Magnetopneumography - Suppression of Background Field Variations in Scanned Data for Inversion Using Multiple Fluxgates

In inversion of magnetic data the key task is the acquisition of sufficient number of measurements and suppression of field variations in them. In Magnetopneumography (MPG) we scan very weak magnetic fields of ferromagnetic dust deposited in the lungs of affected workers. Variations of the background field during scanning may bias the inversion such that the determination of the sources is not possible. Just one Is´ order gradient for each node is not suitable for this kind of scanning, thus more probes were added. These can provide more information for the inversion at one node and should enable partial instant suppression of the far field variations. Subtraction of the gradients can be used or better during the processing one can use fitting of the measured gradients to equations derived from the models to determine the variations as offsets. The main problem is the exact alignment of the sensors and homogeneity of the far field in the sensor´s area.