastname: Dantas
authors.forename: M C
authors.initials: MC
authors.lastname: Lourenço
authors.forename: A M G
authors.initials: AM
authors.lastname: Azeredo
mesh_terms: D000576:Americium / Q000032:analysis / Q000493:pharmacokinetics*; D003198:Computer Simulation; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis; D007719:Knee Joint / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008168:Lung / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D009928:Organ Specificity; D019047:Phantoms, Imaging; D017785:Photons; D011829:Radiation Dosage; D014915:Whole-Body Counting / Q000379:methods* / Q000592:standards
chemical_list: D000576:Americium