title: A Monte Carlo study of lung counting efficiency for female workers of different breast sizes using deformable phantoms.
abstract: There are currently no physical phantoms available for calibrating in vivo counting devices that represent women with different breast sizes because such phantoms are difficult, time consuming and expensive to fabricate. In this work, a feasible alternative involving computational phantoms was explored. A series of new female voxel phantoms with different breast sizes were developed and ported into a Monte Carlo radiation transport code for performing virtual lung counting efficiency calibrations. The phantoms are based on the RPI adult female phantom, a boundary representation (BREP) model. They were created with novel deformation techniques and then voxelized for the Monte Carlo simulations. Eight models have been selected with cup sizes ranging from AA to G according to brassiere industry standards. Monte Carlo simulations of a lung counting system were performed with these phantoms to study the effect of breast size on lung counting efficiencies, which are needed to determine the activity of a radionuclide deposited in the lung and hence to estimate the resulting dose to the worker. Contamination scenarios involving three different radionuclides, namely Am-241, Cs-137 and Co-60, were considered. The results show that detector efficiencies considerably decrease with increasing breast size, especially for low energy photon emitting radionuclides. When the counting efficiencies of models with cup size AA were compared to those with cup size G, a difference of up to 50% was observed. The detector efficiencies for each radionuclide can be approximated by curve fitting in the total breast mass (polynomial of second order) or the cup size (power).
authors.affiliation: Institut für Strahlenforschung, Forschungszentrum-Karlsruhe Institute of Technology, Karlsruhe, Germany. lars.hegenbart@kit.edu
authors.forename: L
authors.initials: L
authors.lastname: Hegenbart
authors.forename: Y H
authors.initials: YH
authors.lastname: Na
authors.forename: J Y
authors.initials: JY
authors.lastname: Zhang
authors.forename: M
authors.initials: M
authors.lastname: Urban
authors.forename: X George
authors.initials: XG
authors.lastname: Xu
mesh_terms: D001940:Breast / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D009010:Monte Carlo Method; D009929:Organ Size; D019047:Phantoms, Imaging; D011877:Radionuclide Imaging
references.citation: Health Phys. 1989 Nov;57(5):747-52
references.pmid: 2592207
references.citation: AJR Am J Roentgenol. 2004 Mar;182(3):713-7
references.pmid: 14975974
references.citation: Phys Med Biol. 2007 Dec 7;52(23):7023-44
references.pmid: 18029991
references.citation: Radiographics. 1999 Sep-Oct;19(5):1303-11
references.pmid: 10489181
references.citation: JAMA. 2006 Apr 5;295(13):1549-55
references.pmid: 16595758
references.citation: Health Phys. 1985 Sep;49(3):419-24
references.pmid: 2993197
references.citation: Health Phys. 2005 Apr;88(4):357-63
references.pmid: 15761297
references.citation: Pediatrics. 2007 Mar;119(3):e624-30
references.pmid: 17332182
references.citation: Ann ICRP. 1979;3(1-4):iii
references.pmid: 20863799
references.citation: Health Phys. 1982 Dec;43(6):930-5
references.pmid: 7152956
references.citation: Ann ICRP. 2002;32(3-4):5-265
references.pmid: 14506981
references.citation: Appl Ergon. 2004 Jul;35(4):353-9
references.pmid: 15159200