Abstract: A tomographic scanner includes an imaging device for obtaining images of the anatomy of a patient. A localizer device such as an articulated arm includes a base portion mounted in a fixed relationship to the imaging device and a free end adapted for selective movement into varied positions near a patient body disposed on the imaging device. A guide device such as grid lattice is attached to the free end of the arm. A position transducer associated with the localizer device generates information as to the position of the localizer and hence the position of the guide device in scanner coordinates. The guide device contains a plurality of needle guides. The position of the guide device is displayed in relation to images of the anatomy of the patient. This information is used by the operator to guide the insertion of brachytherapy seeds in a desired pattern and location in relation to the anatomy of the patient.