Aids in indicating anatomical location for SPECT Imaging. Helps in indicating organ size or region of interest by counting the number of visible “hot and cold” segments for SPECT Imaging. Sources contain 160 microcuries of Co-57 (20 microcuries per segment). Each source contains 8 “hot” 1 cm segments and 9 “cold” 1 cm segments, total length is 6.7 inches (17 cm). Custom sources can be made containing a maximum activity 1.2 millicuries (44.4 MBq).