Retention of indium 111 by incinerator ash

While attempting to trace a 198Au grain lost during a radiotherapy implant procedure, the 171 keV and 245 keV cascade γ rays from 111In were detected in samples of hospital incinerator ash. Indium 111 also produces a peak in its γ-ray spectrum at 416 keV, corresponding to the summation of the separate cascade radiations, and detection of remnants of the gold grain was hindered by the similarity between this sum peak energy and the γ-ray energy (412 keV) of 198Au, and by the similarity between the half-lives of 111In and 198Au (67.2 h and 64.2 h, respectively).