Jasmaniah, Abdul Majid
(2009)
Radiation dose reduction in adult abdorvien and pelvis
CT scan.
Masters thesis, Pusat Pengajian Sains Perubatan.
Abstract
CT scan is an extremely valuable tool as it yields a lot of information regarding the
internal human anatomy. Now with future advances in scanner technology the number of
CT examination will likely continue to rise. Among all CT abdomen and pelvis have the
highest effective dose. Thus it is important to minimize the dose by adjusting scanning
parameter. Major technical factors that influence radiation dose from CT scan include tube
voltage, tube current, scanning time, pitch, slice thickness and scanning volume. In this
study only the tube current (mAs) is adjusted to as minimum as possible while the other
factors are kept constant. The aim of this study is to determine whether a lower radiation dose could be used in adult
abdomen and pelvis CT scan without affecting the diagnostic accuracy of the images. This is a randomised cross sectional prospective trial. Age, gender and abdominal
dimension were recorded from 82 adult patient who underwent contrasted abdomen and
pelvis CT scan from April 2008 until October 2008. 41 patients underwent CT at 240 mAs (control group), and 41 at 180 mAs (trial group-25% dose reduction). The anatomic
details, image quality and the degree of confidence in reaching a diagnosis were graded as
a scale of 1 (unsatisfactory) to 4 (excellent). The difference in perceived image quality between the control and trial group was not
statistically significant (p=O.l4). There is no significant difference in image quality score
in patient with transverse abdominal diameter <34.5 em and ~34.5 em (p=0.20). There is
also no significant difference in image quality score in patient with cross sectional
abdominal area < 800 cm2 and ~ 800 cm2 (p=O. 72) 25% dose reduction can be achieved in adult abdomen and pelvis CT scan if performed at
180 mAs, without deterioration of diagnostic image quality.
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