UBC Theses and Dissertations

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UBC Theses and Dissertations

Intra-operative ultrasound-based augmented reality for laparoscopic surgical guidance Singla, Rohit Kumar


Laparoscopic partial nephrectomy involves the complete resection of a kidney tumour, while minimizing healthy tissue excised, and under a time constraint before irreparable kidney damage occurs. The surgeon must complete this operation in a reduced sensory environment with poor depth perception, limited field of view, and little or no haptic feedback. For endophytic tumours (grows inwards), this is particularly difficult. In order to assist the surgeon, augmented reality can provide intra-operative guidance. Intra-operative ultrasound is low cost, non-ionising, and real-time. This has tremendous potential to guide the surgeon. This thesis details the development of three intra-operative augmented reality systems from a single framework, with augmentations all based on intra-operative ultrasound. The systems were all developed on the da Vinci Surgical System, using it as a development and testing platform. All systems leverage a single fiducial marker called the Dynamic Augmented Reality Tracker which can track the local surface and create a tumour-centric paradigm. A 3D ultrasound volume is reconstructed using a tracked ultrasound transducer. A tumour model is then extracted via manual segmentation of the volume. The three systems were developed and evaluated in simulated robot-assisted partial nephrectomies. The first system shows the feasibility of providing continuous ultrasound-based guidance during excision and achieves a system error of 5.1 mm RMS. Improving on this, the second system demonstrates clinically acceptable system error of 2.5 ± 0.5 mm. The second system significantly reduced healthy tissue excised from an average of 30.6 ± 5.5 cm³ to 17.5 ± 2.4 cm³ (p < 0.05) and reduced the depth from the tumor underside to cut from an average of 10.2 ± 4.1 mm to 3.3 ± 2.3 mm (p < 0.05). The third system is a novel intra-corporeal projector-based system that assists in determining the initial angle of resection. This system is evaluated in a surgeon study with a total of 32 simulated operations and addresses the limitations of conventional augmentations from the laparoscope's point of view. All three systems show their potential benefits in improving laparoscopic surgery with minimal additional hardware. With such image-guidance systems, the widespread adoption of laparoscopic surgery can be facilitated, improving patient care.

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