| 1. |
- Rowa, Per, et al.
(författare)
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Automated Malaria Parasite Detection
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A system for malaria parasite detection in thin blood-smears is presented. Sample slides prepared with standard methods are accepted. A low-cost TV-camera mounted on an ordinary microscope with a computer controlled stage is used as a picture sensor. Frames, digitized in windows of 64 x 64 pixels are fed into a special purpose picture processor at normal frame rate (25 frames/sec). In the picture processor measurements are made on the images at high speed. The classification problem is split into different levels each having different characteristics such as different sampling density. Four classes, three of which are different types of malaria parasites, are recognized. As a whole the classification is best labelled as a sequential pattern recognition procedure.In its preliminary version the system has been run at a speed comparable to that of a human operator, that is l 500 cells per minute. A test on 80 000 cells gave 25 false negatives out of 283 parasites (9%) and 41 false positives (0.05%).
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| 2. |
- Zanoli, Massimiliano, 1989
(författare)
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Ultra wideband microwave hyperthermia for brain cancer treatment
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite numerous clinical trials demonstrating that microwave hyperthermia is a powerful adjuvant modality in the treatment of cancers, there have been few instances where this method has been applied to brain tumors. The reason is a combination of anatomical and physiological factors in this site that require an extra degree of accuracy and precision in the thermal dose delivery. Current clinical applicators are not able to provide such control, partly because they are designed to operate at a single fixed frequency. In terms of treatment planning, the use of a single frequency is limiting as the size of the focal spot cannot be modified to accommodate the specific tumor volume and location. The introduction of ultra wide-band (UWB) systems opens up an opportunity to overcome these limitations, as they convey the possibility of adapting the focal spot and obtaining different power deposition patterns to reduce the heating of healthy tissues. In this thesis, we explore whether the current SAR-based treatment planning methods can be meaningfully translated to the UWB setting and propose new solutions for deep UWB microwave hyperthermia. We analyze the most commonly used cost functions for treatment planning optimization and discuss their suitability for use with UWB systems. Then, we propose a novel SAR-based cost function (HCQ) for UWB optimization that exhibits a high correlation with the resulting tumor temperature. To solve for the HCQ, we describe a novel, time-reversal-based, iterative scheme for a rapid and efficient optimization of UWB treatment plans. Next, we investigate the design possibilities of UWB brain applicators and introduce a fast E-field approximation scheme to quickly explore a large number of array configurations. The method determines the best antenna arrangement around the head with respect to the multiple objectives and requirements of clinical hyperthermia. Together, the proposed solutions manage to achieve the level of tumor coverage and hot-spot suppression that is necessary for a successful treatment. Finally, we investigate the benefit of integrating hyperthermia delivered by an optimized UWB applicator into the radiation therapy plan for a pediatric medulloblastoma patient. The results suggest that UWB microwave hyperthermia for brain cancer treatment is feasible and motivate efforts for further development of UWB applicators and systems.
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| 3. |
- Karlsson, Mattias
(författare)
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Model-based Analysis of Temporal Patterns in Atrioventricular Node Conduction During Atrial Fibrillation
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The lifetime risk of developing atrial fibrillation (AF) is estimated to be between 1in 3 to 1 in 4 individuals, making it the most common arrhythmia in the world.For persistent AF, rate control drugs with the purpose to affect the conduction properties of the atrioventricular (AV) node are the most common treatment. The drug of choice varies between β-blockers and calcium channel blockers, often chosen empirically. This can lead to long periods of time before sufficient treatment is found. However, due to the physiological differences between the drug types, it could be possible to predict the effect of the drugs and thus assist in treatment selection. The main focus of this thesis is therefore to assess drug-dependent differences in the AV node, using non-invasive measurements. This thesis comprises an introduction to the subject as well as two papers. The first paper proposes a framework for assessing the conduction properties of the AV node non-invasively using a mathematical model of the AV node in combination with a genetic algorithm.The second paper is a continuation of the work in paper I, where the proposed workflow was adapted to assess the drug-dependent effect on the AV node of four different rate control drugs during a period of 24 hours.The methods presented in this thesis have made it possible to assess both the refractory period and the conduction delay in the AV node in a robust way using ECG, and by doing so found population-related differences in AV node conduction properties between drug types.
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| 4. |
- Rigato, Cristina, 1989, et al.
(författare)
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Audiometric comparison between Bone Anchored Hearing Aid and Bone Conduction Implant
- 2016
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Ingår i: AudiologyNOW!2016.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Patients suffering from conductive or mixed hearing losses can often be successfully rehabilitated using bone conduction devices (BCDs). Percutaneous BCDs are widely used today, but the trend is to develop transcutaneous solutions able to providing equally good rehabilitation and less complications. Here, the transcutaneous Bone Conduction Implant was compared with percutaneous BCDs under the hypothesis that they are equally effective. Tone and speech audiometry and questionnaires were utilized to assess the overall performance. The outcome confirmed the initial hypothesis.
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| 5. |
- Bondesson, Johan, 1991, et al.
(författare)
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Definition of Tubular Anatomic Structures from Arbitrary Stereo Lithographic Surface
- 2017
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Ingår i: Initiative Seminar Engineering Health, 8-9 November 2017, Chalmers.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An accurate description of anatomies and dynamics of vessels is crucial to understand their characteristics and improve surgical techniques, thus it is the basis, in addition to surgeon experience, on which stent design and operation procedures rely. The process of producing this description is user intensive, and recent improvement in image processing of medical3D imaging allows for a more automated workflow. However, there is a need to bridge the gap from a processed geometry to a robust mathematical computational grid. By sequentially segmenting a tubular anatomic structure, here defined by a stereo lithographic (STL) surface, an initial centerline is formed by connecting centroids of orthogonal cross-sectional contours along the length of the structure. Relying on the initial centerline, a set of non-overlapping 2D cross sectional contours are defined along the centerline, a centerline which is updated after the 2D contours are produced. After a second iteration of producing 2D contours and updating the centerline, a full description of the structure is created. Our method for describing vessel geometry shows good coherence to existing method. The main advantages of our method include the possibility of having arbitrary triangulated STL surface input, automated centerline definition, safety against intersecting cross-sectional contours and automatic clean-up of local kinks and wrinkles.
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| 6. |
- Enejder, Annika, 1969, et al.
(författare)
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SHG Imaging for Tissue Engineering Applications
- 2016
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Ingår i: Second Harmonic Generation Imaging. - : CRC Press. - 9781439849156 - 9781439849149 ; , s. 409-426
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Treatment of lost tissue oen relies on transplantations, either of donor or of autologous tissue. Both alternatives have limitations; there is for example a limited supply of donor transplants, which also require immunosuppression therapy with possible side eects. Transplanted autologous tissue may lack some of the functions of the original tissue and the procedure may also introduce complications at the donor site. In some cases, articial substitutes manufactured from nonbiological materials can be used, for example, synthetic polymer blood vessels or joint replacement prostheses. However, these replacements have drawbacks such as risk for infections, limited material durability, and lack of mechanisms for repair, growth, and remodeling. For these reasons, development of advanced articial tissue constructs with adaptive capabilities is desirable.
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| 7. |
- Davidsson, Johan, 1967, et al.
(författare)
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A Model for Research on Penetrating Traumatic Brain Injuries
- 2019
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Ingår i: Neuromethods. - New York, NY : Springer New York. - 1940-6045 .- 0893-2336. ; 149, s. 47-59
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The animal model presented here produces high-speed penetrating traumatic brain injuries (pen-TBI) to simulate a form of neurotrauma that is severe and is the prevailing TBI in warzones and in areas with high incidence of violence. Commonly, these neurotraumas involve laceration of brain tissue, accompanying hemorrhage, edema, and inflammation. This also occurs in the pen-TBI model designed for rats that is presented here. During trauma, a probe, constructed in one single unit in aluminum and guided by a probe holder, is propelled by a lead bullet and penetrates at high speed into the brain parenchyma of the anesthetized animal. The animal’s head is held in position in a purposely built stereotactic frame. This frame can be adjusted in position relative the tip of the probe so that the tip of the probe is positioned on the exposed dura, using three orthogonally arranged horizontal slides. This procedure will facilitate high similarity in probe penetration location. By adjusting the air pressure in the air-driven accelerator used to accelerate the lead bullet, a large range of probe velocities can be achieved; 110 m/s probe velocity is commonly used. Several probe tip shapes are available for use in the pen-TBI model; pointy, blunt, and flat. The distance the probe penetrates the brain can be controlled. A typical distance is 5.5 mm, and this distance has been found to be almost independent of probe velocity and probe tip shape. After the probe has penetrated the animal, the pen-TBI device facilitates removal of the probe without causing additional brain damage. To do so, the animal is removed using the horizontal slider on the device that moves the animal’s head away from the probe in the direction of probe travel. The pen-TBI device is easy to operate and requires limited pre-trauma and post-trauma surgery. The device induces a small cavity, primary injury in a greater volume of the brain than the cavity and secondary injuries in an even greater volume that is several times that of the primary injury volume. The model appears to produce identical injuries in terms of appearance and dimensions in-between animals of same sex and body mass. The device also produces substantial but short-lived intracranial brain pressure changes, some 8-bar overpressure in the contralateral ventricle has been recorded, with high repeatability.
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| 8. |
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| 9. |
- Candefjord, Stefan
(författare)
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Combining the tactile resonance method and Raman spectroscopy for tissue characterization towards prostate cancer detection
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Prostate cancer (PCa) is the most common male cancer in Europe and the US, and only lung and colorectal cancer have a higher mortality among European men. In Sweden, PCa is the most common cause of cancer-related death for men.The overall aim of this thesis was to explore the need for new and complementary methods for PCa detection and to take the rst step towards a novel approach: combining the tactile resonance method (TRM) and Raman spectroscopy (RS). First, the main methods for PCa detection were reviewed. Second, to establish a robust protocol for RS experiments in vitro, the eects of snap-freezing and laser illumination on porcine prostate tissue were studied using RS and multivariate statistics. Third, measurements on porcine and human tissue were performed to compare the TRM and RS data via multivariate techniques, and to assess the accuracy of classifying healthy and cancerous tissue using a support vector machine algorithm.It was concluded through the literature review that the gold standard for PCa detection and diagnosis, the prostate specic antigen test and systematic biopsy, have low sensitivity and specicity. Indolent and aggressive tumors cannot be reliably dierentiated, and many men are therefore treated either unnecessarily or too late. Clinical benets of the state-of-the-art in PCa imaging - advanced ultrasound and MR techniques - have still not been convincingly shown. There is a need for complementary and cost-eective detection methods. TRM and RS are promising techniques, but hitherto their potential for PCa detection have only been investigated in vitro.In the RS study no evidence of tissue degradation due to 830 nm laser illumination at an irradiance of ∼3 · 1010 W m-2 were found. Snap-freezing and subsequent storage at -80° C gave rise to subtle but signicant changes in Raman spectra, most likely related to alterations in the protein structure. The major changes due to PCa do not seem to be related to the protein structure, hence snap-freezing may be applied in our experiments.The combined measurements on porcine and human prostate tissue showed that RS provided additional discriminatory power to TRM. The classication accuracy for healthy porcine prostate tissue, and for healthy and cancerous human prostate tissue, was > 73%. This shows the power of the support vector machine applied to the combined data.In summary, this work indicates that an instrument combining TRM and RS is a promising complementary method for PCa detection. Snap-freezing of samples may be used in future RS studies of PCa. A combined instrument could be used for tumor-border demarcation during surgery, and potentially for guiding prostate biopsies towards lesions suspicious for cancer. All of this should provide a more secure diagnosis and consequently more effcient treatment of the patient.
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| 10. |
- Fredén Jansson, Karl-Johan, 1988
(författare)
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The Balanced Electromagnetic Separation Transducer for Bone Conduction Audiometry and Hearing Rehabilitation
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hearing via air conduction (AC) and bone conduction (BC) are attributed to bethe natural ways of conducting sound to the cochlea. With AC hearing, air pressurevariations are transmitted to the cochlea via the ear canal, whereas with BChearing, sound vibrations are transmitted through the skull bone to the cochlea.Patients with a hearing loss in the cochlea or auditory nerve are commonly rehabilitatedwith conventional AC hearing aids in the ear canal, but also using cochlearimplants. If the pathway for AC sound to reach the cochlea is obstructed, patientscan often benet from bone conduction devices (BCDs). In order to determinethe type and degree of hearing loss, the BC hearing thresholds are measured usinga bone conduction vibrator, and then analyzed together with the AC hearingthresholds for the diagnosis and to suggest an appropriate rehabilitation alternative.The motor unit in conventional BCDs and bone vibrators are known togenerate high amount of distortion at low frequencies where the Balanced ElectromagneticSeparation Transducer (BEST) principle may oer a new era in BChearing rehabilitation and audiometry.This thesis combines two BC hearing related topics, where the rst topic is anevaluation of a new audiometric bone vibrator, Radioear B81, which is assumedto oer more accurate BC hearing threshold measurements. The second topic isrelated to a new type of active transcutaneous BCD, called the Bone ConductionImplant (BCI), which leaves the skin intact by using a wireless solution thatdoes not require a permanent skin penetration. Even though the applications aredierent, both devices use the BEST principle as motor unit in their design.The audiometric bone vibrator Radioear B81 was found to have an improvedperformance at low frequencies where it can produce higher output levels with lessharmonic distortion than the conventional Radioear B71. In a clinical study of therst six patients, the BCI was found as ecient as already commercially availableBCDs, and with the advantage of not needing a skin penetration. In a technicalevaluation of the BCI, it was shown to be a mechanically robust design and totolerate magnetic resonance imaging at 1.5 Tesla.
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