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  • 1.
    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.

  • 2.
    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.

  • 3.
    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.

  • 4.
    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.

  • 5.
    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.

  • 6.
    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.

  • 7.
    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.

  • 8.
    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.

  • 9.
    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.

  • 10.
    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%.

  • 11.
    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.

  • 12.
    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.

  • 13.
    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.

  • 14.
    Hákonardóttir, Stefanía
    KTH, School of Technology and Health (STH).
    Prosthetic Control using Implanted Electrode Signals2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report presents the design and manufacturing process of a bionic signal messagebroker (BSMB), intended to allow communication between implanted electrodes andprosthetic legs designed by Ossur. The BSMB processes and analyses the data intorelevant information to control the bionic device. The intention is to carry out eventdetection in the BSMB, where events in the muscle signal are matched to the events ofthe gait cycle (toe-o, stance, swing).The whole system is designed to detect muscle contraction via sensors implantedin residual muscles and transmit the signals wireless to a control unit that activatesassociated functions of a prosthetic leg. Two users, one transtibial and one transfemoral,underwent surgery in order to get electrodes implantable into their residual leg muscles.They are among the rst users in the world to get this kind of implanted sensors.A prototype of the BSMB was manufactured. The process took more time thanexpected, mainly due to the fact that it was decided to use a ball grid array (BGA)microprocessor in order to save space. That meant more complicated routing and higherstandards for the manufacturing of the board. The results of the event detection indicatethat the data from the implanted electrodes can be used in order to get sucient controlover prosthetic legs. These are positive ndings for users of prosthetic legs and shouldincrease their security and quality of life.It is important to keep in mind when the results of this report are evaluated that allthe testing carried out were only done on one user each.

  • 15.
    Illerstam, Fredrik
    KTH, School of Technology and Health (STH).
    Quality Assurance of the Spatial Accuracy of Large Field of View Magnetic Resonance Imaging2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In todays Radiotherapy Treatment Planning, RTP, it is common to use Computed Tomography, CT, together with Magnetic Resonance Imaging, MRI, where CT provides electron density information and a geometrical reference, and where MRI provides superior soft tissue contrast. To sim- plify the workflow and improve treatment accuracy, research groups have demonstrated how to exclude CT and use a MRI-only approach. In this thesis, a method for spatial distortion analysis, ultimately enabling quality assurance, QA, of the spatial accuracy of MRI, was defined, tested and evaluated.

    A phantom was built to cover the entire clinical Field Of View, FOV, and 6mm-diameter fluid filled paintball markers were placed in a well-defined geometrical pattern within the phantom, and used as positive contrast. The phantom was imaged with a 3D Fast Gradient Echo sequence and a 3D Fast Spin Echo sequence. The markers were identified in the image data by a MATLAB-algorithm, and the location of the center of mass was calculated for each marker and compared to a theoretical reference. The location error was defined as the spatial distortion - a measurement of the spatial accuracy. Imaging parameters were altered and the effect on the spatial accuracy was analyzed.

    The spatial distortions were successfully measured within the entire (maximal) clinical FOV. It was shown that high readout bandwidth reduced distortions in the frequency encoding direction. These distortions could thus be attributed to B0-inhomogeneities. It was also determined that increasing the readout bandwidth to the maximum value reduced the maximum distortions in the frequency encoding direction to the same level as the maximum distortions in the other two phase-encoding directions of the 3D acquisitions. The voxel size had a very small effect on the spatial accuracy, enabling large voxelsize to be used when imaging the phantom, to decrease the scan time.

    The method was deemed capable of serving as a basis for QA of the spatial accuracy of large FOV MRI, which is needed in future MRI-only RTP approaches. 

  • 16.
    Jernberg, Cassandra
    KTH, School of Technology and Health (STH).
    A Computational Model for Fracture Healing Integrated with Mechanical Stimulation and Growth Factors2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Non-union bone fractures are a standing problem for clinical treatments. It has been found that the exogenous growth factor recombinant human bone morphogenetic protein-2 (rhBMP-2) induces bone healing in potential non-union fractures. However, the currently used clinical dose of rhBMP-2 is high and causes side-effects. Mechanical loading is known to enhance the induced effects of rhBMP-2 in bone healing, which may lead to a reduced required dose. Yet, the exact underlying mechanism is unknown.

    To further investigate the combined role of mechanical loading and rhBMP-2 in the early phase of fracture healing a 2D computational model was developed. The model uses a lattice-based approach where biological rule-based events are combined with finite element analysis to simulate both untreated bone healing progression and when subjected to mechanical loading and rhBMP-2. Two healing cases were investigated:  normal fracture healing in a small bone defect (1 mm gap) and non-union fracture healing in a large bone defect (5 mm gap). By varying the magnitude and timing of applied load as well as the rhBMP-2 dose, a combination that would reduce the currently used rhBMP-2 dose and still enable healing in a large bone defect was searched.

    The model could simulate fracture healing in a large bone defect when subjected to rhBMP-2, independently of the applied load. Also the expected non-union result in a large bone defect without applied rhBMP-2 was obtained. The model could not capture normal fracture healing in a small bone defect as well as bone remodelling.

    It was found that a 50 % reduced rhBMP-2 dose could not induce healing in a large bone defect when applied separately but when applied together with load. Additionally, this combination of stimulation gave similar results compared to other combinations using higher rhBMP-2 doses.

    To conclude, even though the model was able to replicate some of the healing events seen experimentally, it is in need of modifications to correct current deficiencies. Still, after some further development and validation, the model has the potential to be used in future studies of fracture healing when influenced by mechanical loading and rhBMP-2. The found possibility for a reduced dosage of rhBMP-2 when applied together with load has to be further investigated before any conclusions can be drawn.

  • 17.
    Kuutmann, Hanna
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Rosén, Emelie
    KTH, School of Technology and Health (STH), Medical Engineering.
    Smartphone Capnography: Evaluation of the concept and the associated CO2 indicating sensor2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Smartphone capnography is a new concept for respiratory monitoring using a colorimetric sensor in combination with a smartphone and an Android application. Compared to using an infrared spectrophotometric carbon dioxide analyzer (IR-analyzer), the gold standard for respiratory carbon dioxide monitoring, smartphone capnography offers a cheaper and less bulky solution. This master thesis evaluates the performance of smartphone capnography and the colorimetric sensor engineered for this concept. Three different techniques (side stream, shunt stream and main stream) were tested. Additionally, an iPhone application was developed as a proof of concept when using an iPhone for smartphone capnography.

     

    An experimental set-up simulating human breathing was assembled and measurements, at different breathing rates (6-30 breaths/min) and carbon dioxide levels (2-7vol%), were performed with an IR-analyzer as reference. Results showed that capnograms from smartphone capnography was comparable to those from the IR-analyzer and that the approximate accuracy was ±0.25vol% for up to 6 days of use. Results strongly motivate further elaboration of the concept and the three different techniques for measuring.

  • 18.
    Lindskog, Klara
    KTH, School of Technology and Health (STH).
    Development and evaluation of a HRV Biofeedback System2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This is a master thesis project written at the School of Technology and Health within KTH, Flemingsberg. It consisted of making improvements in an existing application for tablets used for training HRV biofeedback that was developed as part of an earlier master thesis within the same school. The software involves the user in paced breathing according to an established method.

    The method with HRV biofeedback visualises and trains HRV while the user performs paced breathing. This means that the user maximises the variations of time between heart beats which may have potential to reduce stress and sustain health.

    To improve the software developed earlier at KTH a new graphical user interface was implemented in form of a simple game. In addition further aspects of the program were improved.

    Furthermore, this thesis tried to find evidence for the optimal frequency and duration of HRV biofeedback training for healthy individuals. For this purpose a literature review was performed, showing a lack of evidence for the effectiveness of HRV biofeedback training in healthy individuals. Therefore a study protocol was developed that can be used in future studies aimed at finding the optimal dosage of HRV biofeedback.

  • 19.
    Lundberg, Simon
    KTH, School of Technology and Health (STH).
    Evaluation of a Motion Simulation Platform for Vestibulo-Ocular Research2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The vestibuloocular reflex can be manually elicited by tilting or rotating the head. Manual techniques serve their purpose well and is the golden standard in the clinical work, but they lack control of velocity and movement pattern. However, motion simulation platforms enable automatic control of both velocity and movement pattern.

    One motion simulation platform, named BIRGIT, has been built at the Department of Clinical Neurosciences at Karolinska Institutet but has not yet been in service and require a performance evaluation.

    The objectives with this thesis is to evaluate the accuracy and precision of BIRGIT and evaluate how bodyweight and movement direction impact the performance. The thesis also evaluate whether it is possible to stabilize the head of the patient during the acceleration phase.

    Repeated measurements of acceleration with different loads, desired ac- celeration, direction and motion type (rotational and translational), are per- formed. Dummies are used to simulate bodyweight in the performance study and real persons are used in the head stabilization study. Analysis of variance (ANOVA) is the main statistical tool.

    The results suggest that the platform does not perform equally at dif- ferent load or directions and that there is a bias between desired and true acceleration. The main problems are an inclination of the rails, upon which the chair is mounted, that causes differences between directions and an un- desirable performance characteristic for rotational motions.

    The stabilization study suggest that the head can be stabilized. 

  • 20.
    Lundberg, Simon
    KTH, School of Technology and Health (STH).
    Evaluation of a Motion Simulation Platform for Vestibulo-Ocular Research2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The vestibuloocular reflex can be manually elicited by tilting or rotating the head. Manual techniques serve their purpose well and is the golden standard in the clinical work, but they lack control of velocity and movement pattern. However, motion simulation platforms enable automatic control of both velocity and movement pattern.

    One motion simulation platform, named BIRGIT, has been built at the Department of Clinical Neurosciences at Karolinska Institutet but has not yet been in service and require a performance evaluation.

    The objectives with this thesis is to evaluate the accuracy and precision of BIRGIT and evaluate how bodyweight and movement direction impact the performance. The thesis also evaluate whether it is possible to stabilize the head of the patient during the acceleration phase.

    Repeated measurements of acceleration with different loads, desired ac- celeration, direction and motion type (rotational and translational), are per- formed. Dummies are used to simulate bodyweight in the performance study and real persons are used in the head stabilization study. Analysis of variance (ANOVA) is the main statistical tool.

    The results suggest that the platform does not perform equally at dif- ferent load or directions and that there is a bias between desired and true acceleration. The main problems are an inclination of the rails, upon which the chair is mounted, that causes differences between directions and an un- desirable performance characteristic for rotational motions.

    The stabilization study suggest that the head can be stabilized. 

  • 21.
    Malgerud, Lovisa
    KTH, School of Technology and Health (STH).
    Ett nytt arbetssystem för nutritionsmonitorering av geriatrikpatienter2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Background: The Swedish population is aging [1] and malnutrition is a common problem among elderly people [2]. A method called food registration is used to monitor the patients’ nutritional intake, with the purpose of reducing the risk of patients deteriorating in nutritional status during hospitalisation. However, the current method is not satisfactory and many food registration lists are incomplete. [3-6] Thus, patients do not receive a qualitative nutritional care since the assessment of the patients’ nutritional status is based on incomplete documentation.

    Purpose: The purpose of this master thesis is to increase the quality in the nutrition monitoring process in the geriatric units B72 and B74 at Karolinska University Hospital in Huddinge, Sweden. This should be done by increasing the prospects of providing caregivers with correct information about the patients’ nutritional intake and make the food registration more complete by introducing a new working system based on Lean Healthcare principles. The new working system should consist of a prototype of a food registration application and a new working approach with clear and standardised responsibilities for all occupational groups and shifts.

    Problem: Is it possible to create a visual and standardised working system that will increase the effectiveness and safety of the nutritional monitoring process?

    Methods: The current nutrition monitoring process was investigated by observations, interviews and timings. In addition, 100 registration lists were scrutinized and errors and missing information were noted and prototype of a food registration application was created using usability inspection methods. The prototype was tested in a usability test and evaluated in a survey that contained a standardised usability index called The System Usability Scale (SUS).

    Results: The review of old registration lists revealed that 59 per cent of the food registration lists missed information on how much the patient had been served and/or had consumed at one or more occasions. On average, each list contained 9.4 errors or points of missinged information. The SUS test generated a usability score of 86.75 out of 100, which is equivalent to an A in the A-F grading system. [7] During the usability test an average of 8.2 errors per test were made, though as 4.4 of these were corrected the net average was 3.8 errors per test. The three most common errors, which accounted for 69.5 per cent of all 82 errors, were to forget to specify quantity (36.6 per cent), to press ‘done’ before everything had been registered (18.3 per cent) and to not find the correct item (14.6 per cent).

    Conclusion: Hopefully, in the future, more food registrations will be correctly performed due to the built in mistake proofing systems of the food registration application and the introduction of the new working approach. The hope is that the new working system will provide caregivers with accurate information on the patients’ nutritional intake so that the patients’ nutritional care can be based on complete documentation. In this way, the quality and safety of the nutrition monitoring process will be increased.

  • 22.
    Mignérus, Elin
    KTH, School of Technology and Health (STH).
    Analysis of the neuronavigation market for development of a new technology: need validation and market aspects2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Neuronavigation is the technology used during brain surgery to verify the location in which the surgeon is working in terms of depth and width. Despite being considered to be helpful, the technology lacks when it comes to the consideration of brain shift, the dynamic changes of the brain during surgery. The purpose of this report was to verify the suspected need of an additional tool and investigate the market size and dynamics.

    The thesis work mainly followed the method of Biodesign – The process of innovating medical technologies, which covers all steps in the innovation process. To fit the specific purpose, the method was partly amended.The results of the report are divided into two categories – need and market. A need statement was developed and the market was mapped in terms of size and other players in the market space.

    The conclusions drawn are that there is a need for technology development in order to safely account for brain shift during tumour resection surgery, but that it is likely to be hard to enter the market due to other researchers who have made more progress in the area.

  • 23.
    Nazari, Sharareh
    KTH, School of Technology and Health (STH), Medical Engineering.
    Investigation of Automatic/Semi-Automatic Registeration of Fiducial Markers in Medical Imaging2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Image-guided neurosurgery interventions are becoming sur- gical procedure routines. We suggest a novel method for automatic marker localization in X-ray images for Leksell SurgiPlan® which is an image-based neurosergical treat- ment planning software provided by Elekta Instrument AB. We implemented an algorithm for fiducial marker localiza- tion based on feature detection, classification and prior geo- metrical knowledge of the markers. Automatic localization ca help to decrease the human error associated with manual registration of these fiducial markers which is the current applied method for X-ray images in Leksell SurgiPlan®. 

  • 24.
    Pavlopoulos, Alexandros Ikaros
    KTH, School of Technology and Health (STH).
    Characterization of the synaptic connectivity patterns of genetically defined neuron types in circuits that regulate dopamine and serotonin2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Lateral Habenula (LHb) have been implicated in both reward-seeking behavior and in depressive disorders due to its modulatory effects on dopamine rich areas. Excitatory projections from LHb target GABAergic interneurons of both ventral tegmental area (VTA) and rostromedial tegmental nucleus (RMTg) and consequently provide strong inhibition on VTA‟s dopaminergic neurons. These reward related signals are provided to LHb from distinct neuronal populations in internal Globus Pallidus (GPi). Here by using a dual viral combination of an adeno-associated helper virus (AAV) and a genetically modified rabies virus that displays specific transsynaptic retrograde spread we are providing anatomical evidence for a strong innervations of the LHb by VGLUT2+ glutaminergic and SOM+ GABAergic GPi neurons. Our results provide the first direct evidence for both an excitatory and an inhibitory projection m, from GPi to the LHb. Given the importance of the LHb as a modulatory nucleus of the dopaminergic system, the definition of its connectivity and function will give valuable insights in the understanding of both reward-seeking behavior and depressive disorders.

  • 25.
    Petit, Clemence
    KTH, School of Technology and Health (STH).
    Brain MRI segmentation for the longitudinal follow-up of regional atrophy in Alzheimer’s Disease2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Brain atrophy measurement is increasingly important in studies of neurodegenerative diseases such as Alzheimer’s disease. From this perspective, a regional segmentation framework for magnetic resonance images has recently been developed by the team that I joined for my master thesis. It combines an atlas fusion and a tissue classification. A graph-cuts optimization step is then applied to obtain the final segmentation from the combination probability maps. To begin with neighboring constraints were integrated into the optimization step so as to prevent some labels to be adjacent in accordance with anatomical criteria. They were successfully tested on a restricted list of patient images which previously presented segmentation errors. Secondly, a multigrid tissue classification was implemented in order to compensate for the effects of intensity inhomogeneities. However, the visual observations on a few cases showed little improvement compared to the increased computation time. Consequently another possibility was investigated to modify the classification. An atlas-based classification was implemented and tested both on a small-scale and a large-scale. The efficiency of the proposed method was visually assessed on a few patients, especially regarding the separation between grey and white matter. The process was then applied on a database containing several hundreds patients and the results demonstrated an improved group separation based on grey matter volume, whose reduction is particularly significant with patients suffering from Alzheimer’s Disease. To conclude, several links of the segmentation framework have been upgraded, which promises good results for future regional atrophy studies.

  • 26.
    Raghavendra, Jammalamadaka
    KTH, School of Technology and Health (STH).
    Optomyography: Detection of muscle surface displacement using reflective photo resistor2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A human body can carry out many physiological complex processes which can be mechanical, electrical or bio-chemical. Each mechanical activity generates a signal that describes the characteristics of the particular action in the form of pressure or temperature. Any irregularity in the process changes the usual functioning thus affecting the performance of the system. Several techniques were introduced to evaluate these muscular signals in order to get a deeper understanding of the medical abnormalities. Displacement sensors, laser optics, electrodes, accelerometers and microphones are some of the widely used devices in measuring the electrical and mechanical activities produced in the muscles.

    The aim of this thesis project was to find and implement a simple non-contact optical method to measure and monitor the displacements caused on the surface of the skin due to muscular movements. In this study, a device was developed using photo electric sensors that can record surface changes caused on the skin due to the movements forearm muscles.

  • 27.
    Raghavendra, Jammalamadaka
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Optomyography - Detection ofmuscle surface displacement using reflective photo resistor.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A human body can carry out many physiological complex processes which can be mechanical, electrical or bio-chemical. Each mechanical activity generates a signal that describes the characteristics of the particular action in the form of pressure or temperature. Any irregularity in the process changes the usual functioning thus affecting the performance of the system. Several techniques were introduced to evaluate these muscular signals in order to get a deeper understanding of the medical abnormalities. Displacement sensors, laser optics, electrodes, accelerometers and microphones are some of the widely used devices in measuring the electrical and mechanical activities produced in the muscles.

    The aim of this thesis project was to find and implement a simple non-contact optical method to measure and monitor the displacements caused on the surface of the skin due to muscular movements. In this study, a device was developed using photo electric sensors that can record surface changes caused on the skin due to the movements forearm muscles.

  • 28.
    Reuterdahl, Hannah
    KTH, School of Technology and Health (STH).
    Mobile Marker-based Augmented Reality as an Intuitive Instruction Manual2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Instruction manuals are supposed to be used to ensure safe and proper use of medical devices. The instruction manuals could be paper or digital docu- ments, animations or videos. Conveying information and instructions through these media might not be the most efficient approach, especially in healthcare where physicians and nurses experience high cognitive load and prefer hands-on experience with the devices [1].

    This thesis investigates how a possibly more efficient and intuitive instruction manual could be developed using mobile marker-based Augmented Reality; a technology that combines a virtual and physical world.

    By analyzing and comparing different marker-based Augmented Reality sys- tems and Software Development Kits (SDKs), the most suitable system, in terms of availability and functionality, was chosen for the implementation. Two mobile AR instruction manual prototypes were developed, as a proof-of-concept, using Unity3D with Qualcomm’s Vuforia extension.

    The resulting prototypes demonstrate the opportunity to integrate informa- tion and instructions in our physical world and the difficulties associated with the interaction and user experience with the relatively novel Augmented Reality interface. 

  • 29.
    Snäll, Jonatan
    KTH, School of Technology and Health (STH).
    Software development of Biosignal Pi: An affordable open source platform for monitoring ECG and respiration2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to handle the increasing costs of healthcare more of the care and monitoring will take place in the patient’s home. It is therefore desirable to develop smaller and portable systems that can record important biosignals such as the electrical activity of the heart in the form of an ECG.

    This project is a continuation on a previous project that developed a shield that can be connected to the GPIO pins of a Raspberry Pi, a credit-card sized computer. The shield contains an ADAS1000, a low power and compact device that can record the electrical activity of the heart along with respiration.

    The aim of this project was to develop an application that can run on the Raspberry Pi in order to display the captured data from the shield on a screen along with storing the data for further processing. The project was successful in the way that the requirements for the software have been fulfilled.

  • 30.
    Suvanen, Johan
    KTH, School of Technology and Health (STH).
    Technical Conditions and Organizational Aspects for Remote Treatment Planning: a Developing Country’s Perspective2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Radiotherapy (RT) is the most common treatment for cancer. The state-of- the-art modality for RT is the linear accelerator. However, the availability for linear accelerators in the developing world is limited due to costs, infrastructure and need for educated personnel. The development in telecommunica- tions can help to increase the availability by connecting radiation RT-centers and have a central treatment planning unit. Scandinavian Care is a com- pany that builds RT-centers in developing countries and has a project in India where three centers should to be connected.

    The thesis objectives were to evaluate technical conditions and discuss or- ganizational aspects for remote treatment planning applied on Scandinavian Care’s project in India. The technical conditions were evaluated with two models derived from Swedish case studies. The models were analyzed using a SWOT-model. The organizational aspects were divided into the organiza- tion of medical physicists and three importtant communication channels.

    The thesis concludes that the technical conditions are possible for the project in India. The best model depends on the frequency of disturbances in the WAN-connection and patient throughput sensitivity. The organization of medical physicists suggests a rotation schedule to promote education, infor- mal communication and variation of tasks. Telemedical conferences and use of software possibilities could ease the feedback. 

  • 31.
    Trowald, Adam
    KTH, School of Technology and Health (STH), Medical Engineering.
    A comparison between synthetic and conventional MRI2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis describes the bene ts and disadvantages of using synthetic Magnetic

    Resonance Imaging (MRI) instead of conventional MRI. The thesis is

    based on a clinical study performed at Orebro University Hospital were 11

    patients diagnosed with Multiple Sclerosis (MS) went through a brain examination

    with both methods. The examination time was measured and compared

    between the two methods, and the quality of the images was analysed by two

    radiologists.

    The study shows that the examination time can be reduced using the synthetic

    method instead of the conventional. The image quality is however not as good

    with the synthetic method which opens a discussion whether the time reduction

    is worth the loss of image quality. However, the conclusions are that the

    method can be useful for patients diagnosed with MS who are examined yearly

    and especially useful as a complement to the conventional sequence to gain

    as much information as possible that can be compared between the patients

    yearly exams. To completely replace other conventional examination types,

    the method has to be further evaluated and equipped with functions that are

    present in the conventional sequences, such as correction for motion artefacts.

  • 32.
    Vinasco Korsfeldt, Ludvig
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Tais, Mazin
    KTH, School of Technology and Health (STH), Medical Engineering.
    The Effects of a Carbon Fiber Table Top on Radiation Dose and Image Quality During Fluoroscopy2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fluoroscopic procedures are commonly used in today’s healthcare and involve ionizing radiation exposure to personnel and patients. During these procedures the patient is placed on a surgical table. The board on which the patient is lying on is referred to as the table top, and how different table top materials affect the image quality and radiation exposure has been investigated in this report. Radiation exposure measurements at different sites have been recorded with both a polymethyl methacrylate (PMMA) and an anthropomorphic phantom representing a patient. Image quality assessment was made in terms of contrast, signal-to-noise ratio and modular transfer function. The result showed that a higher table top attenuation or a higher tube voltage may lead to a lower dose but also a reduction in image quality. The preferred tube voltage and current, and resulting image quality is task dependent, i.e. dependent on the type of clinical procedure, which makes it hard to generalize in the selection of a certain table. Two methods have been proposed when selecting a table, one which can be considered as quantification of the trade-off between image quality and radiation dose, the other one is a fast method for comparing a large amount of tables.

  • 33.
    Voinea, Alexandra
    KTH, School of Technology and Health (STH).
    Effect of GLP-1R Knockout on stroke outcome2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Stroke is the leading cause of disability in adults in westernized societies and it has an important impact on health and economy. Comorbid health conditions such as hypertension, inactive lifestyle, smoking, obesity and diabetes considerably increase the risk of stroke. Moreover, studies have shown an increased probability of stroke occurrence and recurrence in the type 2 diabetes (T2D). Stroke leads to neurological deficits like motor impairments, disabilities and poor quality of life. The need of finding a novel treatment that can assure neuroprotective effects is crucial considering that the incidence of T2D is increasing around the world. Thrombolytic treatment given within 3-4 h from the stroke can assure some protection. Unfortunately, too few patients can benefit of this treatment due to a delayed arrival at the hospital, incorrect diagnoses or other causes. Furthermore, drugs that have shown some neuroprotective effectiveness in the pre-clinical experiments, failed in the clinical trials and today, there is no treatment for stroke based on neuroprotection. Glucagon-like peptide 1 (GLP-1) is a peptide found in L-cells of the small intestine and is secreted after the meal. The activation of its receptor (GLP-1R) increases the glucose-dependent insulin secretion and decreases the glucagon secretion. Exendin-4 (Ex-4) is a GLP-1R agonist that showed efficacy against stroke in diabetes in animal models. Additionally, it has been demonstrated that Ex-4 is acting through the activation of GLP-1R. The aim of the present study was to determine if the receptor itself plays a role in stroke outcome (without Ex-4) and see if the stroke-induced inflammation is affected by the lack of GLP-1R. We compared knockout vs. wild type mice by evaluating the stroke volume and by performing stereological counting of neurons in the striatum and cortex. The results showed no significant differences between the two groups, indicating that the lack of GLP-1R plays no role in stroke outcome.

  • 34.
    Wemmert, Ellinor
    KTH, School of Technology and Health (STH).
    Comparison of two Fluoroscopic Systems used for EVAR Procedures: an Approach to Analyze X-ray Image Quality Limited to Tube Output2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Image quality in medical x-ray imaging is dependent on the characteristics of the x-ray photons produced  by  the  x-ray  tube,  the  detection  of  the  x-ray  photons  in  the  detector  and  the  image processing. X-ray image guidance during endovascular interventions is usually performed with C-arm fluoroscopy. It is of major importance that the image quality is sufficient for the procedure. The understanding of what affects the image quality could be made easier if the performance of the different parts of the system were to be judged separately, rather than considering the system as a whole.  

    The term Image QualityTube Output that is used throughout this thesis describes the image quality that only depends on the characteristics of the x-ray beam, such as spectral distribution and fluence, without the consideration of detector characteristics or image processing. The aim of this thesis was to  propose  a  method  to  evaluate  the  Image  QualityTube  Output  and  then  compare  two  different fluoroscopy systems used for endovascular interventions with respect to Image QualityTube  Output, patient dose and personnel exposure, all as a function of patient thickness.  

    To limit to the x-ray tube output a third x-ray system was used. In that way detector and image processing would be the same and the differences in image quality would only be due to the tube output. The imaging parameters set by the Automatic Dose Rate Control, ADRC, for various patient thicknesses, was found by using Polymethyl-methacrylate, PMMA, as patient. A test object was introduced and exposed together with the PMMA of varying thickness, using the parameters set by the ADRC. The images were evaluated with respect to low contrast sensitivity and contrast to noise ratio, CNR. The effective dose rate to the patient was calculated using Monte Carlo simulation. Finally, the personnel exposure was measured using active dosimeters.

    The  results  showed  differences  in  the  systems  performance  and  Image  QualityTube  Output.  Also interesting differences in the effective dose rate to the patient was found. Altogether the results indicate that the proposed method is a feasible way to compare the Image QualityTube Output of two fluoroscopic systems. 

  • 35.
    Wikström, Stephanie
    et al.
    KTH, School of Technology and Health (STH).
    Huisman, Simon
    KTH, School of Technology and Health (STH).
    The infant incubator from a hygienic and HTO perspective: Using ATP luminescence to identify problem areas and suggesting solutions2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Healthcare associated infections (HCAI) are a major problem in healthcare today. Preterm infants have problems keeping their body temperature within normal boundaries due to heat-loss. They therefore need special care that is administered with the help of incubators, which help minimise the heat loss via convection. Within neonatology the incubator has been identified as one of the contributing factors to HCAI due to the warm and humid environment, making it easy to spread nosocomial flora.

    To assess if the incubator is a factor in the spreading of HCAI this project has focused on ATP+AMP (total ATP) luminescence measurements to find areas in the incubator that are likely to contribute to the spread of HCAI and suggesting solutions to some of these. Adenosine triphosphate (ATP) is found in both organic debris and bacteria and is therefore a good indicator of a problem area due to organic debris acting as nutrients. Only the incubator box of the Giraffe® OmniBed® incubator was studied.

    The cleaning process was observed on multiple occasions and together with interviews resulted in a number of 29 hypothesised problem areas, on or within the incubator box, that were measured before and after cleaning. The results show that incubators collect a substantial amount of total ATP during its use. Measurements also show that parts that are cleaned by a disinfector are cleaner than those parts that are cleaned manually. Areas on the main compartment became more contaminated after cleaning which further indicated that the design of the incubator needs improving. It was also concluded that there often was residue from soap left on the surface of the main compartment resulting in inhibition of the total ATP luminescence reaction. This resulted in unrealistic low values due to the inclusion of foam and soap in the sample and as a result 45 out of 570 measurements were excluded. Caution is advised when using the Kikkoman total ATP luminescence method, especially on the main body (chassis) of the incubator.

    A steam vapour cleaner and flask cleanser brush could be used to better reach and clean areas such as cavities and around the bed heating element. The use of the steam vapour cleaner could also diminish or eliminate the use of surface disinfectant that causes red irritated eyes and dizziness in the cleaning staff. The functionality of the incubator was found to be excellent but major improvements can be made in the incubator design to make the cleaning of the incubator easier.

1 - 35 of 35
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