Paper NEW IN-VIVO CALIBRATION PHANTOMS AND THEIR PERFORMANCE T. Ishikawa,* M. Uchiyama,* M. Hoshi, † J. Takada, † S. Endo, ‡ N. Sugiura, § T. Kosako, § and I. Shimizu** Abstract—New in-vivo calibration phantoms (anthropometric phantoms) were developed to meet the needs for Japanese standard phantoms. Two important characteristics of these phantoms were that (1) they were designed using Japanese body size survey data, and (2) they were designed so that they can be adapted to various positions or geometries. The perfor- mance of these phantoms was tested with respect to body size, activity distribution along the axis, and counting efficiency. The actual dimensions of the anthropometric phantoms were compared with the survey data. Most items (31 of 47) indicated good agreement between the actual values and the survey data for the adult anthropometric phantom. The activity distribu- tion for the anthropometric phantoms was compared with that for block phantoms that simulate a uniform activity distri- bution. The anthropometric phantoms have some gaps in their joints. The measurement results, however, indicated that these gaps did not significantly affect the overall accuracy of the measurements. Differences in counting efficiency between the block phantoms and the anthropo- metric phantoms for the same age were no more than 6%. Health Phys. 82(3):348 –357; 2002 Key words: whole body counting; 137 Cs; phantom; calibration INTRODUCTION INTERCOMPARISON STUDIES of whole-body counters (WBCs) have been conducted previously to check the reliability of whole-body measurements (Fenwick et al. 1991; Kramer 1995; Werner et al. 1995; Neeson et al. 1997; Thime et al. 1998). The Canadian National Calibration Center for In-Vivo Monitoring and the United States Department of Energy (DOE) offered international inter- comparison programs in 1993 and 1996 (Kramer et al. 1999, 2001). There were 83 WBCs in Japan according to a survey in 1994 (Kosako et al. 1994). Only six of these 83 WBCs participated in the international intercomparisons in 1993 and 1996. These six WBCs were calibrated with the BOMAB (Bottle-Manikin-Absorption) phantoms (Kramer et al. 1991). The other 77 WBCs were not calibrated with standard phantoms such as BOMAB phantoms. The inter- national intercomparisons were, therefore, not sufficient to establish adequate quality control for the WBCs in Japan, and a separate intercomparison program was undertaken to check the reliability of the other 77 WBCs. Block phantoms are usually used for calibration in Japan (Ishikawa 2000). They are assemblies of contain- ers filled with radioactive solutions. The block phantoms, until now, have never been standardized, and so it was necessary to develop a standard phantom that can be used for intercomparisons in Japan. Anthropometric phantoms were developed to meet this need for standardization. Two important character- istics of these phantoms were that (1) they were designed using Japanese body size survey data, and (2) they were designed so that they can be arranged in various geom- etries. The performance of these phantoms was tested with respect to body size, activity distribution along the axis of the phantoms, and counting efficiency. This paper describes the design, construction and performance tests for the anthropometric phantoms. DESCRIPTION OF ANTHROPOMETRIC PHANTOMS Design and construction The anthropometric phantoms were developed with the aim of anthropomorphicity. The external shapes of the anthropometric phantoms were designed using the body size data obtained from a national survey of Japanese individuals (JSA 1984). Two anthropometric phantoms of different sizes were designed: an 11-y-old phantom (male) and an adult phantom (male). Forty- seven different items from the body size data were used to design the adult anthropometric phantom, and twenty- six items were used for the 11-y-old anthropometric phantom. Measurement positions for these items are * National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan; † Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami- ku, Hiroshima, 734-8553, Japan; ‡ Faculty of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan; § Research Center for Nuclear Science and Technology, The Univer- sity of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan; ** Japan Atomic Energy Research Institute, 2-4 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki, 319-1195, Japan. For correspondence or reprints contact: T. Ishikawa, Radon Research Group, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan, or email at tetsuo_i@nirs.go.jp. (Manuscript received 28 July 2000; revised manuscript received 13 June 2001, accepted 5 October 2001) 0017-9078/02/0 Copyright © 2002 Health Physics Society 348