Ferromagnetic foreign body detection using magnetics

摘要

A probe instrument using room-temperature sensor(s) that can measure magnetic susceptibilities variations. The instrument includes room temperature magnetic sensors, and detects the sample, that is the tissue response to an applied field coil. The sensors that can be used include magnetoresistive, fluxgate and magnetoinductive sensors. The applied field coil dimensions are chosen so that the applied field is optimized for maximum response from the item of interest while minimizing the effects due to the overlying tissue and at the same time not unduly increasing the sensitivity of the instrument to adjacent organs. To minimize noise introduced in the sensor due to fluctuations in the applied field, the applied field is canceled at the position of the sensor. To overcome variations in the sensor output due to fluctuations in the applied field, change in the ambient temperature and mechanical relaxation of the instrument, the detector assembly is oscillated while the examined patient remains stationary.