Advances in technology enable an ongoing transition from invasive, open surgery to minimally invasive diagnostics and intervention. In the field of oncology, percutaneous techniques have emerged in which a tumour is approached by a needle through the skin using image-guidance. X-ray CT-guided needle placement for biopsy and ablation of tumours in the thorax and abdomen is conventionally performed freehand. The performance of this method is user-dependent and multiple iterations are generally required to achieve satisfactory placement. Tissue damage with accompanied risks, patient X-ray exposure, procedure time and costs increase with each placement iteration. The objective of this research is the development of a system that enables precise CT-guided percutaneous needle placement in the thorax and abdomen in a single insertion.
This project covers the entire strategic, architectural and detailed design and realization of an integrated system from idea to prototype and its validation in pre-clinical setting. The state-of-the-art encompasses a wide variety of needle placement systems, ranging from simple passive aids to fully automated robots. Despite the various attempted strategies and often technically sound solutions, widespread clinical adoption of any system is lacking. A novel system was designed with a focus on clinical acceptability, applicability and usability. The system provides precise alignment of a needle guide with a user-specified target for manual insertion. The needle guide is aimed by a 2-DOFs actuated remote centre of motion (RCM) mechanism, connected to the CT table via a passive 6-DOFs linkage. The linkage allows a physician to manually place the mechanism around the patient to coincide the RCM with the desired skin entry point and push-button lock it. The relevant anatomy of the patient and the system are CT scanned to acquire a 3D image, for automatic system-to-CT registration using incorporated fiducial markers, and for target selection and path approval in a graphical user interface. The needle guide is automatically aimed at the target, which is reached by subsequent manual needle insertion to specified depth. Deceivingly simple in looks and usability, requirements on X-ray transparency demanded resorting to unconventional glass, ceramic and composite precision parts, remote actuation via endless Dyneema cables, fibre optical encoders, carbon nanotube electrical circuits and pneumatic-hydraulic locking systems, all customized and confined in a compact design to meet size and shape requirements.
This project was funded by several funding sources, Demcon and the University of Twente.