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  • 3151.
    Åkerberg, Anna
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Söderlund, Anne
    Mälardalens högskola, Akademin för hälsa, vård och välfärd, Hälsa och välfärd.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Utvärdering av en stegräknarapplikation; mätnoggrannhet i olika mätmiljöer och positioner2014Inngår i: Medicinteknikdagarna 2014 MTD10, 2014Konferansepaper (Fagfellevurdert)
  • 3152.
    Åkerberg, Anna
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Söderlund, Anne
    Mälardalens högskola, Akademin för hälsa, vård och välfärd, Hälsa och välfärd.
    Åkerlind, Charlotta
    Mälardalens högskola, Akademin för hälsa, vård och välfärd, Hälsa och välfärd.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    How can technology promote physical activity? Opinions from physically inactive non-users of self-monitoring technologiesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    BACKGROUND: To achieve a more physically active and healthier population, the opinions of potential future users of physical activity self-monitoring technologies need further investigation. Therefore, the aim of this study was to investigate the opinions of physically inactive non-users of physical activity self-monitoring technologies, regarding how and when technology possibly could measure and encourage physical activity. METHODS: Two focus group interviews were performed, consisting of 11 physically inactive persons who had no previous experience with regular use of physical activity self-monitoring technology. The focus groups were analyzed by qualitative content analysis. RESULTS: The transcripts of the two focus groups resulted in 17 subcategories and five categories, which formed two themes: measurement complexity and performance and basic qualities. CONCLUSION: This study showed that the physically inactive non-users of physical activity self-monitoring technologies had positive, innovative and mainly similar opinions about how technology could promote physical activity. Since the concept of encouragement permeates the results, it can be concluded that the physical activity technology for this particular target group should primarily be based on encouraging features and functions. Further, the study indicated that it is preferable to integrate physical activity self-monitoring technology into already existing technology that the user already owns.

  • 3153.
    Åkerberg, Johan
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Björkman, Mats
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik.
    Safety and Security Experiences from Process Automation Applied to Healthcare and Medical Applications2009Konferansepaper (Fagfellevurdert)
  • 3154.
    Åkerlind, Christina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. FOI, Department Electroopt Syst, SE-58111 Linkoping, Sweden.
    Hallberg, Tomas
    FOI, Department Electroopt Syst, SE-58111 Linkoping, Sweden.
    Eriksson, Johan
    FOI, Department Electroopt Syst, SE-58111 Linkoping, Sweden.
    Kariis, Hans
    FOI, Department Electroopt Syst, SE-58111 Linkoping, Sweden.
    Bergstrom, David
    FOI, Department Electroopt Syst, SE-58111 Linkoping, Sweden.
    Optical polarization - Background and Camouflage2017Inngår i: TARGET AND BACKGROUND SIGNATURES III, SPIE-INT SOC OPTICAL ENGINEERING , 2017, Vol. 10432, artikkel-id UNSP 1043204Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Polarimetric imaging sensors in the electro-optical region, already military and commercially available in both the visual and infrared, show enhanced capabilities for advanced target detection and recognition. The capabilities arise due to the ability to discriminate between man-made and natural background surfaces using the polarization information of light. In the development of materials for signature management in the visible and infrared wavelength regions, different criteria need to be met to fulfil the requirements for a good camouflage against modern sensors. In conventional camouflage design, the aimed design of the surface properties of an object is to spectrally match or adapt it to a background and thereby minimizing the contrast given by a specific threat sensor. Examples will be shown from measurements of some relevant materials and how they in different ways affect the polarimetric signature. Dimensioning properties relevant in an optical camouflage from a polarimetric perspective, such as degree of polarization, the viewing or incident angle, and amount of diffuse reflection, mainly in the infrared region, will be discussed.

  • 3155.
    Åslund, Magnus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lundqvist, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    AEC for scanning digital mammography based on variation of scan velocity2005Inngår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 32, nr 11, s. 3367-3374Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A theoretical evaluation of nonuniform x-ray field distributions in mammography was conducted. An automatic exposure control (AEC) is proposed for a scanning full field digital mammography system. It uses information from the leading part of the detector to vary the scan velocity dynamically, thus creating a nonuniform x-ray field in the scan direction. Nonuniform radiation fields were also created by numerically optimizing the scan velocity profile to each breast's transmission distribution, with constraints on velocity and acceleration. The goal of the proposed AEC is to produce constant pixel signal-to-noise ratio throughout the image. The target pixel SNR for each image could be set based on the breast thickness, breast composition, and the beam quality as to achieve the same contrast-to-noise ratio between images for structures of interest. The results are quantified in terms of reduction in entrance surface air kerma (ESAK) and scan time relative to a uniform x-ray field. The theoretical evaluation was performed on a set of 266 mammograms. The performance of the different methods to create nonuniform fields decreased with increased detector width, from 18% to 11% in terms of ESAK reduction and from 30% to 25% in terms of scan time reduction for the proposed AEC and detector widths from 10 to 60 mm. Some correlation was found between compressed breast thickness and the projected breast area onto the image field. This translated into an increase of the ESAK and decrease of the scan time reduction with breast thickness. Ideally a nonuniform field in two dimensions could reduce the entrance dose by 39% on average, whereas a field nonuniform in only the scanning dimension ideally yields a 20% reduction. A benefit with the proposed AEC is that the risk of underexposing the densest region of the breast can be virtually eliminated.

  • 3156.
    Åslund, Magnus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lundqvist, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Evaluation of an AEC system for scanning photon counting mammography based on variation of scan velocityInngår i: Medical physics (Lancaster), ISSN 0094-2405Artikkel i tidsskrift (Annet vitenskapelig)
  • 3157.
    Åslund, Magnus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lundqvist, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Physical characterization of a scanning photon counting digital mammography system based on Si-strip detectors2007Inngår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 34, nr 6, s. 1918-1925Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge-on geometry connected to photon counting electronics. The pixel size is 50 mu m and the field of view 24 x 26 cm(2). The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the 7.6-206 mu Gy range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a 28 kV W-0.5 mm Al anodefilter combination with an added 2 mm Al filtration.

  • 3158.
    Åslund, Magnus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lundqvist, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Medicinsk avbildning.
    Scatter rejection in multislit digital mammography2006Inngår i: Medical physics (Lancaster), ISSN 0094-2405, Vol. 33, nr 4, s. 933-940Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The scatter to primary ratio (SPR) was measured on a scanning multislit full-field digital mammography system for different thickness of breast equivalent material and different tube voltages. Scatter within the detector was measured separately and was found to be the major source of scatter in the assembly. Measured total SPRs below 6% are reported for breast range 3-7 cm. The performance of the multislit assembly is compared to other imaging geometries with different scatter rejection schemes by using the scatter detective quantum efficiency.

  • 3159.
    Åslund, Magnus
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Fredenberg, Erik
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cederström, Björn
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Danielsson, Mats
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Spectral shaping for photon counting digital mammography2007Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 580, nr 2, s. 1046-1049Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The spectral shaping properties of conventional filters have been evaluated for a photon counting digital mammography system, and the result has been compared with the theoretical spectrum from a multi-prism X-ray lens (MPL). The absorption filters and the MPL were evaluated using a theoretical model of the system which has been verified experimentally. The spectral shaping performance is quantified with the spectral quantum efficiency (SQE), calculated as the polychromatic signal-difference-to-noise ratio (SDNR) squared over the optimal monochromatic SDNR squared at the same average glandular dose. The MPL increases the SQE by 25% compared to the investigated absorption filter when compared with a Tungsten anode. This translates into a potential dose reduction of 20% at maintained SDNR.

  • 3160.
    Åstrand, Anders
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Börje, Ljungberg
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Urologi och andrologi.
    Anders, Bergh
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    Lindahl, Olof
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Prostate cancer detection with a tactile resonance sensor: measurement considerations and clinical setup2017Inngår i: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 17, nr 11, artikkel-id 2453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tumors in the human prostate are usually stiffer compared to surrounding non-malignant glandular tissue, and tactile resonance sensors measuring stiffness can be used to detect prostate cancer. To explore this further, we used a tactile resonance sensor system combined with a rotatable sample holder where whole surgically removed prostates could be attached to detect tumors on, and beneath, the surface ex vivo. Model studies on tissue phantoms made of silicone and porcine tissue were performed. Finally, two resected human prostate glands were studied. Embedded stiff silicone inclusions placed 4 mm under the surface could be detected in both the silicone and biological tissue models, with a sensor indentation of 0.6 mm. Areas with different amounts of prostate cancer (PCa) could be distinguished from normal tissue (p < 0.05), when the tumor was located in the anterior part, whereas small tumors located in the dorsal aspect were undetected. The study indicates that PCa may be detected in a whole resected prostate with an uneven surface and through its capsule. This is promising for the development of a clinically useful instrument to detect prostate cancer during surgery.

  • 3161.
    Åstrand, Anders
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindahl, Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    A flexible resonance sensor instrument for measurements of soft tissue: evaluation on silicone modelsManuskript (preprint) (Annet vitenskapelig)
  • 3162.
    Åstrand, Anders
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Ansättningsvinkelns betydelse vid mätning med piezoelektriska resonanssensorer på vävnadsmodeller av silikon2011Inngår i: Medicinteknikdagarna 2011, 2011, s. 110-110Konferansepaper (Annet vitenskapelig)
  • 3163.
    Åstrand, Anders
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Stiffness measurements on spherical surfaces of prostate models using a resonance sensor2013Inngår i: World Congress on Medical Physics and Biomedical Engineering May 26-31, 2012, Beijing, China / [ed] Mian Long, Springer Berlin/Heidelberg, 2013, s. 1401-1404Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Prostate cancer is one of the most common formsof cancer among men in Europe and the United States.Piezoelectric resonance sensors can be used in medicalresearch for measurements of stiffness of human tissue.Cancer tissue is usually stiffer and has different biomechanicalproperties compared to healthy tissue. The frequency shiftobserved when a piezoelectric resonance sensor comes intocontact with a tissue surface has been suggested to correlatewith the stiffness variations, e.g. due to cancer. An instrumenthas been developed, with which it is possible to scan flat andspherical objects and where the sensor can be tilted fordifferent contact angles. Measurements performed in thisstudy on spherical tissue models made of silicone, showed theimportance of keeping the contact angle perpendicular to thesurface of the sphere. The results are promising for futurestudies on prostate tissue to complete the evaluation of theinstrument.

  • 3164.
    Åstrand, Anders
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Contact angle and indentation velocity dependency for a resonance sensor: Evaluation on soft tissue silicone models2013Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 37, nr 3, s. 185-196Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Human tissue stiffness can vary due to different tissue conditions such as cancer tumours. Earlier studies show that stiffness may be detected with a resonance sensor that measures frequency shift and contact force at application. Through the frequency shift and the contact force, a tissue stiffness parameter can be derived. This study evaluated how the probe application angle and indentation velocity affected the results and determined the maximum parameter errors. The evaluation was made on flat silicone discs with specified hardness. The frequency shift, the force and the stiffness parameter all varied with contact angle and indentation velocity. A contact angle of ≤10° was acceptable for reliable measurements. A low indentation velocity was recommended. The maximum errors for the system were <1.1% of the measured values. It was concluded that contact angle and indentation velocity have to be considered in the clinical setting. The angular dependency is especially important in clinical use for studying stiffness of human soft tissue, e.g. in prostate cancer diagnosis.

  • 3165.
    Åstrand, Anders P.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    A flexible resonance sensor system for detection of cancer tissue: evaluation on silicon2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The most common form of cancer among men in Europe and the US is prostate cancer. When a radical prostatectomy has been found necessary, it is of interest to examine the prostate, as tumour tissue on the capsule might indicate that the cancer has metastased. This is commonly done by a microscope-based morphometric investigation. Tumour tissue is normally stiffer than healthy tissue. Sensors based on piezoelectric resonance technology have been introduced into the medical field during the last decade. By studying the change in resonance frequency when a sensor comes into contact with a material, conclusions can be drawn about the material.

    A new and flexible measurement system using a piezoelectric resonance sensor has been evaluated. Three translation stages, two for horizontal movements and one for vertical movement, with stepper motors are controlled from a PC. A piezoelectric resonance element and a force sensor are integrated into a sensor head that is mounted on the vertical translation stage. The piezoelectric element is connected to a feed-back circuit and resonating at its resonance frequency until it comes into contact with a material, when a frequency shift can be observed. The force sensor is used to measure the applied force between the sensor and the material. These two parameters are combined into a third, called the stiffness parameter, which is important for stiffness evaluation. For measurements on objects with different geometries, the vertical translation stage can be aimed at a platform for flat objects or a fixture for spherical objects. The vertical translation stage is mounted on a manual rotational stage with which the contact angle between the sensor and the measured surface can be adjusted. The contact angles covered are between 0° and 35° from a line perpendicular to the surface of the measured object. The measured objects used were made from silicones of different stiffness and in the shape of flat discs and spheres. The indentation velocity of the sensor can be set at 1 mm/s to 5 mm/s. In the three papers that are the base for this licentiate thesis, we have investigated the dependence of the frequency shift, the applied force and the stiffness parameter on the contact angle, and the indentation velocity at different impression depths. The maximum error for the measurement system has also been determined.

    The results of the measurements indicate that great care must be taken when aiming the sensor against the surface of the point where the measurements are to be performed. Deviations in contact angle of more than iv±10° from a line perpendicular to the surface will result in an underestimation of the frequency shift, meaning that the tissue will be regarded as stiffer than it really is. This result is important as the flat silicone models have a very even surface, which makes a controlled contact angle possible. Biological tissue can have a rough and uneven surface, which can lead to unintentional deviations in the contact angle. The magnitude of the stiffness parameter is favoured by a high indentation velocity compared to a low.

    The evaluation of this measurement system has shown that it is possible to distinguish between soft and stiff silicone models, which have been used in this initial phase of the study. A new feature in this measurement system is the fixture that makes measurements on spherical objects possible and the possibility to vary the angle of contact. This is promising for future studies and measurements on whole prostate in vitro. A future application for this measurement system is to aid surgeons performing radical prostatectomy in the search for tumour tissue on the capsule of the prostate, as the presence of tumour tissue can indicate that the cancer has spread to the surrounding tissue.

  • 3166.
    Åstrand, Anders P
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    A Tactile Resonance Sensor System for Detection of Prostate Cancer ex vivo: Design and Evaluation on Tissue Models and Human Prostate2014Doktoravhandling, med artikler (Annet vitenskapelig)
    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. 

  • 3167.
    Åstrand, Anders P.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet.
    Initial Measurements on Whole Human Prostate ex vivo with a Tactile Resonance Sensor in Order to Detect Prostate Cancer2015Inngår i: 16th Nordic-Baltic Conference on Biomedical Engineering: 16. NBC & 10. MTD 2014 joint conferences. October 14-16, 2014, Gothenburg, Sweden / [ed] Henrik Mindedal, Mikael Persson, Springer International Publishing , 2015, s. 120-123Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Prostate cancer (PCa) is the most common form of cancer among the male population in Europe and the USA. PCa can be suspected by a blood test for a specific prostate antigen, a PSA-test, followed by a digital rectal examination (DRE). The objective with the DRE is to investigate the presence of stiff nodules on the prostate. Stiff nodules can indicate PCa and biopsies are taken from the suspicious parts of the prostate using guidance of a transrectal ultrasound. Microscopic evaluation of the biopsies is used for final diagnosis. Superficial tumor growth on, and beneath the surface of the gland is of special interest as it suggests that the cancer has spread to other parts of the body.

    Tactile resonance sensors can be used to distinguish between areas of different stiffness in soft tissue. The aim was to detect tumors on, and beneath the surface of a whole human prostate ex vivo.

    A tactile resonance sensor system (TRSS) based on a piezoelectric resonance sensor and a force sensor has been used to detect areas with increased stiffness in soft tissue. The TRSS has a rotatable sample holder for measurements on spherical shaped samples. Stiffness measurements were made on samples of porcine muscle tissue with embedded stiff silicone nodules placed under the surface. Further measurements were made on a resected whole human prostate with PCa.

    The results showed that through the measured stiffness parameter, the stiff silicone nodules placed down to 4 mm under the surface could be detected. The measurements on the prostate showed that elevated values of the stiffness parameter correlated (p < 0.05) with areas in the anterior of the prostate where cancer tumors were detected by histopathological evaluation. The tumors were significantly stiffer than the healthy tissue in the dorsal region.

    The results are promising for further development of a clinically useful instrument to detect superficial PCa.

  • 3168.
    Åstrand, Anders P.
    et al.
    Umeå university.
    Jalkanen, Ville
    Umeå university.
    Andersson, Britt M.
    Umeå university.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A flexible sensor system using resonance technology for soft tissue stiffness measurements: evaluation on silicone2011Inngår i: 15th Nordic Baltic Conference on Biomedical Engineering and Medical Physics: 14 - 17 June 2011, Aalborg, Denmark / NBC 2011 / [ed] Kim Dremstrup, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2011, s. 21-24Konferansepaper (Fagfellevurdert)
    Abstract [en]

    One of the most common forms of cancer among men in Europe and the United States is prostate cancer. The cancerous tissue is less soft, and has different biomechanical properties compared to healthy tissue. It has been shown that tactile sensors can be used to distinguish this difference. If a piezoelectric sensor is set to oscillate at its resonance frequency through a feed back circuit, a frequency shift is observed when the sensor comes in contact with a surface. This shift can be correlated to the stiffness of the tissue. A flexible instrument has been developed, with which it is possible to scan both flat and spherical bodies and where the sensor can be tilted to have different contact angles. Measurements performed in this study on flat silicone discs of different stiffness showed a relationship between both the frequency shift and the impression depth for the different silicone discs, when a constant force was applied. The results are promising for future studies on silicone with different geometries and finally on prostate tissue to complete the evaluation.

  • 3169.
    Åstrand, Anders P.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Luleå Univ Technol, Dept Comp Sci, Elect & Space Engn, Luleå, Sweden.
    A flexible sensor system using resonance technology for soft tissue stiffness measurements: evaluation on silicone2011Inngår i: 15TH NORDIC-BALTIC CONFERENCE ON BIOMEDICAL ENGINEERING AND MEDICAL PHYSICS (NBC 2011) / [ed] K. Dremstrup, S. Rees, M.Ø. Jensen, Aalborg: Springer , 2011, s. 21-24Konferansepaper (Fagfellevurdert)
    Abstract [en]

    One of the most common forms of cancer amongmen in Europe and the United States is prostate cancer. Thecancerous tissue is less soft, and has different biomechanicalproperties compared to healthy tissue. It has been shown thattactile sensors can be used to distinguish this difference. If apiezoelectric sensor is set to oscillate at its resonance frequencythrough a feed back circuit, a frequency shift is observed whenthe sensor comes in contact with a surface. This shift can becorrelated to the stiffness of the tissue. A flexible instrumenthas been developed, with which it is possible to scan both flatand spherical bodies and where the sensor can be tilted to havedifferent contact angles. Measurements performed in thisstudy on flat silicone discs of different stiffness showed arelationship between both the frequency shift and theimpression depth for the different silicone discs, when aconstant force was applied. The results are promising forfuture studies on silicone with different geometries and finallyon prostate tissue to complete the evaluation.

  • 3170.
    Åstrand, Anders P
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Andersson, Britt M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Lindahl, Olof A
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Initial Measurements on Whole Human Prostate ex vivo with a Tactile Resonance Sensor in Order to Detect Prostate CancerManuskript (preprint) (Annet vitenskapelig)
  • 3171.
    Åstrand, Anders P.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Jalkanen, Ville
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lindahl, Olof A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Andersson, Britt M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Mätutrustning för kontrollerad mätning och karaktärisering av vävnad2010Inngår i: Medicinteknikdagarna 2010 / [ed] Ronnie Lundström, Umeå: Svensk förening för medicinsk teknik och fysik , 2010, s. 167-167Konferansepaper (Fagfellevurdert)
  • 3172.
    Åström, Freddie
    et al.
    Heidelberg Collaboratory for Image Processing Heidelberg University Heidelberg, Germany.
    Felsberg, Michael
    Linköpings universitet, Institutionen för systemteknik, Datorseende. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Scharr, Hanno
    BG-2: Plant Sciences Forschungszentrum Jülich 52425, Jülich, Germany.
    Adaptive sharpening of multimodal distributions2015Inngår i: Colour and Visual Computing Symposium (CVCS), 2015 / [ed] Marius Pedersen and Jean-Baptiste Thomas, IEEE , 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this work we derive a novel framework rendering measured distributions into approximated distributions of their mean. This is achieved by exploiting constraints imposed by the Gauss-Markov theorem from estimation theory, being valid for mono-modal Gaussian distributions. It formulates the relation between the variance of measured samples and the so-called standard error, being the standard deviation of their mean. However, multi-modal distributions are present in numerous image processing scenarios, e.g. local gray value or color distributions at object edges, or orientation or displacement distributions at occlusion boundaries in motion estimation or stereo. Our method not only aims at estimating the modes of these distributions together with their standard error, but at describing the whole multi-modal distribution. We utilize the method of channel representation, a kind of soft histogram also known as population codes, to represent distributions in a non-parametric, generic fashion. Here we apply the proposed scheme to general mono- and multimodal Gaussian distributions to illustrate its effectiveness and compliance with the Gauss-Markov theorem.

  • 3173.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Functional brain atlas2014Konferansepaper (Annet vitenskapelig)
  • 3174.
    Åström, Mattias
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan. Sapiens Steering Brain Stimulation B.V., The Netherlands .
    Neuronmodeling and DBS electric field simulations2014Konferansepaper (Annet vitenskapelig)
  • 3175.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Diczfalusy, Elin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Computational analysis of the electric field during deep brain stimulation (oral, invited)2010Konferansepaper (Fagfellevurdert)
  • 3176.
    Åström, Mattias
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Diczfalusy, Elin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Software for patient-specific modeling and simulation of deep brain stimulation (poster)2011Konferansepaper (Annet vitenskapelig)
  • 3177.
    Çürüklü, Baran
    et al.
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    Lansner, Anders
    Mälardalens högskola, Institutionen för datavetenskap och elektronik.
    On the development and functional roles of the layer 4 horizontal connections in the primary visual cortex2006Konferansepaper (Fagfellevurdert)
  • 3178.
    Öberg Hed, Kim
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Ytbehandlingsteknik.
    Advanced polymeric scaffolds for functional materials in biomedical applications2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Advancements in the biomedical field are driven by the design of novel materials with controlled physical and bio-interactive properties. To develop such materials, researchers rely on the use of highly efficient reactions for the assembly of advanced polymeric scaffolds that meet the demands of a functional biomaterial. In this thesis two main strategies for such materials have been explored; these include the use of off-stoichiometric thiol-ene networks and dendritic polymer scaffolds. In the first case, the highly efficient UV-induced thiol-ene coupling (TEC) reaction was used to create crosslinked polymeric networks with a predetermined and tunable excess of thiol or ene functionality. These materials rely on the use of readily available commercial monomers. By adopting standard molding techniques and simple TEC surface modifications, patterned surfaces with tunable hydrophobicity could be obtained. Moreover, these materials are shown to have great potential for rapid prototyping of microfluidic devices. In the second case, dendritic polymer scaffolds were evaluated for their ability to increase surface interactions and produce functional 3D networks. More specifically, a self-assembled dendritic monolayer approach was explored for producing highly functional dendronized surfaces with specific interactions towards pathogenic E. coli bacteria. Furthermore, a library of heterofunctional dendritic scaffolds, with a controllable and exact number of dual-purpose azide and ene functional groups, has been synthesized. These scaffolds were explored for the production of cell interactive hydrogels and primers for bone adhesive implants. Dendritic hydrogels decorated with a selection of bio-relevant moieties and with Young’s moduli in the same range as several body tissues could be produced by facile UV-induced TEC crosslinking. These gels showed low cytotoxic response and relatively rapid rates of degradation when cultured with normal human dermal fibroblast cells. When used as primers for bone adhesive patches, heterofunctional dendrimers with high azide-group content led to a significant increase in the adhesion between a UV-cured hydrophobic matrix and the wet bone surface (compared to patches without primers).

  • 3179.
    Ödman, Torbjörn
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Wireless measurement systems for health and safety2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This licentiate thesis presents an advanced wireless system, built on a single hardware platform, for applications in medicine and health. In order to design a single system, adaptable for different context, an accurate system specification is required.

    The technical requirements are authenticated by actual tests in the environment where the system is intended to be used. The results of these measurements give an understanding of the possibilities of designing a real system but also acts as a base for deriving the empirical formulas to be used as the basis of the development and verification.

    In summary, this work has included a larger measurement campaign and a verification of subsystems to support the development of wireless systems on a single hardware platform. This can be used for different measurements in medical healthcare and rescue work.

    Previous systems for endurance tests have limitations in that they are not adapted to different sizes of mammals and they also have shortcomings in the quantification of data and scalability.

    The developed system was validated on mice and humans. On mice the measurement parameters was the hormone dopamine and locomotion. For humans it was measured time for given distances. Both validation tests showed high correlation with the respective reference methods. The correlation coefficients of mice between the developed system and the former system ranged from 0.916 to 0.967. In the validation with humans, runners were clocked by the system clock and a manual stop watch. The lowest correlation coefficient was 0.864. Advantages with the developed system is that it is scalable and measures the activity level quantitatively in the unit meters and it can also be used for different sizes of mammals in different environments.

    In tracking devices for rescue it is important that the transmitted signal can be detected at distances as large as possible. A support in the design work is to simulate path loss. This requires a path loss exponent, which was calculated after the measurement campaign. The results showed that the exponent of the height dependency decreases with antenna height above water. For the frequency 200 MHz, the exponent for the antenna height is 0.4 (vertical polarization) and 1.5 (horizontal polarization). For the distance dependency, the exponent was 3.59 (vertical polarization) and 3.22 (horizontal polarization). The path loss exponent is 2 for both the free space- and the ground reflection model.

    An antenna’s physical dimension is to a large extent dependent on the lowest frequency. The research’s aim was to reduce the physical size by introducing a resonance frequency. The physical length was from the beginning 0.43 meter given by the lowest frequency used (0.7 GHz) and the antenna was reduced in size to 0.22 meter. 

  • 3180.
    Ödman, Torbjörn
    et al.
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system. Saab Electronic Defense Systems, Jönköping, Sweden .
    Lindén, Maria
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Larsson, C.
    Lund University, Lund, Sweden. Saab Dynamics, Linköping, Sweden .
    Reflection/transmission study of two fabrics with microwave properties2014Inngår i: Stud. Health Technol. Informatics, 2014, s. 95-100Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this study, the transmission and reflection of two conductive fabrics are investigated in the frequency range from 2 to 18 GHz. One of the fabrics is a non-woven polypyrrole, and the other consists of a polyethylene warp with steel threads in the weft. Reflection and transmission measurements are performed in order to characterize the electromagnetic properties of the materials. Reflection measurements are performed for two polarizations at normal, 0°, and 60° incident angles. Transmission measurements are also done for two polarization directions at normal incidence. The results show that the fabric with the steel filler reflects most of the incident radiation, and has very low transmission with some polarization dependence. The polypyrrole non-woven fabric, on the other hand, has reflection and transmission properties that show that it is absorbing the incident radiation. Wearable on-body sensors that in addition are comfortable to wear can be integrated in the textile of clothes. These sensors can e.g., be used to monitor health or analyze gait. The fabrics have the potential to be used in health applications when designing on-body sensors, e.g. for movement analysis.

  • 3181.
    Öhberg, Fredrik
    et al.
    Department of Biomedical Engineering and Informatics, University Hospital, Umeå.
    Grip, Helena
    Department of Biomedical Engineering and Informatics, University Hospital, Umeå.
    Wiklund, Urban
    Department of Biomedical Engineering and Informatics, University Hospital, Umeå.
    Sterner, Ylva
    Community Medicine and Rehabilitation, University Hospital, Umeå, Sweden.
    Karlsson, J. Stefan
    Department of Biomedical Engineering and Informatics, University Hospital, Umeå.
    Gerdle, Björn
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Rehabiliteringsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Medicincentrum, Smärt- och rehabiliteringscentrum.
    Chronic Whiplash Associated Disorders and Neck Movement Measurements: An Instantaneous Helical Axis Approach2003Inngår i: IEEE transactions on information technology in biomedicine, ISSN 1089-7771, E-ISSN 1558-0032, Vol. 7, nr 4, s. 274-282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents an assessment tool for objective neck movement analysis of subjects suffering from chronic whiplash-associated disorders (WAD). Three-dimensional (3-D) motion data is collected by a commercially available motion analysis system. Head rotation, defined in this paper as the rotation angle around the instantaneous helical axis (IHA), is used for extracting a number of variables (e.g., angular velocity and range, symmetry of motion). Statistically significant differences were found between controls and subjects with chronic WAD in a number of variables.

  • 3182.
    Öhberg, Fredrik
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Lundström, Ronnie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF). Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Grip, Helena
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Comparative analysis of different adaptive filters for tracking lower segments of a human body using inertial motion sensors2013Inngår i: Measurement science and technology, ISSN 0957-0233, E-ISSN 1361-6501, Vol. 24, nr 8, s. 085703-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For all segments and tests, a modified Kalman filter and a quasi-static sensor fusion algorithm were equally accurate (precision and accuracy similar to 2-3 degrees) compared to normalized least mean squares filtering, recursive least-squares filtering and standard Kalman filtering. The aims were to: (1) compare adaptive filtering techniques used for sensor fusion and (2) evaluate the precision and accuracy for a chosen adaptive filter. Motion sensors (based on inertial measurement units) are limited by accumulative integration errors arising from sensor bias. This drift can partly be handled with adaptive filtering techniques. To advance the measurement technique in this area, a new modified Kalman filter is developed. Differences in accuracy were observed during different tests especially drift in the internal/external rotation angle. This drift can be minimized if the sensors include magnetometers.

  • 3183.
    Öhman, Caroline
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Espino, Daniel M.
    School of Mechanical Engineering, University of Birmingham, Birmingham, UK.
    Baleani, Massimiliano
    Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Italy.
    Erani, Paolo
    Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Italy.
    Juszczyk, Mateusz
    Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Italy.
    Maccarrone, Pierro G.
    Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Italy.
    Falco, Luigi
    Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Italy.
    Toni, Aldo
    Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Italy.
    AN EXPERIMENTAL METHOD TO CHARACTERISE KNEE STABILITY: PRELIMINARY TESTS WITH A PORCINE MODEL2012Konferansepaper (Fagfellevurdert)
  • 3184.
    Öhman, Caroline
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Nouhi, Shirin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Hulsart-Billström, Gry
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Ortopedi.
    Engqvist, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Larsson, Sune
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för kirurgiska vetenskaper, Ortopedi.
    Facilitating separation of bone from bonelike materials in micro-computed tomography images2014Konferansepaper (Fagfellevurdert)
  • 3185.
    Öhman Mägi, Caroline
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Holub, Ondrej
    School of Mechanical Engineering, University of Leeds, UK.
    Hall, Richard M.
    School of Mechanical Engineering, University of Leeds, UK.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    A review of the relationships between density and mechanical properties of vertebral trabecular bone2017Konferansepaper (Fagfellevurdert)
  • 3186.
    Öhman Mägi, Caroline
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Holub, Ondrej
    School of Mechanical Engineering, University of Leeds, UK.
    Hall, Richard M
    School of Mechanical Engineering, University of Leeds, UK.
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Predicting the mechanical properties of vertebral trabecular bone - a review2017Konferansepaper (Fagfellevurdert)
  • 3187.
    Örtenberg, Alexander
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska fakulteten.
    Parallelization of DIRA and CTmod Using OpenMP and OpenCL2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Parallelization is the answer to the ever-growing demands of computing power by taking advantage of multi-core processor technology and modern many-core graphics compute units. Multi-core CPUs and many-core GPUs have the potential to substantially reduce the execution time of a program but it is often a challenging task to ensure that all available hardware is utilized. OpenMP and OpenCL are two parallel programming frameworks that have been developed to allow programmers to focus on high-level parallelism rather than dealing with low-level thread creation and management. This thesis applies these frameworks to the area of computed tomography by parallelizing the image reconstruction algorithm DIRA and the photon transport simulation toolkit CTmod. DIRA is a model-based iterative reconstruction algorithm in dual-energy computed tomography, which has the potential to improve the accuracy of dose planning in radiation therapy. CTmod is a toolkit for simulating primary and scatter projections in computed tomography to optimize scanner design and image reconstruction algorithms. The results presented in this thesis show that parallelization combined with computational optimization substantially decreased execution times of these codes. For DIRA the execution time was reduced from two minutes to just eight seconds when using four iterations and a 16-core CPU so a speedup of 15 was achieved. CTmod produced similar results with a speedup of 14 when using a 16-core CPU. The results also showed that for these particular problems GPU computing was not the best solution.

  • 3188. Örtqvist, Maria
    et al.
    Gutierrez-Farewik, Elena M.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Farewik, Markus
    KTH.
    Jansson, Anna
    Bartonek, Åsa
    Broström, Eva
    Reliability of a new instrument for measuring plantarflexor muscle strength2007Inngår i: Archives of Physical Medicine and Rehabilitation, ISSN 0003-9993, E-ISSN 1532-821X, Vol. 88, nr 9, s. 1164-1170Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives: To test the reliability of a new muscle strength testing instrument (the Strength Measuring Chair [SMC]) designed to quantify isometric strength in the lower extremities, and to determine the agreement between the SMC and an isokinetic dynamometer (Biodex). Design: Isometric strength tests were performed in plantar-flexors with 2 different knee positions (60 degrees, 30 degrees). Measurements were taken at 3 different sessions. Setting: Strength testing laboratory. Participants: Twenty-three able-bodied adults and 15 able-bodied children. Interventions: Not applicable. Main Outcome Measure: Isometric plantarflexor strength. Results: The reliability of isometric strength measurements of plantarflexors taken in the SMC was excellent for both the adult and children groups (intraclass correlation coefficient range,.84-.87). A Bland-Altman 95% limit of agreement test showed no systematic variation in 3 of the 4 SMC test observations; systematic variation was only observed in the adult group at a knee position of 30 degrees. There was no systematic difference in the adult group between the SMC and the isokinetic dynamometer, but there was a systematic variation in the children's group. Conclusions: The SMC reliably measured isometric plantarflexor strength in the tested populations.

  • 3189.
    Östling, Janina
    Stockholms universitet, Naturvetenskapliga fakulteten, Medicinsk strålningsfysik (tills m KI).
    New Efficient Detector for Radiation Therapy Imaging using Gas Electron Multipliers2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Currently film is being replaced by electronic detectors for portal imaging in radiation therapy. This development offers obvious advantages such as on-line quality assurance and digital images that can easily be accessed, processed and communicated. In spite of the improvements, the image quality has not been significantly enhanced, partly since the quantum efficiency compared to film is essentially the same, and the new electronic devices also suffer from sensitivity to the harsh radiation environment. In this thesis we propose a third generation electronic portal imaging device with increased quantum efficiency and potentially higher image quality.

    Due to the parallel readout capability it is much faster than current devices, providing at least 200 frames per second (fps), and would even allow for a quality assurance and adaptive actions after each accelerator pulse. The new detector is also sensitive over a broader range of energies (10 keV - 50 MeV) and can be used to obtain diagnostic images immediately prior to the treatment without repositioning the patient. The imaging could be in the form of portal imaging or computed tomography. The new detector is based on a sandwich design containing several layers of Gas Electron Multipliers (GEMs) in combination with, or integrated with, perforated converter plates. The charge created by the ionizing radiation is drifted to the bottom of the assembly where a tailored readout system collects and digitizes the charge. The new readout system is further designed in such a way that no sensitive electronics is placed in the radiation beam and the detector is expected to be radiation resistant since it consists mainly of kapton, copper and gas.

    A single GEM detector was responding linearly when tested with a 50 MV photon beam at a fluence rate of ~1010 photons mm-2 s-1 during 3-5 μs long pulses, but also with x-ray energies of 10-50 keV at a fluence rate of up to ~108 photons mm-2 s-1. The electron transmission of a 100 μm thick Cu plate with an optical transparency of ~46% was found to be ~15.4%, i.e. the effective hole transmission for the electrons was about one third of the hole area. A low effective GEM gain is enough to compensate for the losses in converters of this dimension. A prototype for the dedicated electronic readout system was designed with 50 x 100 pixels at a pitch of 1.27 mm x 1.27 mm. X-ray images were achieved with a single GEM layer and also in a double GEM setup with a converter plate interleaved. To verify the readout speed a Newton pendulum was imaged at a frame rate of 70 fps and alpha particles were imaged in 188 fps. The experimental studies indicates that the existing prototype can be developed as a competitive alternative for imaging in radiation therapy.

  • 3190.
    Östlund, Britt
    et al.
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap.
    Jonsson, Oskar
    Lunds universitet.
    Dalholm Hornyanszky, Elisabeth
    Lunds universitet.
    Warell, Anders
    Lunds universitet.
    Sperling, Lena
    Lunds universitet.
    Experiences of a User-Centered Approach to Relations between Ageing People and Furniture in the Home Environment2015Konferansepaper (Annet vitenskapelig)
  • 3191.
    Östlund, N.
    et al.
    Department of Biomedcal Engineering and Informatics, Univeristy Hospital of Umeå.
    Karlsson, M.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Karlsson, S.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Berglin, L.
    School of Textiles, University of Borås.
    Lindecrantz, Kaj
    School of Engineering, University of Borås.
    Sandsjö, L.
    National Institute of Working Life, Gothenburg.
    Wiklund, U.
    Engineering and Informatics, Univeristy Hospital of Umeå.
    Multichannel filter for heartbeat detection in noisy ECG recordings2006Inngår i: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING 2006, VOL 14, PTS 1-6 / [ed] Kim, SI; Suh, TS, 2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In ECG signals recorded with smart clothes disturbances as intermittent loss of signal from electrodes, movement artefacts, and electromyographic interference are common. In this study a multichannel method for spatio-temporal filtering is evaluated using ECG signals from a database and with three recordings made with a T-shirt with integrated textile electrodes. The sensitivity and precision of the signals from the database were 99.6% and 98.5%, respectively, if 12 channels were used and the signal-to-noise ratio was -10 dB. The filter gave a sensitivity of 99.6% and a precision of 99.5% in the recordings from the textile electrodes. In conclusion, the results obtained indicated that multichannel spatio-temporal filtration could be a suitable method for heartbeat detection in ECG measurements with textile electrodes.

  • 3192.
    Östlund, Nils
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Wiklund, Urban
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Yu, Jun
    Centre of Biostochastics, SLU.
    Karlsson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Centrum för medicinsk teknik och fysik (CMTF).
    Adaptive spatio-temporal filtration of bioelectrical signals2005Inngår i: Proceedings of The 27th Annual International Conferenceof the IEEE Engineering in Medicine and Biology Society, New York: IEEE Press, 2005, s. 5983-5986Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we show how independent component analysis (ICA) algorithms can be used to perform spatio-temporal filtration of electromyographic (EMG) and electrocardiographic (ECG) signals. The technique was used to decompose the EMG signals into motor unit action potential (MUAP) trains. From the 88 outputs of the adaptive spatio-temporal filtration, three groups of different MUAP train patterns were found. The technique was also used to obtain a fetus' ECG and showed better result compared to using ICA.

  • 3193.
    Östlund, Nils
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Yu, Jun
    SLU, Centre of Biostochastics.
    Karlsson, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Adaptive spatio-temporal filtering of multichannel surface EMG signals2006Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 44, nr 3, s. 209-215Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A motor unit (MU) is defined as an anterior horn cell, its axon, and the muscle fibres innervated by the motor neuron. A surface electromyogram (EMG) is a superposition of many different MU action potentials (MUAPs) generated by active MUs. The objectives of this study were to introduce a new adaptive spatio-temporal filter, here called maximum kurtosis filter (MKF), and to compare it with existing filters, on its performance to detect a single MUAP train from multichannel surface EMG signals. The MKF adaptively chooses the filter coefficients by maximising the kurtosis of the output. The proposed method was compared with five commonly used spatial filters, the weighted low-pass differential filter (WLPD) and the marginal distribution of a continuous wavelet transform. The performance was evaluated using simulated EMG signals. In addition, results from a multichannel surface EMG measurement fro from a subject who had been previously exposed to radiation due to cancer were used to demonstrate an application of the method. With five time lags of the MKF, the sensitivity was 98.7% and the highest sensitivity of the traditional filters was 86.8%, which was obtained with the WLPD. The positive predictivities of these filters were 87.4 and 80.4%, respectively. Results from simulations showed that the proposed spatio-temporal filtration technique significantly improved performance as compared with existing filters, and the sensitivity and the positive predictivity increased with an increase in number of time lags in the filter.

  • 3194.
    Östlund, Nils
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Yu, Jun
    SLU, Centre of Biostochastics.
    Karlsson, Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Improved maximum frequency estimation with application to instantaneous mean frequency estimation of surface electromyography2004Inngår i: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 51, nr 9, s. 1541-1546Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to improve the maximum-frequency estimation. Three methods to estimate the maximum frequency of a bandlimited signal with additive white noise were compared. Two existing methods, the threshold-crossing method (TCM) and the hybrid method, were modified for time-frequency representations. A novel approach, the running-block threshold method (RBTM), was introduced. Based on calculation of detection probability (sensitivity) the RBTM improved the maximum-frequency estimate as compared with the TCM. The maximum-frequency estimation methods were also used to determine the integration interval for instantaneous mean-frequency (IMNF) estimation from synthesized surface electromyography containing white noise. Results showed that the IMNF estimate was improved by using any of the three methods and that the RBTM gave the best IMNF estimate.

  • 3195.
    Östlund, Nils
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Yu, Jun
    SLU, Centre of Biostochastics.
    Roeleveld, Karin
    Karlsson, J Stefan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Adaptive spatial filtering of multichannel surface electromyogram signals2004Inngår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 42, nr 6, s. 825-831Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spatial filtering of surface electromyography (EMG) signals can be used to enhance single motor unit action potentials (MUAPs). Traditional spatial filters for surface EMG do not take into consideration that some electrodes could have poor skin contact. In contrast to the traditional a priori defined filters, this study introduces an adaptive spatial filtering method that adapts to the signal characteristics. The adaptive filter, the maximum kurtosis filter (MKF), was obtained by using the linear combination of surrounding channels that maximises kurtosis. The MKF and conventional filters were applied to simulated EMG signals and to real EMG signals recorded with an electrode grid to evaluate their performance in detecting single motor units. The MKF was compared with conventional spatial filtering methods. Simulated signals, with different levels of spatially correlated noise, were used for comparison. The influence of one electrode with poor skin contact was also investigated. The MKF was found to be considerably better at enhancing a single MUAP than conventional methods for all levels of spatial correlation of the noise. For a spatial correlation of 0.97 of the noise, the improvement in the signal-to-noise ratio, where a MUAP could be detected, was at least 6dB. With a simulated poor skin contact for one electrode, the improvement over the other methods was at least 19 dB.

  • 3196.
    Özarslan, Evren
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Yolcu, Cem
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Herberthson, Magnus
    Linköpings universitet, Matematiska institutionen, Matematik och tillämpad matematik. Linköpings universitet, Tekniska fakulteten.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Westin, Carl-Fredrik
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Laboratory for Mathematics in Imaging, Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA.
    Influence of the Size and Curvedness of Neural Projections on the Orientationally Averaged Diffusion MR Signal2018Inngår i: Frontiers in Physics, E-ISSN 2296-424X, Vol. 6, s. 1-10, artikkel-id 17Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Neuronal and glial projections can be envisioned to be tubes of infinitesimal diameter as far as diffusion magnetic resonance (MR) measurements via clinical scanners are concerned. Recent experimental studies indicate that the decay of the orientationally-averaged signal in white-matter may be characterized by the power-law, Ē(q) ∝ q−1, where q is the wavenumber determined by the parameters of the pulsed field gradient measurements. One particular study by McKinnon et al. [1] reports a distinctively faster decay in gray-matter. Here, we assess the role of the size and curvature of the neurites and glial arborizations in these experimental findings. To this end, we studied the signal decay for diffusion along general curves at all three temporal regimes of the traditional pulsed field gradient measurements. We show that for curvy projections, employment of longer pulse durations leads to a disappearance of the q−1 decay, while such decay is robust when narrow gradient pulses are used. Thus, in clinical acquisitions, the lack of such a decay for a fibrous specimen can be seen as indicative of fibers that are curved. We note that the above discussion is valid for an intermediate range of q-values as the true asymptotic behavior of the signal decay is Ē(q) ∝ q−4 for narrow pulses (through Debye-Porod law) or steeper for longer pulses. This study is expected to provide insights for interpreting the diffusion-weighted images of the central nervous system and aid in the design of acquisition strategies.

  • 3197.
    Özarslan, Evren
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Yolcu, Cem
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten.
    Herberthson, Magnus
    Linköpings universitet, Matematiska institutionen, Matematik och tillämpad matematik. Linköpings universitet, Tekniska fakulteten.
    Westin, Carl-Fredrik
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Laboratory for Mathematics in Imaging, Department of Radiology, Harvard Medical School, Brigham and Women's Hospital, Boston, MA, United States.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Avdelningen för medicinsk teknik. Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Effective Potential for Magnetic Resonance Measurements of Restricted Diffusion2017Inngår i: Frontiers in Physics, E-ISSN 2296-424X, Vol. 5, artikkel-id 68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The signature of diffusive motion on the NMR signal has been exploited to characterize the mesoscopic structure of specimens in numerous applications. For compartmentalized specimens comprising isolated subdomains, a representation of individual pores is necessary for describing restricted diffusion within them. When gradient waveforms with long pulse durations are employed, a quadratic potential profile is identified as an effective energy landscape for restricted diffusion. The dependence of the stochastic effective force on the center-of-mass position is indeed found to be approximately linear (Hookean) for restricted diffusion even when the walls are sticky. We outline the theoretical basis and practical advantages of our picture involving effective potentials.

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