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An edge-based segmentation scheme (i.e. boundary detector) for nuclear medicine images has been developed and consists of a multiresolutional Gaussian-based edge detector working in conjunction with a modified version of Nilsson's A* graph-search algorithm. A multiresolution technique of analyzing the edge-signature plot (edge gradient versus resolution scale) allows the edge detector to match an appropriately sized edge operator to the edge structure in order to measure the full extent of the edge and thus gain the best compromise between noise suppression and edge localization. The graph-search algorithm uses the output from the multiresolution edge detector as the primary component in a cost function which is then minimized to obtain the boundary path. The cost function can be adapted to include global information such as boundary curvature, shape, and similarity to prototype to help guide the boundary detection process in the absence of good edge information.

Single-photon emission computed tomography (SPECT) is a nuclear-medicine imaging technique that has been shown to provide clinically useful images of radionuclide distributions within the body. The problem of quantitative determination of tomographic activity images from a projection data set leads to a mathematical inverse problem which is formulated as an integral equation. The solution of this problem then depends on an accurate mathematical model as well as a reliable and efficient inversion algorithm. The effects of attenuation and Compton scatter within the body have been incorporated into the model in the hopes of providing a more physically realistic mathematical model. The attenuated Radon transform is the mathematical basis of SPECT. In this work, the case of constant attenuation is reviewed and a new proof of the Tretiak-Metz algorithm is presented. A space-domain version of the inverse attenuated Radon transform is derived. A special case of this transform that is applicable when the object is rotationally symmetric, the attenuated Abel transform is derived, and its inverse is found. A numerical algorithm for the implementation of the inverse attenuated Radon transform with constant attenuation is described and computer simulations are performed to demonstrate the results of the inversion procedure. With the use of the single-scatter approximation and an energy-windowed detector, the effects of Compton scatter are incorporated into the model. The data is then taken to be the sum of primary photons and single-scattered photons. The scattered photons are modeled by a scatter operator acting on the original activity distribution within the object where the operator consists of convolution with a given analytic kernel followed by a boundary cut-off operation. A solution is given by first applying the inverse attenuated Radon transform to the data set. This leads to a Fredholm integral equation to which a Neumann series solution is constructed. Again simulations are performed to validate the accuracy of the assumptions within the model as well as to numerically demonstrate the reconstruction procedure.

Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: A digital portal X-ray imaging system was developed to replace the radiographic X-ray films currently used for patient position verification at the National Accelerator Centre (NAC) proton therapy facility. The main advantage of a digital system is the short time in which the image can be obtained. Other advantages include optimisation of the image display, effective archiving of the digital images, access from various locations through data networks, and lower operational costs. The digital system described in this thesis consists of a Gd202S:Tb scintillator screen for converting X-rays to visible light, a protected aluminum front silvered mirror to direct the light to a Charge Coupled Device (CCD) camera for capture and a personal computer for data acquisition, processing and display. Compared with other digital imaging systems, this is a simple, compact and affordable system. The properties of the various components were investigated. The Rarex G-130 (Gd202S:Tb) scintillation screen was chosen for its good spatial resolution, high emission efficiency and good matching between the spectral emission wavelength peak and the quantum efficiency of the CCD camera. The spatial resolution measured for the system with a field of view (FOV) of 290 x 190 mnr' is 1.3 lp/mm, which can be improved by increasing the CCD chip resolution or decreasing the field of view, since the CCD camera limits the spatial resolution. Intrinsic detector noise determines the lower limit of the dynamic range of the detector and is reduced by cooling the CCD camera. A dark current exposure is subtracted from the image to remove the bias signal and background signal level mainly caused by thermal noise. Photon noise, beam in-homogeneity and efficiency variations across the CCD chip are removed by a flat field correction. The digital images obtained with this system compare very well with the currently used radiographic film images and they are satisfactory for the purpose of patient position verification. Using the digital system it is possible to reduce the patient dose by 19 % and still obtain satisfactory image quality. / AFRIKAANSE OPSOMMING: 'n Digitale X-straalafbeeldingstelsel is ontwikkel om die radiografiese X-straalfilm wat tans gebruik word vir die kontrolering van die pasientposisionering voor die toediening van protonterapie by die Nasionale Versnellersentrum, te vervang. Die voordeel van die digitale sisteem is dat die beelde feitlik onmiddellik beskikbaar is. Verdere voordele sluit die optimisering van die vertoon van beeldkontras, effektiewe liassering, vinnige bereik deur datanetwerke en lae lopende kostes in. Die digitale sisteem beskryf in die tesis bestaan uit 'n gadolinium oksi-sulfied (Gd202S:Tb) sintillasieskerm wat X-strale omskakel na sigbare lig, 'n eerste-oppervlak aluminiumspieël wat die lig na 'n digitale kamera (CCD kamera) weerkaats en In persoonlike rekenaar vir dataverwerwing, verwerking en vertoon. Vergeleke met ander digitale stelsels is hierdie digitale beeldingstelsel eenvoudig, kompak en bekostigbaar. Die eienskappe van die verskillende komponente van die stelsel is ondersoek. Die Rarex G- 130 (Gd202S:Tb) sintillasieskerm IS gekies vanweë goeie resolusie, hoë emissiedoeltreffendheid en die hoë omsettingsdoeltreffendheid van die digitale kamera by die spektrale emissiegolflengte van dié sintillasieskerm. Die ruimtelike oplosvermoë van die stelsel is bepaal met In veldgrootte van 290 x 190 mnr' as 1.3 lynpare per millimeter. Die ruimtelike oplosvermoë kan verhoog word deur die kameraresolusie te verhoog of die veldgrootte te verklein, omdat die resolusie van die kamera tans die oplosvermoë van die stelsel beperk. Intrinsieke ruis van die detektor beperk die onderste grens van die dinamiese reikwydte van die detektor en kan verminder word deur die kamera te verkoel. 'n Donkerstroom-beeld word van die X-straalbeelde afgetrek om die voorspanningsein en die agtergrondsein, wat hoofsaaklik veroorsaak word deur termiese ruis, te verwyder. Ruis wat ontstaan as gevolg van fluktuasies in die aantal fotone, nie-homogeniteite in die bundel of variasie van die sensitiwiteit in die skerm word verwyder met behulp van 'n plat vlak beeld. Die digitale beelde verkry met die stelsel vergelyk goed met die beelde wat tans op film geneem word en die beeldkwalitiet is voldoende vir die kontrolering van die pasientopstelling. Dit is moontlik om die pasiëntdosis met 19 % te verminder en steeds voldoende beeldkwaliteit te verkry.

In recent years, a growing number of diagnostic examinations in a hospital are being generated by digitally formatted imaging modalities. The evolution of these systems has led to the development of a totally digitized imaging system, which is called Picture Archiving and Communication System (PACS). A high speed computer network plays a very important role in the design of a Picture Archiving and Communication System. The computer network must not only offer a high data rate, but also it must be structured to satisfy the PACS requirements efficiently. In this dissertation, a computer network, called PACnet, is proposed for PACS. The PACnet is designed to carry image, voice, image pointing overlay, and intermittent data over a 200 Mbps dual fiber optic ring network. The PACnet provides a data packet channel and image and voice channels based on Time Division Multiple Access (TDMA) technique. The intermittent data is transmitted over a data packet channel using a modified token passing scheme. The voice and image pointing overlay are transferred between two stations in real-time to support the consultive nature of a radiology department using circuit switching techniques. Typical 50 mega-bit images are transmitted over the image channel in less than a second using circuit switching techniques. A technique, called adaptive variable frame size, is developed for PACnet to achieve high network utilization and short response time. This technique allows the data packet traffic to use any residual voice or image traffic momentarily available due to variation in voice traffic or absence of images. To achieve optimal design parameters for network and interfaces, the PACnet is also simulated under different conditions.

Thermography is a useful tool for analyzing spinal nerve root irritation, but interpretation of digital infrared images is often qualitative and subjective. A new quantitative, computer-aided method for analyzing thermograms, utilizing the human dermatome map, is presented. Image processing and pattern recognition principles needed to accomplish this goal are discussed. Algorithms for segmentation, boundary detection and interpretation of thermograms are presented. An interactive, user-friendly program to perform this analysis has been developed. Due to the relatively large number of images in an exam, speed and simplicity were emphasized in algorithm development. The results obtained correlate well with clinical data and show promise for aiding the diagnosis of spinal nerve root irritation.

This paper describes the design and simulation of a network interface unit (NIU) for a picture archiving and communication system (PACS) network called PACnet. PACnet is a dual fiber optic ring network under development at the Computer Engineering Research Laboratory of the University of Arizona. This network integrates voice, data, and image communications in a hospital environment and supports a throughput rate between 200-500 megabits per second. At each node in the network, an NIU implements the Data Link Layer and Physical Layer protocols of PACnet. The initial network interface unit design for PACnet was a functional description of NIU protocols and major components. In order to construct a demonstration prototype of PACnet,the NIU description must be refined and an architecture must be specified. The NIU design is specified and simulated using the hardware description language VHDL. Simulation results provide information on NIU timing characteristics and logic families required to implement the NIU.

Though several clinical monitoring ways exist and have been applied to detect cardiac atril fibrillation (A-Fib) and other arrhythmia, these medical interventions and the ensuing clinical treatments are after the fact and costly. Current portable healthcare monitoring systems come in the form of Ambulatory Event Monitors. They are small, battery-operated electrocardiograph devices used to record the heart's rhythm and activity. However, they are not energy-aware ; they are not personalized ; they require long battery life, and ultimately fall short on delivering real-time continuous detection of arrhythmia and specifically progressive development of cardiac A-Fib. The focus of this dissertation is the design of a class of adaptive and efficient energy-aware real-time detection models for monitoring, early real-time detection and reporting of progressive development of cardiac A-Fib.... The design promises to have a greater positive public health impact from predicting A-Fib and providing a viable approach to meeting the energy needs of current and future real-time monitoring, detecting and reporting required in wearable computing healthcare applications that are constrained by scarce energy resources. / by Redjem Bouhenguel. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

A detailed dosimetric comparison between Inverse Planning by Simulated Annealing (IPSA) and Dose Points (DP) optimized treatment plans has been performed for High Dose Rate (HDR) brachytherapy of skin lesions using Freiburg Flap applicator in order to find out whether or not IPSA offers better clinical dosimetric outcomes for lesions categorized into four different curvatures. Without compromising target coverage, IPSA reduced the volume of Planning Target Volume (lesion) that received at least 125% of the prescription dose on average by 41%. It also reduced the volume of the healthy skin surrounding the lesion that receives at least 100% of the prescription dose on average by 42%. IPSA did not show any advantage over DP in sparing normal structures underlying the lesions treated. Although DP optimization algorithm has been regularly used at Lynn Cancer Institute for HDR brachytherapy of skin lesions, recent upgrades in IPSA software have made IPSA more amenable to rapid treatment planning and therefore IPSA can be used either in place of DP or as its alternative. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Cardiac auscultation, an important part of the physical examination, is difficult for many primary care providers. As a result, diagnoses are missed or auscultatory signs misinterpreted. A reliable, automated means of interpreting cardiac auscultation should be of benefit to both the primary care provider and to patients. This paper explores a novel approach to this problem and develops an algorithm that can be expanded to include all the necessary electronics and programming to develop such a device. The algorithm is explained and its shortcomings exposed. The potential for further development is also expounded. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection