title: Determination of age specific ¹³¹I S-factor values for thyroid using anthropomorphic phantom in Geant4 simulations.
abstract: Using anthropomorphic phantom in Geant4, determination of β- and γ-absorbed fractions and energy absorbed per event due to (131)I activity in thyroid of individuals of various age groups and geometrical models, have been carried out. In the case of (131)I β-particles, the values of the absorbed fraction increased from 0.88 to 0.97 with fetus age. The maximum difference in absorbed energy per decay for soft tissue and water is 7.2% for γ-rays and 0.4% for β-particles. The new mathematical MIRD embedded in Geant4 (MEG) and two-lobe ellipsoidal models developed in this work have 4.3% and 2.9% lower value of S-factor as compared with the ORNL data.
authors.affiliation: Health Physics Division, Pakistan Institute of Nuclear Science & Technology, Nilore, Islamabad 45650, Pakistan.
authors.forename: Ziaur
authors.initials: Z
authors.lastname: Rahman
authors.affiliation: Department of Physics & Applied Mathematics, Pakistan Institute of Engineering & Applied Sciences, Nilore, Islamabad 45650, Pakistan.
authors.forename: Syed Bilal
authors.initials: SB
authors.lastname: Ahmad
authors.affiliation: Department of Physics & Applied Mathematics, Pakistan Institute of Engineering & Applied Sciences, Nilore, Islamabad 45650, Pakistan.
authors.forename: Sikander M
authors.initials: SM
authors.lastname: Mirza
authors.affiliation: Health Physics Division, Pakistan Institute of Nuclear Science & Technology, Nilore, Islamabad 45650, Pakistan.
authors.forename: Waheed
authors.initials: W
authors.lastname: Arshed
authors.affiliation: Department of Physics & Applied Mathematics, Pakistan Institute of Engineering & Applied Sciences, Nilore, Islamabad 45650, Pakistan. Electronic address: nasirmm@yahoo.com.
authors.forename: Nasir M
authors.initials: NM
authors.lastname: Mirza
authors.affiliation: Health Physics Division, Pakistan Institute of Nuclear Science & Technology, Nilore, Islamabad 45650, Pakistan.
authors.forename: Waheed
authors.initials: W
authors.lastname: Ahmed
mesh_terms: D065638:Absorption, Radiation; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D000886:Anthropometry / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009928:Organ Specificity; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012984:Software; D013961:Thyroid Gland / Q000378:metabolism*; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals
keywords: Anthropomorphic phantom; Geant4 simulations; Iodine-131; S-factor values; Thyroid