USE OF EXTENDED FOCUS-TO-FILM-DISTANCE TECHNIQUE FOR DOSE REDUCTION IN THE DIAGNOSTIC EXAMINATION OF THE PELVIS

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Date
2007-12
Authors
SIMON, MADUAKONAM NWAFOR
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Abstract
It is essential to reduce the radiation exposure in diagnostic radiology as much as possible because of their inherent danger. This is kwon as ALARA principle. The process of reaching the balance between dose and image quality is optimization. This work is aimed at finding if there are reductions in dose to the pelvis due to a change in focus to film distance (FFD) with the condition that a diagnostic image of the pelvis is obtained. The different examinations involving the direct irradiation of the gonads were studied for the period of six months in the Radiology Department of Ahmadu Bello University Teaching Hospital, Zaria to determine the contributions of pelvic exposure to patient’s radiation hazards. It was found that examinations’ involving the pelvis contributes about 24% of the total collective detriment to the patients. Entrance skin doses were measured using patients and a constructed pelvic phantom by thermoluminescent dosimeters (TLD). Dose to the pelvis was measured at varied FFD from 100145cm. Optical densities were measured at positions of the ovaries and the result showed no significant difference. The radiographs obtained at varying FFDs were found to be of good quality after their assessment by clinicians. The increase in FFD showed dose reduction of 8.95% and 6.30% for fixed and varying collimation settings respectively. The backscatter factor was found to be constant and the percentage reduction in dose due to air attenuation was shown to be significant
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A Thesis Submitted to the Postgraduate School, Ahmadu Bello University, in Partial Fulfillment of the Requirement for the Award of Degree of Master of Science in Radiation Biophysics Department of Physics, Faculty of Science Ahmadu Bello University, Zaria Nigeria DECEMBER, 2007
Keywords
USE OF EXTENDED FOCUS-, TO-FILM-DISTANCE, TECHNIQUE, DOSE REDUCTION, DIAGNOSTIC EXAMINATION, PELVIS
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