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Evaluation Of Doppler Ultrasound Velocity And Flow Measurements, Daniel William Rickey
Evaluation Of Doppler Ultrasound Velocity And Flow Measurements, Daniel William Rickey
Digitized Theses
Doppler ultrasound instruments have been used clinically for about 30 years and have proved to be highly reliable for the detection of arterial disease. In addition, a number of different Doppler instrument designs and techniques have been proposed to provide quantitative measurements such as volume blood flow, percent stenosis, and waveform indices. Before any measurement technique can be used, it must be validated.;We chose a two-pronged approach to the problem of evaluating Doppler ultrasound measurements of blood flow. We first developed a flow system that mimics the vasculature. The flow system comprises a computer-controlled pump, blood mimic, and a wall-less …
Design Of A Collimated Line Source For Transmission Ct Imaging Of The Head With A Spect System, Brad James Kemp
Design Of A Collimated Line Source For Transmission Ct Imaging Of The Head With A Spect System, Brad James Kemp
Digitized Theses
Single photon emission computed tomography (SPECT) has the potential to provide absolute quantitative information about the function of an organ. However, two factors which limit accurate quantification are the attenuation of the gamma rays emitted from the radiopharmaceutical concentration and the inability to define the anatomic region being quantified. Presented in this thesis is an attenuation correction that compensates SPECT brain images for attenuation and a transmission imaging system that (a) provides the distribution of attenuation coefficients required for the attenuation compensation and (b) simplifies regional identification by registering the functional SPECT images onto the anatomic transmission images. The attenuation …
Automated Analysis Of Nuclear Medicine Images: Towards Artificial Intelligence Systems, Piotr Jan Slomka
Automated Analysis Of Nuclear Medicine Images: Towards Artificial Intelligence Systems, Piotr Jan Slomka
Digitized Theses
Automated methods for the analysis of nuclear medicine images could provide an objective diagnosis, and means to transfer sophisticated expertise to less experienced centres. The goal of this study was to develop software methods for the automated analysis of (a) Quality Control (QC) images, and (b) myocardial perfusion tomography images.;The system for the automated analysis of QC images was based on feature extraction algorithms, which provided input to a higher level diagnostic expert system. Several features characterizing QC images were defined. Rule-based and object-oriented expert systems were created to guide personnel in QC procedures, detect gamma camera faults, and suggest …
Estimation Of Haemodynamic Parameters Using Magnetic Resonance Imaging, Richard Frayne
Estimation Of Haemodynamic Parameters Using Magnetic Resonance Imaging, Richard Frayne
Digitized Theses
Techniques have been both analyzed and developed for the estimation of a number of important haemodynamic parameters (including velocity, volume flow rate and shear rate) using a magnetic resonance (MR) scanner. Accurate estimation of these parameters is important because information about the haemodynamic state may (1) aid our understanding of vascular disease processes; and (2) provide a clinically-useful test for the presence of vascular disease.;The objectives of this thesis are: (1) the development of techniques that are necessary for the accurate and precise simulation of physiological flow waveforms in in vitro MR research; (2) the furthering of our understanding of …
Computing The Modulation Transfer Function Of Magnetic Resonance Imagers, Michael C. Steckner
Computing The Modulation Transfer Function Of Magnetic Resonance Imagers, Michael C. Steckner
Digitized Theses
The quality of images produced by imaging devices of all types can be analyzed and quantified by a variety of metrics. Resolution is an important metric for all imaging devices because if the resolution characteristics do not meet the minimum requirements of an application, the resultant image may be unsuitable and possibly misleading. One resolution metric, called the Modulation Transfer Function (MTF), describes the ratio of input to output signal magnitude as a function of spatial frequency. Application of the MTF is limited to systems whose output scales linearly with input (linearity) and produces the same output image regardless of …
Physical Factors Influencing The Quality Of Megavoltage Radiographs, David Anthony Jaffray
Physical Factors Influencing The Quality Of Megavoltage Radiographs, David Anthony Jaffray
Digitized Theses
It has been recognized that improved methods of verifying radiation field placement in external beam radiotherapy are required in order to make frequent checks of field placement feasible. As a result, a large number of electronic portal imaging systems have been developed as possible replacements for film. These developments have produced digital systems with faster acquisition and display (few seconds), but the quality of the images acquired with such systems is still disappointing. The reasons for this are not well known, possibly because relatively few studies of the fundamental physics of imaging at megavoltage energies have been made.;This thesis examines …
Contrast-Enhanced Ct Measurement Of Blood-Brain Permeability In Human Brain Tumors, Wai Tong Yeung
Contrast-Enhanced Ct Measurement Of Blood-Brain Permeability In Human Brain Tumors, Wai Tong Yeung
Digitized Theses
A contrast enhanced CT method was developed for measuring the blood-brain permeability (K) and cerebral plasma volume (V{dollar}\sb{lcub}\rm p{rcub}){dollar} in human brain tumors in-vivo. In patient studies, Isovue 300 (iopamidol) was injected intravenously at a dosage of 1 ml/kg patient body weight. It was followed by serial head scanning of the tumor and arterial blood sampling to measure the contrast concentration in tumor and arterial plasma respectively. The leakage of iopamidol into the brain through the blood-brain barrier was modelled as an exchange process between two compartments, namely, the intravascular plasma space and the tissue interstitial space. Using this compartmental …
Projection Presaturation: A New Approach To Producing Conformal Selective Excitation In Magnetic Resonance, Saryu Singh
Projection Presaturation: A New Approach To Producing Conformal Selective Excitation In Magnetic Resonance, Saryu Singh
Digitized Theses
In recent years, several techniques of volume-selective excitation for extracting signals from a chosen region in a large sample have appeared for various applications in magnetic resonance (MR). Most of these techniques suffer from, at least, the T{dollar}\sb2{dollar}-decay problem, which rules out their application for short T{dollar}\sb2{dollar} species. The remaining methods, while not suffering from the above limitation, are generally sensitive to errors in the radio frequency (rf) tip-angle and imperfections in rf profile, which cause inaccurate localization.;To overcome these problems, I have devised a new method for multi-dimensional spatial localization by accurate outer volume suppression. The method uses a …
Oxygen Diffusion In The Multicell Spheroid In Vitro Tumor Model: Effects On Cell Survival And Radiation Response, Allan John Franko
Oxygen Diffusion In The Multicell Spheroid In Vitro Tumor Model: Effects On Cell Survival And Radiation Response, Allan John Franko
Digitized Theses
No abstract provided.
Growth And Radiation Survival Characteristics Of Cells In An In Vitro Tumor Model, Ralph Edward Durand
Growth And Radiation Survival Characteristics Of Cells In An In Vitro Tumor Model, Ralph Edward Durand
Digitized Theses
No abstract provided.