Affiliations: Department of Biomedical Engineering, Olson Research Center, University of Akron, Akron, Ohio 44325 | Department of Biomedical Engineering, University of Tennessee, Memphis, Tennessee 38163 | Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221
Note: [] To whom correspondence should be addressed.
Note: [] Current address: Department of Physiology, School of Medicine, The Johns Hopkins University, Baltimore, MD 21205.
Note: [] Current address: Picker International, Inc., 595 Miner Road, Highland Heights, OH 44143.
Abstract: A systematic study of the line spread function (LSF) in the drift direction of a high-pressure ionization chamber for x-ray detection and imaging is presented. Experimental results, obtained by operating a KCD krypton-filled detector at pressures up to 60 atm and constant electric field-to-gas pressure ratio, indicate that the width of the LSF increases with the drift distance and decreases with increasing pressure, both effects being quite large. The hypothesis of this paper is that, at sufficiently high pressures, formation of clusters of molecular ions with a unique or narrowed mobility distribution take place by means of energy exchange mechanisms. Therefore, the LSF of the ionic signal becomes narrower and the FWHM of the ionic signal improves significantly with increasing gas pressure. This research is aimed at investigating methods to improve the spatial resolution as part of the development of a large field-of-view prototype digital radiographic scanner operating on kinestatic charge detection principles.
