Imaging probe and method of obtaining position and/or orientation information

A system of an imaging probe for imaging at least part of a tissue of a patient and a magnetometric detector for detecting at least one of a position and an orientation of an elongate medical device relative to the magnetometric detector, wherein the elongate medical device is magnetized, the magnetized elongate medical device and the magnetometric detector are moveable independently from each other relative to a static secondary magnetic field, and the system further comprises:

• at least one fastener for removably attaching the imaging probe to the magnetometric detector;
• and a processing unit that is functionally connected to both the imaging probe and the magnetometric detector, the processing unit to generate an image of the tissue of the patient imaged by the imaging probe, and further to indicate in the image the position of at least a part of the magnetized elongate medical device based on at least one of the position and the orientation information, and the processing unit is further adapted to obtain measurements, in the presence of a magnetic field of the magnetized elongate medical device and the static secondary magnetic field, of at least one of a strength and an orientation of the magnetic field at at least a first position and a second position spatially associated with the magnetometric detector, the second position being distanced from the first position, and combine the measurements to computationally eliminate an effect of the static secondary magnetic field by fitting the measurements to a model of the magnetic field of the magnetized elongate medical device, said model modeling the magnetic field of the magnetized elongate medical device as two spaced-apart magnetic charges;
• and wherein
• the magnetometric detector comprises at least two magnetometers,
• the system stores normalization information representing a calibration of each magnetometer with a homogeneous magnetic field,
• the system is configured to use the stored normalization information to normalize a measurement of each magnetometer to obtain normalized measurements, the normalized measurements being such that the magnetometers measure equal values with regard to gain, offset and orientation, and
• the stored normalization information comprises a gain normalization matrix M and a normalization offset vector β for each magnetometer and the system is configured to use the stored normalization information to normalize measurements of the magnetometers based on the following relationship:
• b=a*M+β
• where a is a vector representing measurements from the magnetometers before the normalization and b is a vector representing the normalized measurements.