Most notably, however, 161Tb emits additional conversion and Auger electrons capable of providing a significantly higher energy deposition per decay in micro-metastases and single cells, with consequent potential for improved therapeutic efficacy as indicated by Monte-Carlo studies [11–14], and, in pre-clinical studies, with tumour-targeting folate conjugate [15] and prostate-specific membrane antigen (PSMA) [16]. This evidence concerns the gene FOLH1 and neoplasm.