A radio-nuclear material delivery system includes: a body; at least one
catheter including a portion arranged within the body and extending along
a longitudinal length of the body, each catheter including a blind lumen
in which a radioactive material is insertable; and a shield arranged on
an exterior of the body and movable along the body in a longitudinal
direction of the catheter. The shield may be made of a tungsten material,
e.g., coated with titanium nitride, for attenuating radiation from the
nuclear material and controlling dosing of radiation for treatment of,
e.g., breast cancer.