Cobalt-60 is a well-established and clinically proven isotope for all HDR brachytherapy treatments. Co-60 has achieved tremendous success and has continued to evolve to support modern HDR brachytherapy needs. The Co-60 source is not only clinically well proven, it is physically well understood and extensively analyzed as well. The treatment with Co-60 leads to lower dose to organs at risk (OAR) than with Ir-192.