System and method for magnetic occult lesion localization and imaging
Systems and methods for marking the location and extent of an anatomical region-of-interest, such as a tumor, using magnetic seeds whose position and orientation are measured or otherwise detected using a detection device that includes two or more magnetic sensors are described. One or more magnetic seeds are implanted to mark and define the center and extent of an anatomical region-of-interest and a magnetic sensor-based detector system is used to accurately identify the location of the magnetic seeds.
1. A method for localizing a magnetic seed that generates a magnetic field, comprising:
moving a detector probe towards the magnetic seed until a first magnetic sensor and a second magnetic sensor each detect a magnetic field generated by the magnetic seed and in response thereto generate signal data representative of the magnetic field, wherein the detector probe comprises a housing with a proximal portion and a distal tip portion, the distal tip portion is angled with respect to the proximal portion, the first magnetic sensor is located in the proximal portion, the second magnetic sensor is located in the distal tip portion, an operative sensor axis of the first magnetic sensor is not parallel with an operative sensor axis of the second magnetic sensor, the operative sensor axis of the second magnetic sensor is not parallel with a central axis of the proximal portion, and at least one of the first magnetic sensor and the second magnetic sensor is arranged in the housing to be offset from the central axis of the proximal portion;
receiving, at a processor, the signal data of the first magnetic sensor and the second magnetic sensor;
processing the signal data to compute a location of the magnetic seed, wherein processing the signal data includes accounting for an anisotropic geometry of the magnetic field generated by the magnetic seed; and
providing an output signal based on the computed location of the magnetic seed.
2. The method of claim 1 , further comprising calibrating the first magnetic sensor and the second magnetic sensor independent from each other based on a known spatial relationship between the first magnetic sensor, the second magnetic sensor, and the Earth's magnetic field.
3. The method of claim 2 , wherein calibrating the first magnetic sensor and the second magnetic sensor subtracts effects of the Earth's magnetic field in the signal data received by the processor from the first magnetic sensor and the second magnetic sensor.
4. The method of claim 2 , wherein calibrating the first magnetic sensor and the second magnetic sensor generates calibration data that are stored in a memory.
5. The method of claim 1 , wherein the processor accounts for the anisotropic geometry of the magnetic field generated by the magnetic seed by using a physical model of the magnetic seed when estimating a distance of the magnetic seed from the detector probe.
6. The method of claim 1 , wherein at least one of the first magnetic sensor and the second magnetic sensor is a magnetometer.
7. The method of claim 1 , wherein at least one of the first magnetic sensor and the second magnetic sensor comprise an array of magnetometers.
8. The method of claim 7 , wherein the array of magnetometers define a viewing window and the processor computes the location of the magnetic seed only when the magnetic seed is located within a volume define by the viewing window.
9. The method of claim 1 , wherein each of the first magnetic sensor and the second magnetic sensor excludes an accelerometer component.
10. The method of claim 1 , wherein the detector probe comprises the first magnetic sensor and the second magnetic sensor and no other sensors.