This paper presents a tracking system using magnetometers, possibly integrable in a deep brain stimulation (DBS) electrode. DBS is a treatment for movement disorders where the position of the implant is of prime importance. Positioning challenges during the surgery could be addressed thanks to a magnetic tracking. The system proposed in this paper, complementary to existing procedures, has been designed to bridge preoperative clinical imaging with DBS surgery, allowing the surgeon to increase his/her control on the implantation trajectory. Here the magnetic source required for tracking consists of three coils, and is experimentally mapped. This mapping has been performed with an in-house three-dimensional magnetic camera. The system demonstrates how magnetometers integrated directly at the tip of a DBS electrode, might improve treatment by monitoring the position during and after the surgery. The three-dimensional operation without line of sight has been demonstrated using a reference obtained with magnetic resonance imaging (MRI) of a simplified brain model. We observed experimentally a mean absolute error of 1.35 mm and an Euclidean error of 3.07 mm. Several areas of improvement to target errors below 1 mm are also discussed.

This article presents a magnetic tracking system using on-chip anisotropic magnetoresistive (AMR) sensors. The system consists of four air-core coils sequentially generating four dc magnetic fields. The implemented localization algorithm is quadrilateration, and the accuracy of the system is dependent on the accuracy of the sensors and the simulated field maps. The performance of the system was evaluated using an in-house magnetic field camera (MFC), and the results showed that the system exhibits mean Euclidean errors below 1 mm where the source produces strong gradients. Given the dimensions of the sensors (0.82 × 0.82 mm²), this system is suitable for tracking minimally invasive surgical tools.

Purpose: The aim of this paper is to introduce a new magnetic field exposimeter device that consists of goggles equipped with magnetic sensors for the assessment of the field exposure of MRI workers' heads. This is not possible with conventional pocket exposimeters. Hence, this device allows head‐level field exposure to be measured, which can induce physiological effects on MRI workers, and which are required to be covered by managing the laboratory‐related safety hazards directive 2013/35/EU. Methods: Using on‐chip monolithic three‐axis Hall effect magnetometers, recently introduced on the market, we developed an exposimeter with unprecedented accuracy, which allows the measurement of the magnetic field closed to the organs which are the most impacted by strong magnetic fields: the brain, the eyes, and the tongue. Results: The exposimeter prototypes were successfully tested around 3 T, 7 T, and 11.7 T MRI scanners on different workers and volunteers in real conditions. Comparisons with chest‐level measurements lead typically to lower values than exposure recorded at the head‐level, confirming the need for such head‐level assessments. Exposure of the head above the limits established by the directive was also recorded (>2 T or >2.7 T/s). Conclusion: This new exposimeter allows for a more accurate assessment of field exposure of MRI workers. Further improvements in the miniaturization and the usability of the exposimeter will allow us to disseminate the device and open the way to a larger‐scale study.