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  • 1.
    Abedan Kondori, Farid
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Yousefi, Shahrouz
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Liu, Li
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Active human gesture capture for diagnosing and treating movement disorders2013Conference paper (Other academic)
    Abstract [en]

    Movement disorders prevent many people fromenjoying their daily lives. As with other diseases, diagnosisand analysis are key issues in treating such disorders.Computer vision-based motion capture systems are helpfultools for accomplishing this task. However Classical motiontracking systems suffer from several limitations. First theyare not cost effective. Second these systems cannot detectminute motions accurately. Finally they are spatially limitedto the lab environment where the system is installed. In thisproject, we propose an innovative solution to solve the abovementionedissues. Mounting the camera on human body, webuild a convenient, low cost motion capture system that canbe used by the patient in daily-life activities. We refer tothis system as active motion capture, which is not confinedto the lab environment. Real-time experiments in our labrevealed the robustness and accuracy of the system.

  • 2.
    Albano, Amanda
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Exploratory statistical study of long-term variability in echocardiographic indices (echocardiovariability) in healthy and diseased1987Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heart rate variability, HRV, has been well researched for some decades. The oscillations of the heart rate is studied over a time period of some minutes up to 24 hours, it is measured with electrocardiography, ECG. From this one has concluded that the heart rate signal oscillates in accordance with the respiration, the resistance in the vessels etc.

    The most frequently used examination method of the heart is done with ultrasound, called echocardiography. One interesting variable at a time is measured and it is measured for a single heartbeat. With inspiration ofthe HRV studies this project focuses on some of the variables measured with ultrasound but over time andsimultaneously. The variables of interest are the myocardial motion and the blood flow in the left part ofthe heart, they are measured over two minutes. To complement these variables the well known variables HRand Resp are measured with ECG and added to the analysis.

    The methods used for analysing the variables are first of all descriptive statistics like mean and standard deviation. Secondly spectral analysis is performed to investigate in which frequencies the variables oscillates. Through coherence this is compared with the spectrum for HR where the three peaks have known origin. Finally principal component analysis, PCA, is performed as a method to compare all variables at the same time.

    The analyses are performed on seven measurements from five (5) healthy persons and five measurementsfrom four (4) patients with the disease FAP (“Skelleftesjukan”). The variables are investigated and described for the healthy persons first, then the healthy persons and patients are compared.

    The result from the study shows that most of the echo-variables oscillate in accordance with the respirationand the heart rate. For a healthy person the oscillations are within normal values and the relative deviation isaround 10%. The patients with FAP are most affected in the variables connected to the myocardium apartfrom HR, which is known since before.

    The coherence between the echo-variables and HR is low in one of VLF, very low frequency, or LF, lowfrequency, region and high in the other. In HF, high frequency, region the coherence is high for all variables.

    Finally the PCA was conducted on measurements from all healthy persons as one data set, from one ofthe healthy persons and from one of the patients with FAP. The analysis showed that for healthy personsrespiration is the process causing most variation and all of the echo-variables have a correlation to therespiration. For a patient with FAP the respiration is not as salient. A PCA over blocks of data at different time points however show that the signals are not oscillating in the same way multivariately over the wholetime series.

  • 3. Andersson, Martin
    et al.
    Mattsson, Soren
    Johansson, Lennart
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Leide-Svegborn, Sigrid
    A biokinetic and dosimetric model for ionic indium in humans2017In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 62, no 16, p. 6397-6407Article in journal (Refereed)
    Abstract [en]

    This paper reviews biokinetic data for ionic indium, and proposes a biokinetic model for systemic indium in adult humans. The development of parameter values focuses on human data and indium in the form of ionic indium(III), as indium chloride and indium arsenide. The model presented for systemic indium is defined by five different pools: plasma, bone marrow, liver, kidneys and other soft tissues. The model is based on two subsystems: one corresponding to indium bound to transferrin and one where indium is transported back to the plasma, binds to red blood cell transferrin and is then excreted through the kidneys to the urinary bladder. Absorbed doses to several organs and the effective dose are calculated for In-111- and In-113m-ions. The proposed biokinetic model is compared with previously published biokinetic indium models published by the ICRP. The absorbed doses are calculated using the ICRP/ICRU adult reference phantoms and the effective dose is estimated according to ICRP Publication 103. The effective doses for In-111 and In-113m are 0.25 mSv MBq(-1) and 0.013 mSv MBq(-1) respectively. The updated biokinetic and dosimetric models presented in this paper take into account human data and new animal data, which represent more detailed and presumably more accurate dosimetric data than that underlying previous models for indium.

  • 4.
    Brantefors, Per
    Umeå University, Faculty of Medicine, Department of Radiation Sciences. Umeå University, Faculty of Science and Technology, Department of Physics. Karolinska Institutet, Department of Clinical Neuroscience.
    Dynamic fMRI brain connectivity: A study of the brain’s large-scale network dynamics2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Approximately 20% of the body’s energy consumption is ongoingly consumed by the brain, where the main part is due to the neural activity, which is only increased slightly when doing a demanding task. This ongoingly neural activity are studied with the so called resting-state fMRI, which mean that the neural activity in the brain is measured for participants with no specific task. These studies have been useful to understand the neural function and how the neural networks are constructed and cooperate. This have also been helpful in several clinical research, for example have differences been identified between bipolar disorder and major depressive disorder. Recent research has focused on temporal properties of the ongoing activity and it is well known that neural activity occurs in bursts. In this study, resting-state fMRI data and temporal graph theory is used to develop a point based method (PBM) to quantify these bursts at a nodal level. By doing this, the bursty pattern can be further investigated and the nodes showing the most bursty pattern (i.e hubs) can be identified. The method developed shows a robustness regarding several different aspects. In the method is two different variance threshold algorithms suggested. One local variance threshold (LVT) based on the individual variance of the edge time-series and one global variance threshold (GVT) based on the variance of all edges time-series, where the GVT shows the highest robustness. However, the choice of threshold needs to be adapted for the aims of the current study. Finally, this method ends up in a new measure to quantify this bursty pattern named bursty centrality. The derived temporal graph theoretical measure was correlated with traditional static graph properties used in resting state and showed a low but significant correlation. By applying this method on resting-state fMRI data for 32 young adults was it possible to identify regions of the brain that showed the most dynamic properties, these regions differed between the two thresholding algorithms

  • 5.
    Farahmand, Dan
    et al.
    Hydrocephalus Research Unit, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Qvarlander, Sara
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Wikkelsö, Carsten
    Hydrocephalus Research Unit, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Tisell, Magnus
    Hydrocephalus Research Unit, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Intracranial pressure in hydrocephalus: impact of shunt adjustments and body positions2015In: Journal of Neurology, Neurosurgery and Psychiatry, ISSN 0022-3050, E-ISSN 1468-330X, Vol. 86, no 2, p. 222-228Article in journal (Refereed)
    Abstract [en]

    Background The association between intracranial pressure (ICP) and different shunt valve opening pressures in relation to body positions is fundamental for understanding the physiological function of the shunt.

    Objective To analyse the ICP and ICP wave amplitude (AMP) at different shunt settings and body positions in patients with hydrocephalus.

    Methods In this prospective study 15 patients with communicating hydrocephalus were implanted with a ligated adjustable ventriculoperitoneal shunt. They also received a portable intraparenchymatous ICP-monitoring device. Postoperative ICP and AMP were recorded with the patients in three different body positions (supine, sitting and walking) and with the shunt ligated and open at high, medium and low valve settings. In each patient 12 10 min segments were coded, blinded and analysed for mean ICP and mean AMP using an automated computer algorithm.

    Results Mean ICP and mean AMP were lower at all three valve settings compared with the ligated shunt state (p<0.001). Overall, when compared with the supine position, mean ICP was 11.5 +/- 1.1 (mean +/- SD) mm Hg lower when sitting and 10.5 +/- 1.1 mm Hg lower when walking (p<0.001). Mean ICP was overall 1.1 mm Hg higher (p=0.042) when walking compared with sitting. The maximal adjustability difference (highest vs lowest valve setting) was 4.4 mm Hg.

    Conclusions Changing from a supine to an upright position reduced ICP while AMP only increased at trend level. Lowering of the shunt valve opening pressure decreased ICP and AMP but the difference in mean ICP in vivo between the highest and lowest opening pressures was less than half that previously observed in vitro.

  • 6.
    Fransson, Samuel
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Validation and Robustness Analysis of Dynamic Contrast Enhanced MRI2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In Dynamic Contrast Enhanced MRI there are several steps from the initial signal to obtaining the pharmacokinetic parameters for tumor characterization. The aim of this work was to validate the steps in the flow of data focusing on T1-mapping, Contrast Agent (CA)-quantification and the pharmacokinetical (PK) model, using a digital phantom of a head. In the Digital Phantom tissues are assigned necessary values to obtain both a regular and contrast enhanced (using Parker AIF) representation and simulating an SPGR signal. The data analysis was performed in a software called MICE, as well as the Digital Phantom developed at the department of Radiation Sciences at Umeå University. The method of variable flip angles for the T1-mapping was analyzed with respect to SNR and number of flip angles, finding that the median value in each tissue is correct and stable. A "two point" inversion recovery sequence was tested with optimal combination of inversion times for white matter and CSF and obtaining correct T1-values when the inversion times were close to the tissue T1, otherwise with large deviations seen. Three different methods for CA-quantification were analyzed and a large underestimation was found assuming a linearity between signal and CA-concentration mainly for vessels at about 60%, but also for other tissue such as white matter at about 15%, improving when the assumption was removed. Still there was a noticeable underestimation of 30% and 10% and the quantification was improved further, achieving a near perfect agreement with the reference concentration, taking the T2*-effect into account. Applying Kety-model, discarding the vp-term, Ktrans was found to be stable with respect to noise in the tumor rim but ve noticeably underestimated with about 50%. The effect of different bolus arrival time, shifting the AIF required in the PK-model with respect to the CA-concentration, was tested with values up to 5 s, obtaining up to about 5% difference in Ktrans as well as the effect of a vascular transport function obtained by the means of an effective mean transit time up to 5 s and up to about 5% difference in Ktrans.

  • 7.
    Grönlund, Christer
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Claesson, Kenji
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Holtermannz, Andreas
    Imaging two-dimensional mechanical waves of skeletal muscle contraction2013In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 39, no 2, p. 360-369Article in journal (Refereed)
    Abstract [en]

    Skeletal muscle contraction is related to rapid mechanical shortening and thickening. Recently, specialized ultrasound systems have been applied to demonstrate and quantify transient tissue velocities and one-dimensional (1-D) propagation of mechanical waves during muscle contraction. Such waves could potentially provide novel information on musculoskeletal characteristics, function and disorders. In this work, we demonstrate two-dimensional (2-D) mechanical wave imaging following the skeletal muscle contraction. B-mode image acquisition during multiple consecutive electrostimulations, speckle-tracking and a time-stamp sorting protocol were used to obtain 1.4 kHz frame rate 2-D tissue velocity imaging of the biceps brachii muscle contraction. The results present novel information on tissue velocity profiles and mechanical wave propagation. In particular, counter-propagating compressional and shear waves in the longitudinal direction were observed in the contracting tissue (speed 2.8-4.4 m/s) and a compressional wave in the transverse direction of the non-contracting muscle tissue (1.2-1.9 m/s). In conclusion, analysing transient 2-D tissue velocity allows simultaneous assessment of both active and passive muscle tissue properties. (E-mail: christer.gronlund@vll.se) (C) 2013 World Federation for Ultrasound in Medicine & Biology.

  • 8.
    Hedlund, Maja
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Hur kan personer med hjärtsvikt testa värden i hemmet, för en snabbare behandling och korrigering av medicinering?2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    - To be trapped in a roller-coaster That ́s how some of the patients are describing the situa- tion of living with heart failure. To be stuck in their home not knowing if they will have to seek care today and not knowing if they will have the energy to attend that birth- day party later this week.Each year 2-3% of the Swedish population are diagnosed with heart failure, which results in 30,000 new individu- als with the disorder. Cardiovascular disease is rapidly in- creasing in the world and before 2030, people with heart failure will increased by 100%. Our improved living condi- tions and better health have allowed us to grow older and made us more dependent on other types of care, care at home.

    Today the patients are only looking for changes in weight and if they have excessive water in their body. What if we could see changes in values before they develop in to symptoms? We could then use a smaller dosage of medicine and minimize the risk of damaging other organs.During my work I have met with patients, husbands, wives and care givers to gain a better insight and understanding of the different stakeholders problems. The common factor is the insufficient methods for monitoring that are being used today, which aren’t optimal for patients, relatives or care givers.That led me to look at non-invasive testing methods (PPG), which would make it possible to see a trend of a patients health. Photoplethysmography (PPG) is a simple and low-cost optical technique that can be used to detect blood volume changes in the microvascular bed of tissue. PPG is most often employed non-invasively and operates at a red or a near infrared wavelength due to its properties to permeate tissue. By sending out different wavelengths and recorde how much is transmit- ted, scattered and absorb, the sensor can measure levels in the blood.

    When the station is done with the test it will send the result automatically to “Mina vårdkontakter” which will be accessible for both care givers and the patient. The profile will provide the patients with test results and a first contact holding advice for immediate and awaiting care. This will educate the patients and lead to them gaining a better understanding of their current health situation.

  • 9.
    Johagen, Daniel
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Svenmarker, Pontus
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Jonsson, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine. Department of Biomedical Engineering and Informatics, Umeå University, Umeå, Sweden.
    Svenmarker, Staffan
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    A microscopic view of gaseous microbubbles passing a filter screen2017In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 40, no 9, p. 498-502Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of this study was to investigate the filtration efficacy of a 38-µm 1-layer screen filter based on Doppler registrations and video recordings of gaseous microbubbles (GME) observed in a microscope.

    Methods: The relative filtration efficacy (RFE) was calculated from 20 (n = 20) sequential bursts of air introduced into the Plasmodex® primed test circuit.

    Results: The main findings indicate that the RFE decreased (p = 0.00), with increasing flow rates (100-300 mL/min) through the filter screen. This reaction was most accentuated for GME below the size of 100 µm, where counts of GME paradoxically increased after filtration, indicating GME fragmentation. For GME sized between 100-250 µm, the RFE was constantly >60%, independently of the flow rate level. The video recording documenting the GME interactions with the screen filter confirmed the experimental findings.

    Conslusions: The 38-µm 1-layer screen filter investigated in this experimental setup was unable to trap gaseous microbubbles effectively, especially for GME below 100 µm in size and in conjunction with high flow rates.

  • 10. Kanitz, Gunter
    et al.
    Cipriani, Christian
    Edin, Benoni B.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Classification of Transient Myoelectric Signals for the Control of Multi-Grasp Hand Prostheses2018In: IEEE transactions on neural systems and rehabilitation engineering, ISSN 1534-4320, E-ISSN 1558-0210, Vol. 26, no 9, p. 1756-1764Article in journal (Refereed)
    Abstract [en]

    Understanding the neurophysiological signals underlying voluntary motor control and decoding them for controlling limb prostheses is one of the major challenges in applied neuroscience and rehabilitation engineering. While pattern recognition of continuous myoelectric (EMG) signals is arguably the most investigated approach for hand prosthesis control, its underlying assumption is poorly supported, i.e., that repeated muscular contractions produce consistent patterns of steady-state EMGs. In fact, it still remains to be shown that pattern recognition-based controllers allow natural control over multiple grasps in hand prosthesis outside well-controlled laboratory settings. Here, we propose an approach that relies on decoding the intended grasp from forearm EMG recordings associated with the onset of muscle contraction as opposed to the steady-state signals. Eight unimpaired individuals and two hand amputees performed four grasping movements with a variety of arm postures while EMG recordings subsequently processed to mimic signals picked up by conventional myoelectric sensors were obtained from their forearms and residual limbs, respectively. Off-line data analyses demonstrated the feasibility of the approach also with respect to the limb position effect. The sampling frequency and length of the classified EMG window that off-line resulted in optimal performance were applied to a controller of a research prosthesis worn by one hand amputee and proved functional in real-time when operated under realistic working conditions.

  • 11. Kleyko, Denis
    et al.
    Hostettler, Roland
    Lyamin, Nikita
    Birk, Wolfgang
    Wiklund, Urban
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Osipov, Evgeny
    Vehicle Classification using Road Side Sensors and Feature-free Data Smashing Approach2016In: 2016 IEEE 19TH INTERNATIONAL CONFERENCE ON INTELLIGENT TRANSPORTATION SYSTEMS (ITSC), IEEE, 2016, p. 1988-1993Conference paper (Refereed)
    Abstract [en]

    The main contribution of this paper is a study of the applicability of data smashing - a recently proposed data mining method - for vehicle classification according to the "Nordic system for intelligent classification of vehicles" standard, using measurements of road surface vibrations and magnetic field disturbances caused by passing vehicles. The main advantage of the studied classification approach is that it, in contrast to the most of traditional machine learning algorithms, does not require the extraction of features from raw signals. The proposed classification approach was evaluated on a large dataset consisting of signals from 3074 vehicles. Hence, a good estimate of the actual classification rate was obtained. The performance was compared to the previously reported results on the same problem for logistic regression. Our results show the potential trade-off between classification accuracy and classification method's development efforts could be achieved.

  • 12.
    Kuenen, Christoffel
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design. Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Transformatie gedreven door Techniek2013In: Nederlands Tijdschrift voor Geneeskunde, ISSN 0028-2162, no 157, article id A7063Article in journal (Other (popular science, discussion, etc.))
    Abstract [nl]

    De bionische mens vertegenwoordigt onze droom van bovenmenselijke krachten.

    Delen van die droom worden op dit moment al verwezenlijkt door kunstmatige systemen die ons motorische of zintui- gelijke vermogen ondersteunen, vergroten of verrijken.

    De aansluiting van die systemen op het lichaam verschillen in invasiviteit.

    De ontwikkeling van prothesen en orthesen wordt gedreven vanuit wetenschap maar met name ook vanuit de mili- taire industrie, en heeft een overwegend technische benadering. 

  • 13.
    Lindahl, Jonatan
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Designing radiation protection for a linear accelerator: using Monte carlo-simulations2019Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The department of Radiation Sciences at Umeå University has obtained an old linear accelerator, intended for educational purposes. The goal of this thesis was to find proper reinforced radiation protection in an intended bunker (a room with thick concrete walls), to ensure that the radiation outside the bunker falls within acceptable levels. The main method was with the use of Monte Carlo-simulations.

    To properly simulate the accelerator, knowledge of the energy distribution of emitted radiation was needed. For this, a novel method for spectra determination, using several depth dose measurements including off-axis, was developed. A method that shows promising results in finding the spectra when measurements outside the primary beam are included. The found energy spectrum was then used to simulate the accelerator in the intended bunker. The resulting dose distribution was visualized together with 3D CAD-images of the bunker, to easily see in which locations outside the bunker where the dose was high.

    An important finding was that some changes are required to ensure that the public does not receive too high doses of radiation on a public outdoor-area that is located above the bunker. Otherwise, the accelerator is only allowed to be run 1.8 hours per year. A workaround to this problem could be to just plant a thorn bush, covering the dangerous area of radius 3m. After such a measure has been taken, which is assumed in the following results, the focus moves to the radiation that leaks into the accelerator’s intended control room, which is located right outside the bunker’s entrance door.

    The results show that the accelerator is only allowed to be run for a maximum of 6.1 or 3.3 hours per year (depending on the placement of the accelerator in the room), without a specific extra reinforced radiation protection consisting mainly of lead bricks. With the specific extra protection added, the accelerator is allowed to be run 44 or 54 hours per year instead, showing a distinct improvement. However, the dose rate to the control room was still quite high, 13.7 μGy/h or 11.2 μGy/h, compared to the average dose received by someone living in Sweden, which is 0.27 μGy/h. Therefore, further measures are recommended. This is however a worst case scenario, since the leakage spectrum from the accelerator itself was simulated as having the same energy spectrum as the primarybeam at 0.1 % of the intensity, which is the maximum leakage dose according to the specifications for the accelerator. This is probably an overestimation of the intensity. Also, the energy spectra of the leakage is probably of lower energy than the primary beam in at least some directions. Implementing more knowledge of the leak spectra in future work, should therefore result in more allowed run hours for the accelerator.

  • 14. Memedi, Mevludin
    et al.
    Nyholm, Dag
    Johansson, Anders
    Palhagen, Sven
    Willows, Thomas
    Widner, Hakan
    Linder, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Westin, Jerker
    Validity and Responsiveness of At-Home Touch Screen Assessments in Advanced Parkinson's Disease2015In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, no 6, p. 1829-1834Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate if a telemetry test battery can be used to measure effects of Parkinson's disease (PD) treatment intervention and disease progression in patients with fluctuations. Sixty-five patients diagnosed with advanced PD were recruited in an open longitudinal 36-month study; 35 treated with levodopa-carbidopa intestinal gel (LCIG) and 30 were candidates for switching from oral PD treatment to LCIG. They utilized a test battery, consisting of self-assessments of symptoms and fine motor tests (tapping and spiral drawings), four times per day in their homes during week-long test periods. The repeated measurements were summarized into an overall test score (OTS) to represent the global condition of the patient during a test period. Clinical assessments included ratings on unified PD rating scale (UPDRS) and 39-item PD questionnaire (PDQ-39) scales. In LCIG-naive patients, the mean OTS compared to baseline was significantly improved from the first test period on LCIG treatment until month 24. In LCIG-non naive patients, there were no significant changes in the mean OTS until month 36. The OTS correlated adequately with total UPDRS (rho = 0.59) and total PDQ-39 (0.59). Responsiveness measured as effect size was 0.696 and 0.536 for OTS and UPDRS, respectively. The trends of the test scores were similar to the trends of clinical rating scores but the dropout rate was high. Correlations betweenOTS and clinical rating scales were adequate indicating that the test battery contains important elements of the information of well-established scales. The responsiveness and reproducibility were better for OTS than for total UPDRS.

  • 15.
    Moberg, Niklas
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Hemodynamic Model of the Cardiovascular System during Valsalva Maneuver and Orthostatic Changes2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of the Master's Thesis was to extend an existing cardiovascular model to include the mechanics of the lung, thus allowing to simulate breathing maneuvers such as the Valsalva maneuver and the Forced Vital Capacity maneuver. This included a remodeling of the pulmonary capillaries and of the existing interactions of the model with the intrathoracic pressure. The existing description of the vascular compartments was found to be insufficient to describe the hemodynamic response to orthostatic changes and was extended to include a compartment representing the upper body. Stress relaxation was included into all the larger vascular compartments. The results showed an improved accuracy of the extended model when subjected to large intrathoracic pressure changes and during orthostatic stress. The internal responses of the newly modeled pulmonary capillaries were studied and verified against literature with satisfying results.

  • 16.
    Pettersson, Charlie
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Modeling and Characterization of a Propagation Channel in a Body-Centric Nano-Network2018Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Researchers have been trying to find smart health solutions that will allow people to continuously monitor their health through applications connected to the internet. One possible solution involve using nano-machines to create body-centric networks. However, the biggest challenge using nano-machines are how they would communicate with the outside world. To investigate this, I have in this thesis developed a multi-layer channel model for human skin tissues and investigated how signals at the terahertz frequency band interact with skin biomaterial. The model is built upon analytical equations describing electromagnetic propagation in a dielectric medium were the electromagnetic properties of human tissue were collected from different sources. The model were implemented in a flexible matlab program able to simulate different numbers of layers from a library with either fixed or random depths. The human skin model used to gather results were chosen to consist of 4 layers of epidermis, dermis, blood and hypodermis, and the depth of the layers were chosen to vary between typical values for the human body. This Matlab based multi-layer channel model was validated by a similar model made in CST Studio Suite, both for a single layer as well as for a 2-layer scenario. Results from the Matlab program showed that the path loss is significantly affected by frequency and material. The expected path loss could therefore vary significantly, however for a human skin model with depths of 1.23, 3.76, 0.21 and 1.38 mm respectively, the path loss was approximately between 250-350 dB for frequencies of 0.5-1.5 THz at the end distance. Finally, numerical analysis were used on 10 data sets created from the multi-layer channel model in order to develop a simple interpolation equation able to describe path loss through the human skin with varying tissue layer depths. The equation had an average mean error of 4.08 \% and a maximum mean error of 6.61\% against 90 different random data sets.

  • 17.
    Pettersson, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Brainball, visualisering av hjärnaktiviteten2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Medical Technology, Research and Development department at University Hospital of Umeå has an existing brainball-table that they want to use at fairs and demonstrations. As a complement to the physical table they want to show a graphical representation of the brainwaves that are used in the game, in order to make it easier for players and any audience to follow along. A program showing the graphical representation of the brainwaves used in the Brainball-game has been developed using the programming language Python with help of the library ”matplot”. The finished program has a simple layout with three graphs, showing the two players brainwaves and their calculated relaxation in comparision with eachother. The brainwaves are sampled and shown in the graphs in real time with a scrolling x-axis with approximately 20 frames per second. Everything is run on a Raspberry Pi 3 computer and because of it’s low performance some functions such as frequency filtration and animation is somewhat limited.

  • 18.
    Sandgren, Kristina
    Umeå University, Faculty of Science and Technology, Department of Physics. Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Centrum för medicinsk teknik och fysik (CMTF).
    Development of a Quality Assurance Strategy for Magnetic Resonance Imaging in Radiotherapy2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Radiotherapy is a common treatment option for malignant tumors. The use of magnetic resonance imaging in radiotherapy is increasing world-wide and sets additional requirements on the image quality compared to diagnostics applications. Thereby, the overall goal of the present project was to develop and implement a structured image quality assurance approach for MRI in radiotherapy. Specific aspects studied was the image quality, spatial accuracy and spin-lattice relaxation time quantification. Measurements using three different phantoms were performed at the positron emission tomography magnetic resonance (PET/MR) scanner at Norrlands Univeristy Hosptial, Umeå. The image quality was evaluated using the American College of Radiology (ACR) phantom and its accompanying tests. ACR phantom measurements were performed once or twice daily throughout the project. The results from the ACR tests were implemented in an automatic analysis program and displayed on a website, accessible from the hospital network. The image quality was found to be constant over time and within acceptance values. Furthermore, the spatial distortion was quantified using a large field of view (FOV) phantom and a spatial analysis program supplied with the phantom. A method to study the reproducibility of the distortion was developed and the distortion in the PET/MR scanner was mapped in different images planes. The image distortion was shown to be reproducible and less than 1 mm inside a volume of 20x20x20 cm3 around the magnetic isocenter, which corresponds to a FOV used in target delineations images. However, outside this volume larger distortions than 2 mm was observed. In order to evaluate the quantification of the spin-lattice relaxation time two methods were evaluated, variable flip angle (VFA) and two point inversion recovery spin echo (IRSE) using the Test object 5 (TO5) phantom. Large variations in the quantification was observed using the VFA method compared to the two point IRSE method when performing phantom measurements. Unfortunately, the two point IRSE method was not adequate when used in head exams in the clinical practice.

  • 19.
    Sjögren, Adam
    Umeå University, Faculty of Science and Technology, Department of Physics.
    The impact of metallic cranial implants on proton-beam radiotherapy treatment plans for near implant located tumours: A phantom study on the physical effects and agreement between simulated treatment plans and the resulting treatment for near implant located cranial tumours2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Within the field of radiotherapy treatments of tumour diseases, the hunt for more accurate and effective treatment methods is a continuous process. For some years ion-beam based radiotherapy, especially the proton-beam based applications, has increased in popularity and availability. The main reason behind this is the fact that ion-beam based applications make it possible to modulate the dose after the planning target volume (PTV) defined by the radiation oncologist. This means that it becomes possible to spare tissue in another way, which might result in more effective treatments, especially in the vicinity of radio sensitive organs. Ion-beam based treatments are however more sensitive to uncertainties in PTV position and beam range as ion-beams have a fixed range depending on target media and initial energy, as opposed to the conventional x-ray beams that do not really have a defined range. Instead their intensity decreases exponentially at a rate dependent of the initial energy and target media. Therefore density heterogeneities result in uncertainties in the planned treatments. As the plans normally are created using a CT-images, for which metallic implants can yield increased heterogeneities both from the implants themselves and so called metal artifacts (distortions in the images caused by different processes as the X-rays used in image acquisition goes through metals). Metallic implants affects the accuracy of a treatment, and therefore also the related risks, so it is important to have an idea of the magnitude of the impact. Therefore the aim of this study is to estimate the impact on a proton-beam based treatment plan for six cranial implants. These were one Ti-mesh implant, one temporal plate implant, one burr-hole cover implant and three craniofix implants of different sizes, which all are commonly seen at the Skandion clinic. Also the ability of the treatment planning system (TPS), used at the clinic, to simulate the effects on the plans caused by the implants is to be studied. From this result it should be estimated if the margins and practices in place at the clinic, for when it is required to aim the beam through the implant, are sufficient or if they should be changed.

    This study consisted of one test on the range shift effects and one test on the lateral dose distribution changes, with one preparational test in the form of a calibration of Gafchromic EBT3 films. The range shift test was performed on three of the implants, excluding the three craniofix implants using a water phantom and a treatment plan created to represent a standard treatment in the cranial area. The lateral dose distribution change test was performed as a solid phantom study using radiochromic film, for two treatment plans (one where the PTV was located \SI{2}{\centi\metre} below surface, for all implants, and one where it was located at the surface, only for the Ti-mesh and the temporal plate). The results of both tests were compared to simulations performed in the Eclipse treatment planing system (TPS) available at Skandion.

    The result of the range shift test showed a maximum range shift of \SI{-1.03 +- 0.01}{\milli\metre}, for the burr-hole cover implant, and as the related Eclipse simulations showed a maximal shift of \SI{-0.17 +- 0.01}{\milli\metre} there was a clear problem with the simulation. However, this might not be because of the TPS but due to errors in the CT-image reconstruction, such as, for example, geometrical errors in the representation of the implants. As the margin applied for a similar situation at the Skandion clinic (in order to correct for several uncertainty factors) is \SI{4.2}{\milli\metre} there might be a need to increase this margin depending on the situation.

    For the lateral distribution effects no definite results were found as the change varied in magnitude, even if it tended to manifest as a decreasing dose for the first plan and a increasing dose for the second. It was therefore concluded that further studies are needed before anything clear can be said.

  • 20.
    Strömberg, Emmalisa
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Analysprogram för grip- och lyftkraft2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    To be able to regulate your grip force and lift an object can be simple for healthy

    people. However, for people with disabilities of neurological diseases such as hydrocephalus

    and Parkinson’s disease it has been found that their diseases can affect

    their grip force. If the grip power is affected, it may be used in healthcare to check

    the course of disease, if it gets better after treatment.

    At the department of Biomedical Engineering - Research and developmet a measurement

    device for analysing grip force and acceleration when lifting an object has been

    developed. In order for this instrument to be more useful in clinical practice, an

    analysis program is required to produce the result after measurements made with

    the equipment. A computerized analysis program has the potential to be significantly

    faster, more efficient and more objective compared to the manual analysis

    used today.

    The purpose of this project was to create an analysis program that can replace the

    work of the manual analysis and which can generate results from measured data.

    The results should not be different between a manual analysis and the automatic

    analysis. The goal was that the analysis should be fast, efficient and objective and

    also provide the same results as a manual analysis would provide.

    The program that was designed became faster and more efficient than the manual

    analysis. Measurements on six healthy volunteers were used to compare the automatic

    and manual analyzes. No significant differences could be detected for any of

    the parameters that were analyzed, and this shows that the results of the automated

    analysis are comparable to the manual analysis and thus can replace these to analyze

    future measurements. However, the automatic analysis has only been tested

    on healthy people, so if the automatic and manual analyzes are comparable even for

    people with a neurological disease should be further investigated before using the

    automatic analysis method on patient data.

  • 21.
    Svensson, Sara
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Science and Technology, Department of Physics.
    Variations in the target definition on CT and MR based treatment plans for radiotherapy2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The introduction of Magnetic Resonance (MR) Imaging in treatment planning for radiotherapy of prostate cancer give rise to new challenges in defining the treatment volume, or the target. Imaging with MR have several advantages, especially better soft-tissue contrast, compared with the standard image modality, Computed Tomography (CT). The purpose of this project was to determine how the target definition varies with the choice of image modality and the systematic differences between them. The purpose was also to determine how the inter- and intra physician variability influences the delineation, depending on which image modality that is used.

    In the project, five physicians delineated the prostate gland on CT and MR images for nine patients. The physicians had no information of which image series that was connected, and were thus delineating independent. After the delineation, the CT and MR image series was set in the same geometrical coordinate system in the treatment planning system Oncentra. The target delineations were analysed by comparing the radial distances from the centre of mass in different directions, such as anterior, posterior, etc. The radial distances were later used to evaluate the variability of the delineations and to determine the inter and intra physician variability in different directions of the targets. ANOVA was also preformed to determine if there is a significant difference between the parameters, as the image modality and the image modalities influence on the physicians delineations.

    A model was made to investigate how the MR delineations differ from a CT defined volume that 95% of the delineations cover, called the ideal CT delineation. From this, the median deviation in different directions  was analysed and it was found that the median value of the MR delineations in different directions was between -0.10-2.27 mm larger than the ideal CT delineation. The fluctuations between the delineations was, however, large. The target volume was larger for CT defined volumes in 87% of the cases, compared with MR targets. The inter physician variability was found to be between 0.54-2.17 mm for the CT based delineations and 0.68-2.08 mm for the MR based target delineations. The intra physician variability was larger than the inter physician variability, between 0.74-2.51 mm for CT based delineations and 0.85-1.45 mm for MR based delineations. The median variability of the delineations were not uniform around the target volume but were larger for example in the superior and inferior directions and had its minimum in the posterior direction. The ANOVA tests showed a significant difference between MR and CT based target delineations, it also shows a relation between the delineating physician and the image modality, meaning that the physicians are delineating different on CT and MR images.

    Target volumes defined on MR images are in general smaller than the CT defined targets. The soft tissue contrast in MR images makes the delineating process easier, however, the analysis of the variability in this project indicates that the variations of MR based target delineations are larger than the CT based. The large variation of the delineations implies that clinical tests should be made to ensure a proper dose coverage before MR could be used as the only image modality in radiotherapy treatment planning of prostate cancer.

  • 22.
    Umefjord, Göran
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
    Hamberg, Katarina
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
    Malker, Hans
    Mid-Sweden Research and Development Centre, County Council of Va¨ sternorrland, Sundsvall, Sweden.
    Petersson, Göran
    Health Institute, Department of Health and Behavioural Science, University of Kalmar, Sweden.
    The use of an internet-based ask the doctor service involving family physicians: evaluation by a web survey2006In: Family Practice, ISSN 0263-2136, E-ISSN 1460-2229, Vol. 23, no 2, p. 159-166Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Internet consultation without a previous relationship between the doctor and the enquirer seems to be increasing in popularity. However, little is known about the advantages, disadvantages or other differences compared with regular health care when using this kind of service. OBJECTIVE: To investigate how an Internet-based Ask the Doctor service out with any pre-existing doctor-patient relationship was used and evaluated by the enquirers. METHODS: We recruited to a web-based survey users of the non-commercial Swedish Internet-based Ask the Doctor service run by family physicians. The survey was conducted between November 2001 and January 2002. Questions included both multiple choice and free text formats, and the results were analysed quantitatively and qualitatively. RESULTS: The survey was completed by 1223 participants. It was mainly women who submitted questions to the service (29% men, 71% women) and also who participated in the survey (26% men, 74% women). Most participants (77%) wrote their question at home, and 80% asked on their own behalf. Almost half of the enquiries (45%) concerned a medical matter that had not been evaluated by a medical professional before. After reading the answer, 43% of the participants indicated that they would not pursue their question further having received sufficient information in the answer provided. The service was appreciated for its convenience and flexibility, but also for reasons to do with the mode of communication such as the ability to reflect on the written answer without having to hurry and to read it more than once. CONCLUSION: In the present study, we found that an Internet-based Ask the Doctor service run by family physicians on the whole was evaluated positively by the participants both in terms of the answers and the service. Internet-based consultation may act as a complement to regular health care. In future studies, the cost-effectiveness, patient security, responsibilities of the Internet doctor and the role of Ask the Doctor services compared with regular health care should be evaluated.

  • 23.
    Wikstrand, Victoria
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Linder, Nadja
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Engström, Karl Gunnar
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Evaluation of the Doppler technique for fat emboli detection in an experimental flow model2008In: The Journal of extra-corporeal technology, ISSN 0022-1058, Vol. 40, no 3, p. 175-183Article in journal (Refereed)
    Abstract [en]

    Pericardial suction blood (PSB) is known to be contaminated with fat droplets, which may cause embolic brain damage during cardiopulmonary bypass (CPB). This study aimed to investigate the possibility to detect fat emboli by a Doppler technique. An in vitro flow model was designed, with a main pump, a filter, a reservoir, and an injector. A Hatteland Doppler probe was attached to the circulation loop to monitor particle counts and their size distribution. Suspended soya oil or heat-extracted human wound fat was analyzed in the model. The concentrations of these fat emboli were calibrated to simulate clinical conditions with either a continuous return of PSB to the systemic circulation or when PSB was collected for rapid infusion at CPB weaning. For validation purpose, air and solid emboli were also analyzed. Digital image analysis was performed to characterize the nature of the tested emboli. With soya suspension, there was an apparent dose response between Doppler counts and the nominal fat concentration. This pattern was seen for computed Doppler output (p = .037) but not for Doppler raw counts (p = .434). No correlation was seen when human fat suspensions were tested. Conversely, the image analysis showed an obvious relationship between microscopy particle count and the nominal fat concentration (p < .001). However, the scatter plot between image analysis counting and Doppler recordings showed a random distribution (p = .873). It was evident that the Doppler heavily underestimated the true number of injected fat emboli. When the image analysis data were subdivided into diameter intervals, it was discovered that the few large-size droplets accounted for a majority of total fat volume compared with the numerous small-size particles (< 10 microm). Our findings strongly suggest that the echogenecity of fat droplets is insufficient for detection by means of the tested Doppler method.

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