Treatment of prostate cancer can be done by performing brachytherapy, where radioactive seeds are transperineally implanted in the prostate via needles. A known problem during treatments with needles is the risk of targeting errors caused by the deviation of the needle from the planned path in the prostate. One of the main sources of this error is the displacement of the prostate due to insertion of the needle. Often, stabilisation needles are used to stabilise the prostate, however, stabilisation needles alter prostate properties, damage tissue, and do not fully reduce prostate displacement. Therefore, in this study, we propose and evaluate an alternative solution that stabilises the prostate without additional tissue damage. The stabilisation solution is a modular suction cup referred as the ProSTATIC, which can be transperineally inserted via a 5 mm incision to attach to the prostate within the rectoprostatic space. The ProSTATIC has a multi-holed design consisting of three structural layers with their functionality; (1) the top to maintain the pressure inside of the suction cup and provide for structural stability, (2) the footprint to adapt and form a closed seal with the prostate surface, and (3) the self-regulating valves to increase the attachment reliability on irregular surface textures. For the footprint, we experimented with micro-patterns and suction hole sizes to increase the overall grip force. The prototype was completely fabricated out of biocompatible and ultrasound-compatible silicone rubber using mould casting. An experimental evaluation showed that the self-regulating valves work only on healthy prostate phantom. On healthy-tumorous and full tumorous tissue phantoms the suction holes deform, hindering the optimal working of the valves and leading to air leaks. Furthermore, only the prototype with the base footprint with enlarged suction holes (from 2 mm to 3.2 mm diameter) and radial ridges was able to generate a maximum grip force higher than the required 5 N for stabilisation and demonstrated that prostate displacement was reduced by 75% during needle insertion without the use of the ProSTATIC. The prototype proposed in this study forms an initial breakthrough in safe and reliable volumetric stabilisation of the prostate during brachytherapy.

Background: The goal of minimally invasive surgery (MIS) is to perform surgery by minimal damaging the body. Compared to traditional open surgery MIS results in faster recovery and lower mortality, and is therefore the preferred method for performing a biopsy. Natural Orifice Transluminal Endoscopic Surgery (NOTES) is a type of MIS where an instrument enters the body through a natural orifice to reach the target. During NOTES an instrument enters the body through a natural orifice to reach the target. Upon entering the body via a natural orifice, first the target area needs to be reached and second, the targeted tissue needs to be transported out of the body for further examination. Currently used instruments for NOTES are suboptimal for transport through tubular organs due to damaging the tissue. In this study, a friction-based transport mechanism, inspired by eggs of parasitic wasps, was developed as an improved tool for NOTES. Additionally, the possibility to steer this instrument was examined as well. Methods: State of the art mechanisms were analysed and selected based on their potential for being used as a flexible system for locomotion through a tubular organ and tissue transport. Requirements of this instrument were determined which were divided into requirements for the flexible shaft and for the actuation of the locomotion and transport mechanism. Requirements were also determined for the additional wish for the instrument to be steerable. Based on these requirements a final design of a flexible shaft and actuation was developed. The design process for steerability of the flexible shaft is described as well, resulting in a tip that can be added to the flexible shaft to add steerability. Performance of the flexible shaft was evaluated based on locomotion through a tube, tissue transport and steerability in a simulated setting. The flexible shaft was tested if it is possible to locomote through a tube, transport tissue and can be steered. Results: The developed instrument was able to locomote in a straight direction and three different configurations: with a bending radius of 80 mm, 105 mm and 130mm and a bending angle of 45°, 30° and 15°, respectively. The locomotion rate in the straight direction was 6.17±0.27 mm/cycle and was 5.21±0.21 mm/cycle in the maximum bent direction (bending radius of 80 mm). The instrument was adequate for the intended use: (1) insertion into a tube, (2) locomote through the tube, and (3) transport tissue out of the tube using the flexible shaft. Adding the tip and attached steering wire ropes with manual operation allowed the shaft to be steered up to an angle of 90° with a bending radius of 58 mm. Discussion and conclusion: A flexible shaft instrument was developed that was able to locomote and transport tissue through a tube. Additionally, a steering tip was designed that allowed to steer the instrument from outside the body/tube. While lower locomotion rates were observed for lower bending radii, the developed design shows great potential for an instrument to perform NOTES with minimal burden for the patient.

In recent years, patient specific instrumentation (PSI) has shown to be a promising application of 3D printing in orthopedic surgery. By aiding the surgeon with accurate placement of instruments such as saws or drills, surgeries can be performed faster, and require less surgeon experience. While most of these devices interface directly with the bone, invasiveness can be greatly decreased by applying the device to the outside of the body. Such an external device also allows for guidance with respect to bones that are too small to place a device on directly, for example the carpal bones in the wrist. In this thesis, an external PSI is designed to aid surgeons in accurately drilling a tunnel through the scaphoid; one of the carpal bones. The main challenge addressed in this thesis is how to rigidly attach a guide to the largely soft and elastic exterior of the hand. This was overcome by ensuring that the guide only contacts the hand at locations where the bone lies directly under the skin. Exact constraint design was applied to determine a minimal set of such contact locations that fully constrain the relevant anatomy. A 3D printed prototype was made for 6 participants and measurements were done to determine the positioning accuracy as well as the stiffness of the connection between the guide and the body. The results show that external PSI is a promising technology for application to wrist surgery, but may not be applicable to other parts of the body due to a limited number of suitable contact locations.