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  • 1 Instituto de Radioproteção e Dosimetria/CNEN Av. Salvador Allende s/n via 9 CEP 22780 Barra da Tijuca Rio de Janeiro (Brazil)
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Abstract  

The construction of reliable bone phantoms to calibrate whole body counting facilities for bone-seeking radionuclides has been a challenge for several research institutes. Different techniques have been applied to get uniform distribution of those nuclides in bone tissue. A241Am skull phantom was developed at the Institute of Radiation Protection and Dosimetry/Brazilian Nuclear Energy Commission's (IRD/CNEN) Whole Body Counting facility, using a dipping procedure. Preliminary tests were performed using non-radioactive ink solution. The first step was to choose the appropriate solvent to be used, since it was observed that acid solutions attack bone tissue. At the second step, pieces of skull were dipped into those solutions to check the extent and homogeneity of the penetration. The third step consisted of verifying the dipping time using a241Am standard solution. The homogeneity was checked with a high-purity germanium detector. Tissue-equivalent material was used to cover the skull surface and to simulate the low energy X and gamma radiation attenuation. The calibration factor and the detection limit were calculated for two phoswich detectors positioned at each side of the head, which is the standard geometry for this kind of measurement.