Enhancements in radiation detection equipment at border crossings and airports resulted in a report to our institution from a 153Sm-EDTMP therapy patient who was questioned after triggering radiation alarms. Using a clinical SPECT camera in its service mode, gamma-ray spectroscopy was performed on three patients whose 153Sm-EDTMP injections were given between 4 mo and 2 y prior to this study. The spectra revealed the presence of high-energy photon peaks characteristic of those from 154Eu. While the presence of 154Eu in 153Sm injections is documented in the literature, the implications of its presence are not widely known. The results of this study show that 154Eu (t1/2 = 8.5 y) remains in the bones in detectable amounts for several years and may create concerning situations for post therapy patients at some security checkpoints. Institutions performing 153Sm-EDTMP therapy may want to inform their patients of this situation and provide a wallet card.