Paper COMPARISON OF TWO LEG PHANTOMS CONTAINING 241 AM IN BONE Gary H. Kramer,* Barry Hauck,* Kevin Capello,* Werner Ru ¨hm, † Nabil El-Faramawy, †‡ David Broggio, § Didier Franck, § Maria Antonia Lopez,** Teresa Navarro,** Juan Francisco Navarro,** Begon ˜a Perez,** and Sergei Tolmachev †† Abstract—Three facilities (CIEMAT, HMGU and HML) have used their in vivo counters to compare two leg phantoms. One was commercially produced with 241 Am activity artificially added to the bone inserts. The other, the United States Transuranium and Uranium Registries’ (USTUR) leg phan- tom, was manufactured from 241 Am-contaminated bones re- sulting from an intake. The comparison of the two types of leg phantoms showed that the two phantoms are not similar in their activity distributions. An error in a bone activity estimate could be quite large if the commercial leg phantom is used to estimate what is contained in the USTUR leg phantom and, consequently, a real person. As the latter phantom was created as a result of a real contamination, it is deemed to be the more representative of what would actually happen if a person were internally contaminated with 241 Am. Health Phys. 101(3):248 –258; 2011 Key words: 241 Am; bones, human; calibration; dosimetry, internal INTRODUCTION THE HUMAN Monitoring Laboratory (HML), which oper- ates the Canadian National Calibration Reference Centre for Bioassay and In vivo Monitoring (Kramer and Lim- son Zamora 1994; Daka and Kramer 2009), has collab- orated with Helmholtz Zentrum Mu ¨nchen–Deutsches Forschungszentrum fu ¨r Gesundheit und Umwelt (HMGU) in Germany and the Centro de Investigaciones Energe ´ticas, Medioambientales y Tecnolo ´gicas (CIEMAT) in Spain to compare the counting characteristics of the United States Uranium and Transuranium Registries’ (USTUR) leg phan- tom held at the United States Department of Energy’s Phantom Library (U.S. DOE 2009) with those of other commercially-available phantoms. The USTUR phantom, the subject of a complete Health Physics journal issue (Breitenstein et al. 1985), has had the 241 Am deposited in bone through a normal metabolic process resulting in an activity distribution that is representative of what may be expected in an exposed human male. Each facility has also previously made measure- ments on a commercially-available leg phantom (not necessarily the same phantom for each facility but all from the same supplier). The commercially-available phantom had the 241 Am artificially distributed in the bone substitute material unlike the USTUR phantom. All three facilities use their partial body or lung counters for the measurement of radioactivity in bone. While each is based on hyperpure germanium, the details of each facility are somewhat different. This paper presents the results of the comparison of the two types of leg phantoms and shows that the two phantom types (commercial vs. USTUR) are not similar in their activity distributions. MATERIALS AND METHODS Human monitoring laboratory Lung counter. The detectors used were developed by ORTEC (Ortec 2010a) using a new front contact technology. This new technology provides excellent energy resolution and peak shape at low energies with large area detectors, which makes them very interesting * Human Monitoring Laboratory, Radiation Protection Bureau, 775 Brookfield Road, Ottawa, Ontario, K1A 1C1 Canada; † Helmholtz Zentrum Mu ¨nchen—German Research Center for Environmental Health, GmbH, Institute of Radiation Protection, Ingolsta ¨dter Land- straße 1, D-85764 Neuherberg, Germany; ‡ On leave from Department of Physics, Faculty of Science, Ain Shams University, 65511 Ab- bassia, Cairo, Egypt; § Institut de Radioprotection et de Su ˆrete ´ Nucle ´- aire, Internal Dose Assessment Laboratory, DRPH/SDI/LEDI, BP-17 F-92262 Fontenay-aux-Roses Cedex, France; ** Centro de Investiga- ciones Energe ´ticas, Medioambientales y Tecnolo ´gicas, Avda. Com- plutense, 22, Madrid 28040, Spain; †† United States Transuranium and Uranium Registries, Washington State University, 2340 Lindberg Loop, Richland, WA 99354. For correspondence or reprints contact: Gary H. Kramer, Human Monitoring Laboratory, Radiation Protection Bureau, 775 Brookfield Road, Ottawa, Ontario, K1A 1C1 Canada, or email at gary.h.kramer@ hc-sc.gc.ca. (Manuscript accepted 20 January 2011) 0017-9078/11/0 Copyright © 2011 Health Physics Society DOI: 10.1097/HP.0b013e3182118f61 248 www.health-physics.com