Call number: LD2668 .T4 1960 K63

High resolution imaging devices have made a digital medical archiving system feasible. The large volumes of information generated must be stored and retrieved at high data rates in order to insure the timely diagnosis of patients. This creates some unique technological challenges that must be resolved, including the problem dealing with multiple vendor products interacting in one environment. The high speed interface card design presented in this thesis is able to deal with different computer host busses as well as different interprocessor communication protocols. The ACR-NEMA standard has been implemented in the design as one possible network protocol that provides a solution that can be easily adapted to different vendors. The design has been analyzed using the Network II.5 simulation language. The simulation was performed to insure that the original objectives are met and to determine the impact on the protocols rated throughput.

This study was conducted to evaluate the effect of communication and information on the potential adoption of optical scanners by hospital pharmacy directors. The study used a randomly selected national mail survey of 600 hospital pharmacy directors. A response rate of 64.17% was attained and the instrument was determined to have adequate reliability. Believability of optical scanner assessment information was compared between directors with high and low optical scanner familiarity. Directors with high familiarity rates the information's influence on their decision to adopt significantly higher than directors with low familiarity. Directors were also asked to rate the importance of the source of information and the optical scanner characteristics when making their decision to adopt. Directors with high familiarity rated management sources, administrative uses and time-savings higher and cost lower in importance. The survey revealed that 18.96% of the respondents were currently using optical scanners, primarily for inventory control.

Submitted in partial fulfillment of the requirements for the Degree of Masters of Business Administration, Durban University of Technology, 2008. / Industrial buying stands for more than half the whole economic activity in industrialised countries. Therefore, it is important to understand how customers of Afrox perform buying activities. The fabrication industry is a fast growing industry and is, therefore, interesting to study. The understanding of the buying behaviour of industrial organisations is of paramount importance to the industrial marketer. The study is a quantitative, cross sectional and descriptive investigation into buyer behaviour in the fabrication industry of Afrox. It highlights that industrial buyer behaviour has an extensive area, both for the practical marketer as well as from an academic perspective. As the fabrication industry is once again expanding, it is of essence to understand the buying behaviour in this industry. This report has the intention of highlighting how industrial buyer behaviour can be described in the fabrication industry. The purpose of this dissertation was to investigate the characteristics of industrial buying behaviour of fabrication customers at Afrox. The purpose has been further developed in forms of research questions dealing with the buying process, buyer behaviour, buying centre and buyer choice criteria. The sample studied is from a current company data base. With regard to the buying process, the most significant factors are price, quality, and technical capability.

This dissertation presents the characterization and evaluation of a new radiological imaging modality, Toshiba Computed Radiography (TCR) 201. The characteristics of the TCR storage phosphor imaging plates such as energy-dependent x-ray quantum efficiency, stored signal decay, low exposure rate signal build-up, and spontaneous and stimulated gain measures are presented. The TCR 201 system is characterized by the signal transfer curve, the total root-mean-squared (rms) output noise, the signal-to-noise ratio, the modulation transfer function (MTF), its noise power spectrum (NPS), and the detective quantum efficiency (DQE). The system rms noise is photon-limited for exposures less than 1.0 mR, but has contributions from phosphor structure and quantization noise for exposures higher than 1.0 mR. The phosphor's information factor is shown to explain deviations from ideal photon-limited noise for exposures of less than 1.0 mR. The MTF of the system is measured for standard imaging plates, 10% at 2.8 lp/mm, and for high resolution imaging plates, 10% at 4.4 lp/mm. An expression for the NPS is statistically derived, and experimental measurements confirm the expression and show an increase in uncorrelated noise power above 1.0 mR which is consistent with rms measurements. Expressions for the DQE are presented. A psychophysical study is performed to directly compare the TCR to film/screen combinations in imaging low-contrast objects. The results of this study show the TCR provides better images for detectability as a function of exposure. Also, the use of the TCR 201 as a two dimensional dosimeter and in single-shot dual energy subtraction is presented.

Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Power equipment suppliers that manufacture goods to customer requirements face various opposing forces, such as increasing customer expectations, increasing competition and escalating costs. To sustain margins, companies need to understand what constitutes customer satisfaction, thereby enabling them to differentiate their goods and services from those of competitors, and to charge appropriately for those goods and services. Although customer satisfaction is important to industrial goods suppliers such as power equipment suppliers, most studies have been conducted in the business-to-consumer (B2C) environment, focusing on consumer goods and services, with very few studies focusing on the business-to-business (B2B) environment. Compounding the difficulties with customer satisfaction for South African industrial suppliers is that most literature on the subject is applicable to markets outside of South Africa. This paper aims to give South African industrial goods suppliers some insight into those factors that improve customer satisfaction. The identification of critical success factors seen as important by customers was, therefore, the focus of this research assignment. First, customer satisfaction as a critical success factor is reviewed by comparing it to other success factors in an attempt to validate whether it influences organisational performance positively. Second, a list of appropriate items comprising customer satisfaction is identified from the literature review, and the differences between direct customers and indirect customers are identified and discussed. To reduce the number of constructs to be surveyed, the variables that make up customer satisfaction were ranked using prioritisation matrices against Porter’s Five Forces model (Porter, 2008) and the Blue Ocean Strategy model (Kim & Mauborgne, 2004). The shortened list comprised 39 items, which measured ten constructs of customer satisfaction. Questionnaires were sent to customer representatives who were critical decision-makers when deciding on purchases of industrial equipment. The responses were evaluated as a complete group and showed some statistical significance between the constructs. The responses were then evaluated according to organisational types, which showed no statistical significant differences or interaction effects.

No description available.

The EPID (electronic portal imaging device) was designed for in vivo imaging of patients during radiotherapy treatment. The ability of EPIDs to promptly acquire two dimensional data, lends them to be considered for use in quality assurance of the linac. This thesis set out to investigate the possibility of using a radionuclide, technetium 99 m (Tc99m), to produce a flood field for the calibration of an EPID, because using a beam calibrated EPID to measure the beam is self-referential. The difference in relative response between the energy spectrum of a 6MV beam and the Tc99m was investigated using EGSNRC DoseXYZ Monte Carlo Modelling. The relative output ratio was calculated to be less than 1.6%. The dose response of the EPID with respect to dose rate was checked using different activities of Tc99m and found to be linear. The flatness from a phantom was calculated, with a model in MATLAB, for a range of heights, overlaps, thickness, and deformations, to find the optimum balances between signal strength and flatness. This model was checked for accuracy using diagnostic radiographic film. The culmination of the energy response, linearity and the calculated flatness is a flood field taken with a flood phantom on the EPID with low signal strength. To get a signal to noise ratio of 3% the mean of over 2000 flood field images were used. This accuracy was not adequate for clinical use but the averaging of pixels it is accurate enough for QA.

The Hotelling trace criterion (HTC) is a measure of class separability used in pattern recognition to find a set of linear features that optimally separate two classes of objects. In this dissertation we use the HTC not as a figure of merit for features, but as a figure of merit for characterizing imaging systems and designing filters for feature enhancement in nuclear medicine. If the HTC is to be used to optimize systems, then it must correlate with human observer performance. In our first study, a set of images, created by overlapping ellipses, was used to simulate images of livers. Two classes were created, livers with and without tumors, with noise and blur added to each image to simulate nine different imaging systems. Using the ROC parameter dₐ as our measure, we found that the HTC has a correlation of 0.988 with the ability of humans to separate these two classes of objects. A second study was performed to demonstrate the use of the HTC for system optimization in a realistic task. For this study we used a mathematical model of normal and diseased livers and of the imaging system to generate a realistic set of liver images from nuclear medicine. A method of adaptive, nonlinear filtering which enhances the features that separate two sets of images has also been developed. The method uses the HTC to find the optimal linear feature operator for the Fourier moduli of the images, and uses this operator as a filter so that the features that separate the two classes of objects are enhanced. We demonstrate the use of this filtering method to enhance texture features in simulated liver images from nuclear medicine, after using a training set of images to obtain the filter. We also demonstrate how this method of filtering can be used to reconstruct an object from a single photon-starved image of it, when the object contains a repetitive feature. When power spectrums for real liver scans from nuclear medicine are calculated, we find that the three classifications that a physician uses, normal, patchy, and focal, can be described by the fractal dimension of the texture in the liver. This fractal dimension can be calculated even for images that suffer from much noise and blur. Given a simulated image of a liver that has been blurred and imaged with only 5000 photons, a texture with the same fractal dimension as the liver can be reconstructed.

The nonlinear optical properties of a semiconductor-doped glass (SDG) channel waveguide were measured on a picosecond time-scale; namely, fluence-dependent changes in the absorption and the refractive index as well as the relaxation time of the nonlinearity. Slower, thermally-induced changes in the refractive index were also observed. The saturation of the changes in the absorption and the refractive index with increasing optical fluence is explained using a plasma model with bandfilling as the dominant mechanism. The fast relaxation time of the excited electron-hole plasma (20 ps) is explained using a surface-state recombination model. A figure of merit for a nonlinear directional coupler fabricated in a material with a saturable nonlinear refractive index is presented. The measured nonlinear change in the refractive index of the SDG saturates below the value required to effect fluence-dependent switching in a nonlinear directional coupler. Experiments with a channel-waveguide directional coupler support this prediction. However, absorption switching due to differential saturation of the absorption in the two arms of the directional coupler was observed.