Robotic System and Co-manipulation Strategy for Ultrasound Guided Radiotherapy

In this thesis, we propose a cooperative robot control methodology that provides real-time ultrasound-based guidance in the direct manipulation paradigm for the planning and the treatment delivery phases of the image-guided radiation therapy (IGRT) in which a clinician and robot share control of a 3D ultrasound (US) probe. The proposed US probe co-manipulation methodology has two goals. The first goal is to provide guidance to the therapists for patient setup on the treatment delivery days utilizing the robot position, contact force, and reference US image recorded during planning. We provide the guidance in the form of virtual fixtures, which are software-generated force and position signals applied to human operators that permit the operators to perform physical interactions, yet retain direct control of the task. The second goal is the real-time target monitoring during fractionated radiotherapy of soft tissue targets, especially in the upper abdomen. The co-manipulation technique is used to locate soft-tissue targets with US imaging for radiotherapy, enabling inexperienced therapists to find an US image which has previously been identified by an expert sonographer on the planning day. Moreover, to compensate for soft tissue deformations created by the probe, we propose a novel clinical workflow where a robot holds the US probe on the patient during acquisition of the planning computerized tomography (CT) image, thereby ensuring that planning is performed on the deformed tissue. Our results show that the proposed co-manipulation technique with virtual fixtures and US image feedback can significantly reduce the time it takes to find the reference US images, it can provide more accurate US probe placement compared to finding the images free hand, and finally, it can increase the accuracy of the patient setup, and thus, the radiation therapy