Background : There have been several advancements in modelling the behaviour of the finger and its internal anatomical structures and in the development of anthropomorphic fingers. Most studies that include ligaments focus on force distribution in the tendon-ligament network for a particular task. In the design of anthropomorphic fingers, especially in two recent projects, ligament attachments have been decided through iterative trials and the the tendon network has been used to control the range of motion of the finger. However, the collateral ligaments also play a major role in limiting the range of motion of the finger in addition to contributing to medial-lateral joint stability.
Aim : The aim of this project is to develop an algorithm to automatically compute coordinates for collateral ligament attachment sites for the Distal Inter-Phalangeal (DIP) joint of the finger, given a required range of motion in terms of maximum flexion and extension angles.
Method : The DIP joint was described in two dimensions (in the sagittal plane) with one degree of freedom (flexion-extension). Constraints were formulated based on geometry and observed and reported ligament length ranges. The model formulation was also informed by insights from the dissection of three preserved human index fingers. The algorithm named ’Auto-LINC’ (Automating Ligament Insertion Coordinates) involved two stages. The first was a combinatorial approach used to establish the best possible combination of attachment sites out of a set of feasible solutions. This was used to seed the second stage - a continuous domain approach used for local optimisation. The algorithm was designed in such a way that the two stages can be used separately or in combination depending on the application.
Results : The attachment sites computed using the combined approach were used to add ligaments to an existing OpenSim simulation model of an anthropomorphic DIP joint to verify that the required range of motion was achieved. The process was illustrated with an example in which 99.6% of the required range of motion was achieved using ligaments with attachment sites computed by Auto-LINC.
Discussion : The use of an algorithm with geometric constraints and objective function yielded feasible solutions in a short time. By adapting the constraints to suit differences in geometry, Auto-LINC
can also be used to predict collateral ligament attachment sites for other flexion-extension joints such as the Proximal Inter-Phalangeal (PIP) joint. Auto-LINC has potential for use in the design of anthropomorphic fingers as it automates the process of deciding ligament attachment sites. It also has potential for use in guiding robot-assisted reconstruction surgery. It can be made more detailed and versatile by adding material properties and constitutive equations and by extension into three dimensions.
Conclusion : Auto-LINC is already usable in its current form to compute form based on function, and has potential for use in automating anthropomorphic design and guiding reconstruction surgery. In
contrast to other published research, Auto-LINC computes ligament attachment sites based on range of motion - in other words, it focuses on moving from function to form rather than form to function.

This thesis is concerned with the technical, physical and computational challenges regarding
the incorporation of microwave tomography in hyperthermia treatments. Hyperthermia is a
clinical technique in which tumorous tissue is heated to gain therapeutic effect for concurrent
radiotherapy. Hyperthermia by microwaves, as performed at the Erasmus Medical Center,
suffers from uncertainties and lacking control. To relieve the burden of uncertainties regarding
dielectric properties and patient positioning, microwave tomography can be used in hyperthermia systems. This could also improve treatments, as it would offer more possibilities for
controlling the delivery. This work is focused on relieving several practical limitations to the
integration of tomography, rather than researching its possibilities. This thesis is accompanied by the literature research “Advancements in Microwave Tomography and Hyperthermia
Treatments” by the same author.

Weak multivalent interactions between receptors and ligands can achieve super selectivity due to enhanced binding from multiple arms, enabling them to differentiate between surfaces with varying receptor densities. However, the theoretical understanding of multivalent binding including the effect of receptor depletion, binding kinetics, and the effect of incorporating different ligands within a single nanostar, is limited. This complicates the interpretations of experiments and restricts the therapeutic potential of multivalent particles. This study implements the Gillespie algorithm, to systemically study their binding kinetics, depletion effects, and the effect of incorporating two different ligands within a single nanostar. These simulations demonstrate a significant reduction in coverage, selectivity, and average number of arms bound per particle in equilibrium at the receptor density regime where receptor depletion is significant. Additionally, receptor depletion causes a dynamic competition between bound and unbound nanostars, leading to a decrease in the average number of arms bound over time. The populations of nanostars with i arms bound have a higher population selectivity than the selectivity considering all bound nanostars. Furthermore, incorporating two types of ligands can enhance selectivity. These insights advance our understanding of multivalent systems, offering the potential for incorporating multivalent particles in therapeutic applications.

Introduction
Osteoarthritis (OA) is a prevalent joint disease affecting 7% of the global population in 2020. Lower limb malalignment emerges as a significant contributor to OA, presenting as varus or valgus misalignment. This deviation induces unicompartmental pathology, leading to the wear and tear of the protective cartilage. Surgical interventions, including osteotomies, are essential in managing unicompartmental knee OA. During osteotomies, hinge fractures are a common complication. This paper focuses on optimizing open wedge osteotomies, specifically exploring complications in medial open wedge distal femoral osteotomy (DFO) using finite element models. And investigates the viability of the medial open wedge DFO compared to the lateral open wedge DFO.
Method
The research employed a systematic approach to investigate ways to avoid hinge fractures in Distal Femoral Osteotomy (DFO). Finite Element Modelling (FEM) served as the cornerstone of our methodology, providing a numerical solution. The process involved the creation of finite element models from CT scans through the subdivision of femoral geometry. The automated generation of these models was facilitated by a combination of 3-matic, Mimics, and Abaqus. Using Python scripting in these different programs, a workflow for model creation and parameter variation was created. The lateral open wedge DFO model, serving as the baseline, underwent systematic alterations to explorethe impact of hinge size, osteotomy gap angle, and other variables. The creation of finite element models involved several key steps, including geometry creation, mesh generation, addition of material properties, and the application of boundary and loading conditions. Material properties were assigned based on a simplified isotropic model derived from Hounsfield units. Extra attention was given to automate the process of model generation to ensure efficiency and reproducibility.
Results
Six distinct models were created with a comprehensive analysis of their attributes and shortcomings. The study finds that the medial open wedge DFO does not induce hinge tension. Comparative analyses in both opening and loading stages reveal nuanced stress and strain differences with the lateral open wedge DFO. No clear conclusion can be given as to the viability of the medial open wedge DFO compared to the lateral open wedge DFO. In-depth exploration indicates that smaller hinges are favourable for osteotomy gap opening, while larger hinges (10mm and above) contribute to stability during loading. Minimal impact on stress concentration is observed for osteotomy gap angle variations. The study explores the effectiveness of drill holes in stress relief, highlighting precision challenges.
Discussion
Acknowledging inherent limitations such as partial volume effects and assumptions about material properties. The study suggests promising avenues for future research. Recommendations for future research include in vivo experiments, exploration of XFEM and fracture mechanics, and further refinement of modelling techniques. This study provides nuanced insights into hinge fractures during open wedge DFO, guiding future research and bridging the gap between finite element modelling and
clinical realities.

The internal carotid arteries (ICAs) are of vital importance in cerebral blood supply. Hence, accurate modeling of its biomechanical behavior is essential for understanding various pathologies and developing effective treatments. However, computational modeling of the ICA often omits the surrounding tissue environment, which likely limits the accuracy of biomechanical simulations. This study aimed to assess the impact of including surrounding tissues in ICA models on simulation outcomes. Using a single patient-specific ICA geometry, four finite element (FE) models were developed and analyzed: an isolated artery (Model 0), an artery with soft tissue interactions (Model 1), an artery with bone interactions (Model 2), and an artery with both soft tissue and bone interactions (Model 3). The surrounding tissues were modeled using elastic spring elements attached to the outer surface of the arterial wall. Different spring stiffness values were assigned to simulate the distinct properties of surrounding tissues in their corresponding artery segments. Simulations were performed using the FEBio software, the models were analyzed for displacement, stress, and strain distributions. Results showed that surrounding tissues significantly affect arterial biomechanics, with bone having a more dominant effect than soft tissue. The combined tissue model (Model 3) provided the most comprehensive and physiologically accurate representation of the ICA, with a 60.5\% reduction in peak displacement, a 6.8\% reduction in peak stress, and a 33.0\% reduction in peak strain compared to the isolated artery model. However, these preliminary findings using a single ICA geometry prevent us from drawing definitive conclusions. Therefore, our study serves as the groundwork for future investigations and highlights the significance of including surrounding tissues in ICA modeling.

The mechanical failure of a temporomandibular joint (TMJ) replacement system can stem from various factors, with one notable cause being the unnatural kinematics and loading observed in prosthetic joint function. Given that,. the primary objective of the study was to investigate whether including functionally graded materials (FGMs) at the site of the prosthetic joint was feasible for achieving a greater resemblance to natural mandibular kinematics, while simultaneously reducing the reaction force exerted on the prosthetic joint. To this end, an FGM-based TMJ implant was designed with the intention of reducing joint reaction forces and enhancing joint flexibility to achieve a more natural kinematic behavior.

In this study, patient-specific finite element models of the intact and implanted mandible were simulated for two different biting tasks: incisal biting (INC) and left group biting (LGF). To incorporate FGMs into the implant design, an initial implant design was voxelized (with a voxel size of 0.25mm x 0.25mm x 0.25mm), allowing each voxel to be assigned a specific material. Subsequently, 10 voxel layers of the same size were added onto the implant head/prosthetic condyle. To investigate the impact of FGMs on mandibular biomechanics, a comprehensive analysis was performed on five distinct implant designs. These designs were differentiated solely by the functional gradient in material properties across the additional 10 voxel layers on top of the implant head. Each voxel (layer) was assigned a value of ρ, which represented the volume fraction of the hard phase.

The five distinct implant designs were as follows: (1) The first design was labelled as the "Polymeric Implant" consisting solely of the hard phase with a volume fraction of ρ=100%. It served as the reference for comparisons with other designs. (2) The second design featured an abrupt hard-soft connection without a gradient. This design was specifically examined to demonstrate the presence of stress concentrations at discrete interfaces between the hard and soft materials in layered composites. It was named "Implant with abrupt hard-soft connection without a gradient". (3) The third design was characterized by an FGM comprising ten discrete values of the volume fraction of the hard phase, ranging from ρ=0% at the surface layer to ρ=90% at the 10th layer with an increment of 10%. This design was designated as "FGM, ρ= [0, 10,…, 90]". (4) The fourth design encompassed an FGM featuring nine distinct values of the volume fraction of the hard phase, ranging from ρ=10% at the two surface layers to ρ=90% at the 10th layer with an increment of 10%. It was referred to as "FGM, ρ= [10, 20,…, 90]". (5) The fifth design comprised an FGM incorporating eight discrete values of the volume fraction of the hard phase, ranging from ρ=20% at the three surface layers to ρ=90% at the 10th layer with an increment of 10%. This design was named "FGM, ρ= [20, 30,…, 90]". The primary objective of investigating the fourth and fifth designs was to analyse the influence of a relatively less soft material at the surface (outer layer) of the implant head.

The biomechanical performance of an implant design was determined by utilizing normalized cross-correlation (similarity) and Euclidean distance (closeness) measurements between the displacement fields of the intact and implanted mandible. The performance of an implant design for a specific biting task was assessed by calculating the average of the percentage errors in each of these quantities. Additionally, the reaction forces on the prosthetic joint were compared between the implanted models.

The results showed that the second design, which featured an abrupt hard-soft connection without a gradient, was not viable. This was due to the presence of stress concentrations, stress increase up to more than ninefold was observed, at discrete interface between materials of contrasting hardness. This phenomenon could result in crack initiation and delamination, significantly compromising the overall performance and durability of the design. The study also revealed that material properties distribution on the surface of the implant head had a crucial impact on regulating mandibular displacements. Notably, greater displacements were observed when the outer layer of the implant head featured relatively softer material.

In comparison to the polymeric implant, “FGM,ρ=[0,10,…90]” implant exhibited an average performance increase of 19% for INC and a 3% performance decrease for LGF regarding mandibular displacement. Additionally, it reduced the joint reaction forces on the prosthetic joint by 8% and 12% during INC and LGF, respectively.

Moreover, the "FGM, ρ=[0,10,…90]" implant increased the mandibular range of motion by 20% during INC and 88% during LGF. Furthermore, it contributed to more symmetrical mandibular movement during INC, while the concept of symmetry was not applicable in the context of LGF.

These results have provided valuable insights for future research and development of TMJ implants, potentially leading to the creation of implants with improved long-term behavior.

Delayed healing or non-union of bone fractures are still clinically and economically relevant problems. Bone healing includes pro- and anti-inflammatory phases, which proved crucial for successful healing. Being able to modulate these inflammatory responses could potentially promote bone fracture healing. Dendritic cells play important roles in the immune response after bone fracture, due to their immune regulating abilities via cytokine secretion and antigen presentation. Therefore, DCs are a target for immunomodulatory therapies. One way of modulating cell behaviour can be altering osmolality in cell microenvironments. This thesis investigates in vitro if environmental osmolality can modulate the inflammatory phenotype of monocyte-derived dendritic cells (moDCs) in 2D and 3D microenvironments.
To exclude adverse effects such as cell death by hypo- or hyper-osmotic conditions, a range was established where moDCs maintain high viability and metabolic activity. Hypo-osmotic medium was established by diluting iso-osmotic cell medium with deionized water. Hyper-osmotic medium was established in two ways, by supplementing iso-osmotic cell medium with either ionic sodium chloride (NaCl) or inert polyethylene glycol (PEG). moDCs maintained high viability and metabolic activity between 210-385 mOsm/kg for NaCl and PEG. The conditions for the hypo- iso- and hyper-osmotic media for all cell culture experiments were defined as 220, 281 and 381 mOsm/kg, respectively.
In 2D cell culture, hypo- or hyper-osmolality did not stimulate a significant change in surface marker expression of activation markers CD40, CD80, CD83, CD86, CD197 and HLA-DR compared to the non-activated control. This suggests that osmolality alone was not sufficient to modulate the inflammatory phenotype. Hereafter, the effect of osmolality on maturation with Lipopolysaccharide (LPS) was investigated. Exposure to hypo- or hyper-osmolality in 2D moDC culture with LPS as maturation factor, showed no significant difference in expression of CD40, CD80, CD83, CD86, CD197 and HLA-DR compared to the activated control. However, a trend was observed in hyper-osmotic medium with PEG and NaCl, where moDCs showed a decrease of CD40 and HLA-DR expression in the PEG condition and a decrease of CD197 in the NaCl condition. This suggests that hyper-osmolality could attenuate the activating capacity of LPS and depending on the osmolyte, can potentially decrease T cell activation or migration of moDCs. Functional analyses such as mixed lymphocyte reaction and migration assays may elucidate if hyper-osmolality can affect moDC T cell activation and migration. For cell culture in 3D microenvironment, the mechanical properties of fracture hematoma were modelled using alginate hydrogels to gain an understanding of the behaviour of DCs during bone healing. Low molecular weight alginate was used to mimic the stress relaxation behaviour. Stiffness was tuned trough ionic crosslinking concentration. The resulting gels had a stiffness of 8±0.3 kPa and stress-relaxation half-time of 199.7±10.8 s. In these 3D microenvironments during LPS maturation, hypo- or hyper-osmolality did not show a significant change in expression of CD40, CD80, CD83, CD86, CD197 and HLA-DR compared to the activated control. This suggests that moDCs were not sensitive to osmolality during maturation with LPS in 3D microenvironments. Comparing the outcomes of 3D to 2D cell culture, moDCs appeared less sensitive to changes in environmental osmolality during LPS maturation in 3D than on 2D substrates.

Overall, for both the 2D and 3D studies, a larger cohort of donors is needed to improve confidence in the results. Based on the trends observed, the outcome of the study does not indicate that osmolality could be used in 3D microenvironments to modulate the inflammatory phenotype of moDCs, as activation markers remained largely unaffected. In 2D cell culture, hyper-osmolality could modulate the inflammatory phenotype of moDCs during maturation with LPS through downregulation of activation markers. Osmolality should be considered when designing immunomodulatory treatments, as osmolality might affect DC maturation in 2D cell culture.

Background
Adolescent idiopathic scoliosis (AIS) with a Cobb angle larger than 45° is a spinal deformity that needs surgical treatment to stop progression and reduce pain. Spinal fusion is a surgical procedure where rods are attached to the spine through screws to diminish the Cobb angle.
Objective
The metal rods are pre-bent to correct the spinal deformity as much as possible. This rod shape is currently based on experience of the orthopedic surgeon. The aim of this thesis is to use Fi-nite element analysis (FEA) to predict a suitable rod shape for AIS patients that need to un-dergo surgery. 
Method
An FE model of an AIS spine was created based on high quality CT images. Rotation of ver-tebrae led to the optimal shape of the spine in the coronal plane. Vertebral bodies in this model were one by one rotated to a new position from top to bottom, to bring the spine to a new state and align it as much as possible to a normal physiological shape. However, alignment of the spine is an iterative process and rotation of every subsequent vertebra affects the shape of the entire spine. For each vertebral rotation, the reaction moments to maintain the new position is determined in the FE spine model. The acquired reaction moments are transferred to an FE rod model to provide the pre-bending of a rod that can bring the spine in its new state.
Results
The FE spine model was corrected to reduce the Cobb angle as much as possible. The highest stresses were found at the spinal apex. The reaction moments were transferred to a rod that became deformed in such a manner that straightened the spine model and corrected the Cobb angle to its pre-determined position with 33% reduction.
Discussion
This is an exploratory study that examines the possibility to predict ideal rod shapes pre-operatively to reduce surgical duration and improve the quality of the procedure. An accessory rod shape was accomplished but could not be validated due to lack of comparable studies. Improved FE spine models will lead to higher reliability of FE pre-bent rod models. This can be accomplished by, for example, inclusion of ligaments, muscles and other structures in the FE model and use of time-dependent material properties. The current model did not lead to a perfect aligned physiological spine and optimization algorithms should be developed in future models to further improve pre-bending of the rods.
Conclusion
Pre-operative prediction can improve the quality and reduce the time of spinal fusion. Im-provements to the FE spine- and rod model, such as automation, generalization, inclusion of more structures, and optimization algorithms will lead to optimal pre-bending of rods and bet-ter and quicker surgical outcome.

Background: The procedure to fit a prosthetic socket to a patient, which can assure the patient’s comfort during activities of daily living, is labour intensive. Such a lengthy procedure could benefit from an automated and more efficient data-driven method capable of automatically tracking the relative movement between the patient’s tibia and the prosthetic socket. To investigate such a method, we acquired in-socket bone displacement data during the physical activities of the prosthetic user. Manually tracking the location of the tibia from, e.g., B-mode (imaging) ultrasound (US) sequences might be a solution, but this is time-consuming, and the interpretation of the sequences is highly operator dependent. Therefore, an automated and efficient method to assess socket fit in US sequences is needed.
Methods: We used an existing 3D U-Net with a long short-term memory module (LSTM) and compared its ability to track a landmark location point on the tibia in US recordings by comparing the displacement and similarity in shape with data obtained from a semi-automatic single-point tracker. To evaluate the performance of the developed automated workflow, we obtained experimental data from three participants who performed three repetitive stepping tasks with their prosthetic leg in a sideways, forward, and backward motion. Three deep learning models were trained with a varying hold-out method (66% training data, 34 % test data) to test the ability to track a landmark location on the tibia in unseen data from one participant. To find the similarity of the deep learning models compared to a semi-automated single point tracker, the normalised root mean squared error (NRMSE) was calculated. We also evaluated the normalised maximum cross-correlation (NMCC) to account for the maximum similarity in displacement trajectory when a delay occurred between the true trajectory and that from the automated model. We analysed the repeatability of each step task per participant with the standard deviation from the mean tibia’s landmark location trajectories.
Results: Due to the delay between the semi-automated single-point tracker and the DL model, the NRMSEs ranged between 27% and 90%. The similarity threshold (0,95) was reached for five trajectories of the tracked point on the tibia in the anterior-posterior direction, with a delay between 1,5% and 8,5% of the step duration. The similarity in the anterior-posterior direction of the tibia’s landmark location trajectory was higher than that in the lateral-medial direction. The SD for all participants was around 1 mm but varied proportionally to the amount of movement observed per participant. The SD of the DL models was similar to that of the semi-automated single-point tracker.
Conclusion: We conclude that a DL model from a 3D U-Net with an LSTM module has the potential to assist prosthetists and researchers in tracking in-socket tibial bone movement in the anterior-posterior direction.

Introduction: A combined bone growth and remodeling model should be created, to investigate the effect of different femur shapes on the risk of developing cam type deformities. The different femur shapes needed for this study can be created using a statistical shape and appearance model (SSAM). The workflow of the combined bone growth and remodeling model has been (semi)-automated for increased efficiency and other future uses. Methods: An algorithm was created that leads the user through a (semi)-automated workflow, where the necessary features are added to the simulation. The model uses remodeling and growth simulations in sequence to estimate both the change in density distribution and in shape. The used loading conditions correspond to the 10% gait cycle phase. The remodeling is driven by strain energy density, and the growth by the osteogenic index. Results: The resulting density distributions are similar to those found in other studies, while the growth model predicts larger changes in the neck-axis angle than other studies. The growth was also predicted for two MRI pilot scans and the predicted growth was similar to the growth found in follow up scans of the same children. To investigate the influence of the bone shape on the development on cam-deformities, three different shape modes were varied and their influence on the osteogenic index in the growth plate was analyzed. The results from this study indicate that an increased femoral neck-axis angle increase the growth stimulation in the cam region of the growth plate. Discussion: The created bone adaptation model performs mostly as expected, only the included growth model occasionally performs unreliably. To improve its reliability, recommendations have been given to improve its behaviour. Because of the increased growth stimulation in the cam region of the growth plate, the results indicate that femurs with a large neck-axis angle have an increased risk of developing cam type deformities. The effect of other shape characteristics is unclear, and more research is recommended to investigate the effect of other characteristics, such as the femoral anteversion.

In the worlds poorest regions there exists an urgent need for surgical care. Open fractures, one of the Bellwether procedures, are treated in only 42% of the health facilities in low- and middle income countries. Worldwide, external fixation is one of the most important treatment methods for open fractures, providing immobilization to the fracture while retaining soft tissue integrity. In LMICs however, is the treatment of open fractures with an external fixator not self-evident. Due to a lack of equipment and incomplete donations, a clear need is indicated for application of a standardized low-cost external fixator system for LMICs. The goal of this thesis is to develop a universal fixator clamp for application in low - and middle income countries, providing fixation to both lower- as upper extremity open fractures. In collaboration with Global Surgery Amsterdam and the Amsterdam University Medical Centre, the design of a predecessor external fixator clamp is improved. The design of this clamp consists of three sloths: 4mm, 5mm, and 8mm. As a consequence, this reduces the number of components needed to perform external fixation. Included factors in this iterative design process are the identification of needs, serving as input for the prototype development of the universal clamp. Based on the defined needs the product requirements are defined, giving prioritization to cost-effectiveness. These requirements served as input for the next phase of the design process. The conceptualization of the refined universal clamp is guided by three subproblems: stability enhancement, weight reduction, and increasing functionality. A material analysis demonstrates aluminium 6061 is the most suitable for this application. Next, the theoretical mechanical behavior of the developed clamp concept is analyzed using two use cases. The final clamp concept is manufactured and compared in six mechanical tests with a state-of-the-art external fixator clamp, the Hoffmann 3, to evaluate the performance. Slippage and rotational tests are performed at three different tightening torques for all three diameters. The universal clamp performs significantly less on all six mechanical tests and as a consequence provides less stability to open fractures in comparison with the Hoffmann 3 clamp. Therefore, further development of the universal fixator is necessary to be successfully adopted as a Lifebox-idea to improve open and neglected fracture treatment in LMICs.

Atrial fibrillation (AF) is the most common form of arrythmia. Without treatment, the heart rhythm usually becomes permanently disrupted and can lead to various heart related complications as stroke or heart failure. Cardiac phantoms are needed for the development of electrophysiological instruments and for training and education of electrophysiologist. A tissue mimicking phantom is an accurate model of organs or tissues mimicking the real life like scenario for a desired goal. Currently, no cardiac phantoms are available containing all requirements needed. Therefore, as a first step towards an applicable cardiac phantom for development of electrophysiology studies, this Master Thesis focused on the design of an anatomically anthropomorphic left atrium (LA) phantom mimicking the dielectric properties of human heart tissue in the frequency range of 10 kHz – 20 kHz. To assess this research goal, the objective was divided into 3 subgoals: 1. Evaluate different tissue mimicking materials with additives to meet the main phantom requirements. Three promising types of phantoms were examined: agar-, gellan gum- and polyvinyl alcohol-cryogel-based (PVA-C) phantoms. The dielectric properties and stiffness of the phantoms were manipulated by varying the concentrations of materials and by using additives. Graphite powder, charcoal powder, salt and sodium acetate were examined for increasing the electrical conductivity and oil, sugar and PVC for decreasing its relative permittivity.2. Extensively evaluate the most promising cardiac phantom materials. The most promising hantom tissue materials, based on the main phantom requirements, was used for the final design of a LA phantom. The cardiac phantom was prepared four times for extensive examination based on all phantom requirements.3. Develop a phantom design with comparable anatomy.
As a last step, the phantom was fabricated with comparable anatomy. In this part, a suitable mould was prepared in order to get a hollow shaped phantom.

Results
A 13,0wt% PVA, 0,15wt% salt and 0,05wt% sodium acetate and tap water solution was used for the final LA phantom design. The flexible cardiac phantom is easily made, affordable and has a shelf life of at least 1 month. The average difference between the target values and the mean of all four prepared cardiac phantom samples is 21.9% and 15.0% for permittivity and conductivity, respectively. Storing the phantoms in an aqueous liquid results in diffusion of salt and sodium acetate and water absorption of the phantom material. Stability is reached after 1 week. Finally, a cylinder-shaped hollow cardiac phantom is produced, with the use of a 3D printed mould, as comparable shape of the LA.
Producing a cardiac phantom of PVA is proved to be a good model. This research shows the design of a low cost, easily produced hollow shaped cardiac phantom consisting of 13.0wt% PVA, 0.15wt% salt and tap water. Even though more future work needs to be done for the development of a cardiac phantom, this research functions as a proof of concept for the development of a flexible phantom with possibilities to manipulate the dielectric properties and to create a hollow shaped phantom. The use of PVA as tissue mimicking material (TMM) and the use of 3D printed PVA for creation of the hollow shapes shows promising results for future development.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine that can be treated by wearing a correctional rigid brace. The goal of brace treatment is prevention of curve progression, and in some cases the curve even decreases. The current problem concerning treatment of AIS lays in the design decisions made during manufacturing of the brace. Correctional forces are applied through static pressure pads added to the inside of the brace. Evaluation of the correct positioning and size of these forces is done through radiographic imaging which allows limited feedback intervals as cumulative exposure to ionizing radiation increases the risk of cancer development. The design of scoliotic braces is currently suboptimal as the manufacturing remains an inefficient process. Moreover, it was hypothesized that the corrective forces show decreasing time dependant behaviour due to viscoelastic properties of the human body adapting to the load.
The objectives of this study were therefore to increase the effectiveness of brace treatment, by determination of the time dependant behaviour and accurate positioning and sizing of correctional forces.
A dynamic brace was developed containing pressure regulated cuffs creating a three-point-bending system on the spine. A healthy (non-scoliotic) test subject wore the brace with the goal of creating a spinal curvature. The cuffs were tested on stress relaxation behaviour, which was needed to determine if possible changes in pressure were due to viscoelasticity of the cuffs or the body. The tests showed that pressure stayed constant over time, which excludes viscoelasticity of the cuffs. Moreover, compression tests were executed on a cuff to determine the relationship between external loads and internal pressures.
Ultrasound (US) imaging was used to evaluate the effect of the three-point-bending system on the spine. The images showed a curvature, but the results varied too much to draw conclusions from, as this imaging technique works best for large scoliotic curves. BoneMRI has higher imaging accuracy and adds an extra dimension, however supine positioning decreases the spinal curvature. The boneMRI results show a subtle curvature after applying pressure. The cuffs lengthened the spine and caused mechanical torsion. After one hour the lengthening remained equal but the mechanical torsion decreased to its starting value. Lengthening of the spine could be useful in brace treatment to create more space between vertebrae and facilitate vertebral realignment.
This research served as a proof of concept which can be further developed by testing on a scoliotic patient with a moderate spinal curvature. This could result in a dynamic brace used as a method to enhance the positioning and sizing of pressure pads for a static brace, or the dynamic brace design needs adjustment to use it as a daily worn brace which keeps correctional forces constant by adjusting pressures automatically.