The present study was implemented using two different X-ray detection systems; a monochromatic X-ray system for X-ray Fluorescence (XRF) and Angular Dispersive X-ray Diffraction (ADXRD) techniques, and a combined Polarized Energy Dispersive X-ray Fluorescence (PEDXRF) and Energy Dispersive X-ray Diffraction (EDXRD) system. As both of these systems involve different techniques, the primary objective of this study was to evaluate the performance and accuracy of each system using results achieved from XRF measurements. The assessment of the two systems was carried out by investigating invasive ductal carcinoma (IDC) of breast and normal surrounding breast tissues. The results established from the two XRF systems are in a very good agreement with each other. The statistical analysis reveals a significant and measurable increase at P<0.01 in the concentration of K, Ca, Zn, Rb and Fe (P<0.05) in the tumor tissue when compared with the healthy tissue. However, the levels of Cl, Cu and Br attained by both systems have not demonstrated a statistically significant difference between the normal and cancerous tissues. Investigating the structural components of the same breast tissues using of the X-ray Diffraction (XRD) spectrometers incorporated in both systems indicated a statistically significant difference in the components of normal and malignant samples. Furthermore, the results have shown a remarkable increase in the fibrous and water contents of the tumour tissue at P<0.01, and a significant increase in the adipose content of the normal tissue at P<0.01. The results acquired from both XRD approaches were shown to be statistically compatible with each other. Overall, the comparisons between the two X-ray detection systems have shown tremendous results for the combined PEDXRF and EDXRD system for the purpose of classifying normal and tumor breast tissues. / Thesis / Master of Science (MSc)

Thesis. 1975. B.S. cn--Massachusetts Institute of Technology. Dept. of Physics. / MICROFICHE COPY AVAILABLE IN ARCHIVES. / Includes bibliographical references. / B.S.cn

The RS 2400 irradiator has been looked to as a replacement for discontinued gamma irradiators. The RS 2400 has a cylindrical, rather than point, x-ray source, which yields higher dose rates. The irradiator unit allows the user to set the current, voltage, and time for which the sample is to be irradiated, but gives no conversion between these values and the dose delivered. Working with Mississippi State University’s Experimental Seafood Processing Laboratory (ESPL), the purpose of this research was to characterize the dose delivered by the RS 2400 for typical operating conditions. The RS 2400 exposure rate increases, as expected, as the current and voltage are increased. The x-ray beam is uniform within 10% at the surface of the x-ray tube over a wide range of voltages, with the exception of the leftmost 5 cm of the tube, where structural supports are located. At the maximum operating parameters (150 kV and 45 mA), the beam has a first half value layer (HVL1) of 13.66 mm aluminum, a homogeneity coefficient of 0.47, and equivalent photon energy (hveq) of 88.5 keV. This suggests a broad energy x-ray beam. The maximum deliverable dose rate to tissue at the surface of the x-ray tube is 65 Gy min-1 ± 3.1%, but it is unlikely that any sample will ever be irradiated this close to the x-ray tube. The standard sample canisters are 7.62 cm in diameter and the maximum deliverable dose rate to tissue at the canister location (with no canister present) is 37 Gy min-1 ± 3.1%. This is similar to the 45 Gy min-1 value that Rad Source Technologies, Inc. gives for the irradiator. Irradiation of live oysters is of primary interest to the ESPL. For irradiation, oysters will most likely be placed in the 10.2 cm diameter plastic canisters since the 7.62 cm diameter canisters are not wide enough to hold larger oysters. The oyster shells and increased distance from the x-ray source reduce the maximum deliverable dose rate to 14.1 Gy min-1 ± 6.5% for thin-shelled oysters and 12.3 Gy min-1 ± 6.2% for thick-shelled oysters.

Thesis (M.S.)--University of Florida, 2003. / Title from title page of source document. Includes vita. Includes bibliographical references.

No description available.

Thesis (Ph.D)--University of Adelaide, 1955. / Typewritten copy.

The ROSAT spacecraft is due for launch in June 1990. On board will be an X-Ray Telescope (XRT) and an XUV Wide Field Camera (WFC). The XRT will perform the first ever imaging all sky survey in the 0.1 keV- 2.0 keV wave-band. This will be complemented by the first all sky survey in the 0.062 keV - 0.21 keV wave-band using the WFC. A scientific simulator has been developed to assist the WFC mission in the following areas: 1. Production of representative telemetry to develop and test the ROSAT WFC ground system software. 2. Determination of optimum parameters for several WFC firmware and hardware features. 3. Evaluation of background radiation effects on operational and astrophysical aspects of the WFC mission. The modelling and simulation of the performance aspects of the WFC telescope and its interaction with the predicted environment is described here. The complete model has been implemented as a user orientated software package and can be run to produce scientific telemetry and other simulated output that interface with the ROSAT WFC ground system software. The results of the simulator provide essential foresight into the following: The efficacy of image analysis software. The efficiency of in-orbit WFC low energy (50 keV) electron rejection. Prediction of all sky exposure coverage, the background environment, and minimum source sensitivity.

X-Ray emission techniques have been developed for the analysis of unusual and difficult samples that cannot be analyzed by conventional analytical techniques. Three X-ray techniques have been investigated, including radioisotope-induced X-ray fluorescence (RXRF), proton-induced X-ray emission (PIXE) and high resolution PIXE. Low flux radioisotope X-ray sources have been used to non-destructively characterize the elements present in photographic papers and emulsions. The information obtained has proven valuable for cataloging and preserving photographic prints of historical significance. Radioisotope X-ray sources have also been used in the development of low-cost, portable instrumentation useful for quantitating a variety of toxicological samples, including urine and feces samples to determine the elimination rates of X-ray contrast media containing dysprosium. The PIXE technique has been applied to the analysis of forensic samples, including bullet lead, tissue fragments and thin metal coatings, and has been compared with other non-destructive methods of analysis. Sample preparation techniques and analytical procedures have been developed for general, thin target, quantitative PIXE analysis. These procedures were applied to the analysis of five NBS standard reference materials, and to the analysis of deep-sea ferromanganese nodules. A high resolution (2 eV) PIXE system has been developed to aid in the deconvolution of overlapping X-ray peaks encountered in conventional PIXE spectra. This system has been applied to the measurement of chemical shifts in the X-ray emisson spectra of transition metal compounds.

No description available.

published_or_final_version / abstract / toc / Physics / Master / Master of Philosophy