title: Measurement of activity in anthropomorphic organ phantoms.
abstract: This paper describes two nondestructive measurement techniques for determining the radioactivity in a homogeneous organ phantom with an acceptable error and the capability of being traceable to the National Institute of Standards and Technology. These two techniques are based on a method developed by Robley D. Evans in 1937 for measuring the amount of radium deposited in a living person. There are two significant improvements in the new techniques: 1) the radially-dependent error is eliminated, and 2) the effect of self absorption in the unknown body is measured and taken into account. The first assay method is a single-source technique involving four measurements and requiring only one standard source, the second one is a double-source technique involving six measurements and requiring two unequal standard sources. Three pairs of lung phantoms radiolabeled with 241Am, 137Cs, and 154Eu were measured with both the single- and double-source techniques. The results imply that the self-attenuation of photons within the organ phantom cannot be neglected, especially at low energies. Finally, potential applications (other than the calibration of bioassay phantoms of the single- and double-source techniques) and their limitations are discussed.
authors.affiliation: Health Physics Department, Pacific Northwest Laboratory, Richland, WA 99352.
authors.forename: T E
authors.initials: TE
authors.lastname: Hui
authors.forename: L L
authors.initials: LL
authors.lastname: Nichols
authors.forename: P C
authors.initials: PC
authors.lastname: Olsen
authors.forename: J C
authors.initials: JC
authors.lastname: McDonald
mesh_terms: D006077:Government Agencies; D006801:Humans; D007753:Laboratories / Q000592:standards; D008168:Lung; D008961:Models, Structural; D011851:Radioactivity; D014481:United States; D014781:Viscera