Development of the calibration scheme and system integration of the Ozyegin biopsy robot (OBR)

Imaging systems can fail to visualize cancerous tissues for proper diagnosis. Needle based procedures, like biopsies, increase the chances of accurate diagnosis of tumors. These procedures also have applications in minimally invasive treatments and regional anesthesia. In recent years, robotic systems have found their way into medical applications of needle based interventions by increasing the accuracy of these procedures. Precise needle positioning is critical in such medical applications. This thesis presents the architecture of a robotic system designed for human biopsies. The system includes a 5 DoF parallel robot that can be used in Ultrasound (US) guided percutaneous needle interventions. US imaging is used as the visual feedback. The imaging system must be calibrated in 3D space before integrated with the biopsy robot. A novel method for 3D space calibration using a multipoint cross-wire phantom is introduced in this dissertation. The calibration process is improved using wires parallel to the US image plane in order to locate the exact image position in 3D space. Most of the methods fail to consider the errors caused by this intrinsic assumption that the plane exists at the midpoint of the US probe's base, while probe holding fixtures can cause minute offsets leading to positional inaccuracies. The final calibration experiments resulted in accuracy of 0.03 mm RMS error. Details of real time functionality of the robotic system components working with spatial and computational synchronization is also presented. The real-time operation enables the robotic system to perform autonomously. This ability is demonstrated by tracking a moving target with the needle tip motion with an RMS error of 0.23 mm.