An Open Framework Enabling Electromagnetic Tracking in Image-Guided Interventions

Abstract

Electromagnetic tracking (EMT) is a core platform technology in the navigation and visualisation of image-guided procedures. The technology provides high tracking accuracy in non-line-of-sight environments, allowing instrument navigation in locations where optical tracking is not feasible. Integration of EMT in complex procedures, often coupled with multi-modal imaging, is on the rise, yet the lack of flexibility in the available hardware platforms has been noted by many researchers and system designers. Advances in the field of EMT include novel methods of improving tracking system accuracy, precision and error compensation capabilities, though such system-level improvements cannot be readily incorporated in current therapy applications due to the 'blackbox' nature of commercial tracking solving algorithms. This paper defines a software framework to allow novel EMT designs and improvements become part of the global design process for image-guided interventions. In an effort to standardise EMT development, we define a generalised cross-platform software framework in terms of the four system functions common to all EMT systems; acquisition, filtering, modelling and solving. The interfaces between each software component are defined in terms of their input and output data structures. An exemplary framework is implemented in the Python programming language and demonstrated with the open-source Anser EMT system. Performance metrics are gathered from both Matlab and Python implementations of Anser EMT considering the host operating system, hardware configuration and acquisition settings used. Results show indicative system latencies of 5 ms can be achieved using the framework on a Windows operating system, with decreased system performance observed on UNIX-like platforms.

Electromagnetic-Guided Interstitial Catheter Navigation for Gynecological Brachytherapy: a Phase I Trial (E-MINT)

“…In a clinical brachytherapy environment, such sources of field distortion include medical imaging devices, patient immobilization equipment and surgical instruments [95]. Furthermore, ferromagnetic objects become strongly magnetic in the presence of an electromagnetic field, which can act as another source of field distortion for EMN [97].…”

Electromagnetic Tracking Using Modular, Tiled Field Generators

“…An open source EMT system [16], [19], [21] was used in this paper to obtain experimental results. A photograph of the system field generator and base station is shown in Fig.…”

“…Sixteen frequencies ranging from 18 to 33 kHz with 1-kHz spacing were chosen. The sensor position update rate was fixed at 30 Hz for all experiments in order to ensure deterministic time intervals between successive position measurements, although the system is capable of increased update speeds [21]. The connectivity between the base stations is illustrated in Fig.…”