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  • 1.
    Ahlberg, Johan
    KTH, School of Technology and Health (STH).
    Real life analysis of myoelectric pattern recognition using continuous monitoring2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of non-invasive signal acquisition methods is today the standard for testing pattern recognition algorithms in prosthetic control. Such research had shown consecutively high performance on both prerecorded and real time data, yet when tested in real life they deteriorate.

    To investigate why, the author who is a congenital amputee, wore a prosthetic system utilizing pattern recognition control on a daily basis for a five-day period. The system generated one new classification every 50 ms and movement execution was made continuously; for classifying open/close; and by winning a majority vote; for classifying side grip, fine grip and pointer. System data was continuously collected and errors were registered through both a manual and an automatic log system.

    Calculations on extracted data show that grip classifications had an individual accuracy of 47%- 70% while open/close got 95%/98%, but if classified according to a majority vote, grips increased their accuracy to above 90% while open/close dropped to 80%. The conclusion was that majority vote might help complex classifications, like fine grips, while simpler proportional movements is exacerbated by majority voting. Major error sources were identified as signal similarities, electrode displacements and socket design.

    After the daily monitoring ended the systems functionality was tested using the "Assessment of Capacity for Myoelectric Control". The ACMC results showed that the system has similar functionality to commercial threshold control and thus is a possible viable option for both acquired and congenital amputees.

  • 2.
    Andersson, Frida
    KTH, School of Technology and Health (STH).
    Finite Element Modeling of Skull Fractures: Material model improvements of the skull bone in theKTH FE head model2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main aim of this project was to develop a model for predicting skull fractures of a 50th percentile male, using a finite element head model developed at the Neuronics department of KTH, Royal Instituteof Technology. The skull bone is modeled as a three layered bone, where the outer and inner tables are modeled as shell elements, while the diploë is modeled by two layers of solid elements. The material model of the tables was changed from the material model MAT_PLASTIC_KINEMATIC to a material model including a damage parameter to soften the damaged material and to enable ploting of the damage of the skull bone. Due to the coarse mesh of the FE head model the material model was not allowed to include any erosion, deleting element as they reach their ultimate strain. With these requests, two materials from the LS-DYNA material library seemed appropriate: material 81,MAT_PLASTICITY_WITH_DAMAGE and material 105, MAT_DAMAGE_2.

    To evaluate these materials and adjust the input parameters a dog bone FE model was developed and tension tests were simulated with this model, equivalent to tension tests performed on equally shaped skull bone specimens. The material simulating a behavior most similar to the behavior from the tension tests turned out to be material 81. This material model was then implemented in the full FE head model for further input parameter adjustment and validation. Four different cadaver experiments were simulated, with different impacting objects: sphere, box, cylinder and flat cylinder surface, and impacted areas of the head: vertex, temporo-parietal and frontal. The forces obtained in the simulations were compared to the forces of the cadaver experiments. The fracture prediction was based on the damage parameter, which could be plotted to visualize the areas where the ultimate strain was exceeded and thereby the area most likely to be fractured. This parameter was then compared to the documented fractures from the cadaver experiments.

    The result showed that using material 81 with the input parameter EPPFR=0.05 gave the overall most accurate forces and fracture predictions. The breaking stress, σB, did not affect the fractures significantly but a reduced σB resulted in reduction of the peak forces. The thickness of the diploë did not have any significant impact on the fracture occurrence, but a thinner diploë had a reducing impact on the peak forces as well.

  • 3.
    Ashfaq, Awais
    KTH, School of Technology and Health (STH).
    Segmentation of Cone Beam CT in Stereotactic Radiosurgery2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    C-arm Cone Beam CT (CBCT) systems – due to compact size, flexible geometry and low radiation exposure – inaugurated the era of on-board 3D image guidance in therapeutic and surgical procedures. Leksell Gamma Knife Icon by Elekta introduced an integrated CBCT system to determine patient position prior to surgical session, thus advancing to a paradigm shift in facilitating frameless stereotactic radiosurgeries. While CBCT offers a quick imaging facility with high spatial accuracy, the quantitative values tend to be distorted due to various physics based artifacts such as scatter, beam hardening and cone beam effect. Several 3D reconstruction algorithms targeting these artifacts involve an accurate and fast segmentation of craniofacial CBCT images into air, tissue and bone.

    The objective of the thesis is to investigate the performance of deep learning based convolutional neural networks (CNN) in relation to conventional image processing and machine learning algorithms in segmenting CBCT images. CBCT data for training and testing procedures was provided by Elekta. A framework of segmentation algorithms including multilevel automatic thresholding, fuzzy clustering, multilayer perceptron and CNN is developed and tested against pre-defined evaluation metrics carrying pixel-wise prediction accuracy, statistical tests and execution times among others. CNN has proven its ability to outperform other segmentation algorithms throughout the evaluation metrics except for execution times. Mean segmentation error for CNN is found to be 0.4% with a standard deviation of 0.07%, followed by fuzzy clustering with mean segmentation error of 0.8% and a standard deviation of 0.12%. CNN based segmentation takes 500s compared to multilevel thresholding which requires ~1s on similar sized CBCT image.

    The present work demonstrates the ability of CNN in handling artifacts and noise in CBCT images and maintaining a high semantic segmentation performance. However, further efforts targeting CNN execution speed are required to utilize the segmentation framework within real-time 3D reconstruction algorithms.

  • 4.
    Beskow, Tua
    KTH, School of Technology and Health (STH).
    Hip impact of the FE-model THUMS: Model adaptation and validation followed by an evaluation of the KTH developed shock absorbing floor system2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Fall accidents leads to an average of three deaths a day in Sweden. The high mortality and morbidity associated with falls among elderly is due to a high risk of falling caused by impaired mobility, sight and balance in combination with increased vulnerability as a result of fragile bones as well as comorbid conditions. Researchers at the department of Neuronics at KTH has developed a shock-absorbing floor that aim to reduce the risk of fall related fractures. The floors has shown promising results in mechanical drop tests but requires further analysis before it can be implemented in retirement homes.

    The goal of this master thesis is to refine, adapt and validate the finite element model THUMS 4.02 for fall simulations. The model will then be used to analyze the shock absorbing ability of various floor systems. Model adaptations included modification of the material properties of the adipose tissue and cartilage in the hips and implantation of tied internal contacts. Validation was performed against data from two experimental studies selected in a literature study, dynamic impact with isolated pelvis and lateral hip impact of complete PMHS.

    The experimental setups were reproduced in LS-Dyna and relatively close agreement for the force curves could be displayed in both cases. The model also showed realistic force response for fall simulations and a force reduction with up to 23% in simulation to the KTH developed floor system, differences could be seen for different fall positions of the model. Fall simulations agreed well with clinically and scientifically documented fracture loads and patterns. Further studies needs to be performed to further validate the model and analyze effect of different geometrical properties of floor system.

  • 5.
    Bu, Yi-Qin
    et al.
    KTH, School of Technology and Health (STH).
    Wang, Jieyu
    KTH, School of Technology and Health (STH).
    Overview of Care Coordination Within Specialized Home Care in Stockholm County2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The ageing population of Sweden is expected to increase throughout the future decades. Changing life-style trends and smaller families in the modern society has decreased the population’s access to informal care. This is expected to entail an increase in the services provided by specialized home care. This thesis studies the work performed by nurses within the department of specialized home care (ASIH) in Stockholm County. The nurses represent the majority of all professions active at ASIH in Stockholm County, which puts their work in particular interest for this thesis. The thesis focuses on the ways the nurses’ work procedures may influence continuity of care and patient safety. Continuity of care is an essential component in qualitative care and is characterized by well-executed coordination and minimization of broken patient appointments. A high level of continuity of care consequently entails a high level of patient safety. Descriptions of continuity of care at ASIH in Stockholm County can therefore provide indications on current care quality and areas of improvement.

    The thesis consists of two parts – a literature review containing international research on continuity within home care and an empirical study containing a retrospective analysis based on the Functional Resonance Analysis Method (FRAM). The empirical study creates an overview of work tasks related to nursing performed at three units of ASIH in Stockholm County. The interdependencies between work tasks are identified and important chain reactions are analyzed.

    The findings from this thesis indicate that extended training programs for nurses in the initial phase of employment is likely to decrease the number of disruptions in the nurses’ work. Furthermore, well-developed routines could facilitate work task procedures which would decrease the number of delays and disruptions in the nurses’ work. It was found that these findings together with information continuity between all parties involved represent significant factors for attaining continuity of care and patient safety at ASIH in Stockholm County.

  • 6.
    Chen, Hongjian
    KTH, School of Technology and Health (STH).
    Towards the Development of the Dual Modal Contrast Agent for Computed Tomography and Ultrasound2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays hybrid imaging modalities are new trends in medical imaging. To improve the diagnostic outcome of hybrid imaging, multimodal contrast agents need to be developed. For example, hybrid contrast agents for computer tomography and ultrasound (CACTUS) are one of those desirable hybrid contrast agents for the modern medical imaging.

    Polyvinyl alcohol (PVA) micro-bubbles (MBs) are one of the latest generations of ultrasound contrast agents (UCAs). PVA MBs are more stable and offer longer circulation and on-shelf storage time compare to other UCAs. However, the current use as contrast agent is limited only to ultrasound imaging.

    In this project, we fabricated and characterized hybrid contrast agents based on PVA MBs.

    Two methods for developing hybrid contrast agents were proposed. The first method is to combine MBs, currently used as an ultrasound contrast agent, with gold nanoparticles that are used as a preclinical contrast agent for computer tomography (CT). The second method is to determine at which concentration plain MBs suspension has both considerable negative contrast in CT and enhancement of the backscattered signal in ultrasound imaging.

    Both methods were evaluated and optimized. A scenario to achieve promising hybrid contrast agent was described in this report.

  • 7.
    Christakopoulos, Fotios
    KTH, School of Technology and Health (STH).
    Modeling of beta-cell Metabolic Activity and Islet Function: a Systems Approach to Type II Diabetes2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Diabetes has gained growing attendance as one of the key non communicable diseases (NCD) with the World Health Organization identifying it as the focus of the World Health Day 2016. It is reported that more than 420 million people suffer from diabetes, a number predicted to rise in the coming years. This report forms part of a broader, long term focus project that aims to establish a systems approach to type 2 diabetes (T2D), the variant that accounts for more than 90% of reported diabetes cases. The broader project objectives are to identify possible biomarkers for the onset and the progression of T2D as a precursor to enable potential future approaches to delay onset, or even reverse disease states, via active bio-compounds and/or establishment of beneficial nutritional patterns.

    The 6-month master’s work reported here is sub-project that focused specifically on cell level vesicle trafficking processes. These processes are believed to be crucial in understanding the formation amyloid plaques, which compromise or kill the insulin secreting beta cells. Up until now, there has been a lack of appropriate experimental techniques to directly observe this process in live cells.  Hence we have developed 2 new techniques:

    (i)               a method of imaging the actin and tubulin network reorganization during exocytosis of the insulin containing granules while exploring novel ways of characterizing the network.

    (ii)             a method of imaging the granules themselves and using particle tracking microrheology to analyze their movement patterns during stimulation with glucose.

    These new techniques open the door to follow up experiments which would allow development of a cell scale mathematical model or simulation correlating short term glucose dynamics to risk of amyloid plaque formation and T2D. 

  • 8.
    Dybäck, Matilda
    et al.
    KTH, School of Technology and Health (STH).
    Wallgren, Johanna
    KTH, School of Technology and Health (STH).
    Pupil dilation as an indicator for auditory signal detection: Towards an objective hearing test based on eye tracking2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    An early detection of hearing loss in children is important for the child's speech and language development. For children between 3-6 months, a reliable method to measure hearing and determine hearing thresholds is missing. A hearing test based on the pupillary response to auditory signal detection as measured by eye tracking is based on an automatic physiological response. This hearing test could be used instead of the objective hearing tests used today. The presence of pupillary response has been shown in response to speech, but it is unstudied in response to sinus tones. The objective of this thesis was to study whether there is a consistent pupillary response to different sinus tone frequencies commonly used in hearing tests and if yes, to determine reliably the time window of this response.

    Four different tests were done. The adult pupillary response in regard to sinus tone stimuli with four frequency levels (500 Hz, 1000 Hz, 2000 Hz and 4000 Hz), and four loudness levels (silence, 30 dB, 50 dB and 70 dB) was tested (N=20, 15 females, 5 males). Different brightness levels and distractions on the eye tracking screen were investigated in three substudies (N=5, 4 females, 1 male). Differences between silence and loudness levels within frequency levels were tested for statistical significance.

    A pupillary response in regard to sinus tones occurred consistently between 300 ms and 2000 ms with individual variation, i.e. earlier than for speech sounds. Differences between silence and loudness levels were only statistically significant for 4000 Hz. No statistical difference was shown between different brightness levels or if there were distractions present on the eye tracker screen.

    The conclusion is that pupillary response to pure sinus tones in adults is a possible measure of hearing threshold for at least 4000 Hz. Larger studies are needed to confirm this, and also to more thoroughly investigate the other frequencies. 

  • 9.
    Fan, Xuelong
    KTH, School of Technology and Health (STH), Medical Engineering.
    Kinematic analysis of traumatic brain injuries in boxing using finite element simulations2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of the thesis was to analyze and evaluate the head injuries due to a striking in a boxing match by LS-DYNA.

    A simplified arm model was built up and was equipped with three segments which were linked with two spherical joints. The strain-stress curves of the boxing glove foam and glove leather were measured in the Neuronic Lab in School of Technology and Health, KTH. The dimension and weight of the model was also set as adjustable to fulfill various requirements in different cases. Then a method was developed to facilitate the simulation. Finally, 39 video clips from the database were processed and the 13 cases were chosen to test the method and to perform the simulations. Additionally, the reliability of the model was assessed by comparing the outcome of the simulations with the results of the visual analysis from a previous study.

    The outcome showed that the model was able to restore the scenario from the videos both quantitatively and qualitatively, but it also suggest a high sensitivity of the model to the data artifacts from the video analysis. Interpretations and suggestions for the future work were also discussed.

  • 10.
    Golfetto, Cristiana
    KTH, School of Technology and Health (STH).
    Assessment of Shear Wave Elastography Acoustic Output - a Simulation and Experimental Study2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Shear Wave Elastography (SWE) is a medical imaging modality which is able to measure tissue stiffness through the speed of ultrasound-induced shear waves. Pre- vious studies have reviewed the safety aspects of clinical ultrasound, highlighting the harmlessness of the technique. However, in arterial SWE the same type of investiga- tion has not been performed for all applications. The present work aimed to develop an experimental setup for the assessment of acoustic output, which is the pressure field generated by an ultrasound transducer. A second aim was to investigate the safety aspects of SWE with particular attention to arterial applications.

    In a first step, FOCUS platform was used to simulate and visualize the pressure and intensity distribution around the focal point in three dimensions. Two studies were performed at different focal depths: 15, 20, 25, 30, and 35 mm. In the first study the number of activated elements was kept constant and equal to 64. In the second study the f-number was constant at approximately 1.3. Push widths in three dimensions were compared at different depths, the push dimension did not change in a pronounced way when the f-number was kept constant, but it did when the number of elements was constant.

    An experimental setup was then developed, made of the programmable ultra- sound system Verasonics with a linear array transducer L7-4 to generate shear waves and a membrane-type hydrophone to analyze the distribution of peak positive pres- sure, peak negative pressure, mechanical index (MI), and spatial peak-time average intensity (ISP T A) at focal depth equal to 35 mm and voltage set at 90 V. The push di- mensions resulting from the hydrophone were compared to FOCUS results, showing similar values especially in x and y direction.

    To conclude, given MI and ISPTA below the safety thresholds of FDA regula- tions, the present work represents an additional step toward in vivo assessment of arterial stiffness by Shear Wave Elastography. 

  • 11.
    Granholm, Hanna
    KTH, School of Technology and Health (STH).
    Patients' Participation in Decisions in an Anaesthesia Healthcare Setting: A survey of patients' and personnel's attitudes and experiences2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A need for the personnel at the Anaesthesiology and Intensive Care Unit at Danderyd Hospital to better understand their patients’ experiences and attitudes towards participation in their care was identified by the Clinical Innovation Fellowship program at Centre for Technology in Medicine and Health. This study aimed to provide the Anaesthesiology and Intensive Care Unit with information on patients and personnel’s experiences and attitudes towards patients’ participation; this would allow them to understand how they should focus their resources. A crosssectional and group comparing survey was performed at the Anaesthesiology and Intensive Care Unit in the spring of 2016. A total of 55 patients scheduled for surgery and 38 from the personnel at the Anaesthesiology and Intensive Care Unit participated. The results show there is high overall satisfaction among the participants of their experiences of patients’ participation. The majority of the patients wanted to be passive in decisions, no connections between personal characteristics and preferred level of participation was found. Patients who did not felt they had been able to participate enough also felt uninformed. Furthermore, physicians seemed to have better opportunities to include patients in decisions compared to the nurses. The healthcare systems should work to adapt the care for each individual patient and to provide them with information suitable for the individual in order to support patients’ participation; IT-systems could be one way of doing this. Future studies should further investigate which factors could influence patients’ participation and how healthcare services and technology could be designed in order to support patient participation.

  • 12.
    Hagman, Anna
    KTH, School of Technology and Health (STH).
    The Knowledge- and Adoption Level of Standards for Technical Interoperability among Providers of Healthcare Information Systems2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis was one of the deliverables of StandIN. The purpose of StandIN was to propose a common framework including standards for technical interoperability. The goal of this thesis was to structure and analyze information about the knowledge- and adoption level of the standards among providers of healthcare information systems (HIS's). Moreover, it aimed to evaluate different aspect that might affect the adoption.

    The target group was providers of HIS's used in Swedish county councils and regions. The information was gathered through a survey and semi-structured interviews, and stored in an Excel database. From the database, Pivot tables and charts were created in order to show the knowledge- as well as adoption level of the different standards. The results were thereafter compared to theory about interoperability and standard adoption.

    It was clear that the knowledge level varied for the different standards. In addition, the adoption level was very low - except from CCOW and HL7 v2. Least adopted were domain-specific standards. The results also indicated a trend for only adopting parts of standards. Moreover, many providers stated that they performed specific integrations rather than followed common standards. This seemed to be due to the choice of standards being too wide, and the actual adoption not being consistent among the different providers. According to the providers, an introduction of a national framework based on uniform and consistent international standards was an awaited solution to the problem.

    A future extension of this thesis would be to perform a similar study involving the customers. The database could also be used to do clustered analyses of the adoption state in different county councils and regions. Moreover, it could be used to analyze the development of standard adoption over time.

  • 13.
    Hendrikse, Natalie
    KTH, School of Technology and Health (STH).
    Development of a Novel Selection Method for Protease Engineering: A high-throughput fluorescent reporter-based method for characterization and selection of proteases2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Proteases are crucial to many biological processes and have become an important field of biomedical and biotechnological research. Engineering of proteases towards therapeutic applications has been limited due to the lack of high-throughput methods for characterization and selection. We have developed a novel high-throughput method for quantitative assessment of proteolytic activity in the cytoplasm of Escherichia coli bacterial cells. The method is based on coexpression of a protease of interest and a reporter complex consisting of an aggregation-prone protein fused to a fluorescent reporter. Cleavage of a substrate sequence situated between the two reporter complex proteins results in increased whole-cell fluorescence proportional to proteolytic activity, which can be monitored using flow cytometry. We have demonstrated that the method can distinguish efficiencies with which Tobacco Etch Virus (TEV) protease processes different substrates. We believe that this is the first method in the field of protease engineering that enables simultaneous measurement of proteolytic activity and protease expression levels and can therefore be applied for substrate profiling, as well as screening and selection of libraries of engineered proteases.

  • 14.
    Jahnsen, Ann-Lena
    KTH, School of Technology and Health (STH).
    Development of a quantum dot based strategy for Gram-specific bacteria differentiation2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Time-consuming diagnosis of bacterial blood stream infections and inappropriate antibiotic therapy have critical implications for patient outcome – with mortality figures rising for every hour of delayed treatment. The development of diagnostic methods that are capable of selective and rapid bacteria detection, and do not rely on preliminary blood culturing and Gram-staining procedures, is imperative in providing effective therapy and preventing multi-resistance. The aim of this dissertation was to develop a quantum dot based and Gram-specific bacteria labelling protocol. Focused on the detection of Gram-negative species, a two-step conjugation protocol was produced to functionalise quantum dots with anti-lipid A antibodies. Ionic adsorption and EDC chemistry were used to obtain oriented and covalent conjugation of antibodies to the quantum dot surface. In order to reduce non-specific binding of unreacted carboxylic groups on the conjugates to the bacterial membrane, and optimise the accuracy of detection, blocking experiments were conducted with molecules that could provide a neutral surface charge and sterically block open sites. To access lipid A on E. coli cells, three different antigen retrieval methods were tested.

    As a result, the developed quantum dot-anti lipid A conjugates were able to detect and specifically label Gram-negative E. coli cells after treatment with 0.6mM EDTA or acetic acid pH 3.58 at 42.5°C. 1% BSA reduced non-specific binding to untreated E. coli cells. Furthermore, in comparison to experiments performed with Tris as a blocking agent, the protein reduced non-specific binding to Gram-positive cells. The results obtained in this project are a step further in the development of a new method to rapidly detect bacteria Gram-specifically.

  • 15.
    Jurcova, Martina
    KTH, School of Technology and Health (STH). Phelma Grenoble INP.
    Validation of simulation tool for C-arm X-ray systems: Source and scatter model2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Continuous improvement of image quality is one of the priorities in medical imaging. Therefore, development of a simulation tool allowing to generate realistic images would be of great value to understand better the impact of the components on the image quality metrics and to choose imaging set-ups or new design features to optimize output of existing systems and to prototype new ones and to formalize the link between objective and subjective image quality metrics.

    Therefore, the purpose of this project, was to contribute to adaptation and validation of an existing simulator for simulation of C-arm X-ray imaging.

    Firstly, the study of the existing simulation tool was performed to choose further development axes.

    Afterwards, preliminary estimations of simulation complexity by evaluating the number of photons for a given imaging examination were performed.

    Previous studies[1] showed the determining impact of focal spot on imaging performance (reducing the limiting spatial frequency in common examination conditions) of X-ray interventional imaging systems.  Therefore, the work focused on the improvements of source model, in particular realistic focal spot was defined and simulations of images with close-to-real sharpness were performed and compared to experimentally acquired images.

    Finally, a part of this project was dedicated to scatter study. An experimental set-up and "scatter map" analysis were designed to determine the scatter evolution as function of imaging field-of-view.  First simulations were also performed.

    [1] Samei, E., Ranger, N., MacKenzie, A., Honey, I., Dobbins, J. and Ravin, C. (2008). Detector or System? Extending the Concept of Detective Quantum Efficiency to Characterize the Performance of Digital Radiographic Imaging Systems 1. Radiology, 249(3), pp.926-937.

  • 16.
    Khoogar, Sayeh
    KTH, School of Technology and Health (STH).
    Implementation of a New Continuous and Wireless Monitoring System: FROM THEORY TO REALITY2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 17.
    Kilinc, Derya
    et al.
    KTH, School of Technology and Health (STH).
    Ghattas, Mattias
    KTH, School of Technology and Health (STH).
    Implementing an Intelligent Alarm System in Intensive Care Units2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today’s intensive care units monitor patients through the use of various medical devices, which generate a high ratio of false positive alarms due to a low alarm specificity. The false alarms have resulted in a stressful working environment for healthcare professionals that are getting more desensitized to triggered alarms and causing alarm fatigue. The patient safety is also compromised by having high noise levels in the patient room, which disturbs their sleep. This thesis has developed an intelligent alarm system with an improved alarm management and the use of 23 intelligent algorithms to minimize the number of false positive alarms. The suggested system is capable of improving the alarm situation and increasing the patient safety in critical care. The algorithms were modeled with fuzzy logics consisting of delays and multi parameter validation. The results were iteratively developed by having focus groups with various experts.

  • 18.
    Kraft, Sandra
    KTH, School of Technology and Health (STH).
    Routine Development for Artefact Correction and Information Extraction from Diffusion Weighted Echo Planar Images of Rats2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Biologists and physicians study complex biologic phenomena in which they use advanced imaging methods. They acquire images containing a lot of information which must be extracted in a correct way. This requires computer skills and knowledge in image processing methods which they seldom have. To overcome the problem, this master thesis aimed to develop a routine for artefact correction and information extraction from images acquired in a research project at the Karolinska Institutet in Stockholm. By developing the routine, the thesis showed how software developed for images of human can be applied to images of rats. The routine handles formatting issues and artefact corrections, calculates diffusion metrics, and performs statistical tests on spatially aligned magnetic resonance images of rats acquired with diffusion weighted echo planar imaging. The routine was verified by analysing the images that it had processed and was considered to create reliable images. Future studies within the field should focus on developing atlases of rats and continue the work with identifying how software developed for images of human can be applied to images of rats. 

  • 19.
    Larsson, Anna
    KTH, School of Technology and Health (STH).
    Implementation of Shear Wave Elastography in Cervical Applications2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Each year million of babies are born pre-term, some of these pre-term births occur due to the motherhaving a too soft cervix which can not withstand the forces the baby exposes it to. The aim of thisstudy was to implement and evaluate a programmable shear wave elastography ultrasound system forcervical applications and investigate the optimal settings of shear wave elastography push voltage andshear wave elastography push focus depth. Shear wave elastography is an ultrasound based imagingmodality aiming to evaluate the tissue elasticity by using acoustic radiation forces to induce shear waves.The propagation of the shear waves through the tissue is then tracked in order to calculate the shearwave velocity which is related to the tissue elasticity. B-mode imaging, pushing sequence and planewave imaging have been implemented and measurements have been conducted on four cervical polyvinylalcohol phantoms. The acquired data has been post-processed using Loupas 2D-autocorrector to gainthe axial displacement and enabling tracking of the shear waves to allow evaluation and optimizationof the implemented method. The implemented shear wave technique showed to be able to distinguishcervical phantoms of dierent elasticity and a high pushing voltage and shallow focus push depth havebeen found to produce the most reliable results.

  • 20.
    Lundbäck, Kristoffer
    et al.
    KTH, School of Technology and Health (STH).
    Dahn, Leonardo
    KTH, School of Technology and Health (STH).
    Preliminary Evaluation of the Clinical Value of an Ultra-Wideband Radar Sensor for Heart Assessment2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heart dysfunction is a worldly widespread problem that currently is one of the leading causes of death. Studies indicate that many deaths related to cardiac dysfunction could have been prevented if discovered early. Contemporarily, ultrasound and electrocardiography are indispensable modalities for diagnostic purposes and analysis of cardiac function.

    The Ventricorder is an Ultra-Wideband radar sensor manufactured by the Norwegian company Novelda. Ventricorder has been shown to be able detect heart movements and breathing but its actual clinical value remains to be investigated. The Cardiac State Diagram (CSD) is a pre-clinical software tool for visualization of the heart's mechanical function. The CSD is confirmed by pilot studies to be able to constitute a basis for diagnosis and cardiac function assessment. Theoretically, the CSD is well suited to be used with the Ventricorder since the Ventricorder detects small changes over time and information about time events is all that is required for the creation of a CSD.

    Contemporarily, ultrasound tissue velocity imaging (TVI) is usually used for production of CSDs and in this master thesis we examined if the Ventricorder can be used to produce CSDs. This was done by mainly comparing velocity data from the Ventricorder with velocity data from temporally synchronized apical four-chamber images acquired with ultrasound TVI. The results indicate that there is an apparent correlation between these data sets and the Ventricorder should therefore be able to produce data that could constitute the basis for the production of a CSD. What remain now is to confirm these results statistically with a larger test group and to investigate whether all the time instants needed for the production of a CSD can be identified objectively.

  • 21.
    Mahbod, Amirreza
    KTH, School of Technology and Health (STH).
    Structural Brain MRI Segmentation Using Machine Learning Technique2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Segmenting brain MR scans could be highly benecial for diagnosing, treating and evaluating the progress of specic diseases. Up to this point, manual segmentation,performed by experts, is the conventional method in hospitals and clinical environments. Although manual segmentation is accurate, it is time consuming, expensive and might not be reliable. Many non-automatic and semi automatic methods have been proposed in the literature in order to segment MR brain images, but the levelof accuracy is not comparable with manual segmentation.

    The aim of this project is to implement and make a preliminary evaluation of a method based on machine learning technique for segmenting gray matter (GM),white matter (WM) and cerebrospinal uid (CSF) of brain MR scans using images available within the open MICCAI grand challenge (MRBrainS13).The proposed method employs supervised articial neural network based autocontext algorithm, exploiting intensity-based, spatial-based and shape model-basedlevel set segmentation results as features of the network. The obtained average results based on Dice similarity index were 97.73%, 95.37%, 82.76%, 88.47% and 84.78% for intracranial volume, brain (WM + GM), CSF, WM and GM respectively. This method achieved competitive results with considerably shorter required training time in MRBrainsS13 challenge.

  • 22.
    Nylund, Andreas
    KTH, School of Technology and Health (STH), Medical Engineering.
    To be, or not to be Melanoma: Convolutional neural networks in skin lesion classification2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Machine learning methods provide an opportunity to improve the classification of skin lesions and the early diagnosis of melanoma by providing decision support for general practitioners. So far most studies have been looking at the creation of features that best indicate melanoma. Representation learning methods such as neural networks have outperformed hand-crafted features in many areas. This work aims to evaluate the performance of convolutional neural networks in relation to earlier machine learning algorithms and expert diagnosis. In this work, convolutional neural networks were trained on datasets of dermoscopy images using weights initialized from a random distribution, a network trained on the ImageNet dataset and a network trained on Dermnet, a skin disease atlas.  The ensemble sum prediction of the networks achieved an accuracy of 89.3% with a sensitivity of 77.1% and a specificity of 93.0% when based on the weights learned from the ImageNet dataset and the Dermnet skin disease atlas and trained on non-polarized light dermoscopy images.  The results from the different networks trained on little or no prior data confirms the idea that certain features are transferable between different data. Similar classification accuracies to that of the highest scoring network are achieved by expert dermatologists and slightly higher results are achieved by referenced hand-crafted classifiers.  The trained networks are found to be comparable to practicing dermatologists and state-of-the-art machine learning methods in binary classification accuracy, benign – melanoma, with only little pre-processing and tuning. 

  • 23.
    Potoshna, Lisa
    KTH, School of Technology and Health (STH).
    Design and Development of a Tracheostomy Tube Test Device2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the NRC (National Respiratory Centre) department at Danderyds Hospital different standard tracheostomy tubes are customized in order to create a more appropriate fit for the individual patient. This master thesis aims to design a theoretical model and build a first prototype of a tracheostomy tube test device that can be used to analyse and compare the physiological performance of different for tracheostomy tubes.

     

    The theoretical model of the device consisted of an artificial lung, artificial trachea and a ventilator, pressure and flow sensors and a data acquisition device. The first prototype was built using equipment available at the NRC department and three experimental set-ups were assembled: one simulating normal breathing and two set-ups simulating coughing. Two artificial tracheas, a small and a large one together with different tracheostomy tubes were used to evaluate the first prototype.

     

    Results showed that the first prototype could be used to compare cuffed fenestrated and non-fenestrated tracheostomy tubes. However, the first prototype was less effective when comparing uncuffed fenestrated and non-fenestrated tracheostomy tubes, which is due to the lack of airway resistance in uncuffed tubes. Results strongly motivate a further development of the device with equipment described in the theoretical model and the future studies should be focused on improving the device. 

  • 24.
    Romero, Vincent
    KTH, School of Technology and Health (STH).
    The Body Profile Score : an assessment of whole body walking patterns in children with cerebral palsy2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Patients with cerebral palsy account for great upper extremities deviationswhile walking. However, the number of studies assessing their upper bodygait kinematics are rare and no studies have been conducted interested inthe whole body kinematics during walking. In this study, we created awhole body index, the Body Profile Score made of modified existing kinematicindexes assessing the gait pattern of children with cerebral palsy. TheBody Profile Score (BPS) is an average of combination of the Gait ProfileScore (GPS), a modified Trunk Profile Score (TPS), a modified Arm PostureScore (APS) and a also new index called Head Profile Score (HPS), basedon a similar calculation. Dierent versions of the BPS were tested on threegroups: a control group, a CP group before botulinum toxin A treatmentand a CP group after botulinum toxin A treatment. The results showed apoor level of linear correlations between the dierent BPS versions and theGait Profile Score, indicating that lower body indexes such as the GPS orGait Deviation Index (GDI) and full body index such as the BPS do not renderthe same information. The BPS is the first index proposing a full bodykinematic analysis and aims at showing that such an analysis is needed ingait assessment of spastic children in order to have a realistic overview ofthe pathological walking condition.

  • 25.
    Röstin, Martin
    KTH, School of Technology and Health (STH).
    Development of a Flexible Software Framework for Biosignal PI: An Open-Source Biosignal Acquisition and Processing System2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As the world population ages, the healthcare system is facing new challenges in treating more patients at a lower cost than today. One trend in addressing this problem is to increase the opportunities of in-home care. To achieve this there is a need for safe and cost-effective monitoring systems. Biosignal PI is an ongoing open-source project created to develop a flexible and affordable platform for development of stand-alone devices able to measure and process physiological signals.

    This master thesis project, performed at the department of Medical Sensors, Signals and System at the School of Technology and Health, aimed at further develop the Biosignal PI software by constructing a new flexible software framework architecture that could be used for measurement and processing of different types of biosignals. The project also aimed at implementing features for Heart Rate Variability(HRV) Analysis in the Biosignal PI software as well as developing a graphical user interface(GUI) for the Raspberry PI hardware module PiFace Control and Display.

    The project developed a new flexible abstract software framework for the Biosignal PI. The new framework was constructed to abstract all hardware specifics into smaller interchangeable modules, with the idea of the modules being independent in handling their specific task making it possible to make changes in the Biosignal PI software without having to rewrite all of the core. The new developed Biosignal PI software framework was implemented into the existing hardware setup consisting of an Raspberry PI, a small and affordable single-board computer, connected to ADAS1000, a low power analog front end capable of recording an Electrocardiography(ECG).

    To control the Biosignal PI software two different GUIs were implemented. One GUI extending the original software GUI with the added feature of making it able to perform HRV-Analysis on the Raspberry PI. This GUI requires a mouse and computer screen to function. To be able to control the Biosignal PI without mouse the project also created a GUI for the PiFace Control and Display. The PiFace GUI enables the user to collect and store ECG signals without the need of an big computer screen, increasing the mobility of the Biosignal PI device.  

    To help with the development process and also to make the project more compliant with the Medical Device Directive a couple of development tools were implemented such as a CMake build system, integrating the project with the Googletest testing framework for automated testing and the implementation of the document generator software Doxygen to be able to create an Software Documentation.   

    The Biosignal PI software developed in this thesis is available through Github at https://github.com/biosignalpi/Version-A1-Rapsberry-PI

  • 26.
    Salhani Maat, Bilhal
    KTH, School of Technology and Health (STH).
    Backprojection-then-filtering reconstruction along the most likely path in proton computed tomography2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The backprojection-then-filtering algorithm was applied to proton CT data to reconstruct a map of proton stopping power relative to water (RSP) in air, water and bone. Backprojections were performed along three commonly used path estimates for the proton: straight line path, cubic spline path, and most likely path. The proton CT data was obtained through simulations using the GEANT4 simulation toolkit. Two elliptical phantoms were inspected, and an accuracy of 0.2% and 0.8% was obtained for the RSP in water and bone respectively in the region of interest, while the RSP of air was significantly underestimated.

  • 27.
    Tsakiraki, Eleni
    KTH, School of Technology and Health (STH).
    Real-time Head Motion Tracking for Brain Positron Emission Tomography using Microsoft Kinect V22016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The scope of the current research work was to evaluate the potential of the latest version of Microsoft Kinect sensor (Kinect v2) as an external tracking device for head motion during brain imaging with brain Positron Emission Tomography (PET). Head movements constitute a serious degradation factor in the acquired PET images. Although there are algorithms implementing motion correction using known motion data, the lack of effective and reliable motion tracking hardware has prevented their widespread adoption. Thus, the development of effective external tracking instrumentation is a necessity. Kinect was tested both for Siemens High-Resolution Research Tomograph (HRRT) and for Siemens ECAT HR PET system. The face Application Programming Interface (API) ’HD face’ released by Microsoft in June 2015 was modified and used in Matlab environment. Multiple experimental sessions took place examining the head tracking accuracy of kinect both in translational and rotational movements of the head. The results were analyzed statistically using one-sample Ttests with the significance level set to 5%. It was found that kinect v2 can track the head with a mean spatial accuracy of µ0 < 1 mm (SD = 0,8 mm) in the y-direction of the tomograph’s camera, µ0 < 3 mm (SD = 1,5 mm) in the z-direction of the tomograph’s camera and µ0 < 1 ◦ (SD < 1 ◦ ) for all the angles. However, further validation needs to take place. Modifications are needed in order for kinect to be used when acquiring PET data with the HRRT system. The small size of HRRT’s gantry (over 30 cm in diameter) makes kinect’s tracking unstable when the whole head is inside the gantry. On the other hand, Kinect could be used to track the motion of the head inside the gantry of the HR system.

  • 28.
    Zhong, Xueying
    KTH, School of Technology and Health (STH), Medical Engineering.
    Mucin preparation and assembly into new biomaterials2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mucins, the main macromolecular constituent responsible for gel-forming property in mucus, have great potential to act as new biological hydrogel for medical applications. Click chemistry reaction is an attractive tool to be applied in both bioconjugation and material science to form covalent bonds between molecules. Herein the click chemistry reaction of tetrazine-norbornene ligation was adapted to form click mucin hydrogel using purified commercial available bovine submaxillary mucin (BSM). This study included the characterization, purification and chemical modification of commercial available BSM. The flow filtration purification was chosen after investigating the effectiveness and yields of four different purification strategies. The reactivity of tetrazine and norbornene-functionalized BSM was evident from the formation of robust mucin hydrogel within minutes after mixing the two components. 

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