Abstract: A shield for use with a radiation detecting probe to effect the detection, localization, imaging or mapping of radiation in a first portion of the body of a living being by use of a hand held, radiation detecting probe. The probe has a conical field of view. The shield comprises a sheet formed of a radiation blocking material, e.g., pure tungsten, tungsten alloys, tungsten powder suspended in gold, pure gold, gold alloys, pure platinum, and platinum-iridium alloys, and is sized to be readily located within a space within the body of the being so that the first portion of the body of the being is interposed between it and the probe, with the shield filling up a substantial portion of the field of view of the probe. In one embodiment the shield is mounted on the probe by an adjustable yoke assembly. In another embodiment the shield is separate from the probe.