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  • 1.
    Afroze, Tonima
    et al.
    KTH, School of Technology and Health (STH).
    Rosén Gardell, Moa
    KTH, School of Technology and Health (STH).
    Algorithm Construction for Efficient Scheduling of Advanced Health Care at Home2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Providing advanced health care at home rather than in a hospital creates a greater quality of life for patients and their families. It also lowers the risk of hospital-acquired infections and accelerates recovery. The overall cost of care per patient is decreased. Manual scheduling of patient visits by health care professionals (HCPs) has become a bottleneck for increased patient capacity at SABH, a ward providing advanced pediatric health care at home (“Sjukhusansluten Avancerad Barnsjukvård i Hemmet” in Swedish), since many parameters need to be taken into account during scheduling. This thesis aims to increase the efficiency of SABH’s daily scheduling of personnel and resources by designing an automated scheduler that constructs a daily schedule and incorporates changes in it when needed in order to remove scheduling as a limitation for increased patient capacity. Requirements on a feasible schedule are identified in cooperation with SABH and literature is investigated about similar areas where the scheduling process has been automated. The scheduling is formulated as a computerized problem and investigated from the perspective of theoretical computer science. We show that the scheduling problem is NP-hard and can therefore not be expected to be solved optimally. The algorithm for scheduling the visits minimizes violations of time windows and travel times, and maximizes person continuity and workload balancing. The algorithm constructs an initial solution that fulfills time constraints using a greedy approach and then uses local search, simulated annealing, and tabu search to iteratively improve the solution. We present an exact rescheduling algorithm that incorporates additional visits after the original schedule has been set. The scheduling algorithm was implemented and tested on real data from SABH. Although we found the algorithm to be efficient, automatic transfer of data from the patient journal system is an imperative for the scheduler to be adopted.

  • 2.
    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.

  • 3.
    Ahmadi, Ajda
    KTH, School of Technology and Health (STH).
    Design of an Improved Rapid Infuser for Safe and Reliable Fluid Resuscitation during Surgical Care2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rapid infusers are used for rapid fluid administration as a part of medical treatment during surgical procedures. The rapid infusers on the market today have proved to present various functional, usability and safety issues for the customers and the problems have not been adequately addressed. This has motivated SLL Innovation to develop a new improved rapid infusion system. The primary reason for considering the development of a rapid infuser device was to meet customer demands and improve safety during the acute situations when the system is to be used. The Quality Function Deployment method was used to describe the design problem systematically and facilitate the development of an improved design. To investigate the users’ issues with existing rapid infusion devices, qualitative semi-structured interviews were conducted individually with hospital staff that had experience with the rapid infuser. Customer requirements were subsequently identified to form a basis for the development process.

    The results of the study indicated an evident demand for a new product. A three-dimensional (3D) computer aided design (CAD) solution was presented with enhanced properties and features that met the specifications identified. All the customer requirements were addressed in the final result. Safety was the highest rated engineering specification, thus a lot of time and effort was dedicated to solutions that could affect the safety of the system positively.

    Although the final design is expected to be more efficient and safer than the competition, further research and work is needed before this can be ensured.

  • 4.
    Alaei, Zohreh
    KTH, School of Technology and Health (STH).
    Molecular Dynamics Simulations of Axonal Membrane in Traumatic Brain Injury2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The following project presents in silico investigation of axonal damage in Diffuse Axonal Injury (DAI). When axons face a shear force, orientation of the lipids in the axonal membrane gets disrupted. Depending on the value of the force, a tensile strain causes the axons to get partially or fully deformed and in some cases a pore forms in the membrane. Using Molecular Dynamic (MD) simulation and a coarse grain model, a series of bilayers with various bilayer structure (single bilayer, parallel bilayer and cylindrical bilayer) and similar composition to biological axonal membrane were simulated. This was initially done to investigate the strain rate dependency of the bilayers, and their viscoelastic ability on returning to their original shape from their deformed forms. To achieve this, various deformation velocities were applied to the bilayers reaching 20% strain and relaxing the bilayer after. Additionally, the bilayers were deformed further until they reached a pore. It was found that the bilayers can almost recover from their deformed forms to their original length when they were deformed at 20% strain level. In conjunction, no correlation between the deformation velocity and lipid deformation was observed. Further, it was found that bilayers with different lipid percentage to axonal bilayer has different strain values for water penetration and for pore formation. The strain value for cylindrical bilayer was found very high compared to the strain values found in vitro. The strain for pore formation of parallel and single bilayer was found to be around 80% to 90% and for water penetration was found to be 70% for single bilayer and 50% for parallel bilayer. A slight difference in strain for pore formation between single and parallel bilayer was found which showed the bilayer structure can play a role in simulation results. The effect of the length in the simulations results was also observed where shorter bilayers showed lower strain for pore formation compared to longer bilayers. 

  • 5.
    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.

  • 6.
    Andersson, Ida
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Hedvall, Anders
    KTH, School of Technology and Health (STH), Medical Engineering.
    Relationships Between Skin Properties and Body Water Level2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A need for a quantitative method to determine body water level has been identified by a team of Clinical Innovation Fellows at the Centre for Technology in Medicine and Health (CTMH). A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing. A possible solution is a sensor that would measure alterations in skin properties due to changes in total body water. CTMH has had an idea of such a sensor, which is evaluated in this work. At an early stage of this evaluation process, it became clear that the research regarding correlations between skin properties and body hydration level was not sufficient to warrant the initiation of a sensor development process. Therefore, the main objective of this thesis became to investigate such correlations.

    An extensive literature review is presented, from which an experiment was developed. The experiment was performed on four human test subjects and involved measurements of skin thickness and elasticity parameters, before and after a weight loss of 3.2-3.7 % due to dehydration. The results showed clear decreases in skin thickness and indications of alterations in skin distensibility as well as in the skin’s immediate elastic response to applied negative pressure. It could also be seen that skin at different body sites does not respond in the same way - calves showed more distinct results than thighs and volar forearm.

    The material provided in this thesis encourages further studies of the correlation between the mentioned properties and total body water. If a predictable correlation can be found, a sensor development process could start. A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing.

  • 7.
    Andersson, Jesse
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Localized Sustainable Water Management in Practice: Ecological Engineering as a means for an eco-cyclic water system at the Berga Greenhouse Project2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AbstractDue to a growing concern towards issues of sustainability and sustainable development as well as resource scarcity there is a need for increased local cultivation. Cold climate conditions in Sweden make greenhouses necessary for the cultivation of many species. In order to increase the sustainability of greenhouse production processes water cycles should be nearly closedloop cycles. To demonstrate this in practice the Berga Greenhouse project under development by the Centre for Health and Building at the Royal Institute of Technology is used to provide a visionary example. Through precipitation data and a water budget analysis a water reclamation rate of 85% was determined in order to bring the facility to water neutral status. On site water treatment through the use of ecological engineering was analyzed through the use of a multiple-case study of three prevalent technologies (Living Machines®, Organica Water, and Solar Aquatics™) which determined that Living Machines® was the most appropriate technology based upon factors related system performance and footprint.

  • 8.
    Andersson, Katarina
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Optimization of the Implantation Angle for a Talar Resurfacing Implant: A Finite Element Study2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Osteochondral lesions of the talus (OLTs) are the third most common type of osteochondral lesion and can cause pain and instability of the ankle joint. Episurf Medical AB is a medical technology company that develops individualized implants for patients who are suffering from focal cartilage lesions. Episurf have recently started a project that aims to implement their implantation technique in the treatment of OLTs.

    This master thesis was a part of Episurf’s talus project and the main goal of the thesis was to find the optimal implantation angle of the Episurf implant when treating OLTs. The optimal implantation angle was defined as the angle that minimized the maximum equivalent (von Mises) strain acting on the implant shaft during the stance phase of a normal gait cycle. It is desirable to minimize the strain acting on the implant shaft, since a reduction of the strain can improve the longevity of the implant.

    To find the optimal implantation angle a finite element model of an ankle joint treated with the Episurf implant was developed. In the model an implant with a diameter of 12 millimeters was placed in the middle part of the medial side of the talar dome. An optimization algorithm was designed to find the implantation angle, which minimized the maximum equivalent strain acting on the implant shaft. The optimal implantation angle was found to be a sagittal angle of 12.5 degrees and a coronal angle of 0 degrees. Both the magnitude and the direction of the force applied to the ankle joint in the simulated stance phase seemed to influence the maximum equivalent strain acting on the implant shaft.

    A number of simplifications have been done in the simulation of this project, which might affect the accuracy of the results. Therefore it is recommended that further, more detailed, simulations based on this project are performed in order to improve the result accuracy.

  • 9.
    Arroyo Porras, Igor Alfredo
    KTH, School of Technology and Health (STH).
    Developing an sleep scorer by using Biosignals in Matlab.: Evaluation for sleep apnea patients.2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, sleep disorders e.g. sleep apnea —the cessation of airflow at the nose and mouth lasting at least 10 second— are a broadly problem around the world. Direct and indirect costs associated to sleep problems are outsize and the quality of patient life is deteriorated because of it. In addition, Sleep is a fundamental part of everyday life, the lack of it or the poor quality of sleep may lead into the development of important diseases. Sleep studies are usually carried out by specialists by means of polysomnography. Polysomnography is a type of sleep study which is consisting of EEG, EOG, EMG, ECG, respiratory signals and/or many other biosignals which together can be used to determine the state of patient’s sleep and any other issue. Nowadays, visual inspection of these signals forms the “gold standard” in sleep clinics. The cost of monitoring a person overnight, the scarcity of beds available and the uncertainty of whether the results are representative of a normal nights’ sleep means that a move to home diagnostics is likely to be advantageous. Therefore, a necessity for home recorders systems capable of perform this kind of analysis has come out. A state machine based automatic scorer is developed and evaluated in Matlab by using 12 recordings of apnoeic patients from sleep heart health study (SHHS) database. By the analysis of EEG, EOG, EMG, Oxygen saturation (Sao2) and respiratory movements signals, the implemented algorithm is trained and evaluated to detect the five stages of subject’s sleep (Wake, N1, N2, N3, or REM) as well as apnoeic episodes according to guidelines from American Academy of Sleep Medicine (AASM). In the final evaluation of algorithms, the automatic scorer achieved 74±5.27% accuracy for all five stages and Cohen’s kappa of 0.5 for the overall set of 12 patients, being the accuracy better for healthier subjects and reaching in this case 78±4.05%. The analysis of the sleep apnea concluded with a sensitivity of 47.08%, a specificity of 83.38%, and an accuracy of 78.1%. Differences in the performance among patients according to their apnea/hypopnea index were significant.

     

    Key Words: Polysomnography, AASM, Sleep apnea/hypopnea.

  • 10.
    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.

  • 11.
    Ayele, Yohannes Haileyesus
    KTH, School of Technology and Health (STH).
    Region-Based Contrast Transfer Function correction for Electron Microscopy Images2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electron crystallography is one of the methods for determining the structure of membrane proteins. However, the resolution that we get from electron crystallography of membrane proteins is limited by crystal disorder and inaccurate determination of contrast transfer function (CTF) parameters. To overcome these problems, we applied single particle refinement with local averaging for long range variation of the crystals and local region-based CTF correction for the tilted images. These two corrections are done on the Melibiose Permease (MelB) data sets and a resolution of 8.6Å is reported.

  • 12.
    Baitar, Rami
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Riskanalys av elsystem med funktions-FMEA2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The risk analysis tool failure mode and effects analysis (FMEA) that analyzes the com-ponents and signals of a electrical system is design dependent and are therefore per-formed late in the development process of electrical systems. This could lead to that some errors are not analyzed in time and may need to be designed away which can lead to increased system complexity as well as longer and more expensive development proc-esses.The objective of this study is that through a literature review identify if there are any methods or approaches that enables Scania to implement a functional hazard analyzes early in the development process of electrical systems and to analyze these.The results of this thesis shows that it is possible to start the FMEA process early in the development process of the electrical system if the engineers have a functional perspec-tive in mind when performing the risk analysis where they list and rank the functions that is provided by the electrical system and their failure modes, failure effects, failure de-tection, severity, probability and occurrence.By using a function based FMEA, the engineer(s) can identify and promptly handle the safety critical functions early in the development process of a electrical system.A existing functionality at Scania has been broken down into functions and a functional hazard analysis has been performed on these as a demonstration of how a function based FMEA can be carried out and look like.

  • 13.
    Bassan, Gioia
    KTH, School of Technology and Health (STH).
    Dual-Probe Shear Wave Elastography in a Transversely Isotropic Phantom2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Shear Wave Elastography (SWE) is an ultrasound based technique which is able to measure tissue stiffness through the speed of induced shear waves. Tissue stiffness is often related to pathological conditions and detecting mechanical changes can help the recognition of potential diseases. The clinical use of SWE is limited to isotropic tissue due to the difficulty in assessing a theoretical model for more complex tissue and this project therefore aimed to evaluate the possibility of obtaining a full mechanical characterization of a transversely isotropic (TI) phantom with dual-probe SWE. A TI hydrogel phantom was developed and mechanical tests were performed to verify its anisotropy and determine the elastic moduli in both the perpendicular and longitudinal directions. Shear moduli were estimated using conventional and dual-probe SWE comparing the results to theoretical pure-transverse (PT) and quasi-transverse (QT) wave propagation modes. Both mechanical and SWE tests showed that the phantoms were transversely isotropic ET/EL=0.81. Moreover, multiple wave propagation modes calculated with dual-probe SWE showed a good agreement with the theoretical curves and indicated the possibility of measuring all the elasticity constants needed to fully characterize an incompressible, TI tissue with dual-probe SWE.

  • 14.
    Baumann, Michael
    KTH, School of Technology and Health (STH).
    Performance of a Micro-CT System: Characterisation of Hamamatsu X-ray source L10951-04 and flat panel C7942CA-222014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis evaluated the performance of a micro-CT system consisting of Hamamatsu microfocus X-ray source L10951-04 and CMOS flat panel C7942CA-22. The X-ray source and flat panel have been characterised in terms of dark current, image noise and beam profile. Additionally, the micro-CT system’s spatial resolution, detector lag and detector X-ray response have been measured. Guidance for full image correction and methods for characterisation and performance test of the X-ray source and detector is presented.

    A spatial resolution of 7 lp/mm at 10 % MTF was measured. A detector lag of 0.3 % was observed after ten minutes of radiation exposure. The performance of the micro-CT system was found to be sufficient for high resolution X-ray imaging. However, the detector lag effect is strong enough to reduce image quality during subsequent image acquisition and must either be avoided or corrected for.

  • 15.
    Bennani, Safia
    KTH, School of Technology and Health (STH).
    An evaluation and improvement of an in vitro heart phantom of the hearts coronary circulation.2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis has been to validate the in-vitro heart simulation model of the coronary arteries called Flowlab, identify limitations and potential problems, and to offer suggestions for improvement. Flowlab emulates arterial characteristics such as pressure and flow, providing a simulation environment with the ability to measure the volumetric coronary blood flow and arterial blood pressure. Compared to current simulation systems, this will give a better understanding of both position and severity of the cardiovascular disease, and also provide essential information regarding the hemodynamics in the coronary arteries.

     

    To understand the fluid dynamics of the coronary system and gain a deeper understanding of the arterial function and physiology, the first phase of this thesis will focus on gathering information regarding the anatomy, physiology and hemodynamics of the coronary arteries. This will also be done to provide the Flowlab construction with appropriate measurements for the coronary simulation pipe, and input data for its final design.

     

    The Flowlab construction will then be tested to verify the accuracy of the produced values compared with the sought after values of pressure and flow, to further enable an adjustment of the system.

     

    The results from the test show that the final calibration of the simulation environment was not sufficient to produce an accurate result for both pressure and flow regulation, only flow. The flow had an accuracy of 10 %, while the generated pressure was underestimated at low pressures and overestimated at high pressure at up to 20 %. An accuracy of 10 % for generated flow is satisfying and sufficient; meanwhile the pressure calibration had to be altered for more reliable data.

     

    The analysis also revealed several shortages in the design of the Flowlab system that needed to be adjusted for more consistent pressure and flow measurements.

  • 16.
    Berndtsson, Andreas
    KTH, School of Technology and Health (STH), Medical Engineering.
    Heart Rate Variability Biofeedback for Android2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heart rate variability (HRV) is the variations in time between consecutive heart beats, and reflects the functioning of the autonomic nervous system. Not only is HRV a good marker for many physiological disorders, but it is well known that HRV can be altered consciously by different approaches even though it is controlled by the autonomic nervous system. Respiration is an important factor in modulating HRV and this property is utilized in HRV biofeedback, which is a method that aims at increasing heart rate variability. HRV biofeedback systems typically measures heart rate variability and display the parameters on a screen, enabling the user to gain control and increase heart rate variations. In this thesis a software for biofeedback of heart rate variability is presented. The software was implemented for Android and runs on a tablet computer to make the biofeedback system portable and more accessible than most other biofeedback systems. The developed software has proven to be fully functional in real-time providing the user with reliable information. A small pilot study on healthy volunteers has also been made to evaluate the effects of the biofeedback training. These measurements give a preliminary indication that biofeedback session with the proposed solution increases HRV. However, a more comprehensive study with a larger population needs to be carried out in order to confidently confirm the positive effects of biofeedback sessions with the software. 

  • 17.
    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.

  • 18.
    Björklund, Tomas
    KTH, School of Technology and Health (STH).
    Automatic evaluation of breast density in mammographic images2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this master thesis is to develop a computerized method for automatic estimation of the mammographic density of mammographic images from 5 different types of mammography units.

     

    Mammographic density is a measurement of the amount of fibroglandular tissue in a breast. This is the single most attributable risk factor for breast cancer; an accurate measurement of the mammographic density can increase the accuracy of cancer prediction in mammography. Today it is commonly estimated through visual inspection by a radiologist, which is subjective and results in inter-reader variation.

     

    The developed method estimates the density as a ratio of #pixels-containing-dense-tissue over #pixels-containing-any-breast-tissue and also according to the BI-RADS density categories. To achieve this, each mammographic image is:

    • corrected for breast thickness and normalized such that some global threshold can separate dense and non-dense tissue.
    • iteratively thresholded until a good threshold is found.  This process is monitored and automatically stopped by a classifier which is trained on sample segmentations using features based on different image intensity characteristics in specified image regions.
    • filtered to remove noise such as blood vessels from the segmentation.
    • Finally, the ratio of dense tissue is calculated and a BI-RADS density class is assigned based on a calibrated scale (after averaging the ratings of both craniocaudal images for each patient). The calibration is based on resulting density ratio estimations of over 1300 training samples against ratings by radiologists of the same images.

     

    The method was tested on craniocaudal images (not included in the training process) acquired with different mammography units of 703 patients which had also been rated by radiologists according to the BI-RADS density classes. The agreement with the radiologist rating in terms of Cohen’s weighted kappa is substantial (0.73). In 68% of the cases the agreement is exact, only in 1.2% of the cases the disagreement is more than 1 class.

  • 19.
    Bodin, Ida
    KTH, School of Technology and Health (STH), Ergonomics.
    Using Cognitive Work Analysis to identify opportunities for enhancing human-heavy vehicle system performance2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the road transportation industry development is moving towards more advanced technology and the use of automation in the driving environment is increasing. Regarding the safety risks associated with an unconsidered use of a high degree of automation, it is expensive to develop automatic systems dealing with complex situations. As there is still much improvement to do in this area, this thesis aims to contribute to developing safe autonomic systems to assist truck drivers.

    The aim of the study was twofold, namely 1) to use Cognitive Work Analysis to identify opportunities for enhancing human-heavy vehicle system performance and 2) to contribute to improving the possibilities for identifying opportunities for enhancing system performance through the development of a method of prioritizing Activities using a Contextual Activity Template.

    To identify the opportunities for improvement, the first two phases of a Cognitive Work Analysis (CWA) – Work Domain Analysis (WDA) and Control Task Analysis (ConTA), were conducted.

    To complete the WDA, five hours of interviews were conducted with a senior technical adviser from Scania CV AB as well as a two hour interview with an experienced commercial driver. Additionally, an observation study was conducted during which three video cameras were used to capture sixteen hours of footage (per camera) from 35 hours (2500kms) of observation (one driver/day over a four day period). During the observation study, drivers were asked to talk out loud about the information needed, decisions made and to provide some rational for their behavior at that time with respect to their driving activities. A total of 40 minutes of talk out loud video data was collected per driver. Finally, around five hours of follow-up interviews were conduct-ed during which these drivers reviewed the videos collected during the observation study.

    The results from the WDA were presented in an Abstraction Hierarchy. The overall functional purpose of the system was defined as Goods Distribution via Road Transportation with the values and priorities being Effectivity and Efficiency, Safety, Comfort, Laws/regulations, Reputation, and Organizational Regulations. For the WDA in the current thesis, the AH was completed for the first three values listed above. In total the AH included 343 nodes (39 at the Purpose Related Functions level, 77 at the Object Related Processes level, and 211 at the Physical Objects level).

    The means by which the physical objects were used in different situations was described using a Contractual Activity Template. The object related processes defined in the AH were crosschecked with 42 situations identified during the observation study. Eight hours of further interviews were conducted with the previously-observed drivers to better understand the relationship between the object related processes and the situations. The object related process-situations matrix was then prioritized according to importance and frequency. On the basis of this prioritization, a set of potential improvement areas were identified, as for example communication and visibility during highway driving.

  • 20.
    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.

  • 21.
    Buizza, Giulia
    KTH, School of Technology and Health (STH).
    Classifying patients' response to tumour treatment from PET/CT data: a machine learning approach2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Early assessment of tumour response has lately acquired big interest in the medical field, given the possibility to modify treatments during their delivery. Radiomics aims to quantitatively describe images in radiology by automatically extracting a large number of image features. In this context, PET/CT (Positron Emission Tomography/Computed Tomography) images are of great interest since they encode functional and anatomical information, respectively. In order to assess the patients' responses from many image features appropriate methods should be applied. Machine learning offers different procedures that can deal with this, possibly high dimensional, problem.

    The main objective of this work was to develop a method to classify lung cancer patients as responding or not to chemoradiation treatment, relying on repeated PET/CT images. Patients were divided in two groups, based on the type of chemoradiation treatment they underwent (sequential or concurrent radiation therapy with respect to chemotherapy), but image features were extracted using the same procedure. Support vector machines performed classification using features from the Radiomics field, mostly describing tumour texture, or from handcrafted features, which described image intensity changes as a function of tumour depth. Classification performance was described by the area under the curve (AUC) of ROC (Receiving Operator Characteristic) curves after leave-one-out cross-validation. For sequential patients, 0.98 was the best AUC obtained, while for concurrent patients 0.93 was the best one. Handcrafted features were comparable to those from Radiomics and from previous studies, as for classification results. Also, features from PET alone and CT alone were found to be suitable for the task, entailing a performance better than random.

  • 22.
    Bährecke, Niklas
    KTH, School of Technology and Health (STH).
    Automatic Classification and Visualisation of Gas from Infrared Video Data2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Optical gas imaging denotes the visualisation of gases by means of an infrared camera, which allows operators to quickly, easily, and safely scan a large area and therefore plays a major role in the early detection and repair of gas leaks in various environments within the petrochemical industry such as processing plants and pipelines, but also in production facilities and hospitals. Thereby they help to avert damage to the environment as well as to health and safety of workers or inhabitants of nearby residential areas. The current generation of thermal gas cameras employs a so-called high-sensitivity mode, based on frame differencing, to increase the visibility of gas plumes. However, this method often results in image degradation through loss of orientation, distortion, and additional noise. Taking the increased prevalence and sinking costs for IR gas cameras – entailing an increased number of inexperienced users – into consideration, a more intuitive and user-friendly system to visualise gas constitutes a useful feature for the next generation of IR gas cameras. A system that retains the original infrared video images and highlights the gas cloud, providing the user with a clear and distinct visualisation of gas on the camera’s display, would be one example for such a visualisation system. This thesis discusses the design of such an automatic gas detection and visualisation framework based on machine learning and computer vision methods, where moving objects in video images are detected and classified as gas or non-gas based on appearance and spatiotemporal features. The main goal was to conduct a proof-of-concept study of this method, which included gathering examples for training a classifier as well as implementing the framework and evaluating several feature descriptors – both static and dynamic ones – with regard to their classification performance in gas detection in video images. Depending on the application scenario, the methods evaluated in this study are capable of reliably detecting gas.

  • 23.
    Carlsson, Tor
    KTH, School of Technology and Health (STH).
    Individualized Motion Monitoring by Wearable Sensor: Pre-impact fall detection using SVM and sensor fusion2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Among the elderly, falling represents a major threat to the individual health, and is considered as a major source of morbidity and mortality. In Sweden alone, three elderly are lost each day in accidents related to falling. The elderly who survive the fall are likely to be suffering from decreased quality of life. As the percentage of elderly increase in the population worldwide, the need for preventive methods and tools will grow drastically in order to deal with the increasing health-care costs. This report is the result of a conceptual study where an algorithm for individualized motion monitoring and pre-impact fall detection is developed. The algorithm learns the normal state of the wearer in order to detect anomalous events such as a fall. Furthermore, this report presents the requirements and issues related to the implementation of such a system. The result of the study is presented as a comparison between the individualized system and a more generalized fall detection system. The conclusion is that the presented type of algorithm is capable of learning the user behaviour and is able to detect a fall before the user impacts the ground, with a mean lead time of 301ms.

  • 24.
    Carlström, Malin
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Design for Human Behaviour and Automation: Development and Evaluation of a Holistic Warning Approach2014Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A human-centered approach when developing new support systems in vehicles has the potential to enable the driver to make safe decisions in the transition between manual and automatic control. However, careful considerations have to be taken. Not only would the design of the systems, in terms of interface be important, but also what kind of activities the systems support. The aim of this study was to identify an appropriate activity to support the cognitive processes for truck drivers, develop an interface for this activity, and evaluate it in driving situations. This was executed in three sub-studies: the Pre-study, the Design-study, and the Evaluation study.

    In the Pre-study, the aim was to investigate for what kind of driver-related activity distribution and long haulage truck drivers need a driver support and interface. This was investigated via contribution from truck drivers, HMI/Ergonomics experts, as well as engineers. The activity chosen to support was detecting objects around the vehicle. However, reconsiderations were made due to constrains in the simulator. Suggested by Scania’s Vehicle Ergonomics group a holistic system was chosen; an interface approach enabling for more technologies to be included within the same interface, reducing the amount of modalities a driver can be exposed to.

    The Design-study addressed the aim of designing an interface for the Holistic system with truck drivers’ cognitive workload in focus. A LED-prototype was built running along the window edges inside the cab of Shania’s Vehicle Ergonomics groups’ simulator, to create warning signal concepts. Literature findings, the LED-prototype, and the simulator were used in an iterative process to design and improve warning signal concepts, until two final concepts were created. The holistic system informs of hazards around and near the vehicle by lighting the area risky objects occurs to guide drivers’ attention and this was done either with 1) the informative display or, 2) the directional display. The Informative display conveys information of a hazard location and type, and the Directional display exclusively conveys information of the hazard location.

    The Evaluation study explored how drivers were affected by, and how they perceived, the holistic interface design regarding mental workload and hazard detection. A user simulator test was designed to collect data within the areas of ‘Event detection’, ‘Workload’, ‘Driving performance’ and ‘Subjective opinion’. Fourteen professional truck drivers assessed three conditions: 1) Baseline (driving without a system), 2) the Informative display, and, 3) the Directional display, while being exposed to potential hazards. To further increase workload, a secondary task was performed at the end of each condition.

    The results showed that the Informative display did not only result in more ‘Detection hits’, instances when a driver responded to a present hazard, but also significantly decreased reaction time to detect a hazard. However, in terms of acceptance, the two concepts were considered equally preferred. As the Informative display showed to be more efficient in terms of hazard detection, this should be investigated further. A holistic interface enables for more systems to be included within the same interface, reducing the amount of alarms and modalities drivers are exposed to if designed skillfully. Thus, more support systems can be included in future vehicles, without causing unnecessary distraction when applying a holistic interface approach.

  • 25.
    Carnevale Lon, Sergio Christian
    KTH, School of Technology and Health (STH).
    A new helmet testing method to assess potential damages in the Brain and the head due to rotational energy2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Preservation and protection of the head segment is of upmost importance due to the criticality of the functions entailed in this section of the body by the brain and the nervous system. Numerous events in daily life situations such as transportation and sports pose threats of injuries that may end or change a person’s life.

    In the European Union, statistics report that almost 4.2 million of road users are injured non-fatally, out of which 18% is represented by motorcyclist and 40% by cyclists, being head injuries 34% for bicyclists, and 24% for two-wheeled motor vehicles. Not only vehicles, are a source of injuries for the human head according to the injury report, 6,1 million people are admitted in hospitals for sports related injuries, where sports such as hockey, swimming, cycling presented head injuries up to 28%, 25% and 16% respectively (European Association for Injury Prevention and Safety Promotion, 2013). 

    According to records the vast majority of head crashes result in an oblique impact (Thibault & Gennarelli, 1985). These types of impacts are characterized for involving a rotation of the head segment which is correlated with serious head injuries. Even though there is plenty of evidence suggesting the involvement of rotational forces current helmet development standards and regulations fail to recognize their importance and account only for translational impact tests.

    This thesis contains an evaluation for a different developed method for testing oblique impacts. In consequence a new test rig was constructed with basis on a guided free fall of a helmeted dummy head striking an oblique (angled) anvil which will induce rotation.

    The results obtained are intended to be subjected to a comparison with another oblique test rig that performs experiments utilizing a movable sliding plate which when impacted induces the rotation of a dropped helmeted dummy head. The outcome will solidify the presence of rotational forces at head-anvil impact and offer an alternative testing method.

    After setting up the new test rig; experiments were conducted utilizing bicycle helmets varying the velocities before impact from 5m/s to 6m/s crashing an angled anvil of 45°. Results showed higher peak resultant values for rotational accelerations and rotational velocities in the new test rig compared to the movable plate impact test, indicating that depending on the impact situation the “Normal Force” has a direct effect on the rotational components. On the other hand a performed finite element analysis predicted that the best correlation between both methods is when the new angled anvil impact test is submitted to crashes with a velocity before impact of 6 m/s at 45° and the movable sliding impact test to a resultant velocity vector of 7,6m/s with an angle of 30° .

    In conclusion the new test method is meant to provide a comparison between two different test rigs that will undoubtedly have a part in the analysis for helmet and head safety improvements.

  • 26.
    Carniello, Vera
    KTH, School of Technology and Health (STH).
    Tailoring interactions betweendegradable polymers and proteins,exploiting nanodiamond particlesand Quartz Crystal Microbalance2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Quartz Crystal Microbalance (QCM) is a sensitive and effective technique to analyze mass changes at the interface between a solid material and a liquid environment. In this Master thesis, QCM was employed for evaluating the interactions between selected degradable polymers and nanodiamond particles (nDP), fibronectin and the growth factor BMP-2.

     

    Many parameters must be adapted to allow QCM measurements involving degradable polymers. These parameters were then tailored to allow QCM measurements with PLA, poly(LLA-co-CL), poly(TMC-D-LA) and PS.

     

    Moreover, QCM provides quantitative measurements of protein adsorption on degradable polymers. The behavior of PLA and poly(LLA-co-CL) was further evaluated and compared with respect to protein adsorption. This behavior was demonstrated to be different for the two polymers considered and to be dependent on protein concentration in solution.

     

    Eventually, exploiting QCM it was also possible to assess the relationship between nDP and the adsorption of fibronectin and BMP-2 onto PLA and poly(LLA-co-CL).

  • 27.
    Charalampidis, Vasileios
    KTH, School of Technology and Health (STH).
    Real-Time Monitoring System of Sedentary Behavior with Android Wear and Cloud Computing: An office case study2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, prolonged sitting among office workers is a widespread problem, which is highly related to several health problems. Many proposals have been reported and evaluated to address this issue. However, motivating and engaging workers to change health behavior to a healthier working life is still a challenge.

    In this project, a specific application has been deployed for real-time monitoring and alerting office workers for prolonged sitting. The proposed system consists of three distinct parts: The first one is an android smartwatch, which was used to collect sensor data e.g., accelerometer and gyro data, with a custom android wear app. The second one is an android application, which was developed to act as a gateway for receiving the smartwatch’s data and sending them to IBM Bluemix cloud with MQTT protocol. The final part is a Node-Red cloud application, which was deployed for storing, analyzing and processing of the sensor data for activity detection i.e., sitting or walking/standing. The main purpose of the last one was to return relevant feedback to the user, while combining elements from gaming contexts (gamification methods), for motivating and engaging office workers to a healthier behavior.

    The system was firstly tested for defining appropriate accelerometer thresholds to five participants (control group), and then evaluated with five different participants (treatment group), in order to analyze its reliability for prolonged sitting detection. The results showed a good precession for the detection. No confusing between sitting and walking/standing was noticed. Communication, storage and analysis of the data was successfully done, while the push notifications to the participants, for alerting or rewarding them, were always accurate and delivered on time. Every useful information was presented to the user to a web-based dashboard accessed through a smartphone, tablet or a PC.    

    The proposed system can easily be implemented at a real-life scenario with office workers. Certainly, there is a lot space for improvement, considering mostly the type of data registered at the system, the method for sitting detection, and the user interface for presenting relevant information.

  • 28.
    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.

  • 29.
    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. 

  • 30.
    Christiansson, Samuel
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Potentialen för spillvärmeuppvärmda växthus i Sverige: ur ett hållbarhetsperspektiv2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Sammanfattning

    Denna studie är en delstudie i ett större växthusprojekt som drivs av KTH Centrum för Hälsa och Byggande i Haninge utanför Stockholm. Projektet inbegriper ett integrerat spillvärme- och växthussystem med besöks- och forskningsändamål, placerat i anslutning till en reningsanläggning och ett naturbruksgymnasium. Studiens primära syften är att undersöka spillvärmepotentialen och potentialen för uppvärmning av växthus med spillvärme i Sverige. De sekundära syftena är att undersöka vilka hållbarhetsaspekter som kan identifieras som viktiga för spillvärme-växthus-system och att göra en idé- och informationssammanställning för dem som vill bygga spillvärme-växthus-system, med bland annat tips om hur produktpriser kan beräknas, vilka nyckeltal som kan användas för energikalkyler och vilka användningsområden som finns med ett växthus. Rapporten får ett visst fokus på livsmedels- och tomatodling, eftersom både tidigare studier och den fallstudie som ingår i rapporten handlade om detta. Studiens avsikt är dock att förespråka för en bredare syn på växthusanvändning.

    Studien visar att det finns stora spillvärmepotentialer bland särskilt högtempererade spillvärmekällor på västkusten och medeltempererade spillvärmekällor i Stockholmsområdet, eftersom dessa områden har både god spillvärmepotential och stor befolkning. Växthus kan byggas nära spillvärmekällan och kräver inte lika höga ingångstemperaturer som exempelvis fjärrvärmenäten, vilket gör spillvärme-växthus-system mer flexibla än spillvärme-fjärrvärme-system. Studien visar på viktiga fysiska, ekonomiska och organisatoriska förutsättningar för att bygga spillvärme-växthus-system, att det finns biologiska, sociala och kulturella potentialer med växthusen och vidare att det finns flera intressanta hållbarhetsaspekter med spillvärme-växthus-system, särskilt om de byggs rätt från början.

    Så gjordes i Habo, där studiens fallstudie gjordes. I Habo drivs ekologisk växthusodling med hjälp av spillvärme från en närliggande och elproducerande biogasanläggning, där de organiska resurserna består av gödsel och godisrester från en lokal godisindustri. Hela spillvärme-växthus-systemet är småskaligt och i stort sett kretsloppsanpassat. Modellen rekommenderas starkt både för projektet i Haninge och var helst man funderar på att bygga spillvärme-växthus-system, eftersom det överallt finns och alltid kommer att finnas tillgång på organiskt avfall. Energistudier visar att det finns stor potential i det organiska avfallet, särskilt från jordbruk

  • 31.
    Dahlgren, Sofia
    KTH, School of Technology and Health (STH).
    Evaluation of a Flooring System to Help Reduce Fall-Related Injuries among Elderly: A Compilation of Requirements together with Hip Impact Simulations, using a Computational Human Body Model2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fall-related incidents are the most common cause of injury among elderly, and may result in hip fractures. Svein Kleiven and Hans von Holst, professors at the Royal Institute of Technology, have developed a technology for a compliant flooring system with the intention of reducing the peak force acting on the proximal femur during a fall. A project is underway to make the floor commercially available, where this thesis was a part of the first phase of the project.

    The goal with this thesis was to modify a computational human body model (HBM) to predict hip fractures when falling, using different material and geometry regarding the flooring system. It was also to compile a set of requirements that the final product would need to fulfill.

    The human body model was validated and modified using a study where cadavers had been tested. With the Finite Element Method (FEM), impacts were performed with the human body model and a flooring system. Requirements regarding the flooring system were compiled using literature studies, a study visit in a geriatric care facility and dialogues with well-informed people.

    Modifications involving contacts, material and the proximal femur were made on the model. A total of 18 simulations were performed using different flooring systems. When compared to rigid floor condition, all configurations showed a reduction in peak force on the proximal femur. The maximal attenuation was calculated to 33.04%, provided by pins with a diameter of 3 mm and with a distance of 5 mm between their midpoints.

  • 32.
    Damberg, Emmy
    KTH, School of Technology and Health (STH).
    Data Mining for Description and Prediction of Antibiotic Treated Healthcare-Associated Infections2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Healthcare-associated infections is the most common healthcare related injury and affect almost every tenth patient. With the purpose of reducing these infections Infektionsverktyget, The Anti-Infection Tool, was developed for registration and feedback of infection data. The tool is now used in all Swedish county councils resulting in a wealth of data. The purpose of this thesis was thus to investigate how data mining can be applied to describe patterns in this data and predict patient outcomes regarding healthcare-associated infections that need to be treated with antibiotics.

    Data mining was performed with Microsoft SQL Server 2008 in which models based on six different data mining algorithms with different parameter settings were developed. They used the attributes gender, age and previous diagnoses and medical actions as inputs and antibiotic treated healthcare-associated infection outcome as output. The predictive performance of the models was evaluated using 5-fold cross validation and macro averaged measures of recall, precision and F-measure. Patterns generated by selected models were extracted.

    Models based on the Naive Bayes algorithm showed the highest predictive capabilities with respect to recall and models based on the Decision Trees algorithm with low pruning had the highest precision. Although, none were considered to perform sufficiently well and several areas of improvement were identified. The most important factor in the inadequate performance is believed to be the relatively rare occurrences of infections in the dataset. Extracted patterns based on the Association Rules algorithm were considered the easiest to interpret. Patterns included clinically valid and invalid as well as trivial relationships.

    Future studies should be focused on further model improvements and gathering of more patient data. The idea is that data mining in Infektionsverktyget in the future could be used both to provide ideas for further medical research and to identify risk patients and prevent healthcare-associated infections in daily clinical work.

  • 33.
    Danielsson, Åsa
    KTH, School of Technology and Health (STH).
    Karaktärisering och vidareutveckling av teknik för provsamling av utandade partiklar2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Analysis of drug particles in exhaled air is a new research area with great potential for medical diagnoses. A major advantage is that sampling can be performed much easier and that the procedure may be perceived as less intrusive than, for example, blood or urine samples.

    The overall aim of this thesis work was to investigate some of the properties of a sampler named SensAbues, which is designed to collect particles in exhaled air. Another part of the purpose was to examine the variation in the results of previous research related to drugs through expiration. The work was based on literature studies and six separate experiments. Experiments I-III was related to SensAbues properties. The properties examined were the sampler's flow resistance (experiment I), how the particles are distributed over the sampler (experiment II) and particle statistics regarding exhaled particles and the sampler's collection effectiveness (experiment III). In experiments IV-VI previous research results variety was examined based on primarily three hypotheses: 1) Increased resistance would stimulate the amount of exhaled particles and thereby increase the concentration (experiment IV). 2) That a special breathing maneuver would stimulate the amount of exhaled particles and thereby increase the concentration (experiment V). 3) That particles from the oral cavity, such as saliva, would contaminate the filter and explain the variation in previous research results (experiment VI).

    The results from experiment I show that most of the flow resistance is located in the sampler's nozzle. In experiment II it shows that there is a great distribution of methadone particles over the sampler's different parts. Only a small part, about 3% of methadone particles exhaled trapped in the filter, which is the part that is analyzed in the laboratory. In experiment II, it is not possible to draw any conclusions about the sampler's efficiency, this examined in experiment III. In experiment III the sampler's effectiveness is examined and the results show that the sampler captures approximately 99% of exhaled particles (all exhaled particles, not drug particles). Results in experiment IV showed that the increased flow resistance does not seem to have any bearing on the particle concentration (generally exhaled particles, not drug particles). The results of experiment V did not show that the particular breathing maneuver contributes to increased concentration of exhaled drug particles compared with normal breathing. The most likely reasons for the variation in previous research are that particles from the mouth contaminate the filter, as shown in the results of experiment VI. Experiments I-VI leads to recommendations for further development of the sampler.

  • 34.
    Darvish, Darvish
    et al.
    KTH, School of Technology and Health (STH).
    Öçba, F.Nadideh
    KTH, School of Technology and Health (STH).
    Presentation and evaluation of gated-SPECT myocardial perfusion images: Radial Slices - data reduction without  loss  of  information2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

     

    Single photon emission tomography (SPECT) data from myocardial perfusion imaging (MPI) are normally displayed as a set of three slices orthogonal to the left ventricular (LV) long axis for both ECG-gated (GSPECT) and non-gated SPECT studies. The total number of slices presented for assessment depends on the size of the heart, but is typically in excess of 30. 

    A requirement for data presentation is that images should be orientated about the LV axis; therefore, a set of radial slice would fulfill this need. Radial slices are parallel to the LV long axis and arranged diametrically. They could provide a suitable alternative to standard orthogonal slices, with the advantage of requiring far fewer slices to adequately represent the data.

    In this study a semi-automatic method was developed for displaying MPI SPECT data as a set of radial slices orientated about the LV axis, with the aim of reducing the number of slices viewed, without loss of information and independent on the size of the heart. Input volume data consisted of standard short axis slices orientated perpendicular to the LV axis chosen at the time of reconstruction.

     The true LV axis was determined by first determining the boundary on a central long axis slice, the axis being in the direction of the y-axis in the matrix. The skeleton of the myocardium were found and the true LV axis determined for that slice. The angle of this axis with respect to the y-axis was calculated. The process was repeated for an orthogonal long axis slice. The input volume was then rotated by the angles calculated.

    Radial slices generated for presentation were integrated over a sector equivalent to the imaging resolution (1.2 cm); assuming the diameter of the heart is about 8cm then non-gated data could be represented by 20 radial slices integrated over an 18 degree section. Gated information could be represented with four slices spaced at 45 intervals, integrated over a 30 degree sector.

  • 35.
    Di Sopra, Lorenzo
    KTH, School of Technology and Health (STH).
    Geometric Misalignment Calibration and Detector Lag Effect Artifact Correction in a Cone-Beam Flat Panel micro-CT System for Small Animal Imaging2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cone-beam flat panel micro-CT is a high definition imaging system. It acquires projections of an object or animal to reconstruct a 3D image of its internal structure. The device is basically composed by a radiation tube and a detector panel, which are fixed to a gantry that rotates all around the test subject. The micro-CT system is affected by several imperfections and problems, that might lead to serious artifacts that deteriorate the quality of the reconstructed image. In particular, two issues have been discussed in the present work: the source-panel geometric misalignment and the detector lag effect. The first problem concerns the consequences of systems where the different elements are not perfectly aligned to each other. The second issue regards the residual signal, left in the detector's sensor after a projection acquisition, which affects the following frames with ghost images. Both these arguments have been investigated to describe their characteristics and behaviour in a typical acquisition protocol. Then two correction methods have been presented and tested on a real micro-CT device to verify their effectiveness in the artifacts compensation. In the end, a comparison between images before and after the corrections is provided and future prospects are discussed.

  • 36.
    Dizon, Lucas
    et al.
    KTH, School of Technology and Health (STH).
    Johansson, Martin
    KTH, School of Technology and Health (STH).
    Atrial Fibrillation Detection Algorithm Evaluation and Implementation in Java2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Atrial fibrillation is a common heart arrhythmia which is characterized by a missing or irregular contraction of the atria. The disease is a risk factor for other more serious diseases and the total medical costs in society are extensive. Therefore it would be beneficial to improve and optimize the prevention and detection of the disease.

     

    Pulse palpation and heart auscultation can facilitate the detection of atrial fibrillation clinically, but the diagnosis is generally confirmed by an ECG examination. Today there are several algorithms that detect atrial fibrillation by analysing an ECG. A common method is to study the heart rate variability (HRV) and by different types of statistical calculations find episodes of atrial fibrillation which deviates from normal sinus rhythm.

     

    Two algorithms for detection of atrial fibrillation have been evaluated in Matlab. One is based on the coefficient of variation and the other uses a logistic regression model. Training and testing of the algorithms were done with data from the Physionet MIT database. Several steps of signal processing were used to remove different types of noise and artefacts before the data could be used.

     

    When testing the algorithms, the CV algorithm performed with a sensitivity of 91,38%, a specificity of 93,93% and accuracy of 92,92%, and the results of the logistic regression algorithm was a sensitivity of 97,23%, specificity of 93,79% and accuracy of 95,39%. The logistic regression algorithm performed better and was chosen for implementation in Java, where it achieved a sensitivity of 97,31%, specificity of 93,47% and accuracy of 95,25%.

  • 37.
    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. 

  • 38.
    Eghbali, Ladan
    KTH, School of Technology and Health (STH).
    The impact of defective ultrasound transducers on the evaluation results of ultrasound imaging of blood flow2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Following X-Ray, Ultrasound is now the most common of all the medical imaging technologies specifically in obstetrics and cardiology. Plus that the ultrasound hazards perceived to be insignificant compared with X-rays. Considering the fact that the study of cardiovascular diseases, blood flow patterns and the fetal development is essential for human life, the accuracy and proper functioning of ultrasonic systems is of great importance. Hence quality control of ultrasonic transducers is necessary.

    In this thesis, a system to standardize the acceptance criteria for quality control of ultrasonic transducers is described. On this ground a study on ultrasound images conducted to compare and evaluate the quality resulted from different types of transducers in different conditions, i.e. defective or functional.

    A clinical study was also carried out to evaluate our hypothesis in real cases at department of Cardiology and department of genecology. Results from this study show that the perception of quality is somewhat subjective and clinical studies are time-consuming. But quality factors such as the ability to accurately identify anatomical structure and functional capabilities are of great importance and help.

  • 39.
    Eghbali, Ladan
    KTH, School of Technology and Health (STH).
    The impact of defective ultrasound transducers on the evaluation results of ultrasound imaging of blood flow2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Following X-Ray, Ultrasound is now the most common of all the medical imaging technologies specifically in obstetrics and cardiology. Plus that the ultrasound hazards perceived to be insignificant compared with X-rays. Considering the fact that the study of cardiovascular diseases, blood flow patterns and the fetal development is essential for human life, the accuracy and proper functioning of ultrasonic systems is of great importance. Hence quality control of ultrasonic transducers is necessary.

    In this thesis, a system to standardize the acceptance criteria for quality control of ultrasonic transducers is described. On this ground a study on ultrasound images conducted to compare and evaluate the quality resulted from different types of transducers in different conditions, i.e. defective or functional.

    A clinical study was also carried out to evaluate our hypothesis in real cases at department of Cardiology and department of genecology. Results from this study show that the perception of quality is somewhat subjective and clinical studies are time-consuming. But quality factors such as the ability to accurately identify anatomical structure and functional capabilities are of great importance and help.

  • 40.
    Egnell, Liv
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics. KTH, School of Technology and Health (STH).
    Transient State Monitoring and Fluorescence Correlation Spectroscopy of Flavin Adenine Dinucleotide2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Many human diseases including cancer have been associated with altered cellular metabolism and a changed oxygen consumption in cells. Fluorophores are sensitive to their local environment due to their long life times in transient dark states. A recent study successfully utilized this sensitivity to image differences in oxygen concentrations in cells using transient state (TRAST) microscopy together with fluorescent labels [1]. A natural continuation of this study is to investigate the possibilities of using this method with natural fluorophores already present in cells and thereby avoid articial labeling.

    Flavin adenine dinucleotide (FAD) is an auto fluorescent coenzyme that is naturally present in cells and involved in cellular metabolism. This project is an exploratory pilot study for cellular measurements with the aim to investigate if FAD can be used to probe oxygen concentrations in aqueous solution using transient state monitoring and fluorescence correlation spectroscopy (FCS). This thesis includes the results from FCS and TRAST experiments on FAD in aqueous solutions with different oxygen concentrations as well as different ascorbic acid concentrations. The performed experiments showed that FAD monitored with TRAST is sensitive to differences in oxygen concentrations for the aqueous solutions used in this study.

  • 41.
    Elfström, Anna
    et al.
    KTH, School of Technology and Health (STH).
    Grunditz, Anna
    KTH, School of Technology and Health (STH).
    Evaluation of Sternum Closure Techniques Using Finite Element Analysis2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In an open thoracic surgery the surgeon dissociate the sternum, the breastbone, into two halves to be able to perform the operation. At the end of the surgery a standard technique is used which to close the sternum. The technique is based on steel wires that are wrapped around the halves of the sternum to close it. This technique is the most cost effective technique available on the market today but is still not optimal because it can cause infection, wound rupture and pain for the patient.

    The goal with this master thesis was to, with the help of finite element method, to find out which closure technique is the best one to close the sternum and to provide suggestions for improvement. This was done with respect to the aspects of how large the displacement between the sternum halves is and how much the stresses generated by the implants affect the sternum.

    Using literature studies and interviews three techniques were chosen to be simulated; the standard technique, Zipfix and Sternal Talon. Their implants consisted of stainless steel, PEEK and titanium respectively and the materials were simulated with every technique. In the lower part of the sternum it is a greater displacement between the two halves after simulation than in the rest of the sternum. An improvement was hence to simulate Zipfix and Sternal Talon with an extra steel wire in the lower part.

    Zipfix with the implants of titanium and the standard technique with the implants of stainless steel provided the best results with respect to the two aspects. The two improvements produced smaller displacement but the stresses were higher.

  • 42.
    Elmasoudi, Solayman
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Finite element modelling of a pedestrian impact dummy2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 43.
    Falck, Josefina
    KTH, School of Technology and Health (STH), Medical Engineering.
    Effect of side windows, stiffening plate and roof sheet on the stiffness of the bus body2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As a bus developer, Scania focus to construct a safe vehicle for the passengers, i.e. high strength of the bus structure and good comfort, which is also profitable for the operator, i.e. high passenger capacity and low fuel consumption. The trade-off when developing a bus body structure is to get both high stiffness and low weight. The bus body including exterior panels plays together with the chassis an important role for the stiffness of the bus. By gathering knowledge about how various exterior panels affects the stiffness of the bus body, the design of the panels can be optimized with respect to high stiffness and low weight. Also from a calculation point of view is it of interest to know how important different panels are for the stiffness of the bus body, in order to make conscious simplifications in the calculation model.

    The aim with this master thesis was to investigate how the stiffening plate, side windows and roof sheet influence the strength of the bus body. How the thickness of the side windows affects the stiffness of the bus body is also investigated. The investigations were made as a relative comparison between a complete bus and comparison models.

     

    The results showed that exterior panels participate in distributing load. By distributing the load, the load uptake gets more efficient since a bigger part of the bus structure is used to take up the load. The side windows affect the stiffness for all tested load cases, with increased importance for the load case where a gravity field is applied in the longitudinal direction, for the torsion load case and when a load is applied to the power train in vertical direction. The roof sheet has a high impact on the stiffness in the torsion load case, but has negligible influence on the stiffness of the bus body for the other tested load cases. The stiffening plate has little influence on the stiffness of the bus body in general and is negligible for all tested load cases except for when a lateral load is applied as either a gravity field or locally to the power train.

     

    Thinner side windows are shown to have a positive influence on the stiffness of the bus body.

  • 44.
    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.

  • 45.
    Friedrich, Anja
    KTH, School of Technology and Health (STH).
    A new seeding and conditioning reactor for vascular tissue engineering2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 46.
    Gao, Bo
    KTH, School of Technology and Health (STH).
    Multigrid reconstruction of micro-CT data2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The group of Medical Imaging at School of Health and Technology is developing a micro-CT scanner for small animal imaging. Micro-CT refers to reconstructing CT image with resolution in scale of micrometer, and this goal is achieved by acquiring projection data with high resolution. Nevertheless, high resolution projection data and high resolution recon- struction image have introduced the problem of memory insufficiency, as more points need to be processed during micro-CT reconstruction.

    For this reason, this paper has investigated how to alleviate the burden on computers memory through applying multi-grid reconstruction algo- rithms, which means to reconstruct region of interest (ROI) with high resolution while reconstructing background with lower resolution. By do- ing that, pixels being considered in the reconstruction space has been decreased and normal computers will be capable to handle reconstruction of micro-CT image.

    Through testing on numerical data (Shepp Logan Phantom), it can be concluded that multi-grid reconstruction algorithm could reconstruct high fidelity ROI with much faster speed comparing to full resolution reconstruction. Moreover, this proposed technique can also give decent reconstruction to data acquired from micro-CT scanner. 

  • 47.
    Gibert, Guillaume
    KTH, School of Technology and Health (STH).
    Quantification of the Cerebral Perfusion with the Arterial Spin Labelling 3D-MRI method. Quantification of the Cerebral Perfusion with the Arterial Spin Labelling 3D-MRI method2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Arterial Spin Labelling (ASL) method is a Magnetic Resonance technique used toquantify the cerebral perfusion. It has the big advantage to be non-invasive so doesn’tneed the injection of any contrast agent. But due to a relatively low Signal-to-NoiseRatio (SNR) of the signal acquired (only approximately 1% of the image intensity), ithas been hampered to be widely used in a clinical setting so far.The primary objective of this project is to make the method more robust by improvingthe quality of the images, the SNR, and by reducing the acquisition time. DifferentASL protocols with different sets of parameters have been investigated. The modificationsperformed on the protocol have been investigated by analyzing images acquired onhealthy volunteers. An optimized protocol leading to a good trade-off between the differentaspects of the method, has been suggested. It is characterized by a 3:43:44:0mm3with a two-segment acquisition.A more advanced ASL method implies the acquisition of images at different inversiontimes (TI), which is called the mutli-TI method. The influence of the range of TI used inthe method has been explored. An optimized TI range (from 410ms to 3860ms, sampledevery 150ms) has been suggested to make the ASL method as performant as possible.A numerical model and a fitting algorithm have been used to extract the informationon the perfusion from the images acquired. Different models have been investigated aswell as their influence on the reliability of the results.Finally, a criterion has been implemented to evaluate the reliability of the results sothat the clinician or the user of the method can figure out how much he can count onthe results provided by the method.

  • 48.
    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. 

  • 49.
    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.

  • 50.
    Grishenkov, Dmitry
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Ultrasound. KTH, School of Technology and Health (STH), Medical Engineering.
    Diagnostic Power of Different Tissue Doppler Parameters during Ultrasound Cardio-Vascular Investigation2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The department of Medical Technology, where I have done Master thesis project, develops and researches new method and technique within areas where ultrasound can be used to obtain the image of anatomical structure, functional capabilities and to suggest required treatment.

    Nowadays cardio-vascular diseases, such as infarct, atherosclerosis and ischemic syndrome, are one of the most widespread diseases in the world that’s why timely detection, identification and treatment are so important.

    The Master of Science qualification report consists 3 major parts: Medico-biological part, Design and Research parts.

    In Medico-biological part has been analyzed anatomical and physiological structure of the heart, current status of echocardiography with comparing with other techniques, summary of ultrasound methods with list of parameters that can be achieved is presented.

    In Design part has been developed new graphical modality based on Delta-V pump model using vector based statistical analysis for identification patients with ischemia. Software algorithm for automatically determine characteristic points for state diagram written in MatLab has been developed and implemented.

    In Research part in the first task using commercially available software based on Principal Component Analysis collected data from the hospital patients has been studied, results proved hypothesis concerning time variables importance; in the second task graphical module has been examined using collected data from the hospital patients both normal and with different cardio-vascular disease, and the results show good detection power of the algorithm.

    At the end of the project presentation has been done and report has been published.

    This project has been done in collaboration with the biggest medical institute in Sweden – Karolinska Institute - and results will be used in medical practice in Karolinska University Hospital in Huddinge and for future scientific needs.

     

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