Abstract: A radioactive substance administrator including a syringe structured to receive a dosage of the radioactive substance therein; a containment housing structured to contain the syringe and including a radioactivity retardant material, structured to substantially attenuate the emergence of radioactivity through the containment housing, and a plunger track structured to contain a plunger assembly of the syringe movably therein; an exterior actuation assembly operatively associated with the containment housing and structured to actuate the plunger assembly of the syringe; and a secondary shielding assembly operatively associated with an outlet of the containment housing and structured to permit the passage of the radioactive substance to the patient while also attenuating radioactivity emerging from the outlet of the containment housing and radioactivity emanating from the radioactive substance exiting the containment housing.