Magnetic field probe for determining a disposition of an implantable marker using two or more detection zones

During both invasive and non-invasive treatments and therapies, health professionals need to accurately locate areas of interest. Inaccuracies may mean that not all the area is treated, or the treatment is incomplete. Electro-magnetic and RFID (Radio-Frequency Identification) markers have been developed, but these are bulky and prone to failure. For example, any inaccuracy may result in an incomplete resection or removal of the lesion, requiring additional treatments.A magnetic field probe 100, 101 is provided for determining an angular disposition 180, 190 of an implantable magnetic marker 200, the probe comprising: a first magnetic sensor 110 close to the distal end 160, and a second magnetic sensor 120, closer to a proximal end 165, configured to determine two or more magnetic field vectors of the marker 200; the probe being further configured: to define two or more marker detection zones 170, 171, 172, 173, 174, extending from the distal end 160; to determine the angular disposition 180, 190 to the implantable marker 200; and to determine whether the angular disposition 180, 190 substantially coincides with one of the two or more marker detection zones 170, 171, 172, 173, 174, thereby determining that the marker falls within the one marker detection zones.By defining two or more marker detection zones, and configuring the probe to determine whether the magnetic marker appears to be within the one marker detection zone, a simplified and intuitive decision algorithm is provided for indicating the disposition of the marker relative to the probe.