Navigation of the drilling capsule

• Applicant: Professor Dr.-Ing. Dieter W. Fellner
• Subject Area: Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics ; Image and Language Processing, Computer Graphics and Visualisation, Human Computer Interaction, Ubiquitous and Wearable Computing
• Term: from 2010 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 179880849

Main topics in this subproject are the automatic detection of the instrument position and the trajectory control. The extension of the planning of straight access paths - for multi-port bone surgery - to nonlinear paths requires an adjustment of the instrument monitoring and the trajectory control. In order to follow a pre-planned trajectory with the instrument precisely, the six degrees of freedom of the drilling capsule must be determined. In the initial phase of the project, we developed methods, which allow an accurate determination of the instrument position using a C-arm cone beam computed tomography system (CBCT). However, these methods are limited to the detection of five degrees of freedom. Furthermore, acceptable levels of radiation must not be violated, thus, a continuous data acquisition is not possible. To overcome the aforementioned shortcomings, an additional tracking system should be considered. The electromagnetic tracking (EMT) is suitable, thanks to the used small sensors, which can be continuously tracked, even if they are hidden. Due to the limited EMT accuracy, intra-operative CBCT projections are acquired and used to determine the exact instrument location, and based on it, the EMT data is adjusted for the following time period. Between successive CBCT scans, the instrument is continuously tracked using the EMT system. The scan time intervals have to be investigated in order to minimize the radiation exposure without endangering the patient. These intervals depend principally on the accuracy of the EMT system, the shape of the planned trajectory, and the distances to the risk structures. A suitable control concept will be designed to synchronize and control the various components (planning system, EMT, C-arm, and drilling capsule). By a meaningful integration of the two tracking systems (EMT and C-arm), safe continuous monitoring and control are feasible. Furthermore, a visual feedback - on the instrument position relative to the patient anatomy- has to be offered.

• DFG Programme: Research Units
• Subproject of: FOR 1585: Multiport Bone Surgery at the Otobase
• Participating Person: Professor Dr.-Ing. Georgios Sakas