Effective atomic numbers of some tissue substitutes by different methods: A comparative study

Abstract

Effective atomic numbers of some human organ tissue substitutes such as polyethylene terephthalate, red articulation wax, paraffin 1, paraffin 2, bolus, pitch, polyphenylene sulfide, polysulfone, polyvinylchloride, and modeling clay have been calculated by four different methods like Auto-Zeff, direct, interpolation, and power law. It was found that the effective atomic numbers computed by Auto-Zeff, direct and interpolation methods were in good agreement for intermediate energy region (0.1 MeV < E < 5 MeV) where the Compton interaction dominates. A large difference in effective atomic numbers by direct method and Auto-Zeff was observed in photo-electric and pair-production regions. Effective atomic numbers computed by power law were found to be close to direct method in photo-electric absorption region. The Auto-Zeff, direct and interpolation methods were found to be in good agreement for computation of effective atomic numbers in intermediate energy region (100 keV < E < 10 MeV). The direct method was found to be appropriate method for computation of effective atomic numbers in photo-electric region (10 keV < E < 100 keV). The tissue equivalence of the tissue substitutes is possible to represent by any method for computation of effective atomic number mentioned in the present study. An accurate estimation of Rayleigh scattering is required to eliminate effect of molecular, chemical, or crystalline environment of the atom for estimation of gamma interaction parameters.

Determinação de números atômicos efetivos de materiais radiologicamente equivalentes ao tecido humano e à água

“…Nas Figuras 1-5, é possível observar discrepâncias nos valores de número atômico efetivo entre os métodos utilizados. Essas discrepâncias também foram verificadas em outros trabalhos comparativos 8,17,18 . As variações podem ser resultado de parâmetros de entrada diferentes ou ferramentas matemáticas utilizadas em cada um desses métodos.…”

“…Manjunatha e Rudraswamy 7 determinaram os números atômicos efetivos de 34 tecidos diferentes de órgãos humanos. Singh 8 determinou o número atômico efetivo para materiais simuladores de tecido humano.…”

Detection of therapeutic radiation in three-dimensions

“…The observed sensitivity was in the order R 3 C–I > R 3 C–Br > R 3 C–Cl [ 42 – 44 ]. Due to the high electron density of radical initiators containing iodine even at relatively low concentrations (100 mM) result in dosimeters that are not tissue equivalent [ 43 – 45 ].…”

Characterisation of Rhizophora Particleboard Using Bio-Oil-Based Phenol Formaldehyde (Pf) Resin

“…From there, the average atomic number of all particleboards was calculated and compared with those of water (7.42) (Singh and Badiger, 2014). The average atomic number of natural Rhizophora hardwood was previously reported at 7.28 (Marashdeh et al, 2012).…”