Treatment methods for spinal disorders involving spinal fusion surgery often entail lengthy and expensive procedures, with a risk of damage to surrounding tissues. Breach detection tools aid in precise pedicle screw placement, thereby reducing the risk of complications or misalignment, and minimizing the need for follow-up surgeries. Accurate placement of pedicles in the vertebrae is crucial in spinal fusion surgery, as improper positioning can result in breaches that potentially harm neural tissues. This study proposes a handheld bone sensing device capable of measuring real-time reflected light from tissue using carefully selected optical elements. The selection of these optical elements was guided by analyzing porcine absorption spectra and conducting Monte Carlo light reflectance simulations. The device is designed to provide consistent real-time feedback by incorporating an electronic circuit optimized to minimize environmental signal interference. A prototype, named the optics-based bone quality sensing device, was developed using electrical discharge machining parts, 3D printed parts, an Arduino Uno, a custom-made printed circuit board (PCB), and off-the-shelf optical components such as laser and photodiodes coupled into optical fibers. Experimental validation with ex vivo porcine vertebrae revealed that the device could not detect sufficient reflected light to differentiate between cortical and cancellous bone. Despite this, the study marks significant progress in creating a handheld bone sensing device that utilizes real-time reflected light sensing minimizing interference. This device represents an important step towards developing tools to assist in precise pedicle screw placement for the treatment of spinal disorders.

This research project presents a COMSOL model that simulates the measurement of elastic waves within a solid domain generated by the photoacoustic (PA) effect. The model may facilitate the development of a novel, forward-looking PA endoscope that integrates a relatively new PA imaging method for the first time. PA endoscopy is used to image tissue layers up to several millimeters deep, with applications including intravascular imaging and imaging of the gastrointestinal tract. The most challenging requirement is achieving a frame rate exceeding 20 Hz while maintaining a reasonable resolution. Recently, novel imaging techniques, such as photoacoustic topography through an ergodic relay (PATER), have been explored based on a single sensor and acoustic cavity, which reduces complexity and speeds up frame rates. A numerical model could be beneficial to facilitate the design of this novel PA endoscope. However, the modelling of this process is not straightforward due to the time dependency and high frequencies involved. An important aspect of this model is a highly tunable but representative PA signal source. The ability to change the input signal such that the frequency content does not exceed what could be measured allows for using a mesh size that is not smaller than necessary. Validation of a 2D version of the model against experimental data was performed, and the computational costs were explored with the help of the DelftBlue cluster.

Reliable assembly methods are needed to translate new endoscopic probes from the research phase to clinical testing. Design variation complicates standardized assembly and leads to a lengthy process creating inaccurate prototypes, preventing repeatable research. This thesis proposes a strategy for selecting the most effective assembly method by examining alignment and bonding relations among parts. Considering the manufacturing tolerances of the optical parts leading to a loss of image quality, an approach for testing is selected to align the gradient index (GRIN) lens and fibre. This approach implements an active alignment procedure and reaches a sensitivity of 3𝜇𝑚 for the concentricity, 0.4 deg for the colinearity and 40𝜇𝑚 for the separation distance. These results validate a better result than reachable with passive alignment. An optimization algorithm could replace the manual comparison of the ideal beam profile for increased repeatability. To advance the research to the assembly of complete prototypes, more components of the probes should be added to the investigation and a method for fixing the components to the housing should be introduced.

The investigation of the interaction between lasers and brain tissue holds significant theoretical and practical significance in the field of brain physiology studies. A two-dimensional finite element-based simulation model was constructed using the commercial finite element simulation software COMSOL Multiphysics to investigate the propagation of light and photon correlation in tissues. The simulations included static and dynamic conditions of light propagation in tissue. In both cases this diffuse light propagation itself was studied along with photon correlation using the solution of the diffusion equation. Subsequently, the obtained simulation results are assessed and summarized by considering the outcomes of data fitting. The findings indicate that the accuracy of simulating light propagation is higher for larger sizes, although satisfactory results can be achieved for correlation propagation simulations in the small size range. The simulation results remain unaffected by the refinement of the mesh, provided that the fundamental criteria for mesh size are satisfied.

Bio-imaging plays an essential role in life sciences and medicine. Recently, structured illumination has emerged as a promising super-resolution technique. However, in the case of thick scattering media, the benefits of structured illumination can be significantly reduced compared to conventional illumination methods, resulting in significant degradation of imaging quality. Therefore, the question of dealing with the challenges posed by structured illumination in scattering media has become a topic of considerable focus. In this thesis, an experimental setup aimed at achieving super-resolution imaging using structured illumination is developed. The factors influencing the imaging process are systematically analyzed. At the same time, machine learning methods for recovering structured illumination patterns propagated through scattering media are explored. Overall, this research tackles the challenge of improving super-resolution imaging through scattering medium thereby contributing to the development of biological and medical imaging technologies.

Atrial fibrillation is a cardiac arrhythmia resulting from abnormal electrical conduction and impulse formation within the atria. To address this condition, a minimally invasive procedure called cardiac ablation is performed. Real-time visual feedback during this procedure plays a critical role in determining its success.

Photoacoustic imaging is a technique capable of providing real-time visual feedback. Integrating photoacoustic capabilities into existing Radiofrequency ablation catheters poses a significant challenge, which this thesis addresses. The proposed integrated solution employs optical fibers for light delivery and an ultrasound transducer for signal reception.

This work investigates the design of two light delivery systems for integrated photoacoustic-guided surgery. Monte Carlo simulations are employed to study three-dimensional light propagation in tissue, informing the catheter design specifications. Optimal fiber distances and orientations within the catheter are determined based on normalized fluence values and illumination spot size—critical parameters for assessing the amount of delivered light, its area of coverage, and depth of penetration. The methodology presented applies to various photoacoustic applications.

The simulation study was able to successfully inform design specifications and it was able to establish a relation between design variables and the evaluation criteria such that it can be referred to for future designs. The comparative study yielded a better-performing design configuration and its optimal specifications were found out. This proves the use of a simulation-based evaluation to design a photoacoustic intracardiac catheter. In the final phase of this research, an experiment is set up to validate the light delivery of the design, which provides a clear outlook for the future of these designs into fabricated products.

Integrated operating rooms (OR) have shown to be promising in meeting the challenges created by the increased complexity in the OR, by improving the quality of care, simplifying the clinical workflows, and reducing equipment-related incidents and surgical errors. Although several systems that integrate medical devices have been developed, surgical energy devices have yet to be integrated into these systems. Current measurement systems of surgical energy devices are not yet suitable for this integration, due to a lack of being manufacturer-independent and being limited in the amount of measured information. Therefore, the main objective of this thesis is the development of a manufacturer-independent measuring system that can estimate and communicate the state of any surgical energy device in real time. To realize this goal, a measurement system has been developed that measures the state of any surgical energy device through image recognition. The system is integrated into the OPeLiNK system of the Smart Cyber Operating Theatre, SCOT. It can however, be integrated in any of the other integrated ORs. The system has been tested through several experiments, showing that the accuracy and measuring speed meet the requirements of 90% and 0.2s. The system outperforms the state of the art in the amount of data that is being measured in real time at the cost of a small delay of 0.07s. Currently the bottleneck is the communication through the OPeLiNK system, where the communication frequency has a set limit of 1Hz. It can be concluded that the developed measurement system can be used for the integration of surgical energy devices in the integrated operating room. The next step is to further improve the system in terms of robustness, easier use, and increased measurement capabilities.