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Document Type:Latin Dissertation
Language of Document:English
Record Number:53394
Doc. No:TL23348
Call number:‭MR00785‬
Main Entry:Mohammad Nisar
Title & Author:Coherent scatter x-ray imaging of plastic and water phantomsMohammad Nisar
College:Carleton University (Canada)
Date:2005
Degree:M.Sc.
student score:2005
Page No:85
Abstract:Conventional medical x-ray imaging, based on the transmission of primary photons, works well to distinguish between hard and soft tissues. Up to 90% of the photons that reach the image receptor, however, are coherently or incoherently scattered, and so there is growing interest in utilizing scattered x-rays for diagnosis. Low-angle scattered photons can only be distinguished from primary on the basis of direction and consequently a well-collimated x-ray system is required. A hexagonal array of seven 1.5 mm diameter pinholes is designed and tested to record the diffraction patterns of plastics and tissues in air and in a water tank. These materials are amorphous solids and result in rotationally-symmetric diffraction patterns which are characteristic of the materials. The intensities of the diffraction patterns are numerically integrated over concentric rings and the scatter images are made by assigning the ring sums as the pixel values. Test images are made of 1 cm thick targets in air and the tube is operated with technique factors ranging from 50 kVp 6000 mAs to 120 kVp 300 mAs for these measurements. The angle-sensitive scatter images exhibit variation of contrast among different materials with angle. To investigate the potential application of the coherent-scatter imaging technique as a diagnostic tool in medical radiology a thick water/plastic phantom is also examined. Using single-beam geometry it has been found that different types and thicknesses of plastics embedded in a 10 cm and in a 20 cm thick water phantom at different depths can be distinguished on the basis of the shape of the scatter pattern radial profile and on its relative intensity. For thick phantom measurements the tube is operated with technique factors ranging from 120 kVp 1500 mAs to 120 kVp 7000 mAs. The scatter patterns are recorded on a storage phosphor image plate.
Subject:Pure sciences; Radiation; 0756:Radiation
Added Entry:P. C. Johns
Added Entry:Carleton University (Canada)