A spacer/injector needle for 125I and other radioactive sources is described. Exposure is minimized by speed, distance, and (in the case of 125I) the low energy of the source shielded within the needle. Afterloading can easily be performed using small trocars. A readily attached plunger gives the needle a syringe (injection) action, while a rapid seed loader reduces loading time as well as the number of needles required when loading is carried out in the operating room.