Please use this identifier to cite or link to this item: https://www.um.edu.mt/library/oar/handle/123456789/52779
Title: A re-evaluation of the effectiveness of a standard anti-scatter techniques : a comparative study between film and direct digital radiography.
Authors: Cassar, Daniela
Keywords: Radiography, Medical -- Digital techniques
Diagnostic imaging
X-rays
Imaging systems in medicine
Issue Date: 2008
Citation: Cassar D. (2008). A re-evaluation of the effectiveness of a standard anti-scatter techniques : a comparative study between film and direct digital radiography (Bachelor's dissertation).
Abstract: Objectives: The objectives of the study were to compare the effect on image contrast of the two main anti-scatter techniques (i.e., grids and air-gap) when used in screen film and direct digital radiography system and determine to what extent the higher contrast resolution of direct digital radiography (when compared to that of screen film radiography) helps in reducing the effect of scatter on image contrast. Research Design: The study was conducted using a prospective experimental design using direct observation for data collection. Image contrast of an aluminum disc test object placed above a water filled container was directly measured. Contrast was reduced by varying amounts of scatter produced by different thickness of water. Contrast ratios were measured for both screen film and direct digital radiography. Contrast improvement factor, K and Effectiveness, E values were measured for both anti-scatter techniques using both screen film and direct digital systems and the results were compared. The whole experiment was repeated at 100kV to study the effect of voltage change on the effectiveness of the anti-scatter techniques. Results: The main results of the study were: a. Contrast ratio decreased as scatter increased in both screen film and direct digital radiography. However it was found that in direct digital radiography, contrast ratio decreased with increasing scatter to a lesser extent than in screen film. Moreover the differences between the values of contrast ratio at the two voltages were higher for direct digital radiography than in screen film radiography. This is probably due to the higher contrast resolution of direct digital radiography. b. Contrast improvement factor increased as scatter increased for both anti-scatter techniques. The results suggest that the contrast improvement factor for both grid and air-gap are similar under the experimental conditions of the study both in the case of screen film and in the case of direct digital radiography. In screen film there was a higher kV dependence of contrast improvement factor than in direct digital radiography. c. The effectiveness of the anti-scatter techniques to improve image contrast decreased with increasing scatter and increasing voltage in both screen film and direct digital radiography. The values of effectiveness for both grid and air-gap were similar (within the 95% confidence level) under the experimental conditions used in the study in the case of screen film. However there are indications that values of effectiveness for grid are higher in direct digital radiography than is screen film. This may represent an advantage of grid over air-gap when using direct digital radiography. Conclusions: On the basis of this study, the researcher concluded that under the simple experiment conditions of the study there may be less need for anti-scatter techniques in direct digital radiography than in screen film and that there are indications that the grid may perform better than air-gap in direct digital system. The results are probably due to the higher contrast resolution of direct digital radiography.
Description: B.SC.(HONS)RADIOGRAPHY
URI: https://www.um.edu.mt/library/oar/handle/123456789/52779
Appears in Collections:Dissertations - FacHSc - 2008
Dissertations - FacHScRad - 2008

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