Développement d'un système de tomographie optique laminaire pour application à l'imagerie de la moelle épinière du petit animal

Accélération d'une approche régularisée de reconstruction en tomographie à rayons X avec réduction des artéfacts métalliques

Système médical intégré de radar pour la surveillance de précision des battements cardiaques et du statut respiratoire

Chioukh, Lydia (2009)  

  Mémoire de maîtrise, École Polytechnique de Montréal.

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Résumé

Résumé: La technologie radar, longtemps réservée au domaine militaire, est maintenant disponible dans le domaine civil pour l’avertissement de collision automobile, ainsi que dans le secteur biomédical pour la mise au point de systèmes de « monitoring » permettant de suivre de manière non invasive les fonctions vitales du patient telles que la respiration ou le rythme cardiaque. Placés au plafond d'une chambre d'hôpital, les systèmes RF biomédicaux peuvent suivre les rythmes cardiaques ou respiratoires de plusieurs patients en même temps. Il est également possible avec ces systèmes de donner l'alarme rapidement dans le cas d'apnée du sommeil ou du syndrome de mort subite chez les nouveaux nés. Une autre application est la surveillance des fonctions vitales du fœtus dans le ventre d’une mère lors de grossesses critiques. Dans un contexte quelque peu différent, ces systèmes RF biomédicaux sont actuellement étudiés pour une surveillance des zones de haute sécurité ou pour la recherche de survivants lors de séismes ou autre catastrophe. Pour cette dernière application, le système RF doit être capable d’assurer deux fonctions: la détection des signaux vitaux et la localisation d’une cible. L’objectif de ce projet de recherche est de concevoir des systèmes radars Doppler permettant de détecter les battements cardiaques et la respiration d’un patient sans contact direct avec la peau. Une analyse de ces systèmes tenant compte des ondes électromagnétiques des tissus humains est proposée. De plus, plusieurs prototypes sont fabriqués et testés. La conception et les résultats de simulations et de mesures sont présentés dans ce mémoire. Trois systèmes opérants à des fréquences différentes ont été réalisés : 5.8 GHz, 24 GHz et 35 GHz. Le choix de la fréquence est justifié par la tendance de miniaturisation du système et l’appartenance à la bande ISM (Industriel, Scientifique, et Médical). Outre les fréquences d’opérations, ces systèmes diffèrent également dans leur architecture et les technologies utilisées. Leurs performances obtenues expérimentalement sont comparées et discutées. De plus, des méthodes de traitement du signal sont appliquées pour séparer le signal du battement de cœur et celui de la respiration.

ABSTRACT: 

Radar technology, long limited to military applications, is now available to the civilian sectors such as automotive collision warning in traffic controls and safe navigations, and in the biomedical sector for the development of systems of non-invasive monitoring of patient's vital signs such as breathing and/or heartbeats. Positioned over the ceiling of a hospital care room, such RF systems can monitor the cardiological activities or respiratory status of several patients simultaneously. With these systems it is also possible to give a fast emergency alarm in the case of a sleep apnea syndrome or sudden death in neonates. Another application is the monitoring of vital functions of the foetus inside the womb of a mother during abnormal pregnancy. In a somewhat different context, these RF biomedical systems are currently designed for surveillance of high security areas or for searching and rescuing of survivors after earthquakes or other disasters. For this last application, the RF system must be able to do two functions: the vital signal detection and the local positioning. The objective of this research project is to design a Doppler radar system to detect the heartbeat and respiration status of a patient without direct skin (invasive) contact. An analysis of the proposed system taking into account the electromagnetic wave propagation in human tissue is proposed. In addition, several prototypes are fabricated and tested. The design, simulation results and measurements are presented in this thesis. Three systems operating at different frequencies were built up: 5.8 GHz, 24 GHz, and 35 GHz. The choice of frequency is justified by the trend of miniaturization and to fulfill the ISM band (Industrial, Scientific and Medical) specifications. Besides the frequency of operation, these systems also differ in their architectures and technologies. Their experimental performances are compared and discussed. In addition, different signal processing methods are used to separate the heartbeat signal from its respiration counterpart, and the experimental results are compared while some important conclusions are reached.

Left Ventricular Viability Maps : Fusion of Multimodal Images of Coronary Morphology and Functional Information

Béliveau, Pascale (2009)  

Mémoire de maîtrise, École Polytechnique de Montréal.

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Résumé

RÉSUMÉ Les maladies coronariennes demeurent encore la première cause de décès aux Etats-Unis étant donné que le taux de mortalité lié à ces maladies enregistré en 2005 est d’une personne sur cinq. Les sténoses (obstructions des artères coronaires) se manifestent par un rétrécissement du diamètre des coronaires, produisant une ischémie soit une réduction du flot sanguin vers le myocarde (le muscle cardiaque). Dans les cas les plus graves, les cellules qui composent le myocarde meurent définitivement et perdent leur fonction contractile. En présence de cette maladie les cliniciens ont recours à l’imagerie médicale pour étudier l’état du myocarde afin de déterminer si les cellules qui le composent sont mortes ou non ainsi que pour diagnostiquer les sténoses dans les coronaires. Actuellement, le clinicien utilise l’imagerie nucléaire pour étudier la perfusion du myocarde afin de déterminer son état. Une projection de cette information sur un modèle segmenté du myocarde, soit le modèle à 17-segments, établie le lien entre les zones atteintes et les coronaires qui sont les plus responsables de leur irrigation. Ce n’est que par la suite, lors d’une angiographie, que le clinicien pourra identifier les sténoses et possiblement intervenir par revascularisation. Une autre méthode de visualisation de la structure coronarienne et de la présence de sténoses est la méthode Green Lane. Le clinicien reproduit la structure des coronaires sur une carte circulaire en se basant sur l’angiographie. L’objectif de notre projet de recherche est de créer un modèle spécifique au patient où il serait possible de voir les territoires coronariens sur la surface du myocarde fusionnés avec la viabilité myocardique. Ce modèle s’adapterait au patient et permettrait l’étude d’autres groupes de coronaires, ce qui n’est pas possible avec le modèle à 17-segments qui est fixe et ne présente que les trois groupes principaux de coronaires (coronaire droite, gauche et circonflexe). De plus, ce modèle divise la surface de l’épicarde en segments à partir de données statistiques qui sont limitées par la nature et la représentativité de l’échantillon de la population considérée et ne permet pas de visualiser la distribution de perte de viabilité sur la surface épicardique.

ABSTRACT

 Coronary heart disease (CHD) can be attributed to the build up of plaque in the coronary arteries (atherosclerosis) which leads to ischemia, an insufficient supply of blood to the heart wall, which results in myocardial dysfunction. When ischemia remains untreated an infarction may appear (areas of necrosis in cardiac tissues) and consequently the heart’s contractility is affected, which may lead to death. This disease is the basis of one of every five deaths in the United States during 2005, elevating this disease to the largest cause of death in United States. In standard clinical practice, perfusion and viability studies allow clinicians to examine the extent and the severity of CHD over the myocardium. Then, by consulting a population-based coronary territory model, such as the 17-segment model, the clinician mentally integrates affected areas of myocardium, found in nuclear or magnetic resonance imaging, to coronaries that typically irrigate this region with blood. However, population-based models do not fit every patient. There are individuals whose coronary tree structure deviates from that of the majority of the population. In addition, the 17-segment model limits the number of coronary groups to three: left coronary artery (LAD), right coronary artery (RCA) and left circumflex (LCX). Moreover this map is not continuous; it divides the myocardial surface in segments.Our objective is therefore to create a patient-specific map explicitly combining coronary territories and myocardial viability. This continuous model would adapt to the patient and allow the study of groups of coronary unavailable with standard models. After having identified loss of viability, the clinician would use this model to infer the most likely obstructed coronary artery responsible for myocardial damage. Visualization of the loss of viability along with coronary structure would replace the physician’s task of mentally integrating information from various sources.

Heat Transfer Model for Menorrhagia

Ashraf, Shabina (2012) 

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Abstract

Thermal balloon ablation is a modern non surgical procedure for the treatment of menorrhagia. It works on the principle of ablating the endometrial layer beyond a point of
regeneration thereby reducing blood loss. Mathematical modelling of this procedure helps in improving accuracy of the treatment which reduces adverse affects of the procedure thereby making the procedure safer. Pennes bio-heat equation is used to calculate transient temperature in the uterine cavity. Thermal injury integral is used to calculate the irreversible thermal destruction of the uterine tissue. When thermal injury integral equals to or is greater than 1, the tissue is destroyed which prevents regeneration of the endometrium. The presented mathematical model is verified with the published experimental findings to check the validity of the model. The effect of overall convective heat transfer coefficient and balloon fluid temperature on tissue damage is studied. For an overall convective heat transfer coefficient above 2000Wm-2K-1, maximum depth of ablation at 87°C was 3.77mm. For
higher fluid temperature, depth of ablation is found to increase. At a fluid temperature of 93°C, depth of ablation is found to be 4.39mm for an overall convective heat transfer coefficient 1000Wm-2K-1. The temperature at the surface of endometrium is found to increase with the increase in fluid temperature and also with the increase in overall convective heat transfer coefficient. The obtained results are valid in the absence of any pathological
condition. In case of existing pathological conditions, the effects caused by them are also to be included. Thus, mathematical modelling involving convective heat losses is an effective tool to make thermal balloon procedure more accurate.

Item Type:	Thesis (BTech)
Uncontrolled Keywords:	menorrhagia, thermal ballon ablation, ablation depth, endometrial surface temperature, overall convective heat transfer coefficient

Investigation on the effect of zinc oxide nanoparticles in the aggregation of hen egg lysozyme

Arakha, Manoranjan (2012)

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Abstract

Protein misfolding and aggregation are responsible for several human pathologies commonly known as protein misfolding diseases. The various examples of protein misfolding diseases are: Alzheimer disease, spongiform encephalopathy, diabetes type 2, serpin-deficiency disorder, Huntington disease, Parkinson disease, amyloid polyneuropathy, and several others. The current research work was carried out to investigate the potential of ZnO nanoparticle to prevent lysozyme aggregation. ZnO nanoparticles were synthesized by chemical precipitation method from Zinc acetate dihydrate and urea. The optical, morphological and structural properties of synthesized ZnO nanoparticles have been studied using UV-Vis spectrophotometer, SEM, DLS, XRD and EDS. UV-Vis spectroscopic study shows that ZnO nanoparticles have surface plasmon resonance at 375nm. DLS analysis shows the average size of synthesized ZnO nanoparticle to be 68 nm. The EDS analysis shows the elemental composition of synthesized ZnO naoparticles and XRD study confirms the wurtzite structure of ZnO nanoparticles. The lysozyme aggregation was prepared by heating the native lysozyme at 1000C. The effect of ZnO nanoparticles on the aggregation of lysozyme was studied. DLS analysis shows the mean size of the aggregates decreases with increasing concentration of ZnO nanoparticle (NP), which was further confirmed by SEM analysis. UV-Vis and Fluorescence spectroscopic studies were performed to analyze the structural changes of lysozyme upon binding with nanoparticles. The Congo red assay was performed to study the formation of amyloid fibrils.

Item Type:	Thesis (MTech)
Uncontrolled Keywords:	Protein misfolding, Aggregation, Nanoparticles, Zinc oxide, Congo red assay

Modification of collector of Electro spinning Machine for the fabrication of 3-D nanofibrous scaffold for Tissue Engineering applications

Animesh, Amulya and Mishra, Vivek (2012) 

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Abstract

The present work deals with the modification of collector system of the existing Free liquid surface type electrospinning machine to prepare 3-D Nanofibrous scaffold. Initially the trial has been given to prepare 2-D electrospun nanofibers using PVA polymer solution. To make 3-D nanofibrous scaffold, a cylindrical pipe made up of plastic material with required diameter was introduced as the collector. A motor attached to the collector to rotate at its horizontal axis thus acting as a guide to the charged polymer jet to let it deposit around its curved surface area. The cylindrical-shaped nanofibrous PVA scaffolds were then prepared that can be useful for tissue engineering application especially in the development of vascular blood vessels implant.

Item Type:	Thesis (BTech)
Uncontrolled Keywords:	Key words: Tissue engineering, 3-D nanofibrous scaffolds, cylindrical fibers, vascular blood vessels implant.

Electrophoretic deposition of hydroxy-apatite on Ti6Al4V

Anand, Rajan (2012)

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Abstract

In the present study, electrophoretic deposition of sintered and non sintered hydroxyapatite on Ti6Al4V has been carried out at a constant voltage of 30V for 5, 10 and 15 minute duration at different pH values of 1.5, 2.5 and 3.5 respectively for improving the property of coated layer. An uniform coating of hydroxyapatite (HAp) will results in a better cellular activity. As-received Ti-6Al-4V samples are polished by following the standard metallographic technique to prepare a scratch free surface. After coating under different processing conditions the surface are characterized by scanning electron microscopy (SEM) for morphological studies and x-ray diffraction technique for phase analysis. SEM images show that at lower pH value 1.5 and constant voltage 30V crack were not present at coating surface. Comparison between sintered (900˚ for 2 hrs) and non-sintered hydroxyapatite deposition and phase characterization analysis was done by XRD analysis. XRD analysis indicated that before sintering, some other compounds were present in HAp powder but after sintering they were not oxidized. The presence of chemical elements on the deposited surface was assessed by EDS.
(Keywords: Ti6Al4V, Electrophoretic deposition, Hydroxyapatite, XRD, SEM, EDS )

Item Type:	Thesis (BTech)
Uncontrolled Keywords:	Keywords: Ti6Al4V, Electrophoretic deposition, Hydroxyapatite, XRD, SEM, EDS

Modeling of Light Distribution in Tissue by Monte Carlo Simulation

 Priyanka (2012) 

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Abstract

Laser has got a property of having high irradiance and penetration power to be used for different medical purposes such as diagnostic, imaging, and treatment of several diseases. When laser interacts with tissue (considering particle nature of laser light), photons get absorbed, scattered or transmitted depending upon optical properties of the tissue. For laser treatment, information such as fluence rate, reflectance, power, spot size etc. should be known a priori. The optical properties of tissue affect the photon distribution inside the tissue. Therefore, Monte Carlo method is used to simulate photon distribution. The effect of variation of scattering coefficient, anisotropy, and refractive index of tissue (optical properties) on fluence rate and reflectance is studied. The scattering coefficient variation shows changes in fluence rate, in which penetration of photon is high for lower scattering coefficient and decreases as the coefficient increases. Photons get evenly distributed for lower value of anisotropy of the tissue. Parametric studies suggested that refractive index did not have significant effect on the fluence rate and the reflectance.

Item Type:	Thesis (BTech)
Uncontrolled Keywords:	photon distribution, optical parameters, Monte Carlo simulation.

Numerical Modeling of Amperometric Biosensor

., Nikhil (2012) Numerical Modeling of Amperometric Biosensor. BTech thesis.

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Abstract

Amperometric biosensor is a type of biosensor which measures the change in the current of a working indicator electrode by direct electrochemical oxidation or reduction of the products of a biochemical reaction. In these types of biosensors, the potential at the electrode is made constant during the measurement of current. These are known to be reliable, cheap and highly sensitive for environment, clinical and industrial purposes. These biosensors have plethora of applications in diverse fields; hence mathematical modeling of the same is highly desirable. This can help in prefiguring its various characteristics. A mathematical model is proposed which can study the cyclic conversion of substrate in an amperometric biosensor. The governing parameters for the Michaelis-Menten kinetics of enzymatic reactions are the enzyme kinetic rate and the diffusion rate across the enzymatic layer. Relative influence of these parameters is decided by a non dimensional number called Damkohler number, which is a ratio of the rate of enzymatic reaction to the rate of diffusion. The effect of Damkohler number on the current density, substrate concentration, and product concentration has been studied. It has been observed that when the Damkohler number is low then enzyme kinetics controls the biosensor response whereas when it is high (of the order of 1) the response is under control of diffusion rate. The current density is found to increase with the decrease in Damkohler number and vice versa.

Item Type:	Thesis (BTech)
Uncontrolled Keywords:	Biosensor