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  • 1.
    Arnlund, Caroline
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utveckling av sensor för mätning av hjärtaktivitet2014Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Motion analysis is a necessary tool when it comes to evaluation, monitoring and diagnosis of all the diseases that affect the human musculoskeletal system. There are only a few clinical walking laboratories in Sweden, where the patients can receive a more detailed and objective evaluation of their walking patterns. The problem with these laboratories is that they are relatively expensive and resource-demanding.

    The department of research and development at NUS has initiated a research project where AnyMo, a mobile system for measuring of moving patterns, was produced. The aim of this thesis was to further develop the existing system to simultaneously measure the electrical activity of the heart (ECG).

    The parts that were constructed during this project was an ECG sensor and a Master Unit, coupled to an existing motion sensor (part of the AnyMo system). The information that was collected from these sensors was stored locally in a memory on the system’s Master Unit.

    The finished product was tested and evaluated on a stationary bike at different pace and heart rate.

  • 2.
    Blusi, Madeleine
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation. Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Nieves, Juan Carlos
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Feasibility and Acceptability of Smart Augmented Reality Assisting Patients with Medication Pillbox Self-Management2019In: Studies in Health Technology and Informatics, ISSN 0926-9630, E-ISSN 1879-8365, p. 521-525Article in journal (Refereed)
    Abstract [en]

    Complex prescribed medicine regimens require extensive self-management. Handling multiple pills can be confusing; using a pillbox organiser is a common strategy. A smart Medication Coach Intelligent Agent (MCIA) can support patients in handling medicine. The aim of this research was to evaluate the feasibility and acceptability of the MCIA. A prototype was tested with 15 participants, age 17-76, filled a pillbox according to prescription assisted by the MCIA implemented in a Microsoft HoloLens. A quantitative method using questionnaires was applied. Results showed that using the MCIA implemented in an AR-headset, to assist people with prescribed polypharmacy regimen in filling a pillbox, was feasible and acceptable. There was a difference related to age regarding people's willingness to use an AR-headset for medication self-management. People older than 65 felt less comfortable using the technology and were also more hesitant to use the technology than those under 65.

  • 3. Clemente, Francesco
    et al.
    D'Alonzo, Marco
    Controzzi, Marco
    Edin, Benoni B.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Physiology.
    Cipriani, Christian
    Non-Invasive, Temporally Discrete Feedback of Object Contact and Release Improves Grasp Control of Closed-Loop Myoelectric Transradial Prostheses2016In: IEEE transactions on neural systems and rehabilitation engineering, ISSN 1534-4320, E-ISSN 1558-0210, Vol. 24, no 12, p. 1314-1322Article in journal (Refereed)
    Abstract [en]

    Human grasping and manipulation control critically depends on tactile feedback. Without this feedback, the ability for fine control of a prosthesis is limited in upper limb amputees. Although various approaches have been investigated in the past, at present there is no commercially available device able to restore tactile feedback in upper limb amputees. Based on the Discrete Event-driven Sensory feedback Control (DESC) policy we present a device able to deliver short-lasting vibrotactile feedback to transradial amputees using commercially available myoelectric hands. The device (DESC-glove) comprises sensorized thimbles to be placed on the prosthesis digits, a battery-powered electronic board, and vibrating units embedded in an arm-cuff being transiently activated when the prosthesis makes and breaks contact with objects. The consequences of using the DESC-glove were evaluated in a longitudinal study. Five transradial amputees were equipped with the device for onemonth at home. Through a simple test proposed here for the first time-the virtual eggs test-we demonstrate the effectiveness of the device for prosthetic control in daily life conditions. In the future the device could be easily exploited as an add-on to complement myoelectric prostheses or even embedded in prosthetic sockets to enhance their control by upper limb amputees.

  • 4.
    Edström, Linnéa
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Armbandsbaserad pulsoximetri: Ett egenkonstruerat system med reflekterande teknik och jämförelse mot traditionell mätteknik vid normal och nedsatt hudtemperatur2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this report a low-cost, portable and wearable design of a new system with reflective technologyfor pulse oximetry is presented. The work has been executed as a project, including electronics construction, software development, a design of the embedding for the prototype and continuous tests of both the hardware and software during the work in progress.

    The result of this work is a prototype system for pulse oximetry. The system can communicate through Bluetooth wireless interface with a PC, laptop or smartphone which supports Bluetooth 4.0. The measurements are shown in real time on a PC/laptop/smartphone. The software is written in mbed with the language C++ for the microprocessor. The project demands different technical skills like signal processing, programming, electronic design and microprocessors. Over all the project is a good introduction for medical technology and a basis for electronic engineers.

    The purpose and goal with the thesis is considered to be reached for the most part and further testing and development of the product is possible.

  • 5.
    Edström, Urban
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Nackvinkelmätningar vid thoraxoperation: Kan prismaglasögon underlätta arbetet för operationssjuksköterskor?2017Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 6.
    Eklund, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Resonator sensor technique for medical use: an intraocular pressure measurement system2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the work of this doctoral dissertation a new resonator sensor technique, first presented in 1989, has been further developed and evaluated with focus on technical characteristics and applications within the medical field.

    In a first part a catheter-type tactile sensor using the resonator sensor technique was evaluated in a silicone model and applied to human prostate in vitro. The main finding was that different histological compositions of prostate tissue correlated with the frequency shift, .fS, of the resonator sensor and that the common property was the hardness of the tissue. The results indicated that hardness of the prostate tissue, and maybe hardness of human tissue in general, can be expressed according to a cone penetration standard (DIN ISO 2137) and that the hardness can be measured with this tactile sensor system. The tissue hardness application for the resonator sensor technique has to be further developed and evaluated in a larger study. The study also produced results that has led to the basic understanding of the resonator sensor system. One important result was that .fS of the sensor system was related to the contact area between sensor and sample. This indicated that the resonance sensor could be used for contact area measurement.

    In a second part, containing three studies, the area-sensing capability from the first study was utilised in the development and evaluation of the applanation resonator sensor (ARS) for measurement of intraocular pressure (IOP). For the purpose of evaluating IOP-tonometers, an in vitro pig-eye model was developed, and it was shown that a saline column connected to the vitreous chamber could be used successfully to induce variations in IOP.

    A ARS sensor with a flat contact surface was applied onto the cornea with constant force and .fS was measured. A mathematical model based on the Imbert-Fick law and the assumption that .fS was linearly related to contact area was proposed and verified with a convincing result. IOP measured with the ARS correlated well (r=0.92, n=360) with the IOP elicited by a saline column.

    The ARS in a constant-force arrangement was evaluated on healthy human subjects in vivo. The results verified the sensor principle but revealed a nonnegligible source of error in off-centre positioning between the sensor and cornea. The sensor probe was redesigned and evaluated in the in vitro model. The new probe, with a spherical contact surface against the eye reduced the sensitivity to off-centre positioning. It was also shown that a .fS normalisation procedure could reduce the between-eye differences.

    The ARS method for IOP measurement was further developed using combined continuous force and area measurement during the dynamic phase when the sensor initially contacts the cornea. A force sensor was included with the resonator sensor in one probe. Evaluation was performed with the in vitro pig-eye model. The hypothesis was that the IOP could be deduced from the differential change of force and area during that phase. The study showed good accuracy and good reproducibility with a correlation of r=0.994 (n=414) between measured pressure in the vitreous chamber and IOP according to the ARS. Measurement time was short, 77 ms after initial contact. Problems with inter-eye differences and low resolution at high pressures were reduced. The ARS method is the first to combine simultaneous, continuous sampling of both parameters included in the applanation principle. Consequently, there is a potential for reducing errors in the clinical IOP tonometry.

  • 7.
    Eklund, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Koskinen, Lars-Owe D
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery.
    Williams, Michael A
    Luciano, Mark G
    Dombrowski, Stephen M
    Malm, Jan
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neuroscience.
    Hydrodynamics of the CertasTM programmable valve for the treatment of hydrocephalus2012In: Fluids and barriers of the CNS, ISSN 2045-8118, Vol. 9, no 1, p. 12-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The new CertasTM shunt for the treatment of hydrocephalus has seven standard pressure settings that according to the manufacturer range from 36 to 238 mmH2O, and an additional "Virtual Off" setting with an opening pressure >400 mmH2O. Information on actual pressure response and reliability of shunt performance is important in clinical application, especially the "Virtual Off" setting as a non-surgical replacement for shunt ligation. The objective of this study was to evaluate the in-vitro hydrodynamic performance of the CertasTM shunt.

    METHODS: Six new CertasTM shunts with proximal and distal catheters were tested with an automated, computerized test system that raised the pressure from zero to a maximum pressure and back to zero at each valve setting. Opening pressure and flow resistance were determined.

    RESULTS: For settings 1-7 the measured opening pressure range was 26 to 247 mmH2O, and the mean change in opening pressure for a one-step adjustment was between 33 and 38 mmH2O. For setting 8 ("Virtual Off") the measured mean opening pressure was 494 +/- 34 mmH2O (range 451 to 556 mmH2O). The mean outflow resistance was 7.0 mmHg/ml/min (outflow conductance 17.9 ul/s/kPa).

    CONCLUSIONS: The six shunts had similar characteristics and closely matched the manufacturer's specifications for opening pressure at settings 1-7. The opening pressure for the "Virtual Off" setting was nearly 500 mmH2O, which is 100 mmH2O higher than the manufacturer's specification of ">400" and should be functionally off for most patients with communicating hydrocephalus. Clinical studies are needed to evaluate if the CSF dynamic profile persists after implantation in patients.

  • 8.
    Fredriksson, Simon
    Umeå University, Faculty of Science and Technology, Umeå Institute of Design.
    Ventum: Freedom of movement for children receiving respiratory treatment2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report is showing the process and result from a project collaboration between Norrlands University hospital and  design student Simon Fredriksson. 

    Respiratory treatment is carried out on patients that for some reason fail to breathe sufficiently to assimilate enough oxygen to survive. The reason for why a person needs respiratory treatment can be many and the length of the treatment varies a lot. It can stretch from a couple of hours during surgery to years in treatment for example Chronic obstructive pulmonary disease (COPD) or Immature lungs. 

    The project focus have been to look at how to increase the freedom of movement for kids receiving respiratory treatment. Respiratory treatment are complex and involves advanced equipment. It´s demanding both physically and mentally both for patient and involved family and can in some cases carry on for several years.    A young child with impaired breathing should still have the freedom of movement and not have to be restricted to the length of a respirator hose and depend on others to be able to move around. Learning how to crawl walk and freely move around should be every childs right. The quote are from  the National heart, lung and blood institute in America. My aim is to create a concept that will offer that movement and prove them wrong.

    This project is carried out in collaboration with the Neonatal intensive care unit (NICU) at Norrlands University hospital in Umeå.

  • 9.
    Fuchs, Gabriel
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Berg, Niclas
    Eriksson, Anders
    Wittberg, Lisa Prahl
    Detection of Thrombosis in the Extracorporeal Membrane Oxygenation Circuit by Infrasound: Proof of Concept2017In: Artificial Organs, ISSN 0160-564X, E-ISSN 1525-1594, Vol. 41, no 6, p. 573-579Article in journal (Refereed)
    Abstract [en]

    As of today, there exist no reliable, objective methods for early detection of thrombi in the extracorporeal membrane oxygenators (ECMO) system. Within the ECMO system, thrombi are not always fixed to a certain component or location in the circuit. Thus, clot fragments of different shapes and consistencies may circulate and give rise to vibrations and sound generation. By bedside sound measurements and additional laboratory experiments (although not detailed herein), we found that the presence of particles (clots or aggregates and fragments of clots) can be detected by analyzing the strength of infra-sound (< 20 Hz) modes of the spectrum near the inlet and outlet of the centrifugal pump in the ECMO circuit. For the few patients that were considered in this study, no clear false positive or negative examples were found when comparing the spectral approach with clinical observations. A laboratory setup provided insight to the flow in and out of the pump, confirming that in the presence of particles a low-amplitude low-frequency signal is strongly amplified, enabling the identification of a clot.

  • 10.
    Kinnunen, Jussi
    et al.
    Department of Physics and Mathematics, University of Eastern Finland, Joensuu, Finland.
    Kokkonen, Harri
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Kovanen, Vuokko
    Department of Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
    Hauta-Kasari, Markku
    School of Computing, University of Eastern Finland, Joensuu, Finland.
    Vahimaa, Pasi
    Department of Physics and Mathematics, University of Eastern Finland, Joensuu, Finland.
    Lammi, Mikko
    Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Töyräs, Juha
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Jurvelin, Jukka
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Nondestructive fluorescence-based quantification of threose-induced collagen cross-linking in bovine articular cartilage2012In: Journal of Biomedical Optics, ISSN 1083-3668, E-ISSN 1560-2281, Vol. 17, no 9, p. 97003-, article id 22975679Article in journal (Refereed)
    Abstract [en]

    Extensive collagen cross-linking affects the mechanical competence of articular cartilage: it can make the cartilage stiffer and more brittle. The concentrations of the best known cross-links, pyridinoline and pentosidine, can be accurately determined by destructive high-performance liquid chromatography (HPLC). We explore a nondestructive evaluation of cross-linking by using the intrinsic fluorescence of the intact cartilage. Articular cartilage samples from bovine knee joints were incubated in threose solution for 40 and 100 h to increase the collagen cross-linking. Control samples without threose were also prepared. Excitation-emission matrices at wavelengths of 220 to 950 nm were acquired from the samples, and the pentosidine and pyridinoline cross-links and the collagen concentrations were determined using HPLC. After the threose treatment, pentosidine and lysyl pyridinole (LP) concentrations increased. The intrinsic fluorescence, excited below 350 nm, decreased and was related to pentosidine [r=−0.90, 240/325nm (excitation/emission)] or LP (r=−0.85, 235/285nm) concentrations. Due to overlapping, the changes in emission could not be linked specifically to the recorded cross-links. However, the fluorescence signal enabled a nondestructive optical estimate of changes in the pentosidine and LP cross-linking of intact articular cartilage.

  • 11.
    Lindberg, Simon
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Utveckling av system för mätning av fysisk aktivitet: En jämförande studie mot kommersiella aktigrafisystem2016Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    This report will show how the development of a prototype for the storage of physical movements has been developed. Which components that have been chosen and why. The work is performed on behalf of the Biomedical Engineering - Research and Development (MT-FoU) at Umeå University, Sweden. MT-FoU has also assisted with the software and the possibility of 3D printing of containers for the prototype. The prototype can store information about movement using the accelerometer, gyroscope and magnetometer. The information is stored on an SD card and then transmitted wirelessly via a network router to the clientside using WiFi. Physical activity has been shown to be a more important part of human health than previously thought. It´s always important to move much but it´s also important that we move in a right way as well. With the help of this product information on moves during a training session is recorded and analyzed. In this report, the reliability of the product is measured with the help of two other commercial products which data is compared against.

  • 12.
    Lötjönen, Pauno
    et al.
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Julkunen, Petro
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Töyräs, Juha
    Department of Physics, University of Kuopio, Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
    Lammi, Mikko
    Institute of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland: Department of Biosciences, Applied Biotechnology and Biocenter Kuopio, University of Kuopio, Kuopio, Finland.
    Jurvelin, Jukka
    Department of Physics, University of Kuopio, Kuopio, Finland; Department of Physics, University of Kuopio, Kuopio, Finland.
    Nieminen, Heikki
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Strain-dependent modulation of ultrasound speed in articular cartilage under dynamic compression.2009In: Ultrasound in Medicine and Biology, ISSN 1879-291X, Vol. 35, no 7, p. 1177-1184, article id 19427104Article in journal (Refereed)
    Abstract [en]

    Mechanical properties of articular cartilage may be determined by means of mechano-acoustic indentation, a clinically feasible technique for cartilage diagnostics. Unfortunately, ultrasound speed varies in articular cartilage during mechanical compression. This can cause significant errors to the measured mechanical parameters. In this study, the strain-dependent variation in ultrasound speed was investigated during dynamic compression. In addition, we estimated errors that were induced by the variation in ultrasound speed on the mechano-acoustically measured elastic properties of the tissue. Further, we validated a computational method to correct these errors. Bovine patellar cartilage samples (n = 7) were tested under unconfined compression. Strain-dependence of ultrasound speed was determined under different compressive strains using an identical strain-rate. In addition, the modulation of ultrasound speed was simulated using the transient compositional and structural changes derived from fibril-reinforced poroviscoelastic (FRPVE) model. Experimentally, instantaneous compressive strain modulated the ultrasound speed (p < 0.05) significantly. The decrease of ultrasound speed was found to change nonlinearly as a function of strain. Immediately after the ramp loading ultrasound speed was found to be changed -0.94%, -1.49%, -1.84%, -1.87%, -1.89% and -2.15% at the strains of 2.4%, 4.9%, 7.3%, 9.7%, 12.1% and 14.4%, respectively. The numerical simulation revealed that the compression-related decrease in ultrasound speed induces significant errors in the mechano-acoustically determined strain (39.7%) and dynamic modulus (72.1%) at small strains, e.g., at 2.4%. However, at higher strains, e.g., at 14.4%, the errors were smaller, i.e., 12.6% for strain and 14.5% for modulus. After the proposed computational correction, errors related to ultrasound speed were decreased. By using the correction, with e.g., 2.4% strain, errors in strain and modulus were decreased from 39.7% to 7.2% and from 72.1% to 35.3%, respectively. The FRPVE model, addressing the changes in fibril orientation and void ratio during compression, showed discrepancy of less than 1% between the predicted and measured ultrasound speed during the ramp compression.

  • 13.
    Myllymaa, Sami
    et al.
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Myllymaa, Katja
    Department of Physics, University of Kuopio, Kuopio, Finland; Microsensor Laboratory, School of Engineering and Technology, Savonia University of Applied Sciences, Kuopio, Finland.
    Korhonen, Hannu
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Department of Applied Biotechnology, University of Kuopio, Kuopio, Finland; Biocenter Kuopio, Kuopio, Finland.
    Tiitu, Virpi
    Department of Anatomy, University of Kuopio, Finland.
    Lappalainen, Reijo
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Surface characterization and in vitro biocompatibility assessment of photosensitive polyimide films.2010In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 76, no 2, p. 505-511, article id 20060691Article in journal (Refereed)
    Abstract [en]

    Polyimide (PI) is a commonly used polymer in microelectronics. Recently, numerous PI-based flexible neural interfaces have been developed for reducing mechanical mismatch between rigid implant and soft neural tissue. Most approaches employ non-photosensitive PI, which has been proven earlier to be biocompatible. However, photosensitive polyimide (PSPI) would simplify device fabrication remarkably, but its biocompatibility has been only sparsely reported. In this study, cytotoxicity of spin-coated PSPI (HD Microsystems PI-2771) and conventional PI (HD Microsystems PI-2525) films were evaluated in vitro using BHK-21 fibroblasts according to the ISO-10993-5 standard. PSPIs were tested as cured at a temperature of 200 degrees C (PI-2771-200) and 350 degrees C (PI-2771-350). The PI film surfaces were characterized in terms of their roughness, energy and zeta potential which are hypothesized to affect cell-material interactions. The values of the total surface free energy (SFE), and its polar and dispersive component, were significantly (p<0.001) greater for the PI-2525 film (SFE: 47.3 mJ/m2) than for the PI-2771-200 (25.6 mJ/m2) or PI-2771-350 films (26.2 mJ/m2). The curing temperature of the PI-2771 had a significant effect on the zeta potential values (p<0.001), but not on surface energy (p=0.091) or roughness (p=0.717). The results from the MTS proliferation assays and live/dead staining revealed that PSPI is almost as non-cytotoxic as conventional PI and polyethylene (negative control). The morphology and spreading of BHK-21 cells were similar on all the PI materials tested. In conclusion, PSPI seems to be a promising biocompatible material, while further studies in vitro and in vivo are needed to clarify the long-term effects.

  • 14.
    Robertsson, Joel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    CCD-baserad avvikelsemätning på röntgenstrålfältskant: Framtagande av en prototyp för mätning av avvikelse mellan röntgenstrålfält och ljusfält vid konventionell röntgen2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report presents the development of a measurement device for field congruence measurement between light and x-ray field at conventional radiography equipment.

    The project resulted in a prototype which uses CCD-line sensors to measure light intensity and determine field edges. In a sensor set one sensor is exposed through a hole in the protective casing while the second sensor is incased and covered with a thin screen of fluorescent material. The prototype is a stand-alone, battery powered unit with an interface were a TFT-screen and buttons is used to navigate in menus.

    The prototype calculate the congruence within <1mm certainty (theoretically lower). All components are mounted in a 3D printed casing.

     

    This work has been executed as a project on behalf of the County Council of Värmland, who provided with support and x-ray equipment for test measurements. The project includes PCB-construction, 3D-design in CAD, electronics construction and software development in the programing language C.    

  • 15.
    Schmidtlein, Charles R.
    et al.
    Memorial Sloan Kettering Cancer Center.
    Turner, James N.
    State University of New York at Binghamton.
    Thompson, Michael O.
    Cornell University.
    Mandal, Krishna C.
    University of South Carolina.
    Häggström, Ida
    Memorial Sloan Kettering Cancer Center.
    Zhang, Jiahan
    State University of New York Upstate Medical University.
    Humm, John L.
    Memorial Sloan Kettering Cancer Center.
    Feiglin, David H.
    State University of New York Upstate Medical University.
    Krol, Andrzej
    State University of New York Upstate Medical University.
    Initial performance studies of a wearable brain positron emission tomography camera based on autonomous thin-film digital Geiger avalanche photodiode arrays2017In: Journal of Medical Imaging, ISSN 2329-4302, E-ISSN 2329-4310, Vol. 4, no 1, article id 011003Article in journal (Refereed)
    Abstract [en]

    Using analytical and Monte Carlo modeling, we explored performance of a lightweight wearable helmet-shaped brain positron emission tomography (PET), or BET camera, based on thin-film digital Geiger avalanche photodiode arrays with Lutetium-yttrium oxyorthosilicate (LYSO) or LaBr3 scintillators for imaging in vivo human brain function of freely moving and acting subjects. We investigated a spherical cap BET and cylindrical brain PET (CYL) geometries with 250-mm diameter. We also considered a clinical whole-body (WB) LYSO PET/CT scanner. The simulated energy resolutions were 10.8% (LYSO) and 3.3% (LaBr3), and the coincidence window was set at 2 ns. The brain was simulated as a water sphere of uniform F-18 activity with a radius of 100 mm. We found that BET achieved >40% better noise equivalent count (NEC) performance relative to the CYL and >800% than WB. For 10-mm-thick LaBr3 equivalent mass systems, LYSO (7-mm thick) had similar to 40% higher NEC than LaBr3. We found that 1 x 1 x 3 mm scintillator crystals achieved similar to 1.1 mm full-width-half-maximum spatial resolution without parallax errors. Additionally, our simulations showed that LYSO generally outperformed LaBr3 for NEC unless the timing resolution for LaBr3 was considerably smaller than that presently used for LYSO, i.e., well below 300 ps.

  • 16.
    Sångberg, Viktor
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Gatingfantom, återskapande av andningsrörelser2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Norrlands universitetssjuk i Umeå har saknat en bra metod för att kontrollera sin gatingutrustning till sina strålbehandlingsacceleratorer. Testfantomen de har fått från tillverkarna är väldigt simpla och inte speciellt verklighetstrogna. Därför har de varit behov av ett bättre fantom som kan simulera mer verklighetstrogna andningslösningar. Detta examensarbete har gått ut på att ta fram ett sådant fantom.

    Fantomet skall kunna styras via en dator och simulera en andningskurva som definieras i datorn. Fantomet skall kommunicera via en USB-kontakt och ta emot information seriellt. Datorn skall skicka information till en mikrokontroller som beroende på detstyr en stegmotor via en drivkrets som återskapar en andningsrörelse.

    Programmet som skickar data har utvecklats påNorrlands Universitetssjuk.Detta projekt har gått ut på att tillverka kretskort, programmera en mikrokontroller samt få kommunikationen mellan alla delar att fungera. Examensarbetethar utförts av en student på Umeå universitet, Högskoleingenjörsprogrammet Tillämpad elektronik med inriktning medicinsk teknik.

    Resultatet av projektetblev ett fullt fungerande fantom som (i stort sett) kanåterskapa andningsrörelsen hos en människa under normala omständigheter. Detta examensarbete har varit både roligt och lärorikt.

  • 17.
    Åstrand, Anders P
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    A Tactile Resonance Sensor System for Detection of Prostate Cancer ex vivo: Design and Evaluation on Tissue Models and Human Prostate2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background

    The most common form of cancer among males in Europe and the USA is prostate cancer, PCa. Surgical removal of the prostate is the most common form of curative treatment. PCa can be suspected by a blood test for a specific prostate antigen, a PSA-test, and a digital rectal examination, DRE where the physician palpates the prostate through the rectum. Stiff nodules that can be detected during the DRE, and elevated levels of PSA are indications for PCa, and a reason for further examination. Biopsies are taken from the prostate by guidance of a transrectal ultrasound. Superficial cancer tumours can indicate that the cancer has spread to other parts of the body. Tactile resonance sensors can be used to detect areas of different stiffness in soft tissue. Healthy prostate tissue is usually of different stiffness compared to tissue with PCa.

    Aim

    The general aim of this doctoral thesis was to design and evaluate a flexible tactile resonance sensor system (TRSS) for detection of cancer in soft human tissue, specifically prostate cancer. The ability to detect cancer tumours located under the surface was evaluated through measurements on tissue phantoms such as silicone and biological tissues. Finally measurements on resected whole prostate glands were made for the detection of cancer tumours.

    Methods

    The sensor principle was based on an oscillating piezoelectric element that was indented into the soft tissue.  The measured parameters were the change in resonance frequency, Δf, and the contact force F during indentation. From these, a specific stiffness parameter  was obtained. The overall accuracy of the TRSS was obtained and the performance of the TRSS was also evaluated on tissue models made of silicone, biological tissue and resected whole human prostates in order to detect presence of PCa. Prostate glands are generally spherical and a special rotatable sample holder was included in the TRSS. Spherically shaped objects and uneven surfaces call for special attention to the contact angle between the sensor-tip and the measured surface, which has been evaluated. The indentation velocity and the depth sensitivity of the sensor were evaluated as well as the effect on the measurements caused by the force with which spherical samples were held in place in the sample holder. Measurements were made on silicone models and biological tissue of chicken and pork muscles, with embedded stiff silicone nodules, both on flat and spherical shaped samples. Finally, measurements were made on two excised whole human prostates.

    Results

    A contact angle deviating ≤ 10° from the perpendicular of the surface of the measured object was acceptable for reliable measurements of the stiffness parameter. The sensor could detect stiff nodules ≤ 4 mm under the surface with a small indentation depth of 0.4 to 0.8 mm.

    Measurements on the surface of resected human prostate glands showed that the TRSS could detect stiff areas (p < 0.05), which were confirmed by histopathological evaluation to be cancer tumours on, and under the surface.

    Conclusions

    A flexible resonance sensor system was designed and evaluated on soft tissue models as well as resected whole prostate glands. Evaluations on the tissue models showed that the TRSS can detect stiffer volumes hidden below the surface on both flat and spherical samples. The measurements on resected human prostate glands showed that PCa could be detected both on and under the surface of the gland. Thus the TRSS provides a promising instrument aimed for stiffness measurements of soft human tissue that could contribute to a future quantitative palpation method with the purpose of diagnosing cancer. 

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