Establishing dose reference level for computed tomography (CT) examinations in Malaysia

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Date
2009
Authors
Abdullah, Arif
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Abstract
This study is conducted with the collaboration of the Malaysian Atomic Energy Licensing Board (AELB) in order to establish dose reference level (DRL) for computed tomography (CT) examinations in Malaysia. 426 examinations for standard adult patients and 26 examinations for paediatric patients comprising different types of CT examinations were collected from 33 out of 109 (30.3%) hospitals that have CT scanner in Malaysia. Measurements of Computed Tomography Dose Index in air (CTDIair) were done at every CT scanner in the hospitals that were involved in this study to investigate the scanner-specific values comparable to the data published by the ImPACT. Effective doses for all CT examinations were calculated using ImPACT Dosimetry Calculator for both ImPACT CTDIair and measured CTDIair values as a comparison. This study found that 4% to 22% of deviations between both values and the deviations represent the dose influence factors contributed by the CT machines. Every protocol used at certain CT examinations were analysed and it was found that tube potential (kVp) was not the main contribution for effective doses deviation. Other scanning parameters such as tube current – time product (mAs), scan length and nonstandardisation in some of the procedures were significant contributors to the effective dose deviations in most of the CT examinations. Effective doses calculated using ImPACT CTDIair were used to compare with other studies to provide an overview of CT practice in Malaysia. Effective doses for examinations of routine head, routine chest and pelvis are within the same range with studies conducted for the European guidelines, the UK and Taiwan. For the routine abdomen examination, the effective dose is still within the range compared to the studies for European guidelines and Taiwan, but 55.1% higher than the value from the study conducted in the UK. Lastly, this study also provided the third quartile values of effective doses for every CT examination collected in this study so that they could be used as reference in establishing the dose reference level of CT examinations in Malaysia.
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Master
Keywords
Science Physic , Dose reference level , Computed tomography (CT) examinations
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