Locating metal shrapnel in human body using GMR sensors

Injury due to metal shrapnel is a major cause of death in victims of bomb blast, land mines and gun fire. To recover these shrapnel surgically, surgeons use imaging systems for locating them inside the victim´s body. Since these shrapnel are normally mobile, by the time the surgery starts, their positions would have changed making it very difficult for the surgeon to recover them. In certain cases, the shrapnel that are visible in the images can become untraceable during surgery. Giant Magneto Resistance (GMR) type sensor based tool to aid a surgeon to locate shrapnel was found to have poor depth response characteristics compared to inductive proximity sensor based tool. This paper presents the details of new schemes that were evaluated to improve the detection depths of the GMR sensor based shrapnel detectors. Results on prototype detectors built and tested establish the feasibility of the proffered schemes.