Lens dose reduction in pediatric : modified baseline in CT brain

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Lens dose reduction in pediatric : modified baseline in CT brain


Author: Choi, Hon-wing
Title: Lens dose reduction in pediatric : modified baseline in CT brain
Degree: M.Sc.
Year: 2004
Subject: Hong Kong Polytechnic University -- Dissertations
Brain -- Tomography
Pediatric radiography
Radiation -- Dosage
Department: Dept. of Optometry and Radiography
Pages: 86, [30] leaves : ill. (some col.) ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1756629
URI: http://theses.lib.polyu.edu.hk/handle/200/3207
Abstract: The frequency of CT brain examinations is increasing worldwide and their contribution to the total collective dose to the population is significant. Hence, management of patient dose is crucial. The aim of this study was to determine the effect of use two different scan planes in routine CT brain on lens dose reduction and resultant image quality in pediatrics. Fifty-two pediatric patients with CT brain request, aged from 1-12 years old were selected for this study. They were randomly divided into two equal groups to receive the CT brain scan. One group underwent scanning with the use of a modified (supra-orbitomeatal, SOM) baseline and the other group with the orbitomeatal (OM) baseline. In addition an adult head phantom was scanned with the use of the two scan planes. With the use of the SOM baseline instead of OM baseline, the eye lens was avoided from direct irradiation of X-ray slit beam. On average, the measured lens dose can be reduced by 82%. The degree of lens dose reduction was nearly the same as that in adult phantom which had 84% dose reduction. The resultant images were evaluated by five radiologists for image quality and overall diagnostic value using the five point confidence scale. Results showed that the image quality and overall diagnostic value were excellent (mean score < 2) and similar in both scanning planes. Reliability tests showed the results were consistent. In conclusion, the use of the SOM baseline instead of the OM baseline in routine CT brain scan is highly recommended to reduce the lens dose especially for the pediatrics whose eye lens are more radiosensitive.

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