Abstract
Background: Diagnostic reference levels for a number of common diagnostic radiological exami- nations against which individual centres could compare their performance have been recom- mended by relevant international agencies. Due to variations in different populations globally, lo- cal and national diagnostic reference levels are more reliable. To the best of our knowledge, no centre-specific study has been carried out and national surveys are not available. Objective: To establish a preliminary local and national diagnostic reference level in Nigeria. Methods: A pros- pective and cross-sectional study involving 30 conscious paediatrics and adult patients referred for head computed tomography scan. They were positioned supine and scanned according to the standard protocol for head computed tomography with manual mA selection. The total dose- length products were recorded at the end of the pre-contrast and post-contrast sequences respec- tively. The pre-contrast dose was taken into cognizance in the determination of the post-contrast value. The effective dose was established by multiplying the dose-length product by 0.0023 mSv∙mGy −1 ∙cm −1 , a conversion coefficient for brain tissue adopted from the European Commission. Statistical Package for Social Sciences version 17.0 was used to analyze the data. Results: 30 pae- diatrics and adult patients of mixed gender participated in the study. Their ages ranged from 1 to 74 years with a mean age of 41.47 ± 23.30 years. The pre-contrast effective dose ranged from 1.93 mSv to 3.32 mSv with mean of 2.56 ± 0.51 mSv and 75 th percentile of 3.11 mSv while the post- contrast effective dose ranged from 4.06 mSv to 6.97 mSv with mean of 5.27 ± 0.97 mSv and 75 th percentile of 6.13 mSv. The mean effective dose from this work and two other isolated studies was * Corresponding author.
Highlights
Computed tomography (CT) is associated with relatively high radiation doses, with a corresponding increased risk of carcinogenesis
The effective dose was determined by multiplying the dose-length product (DLP) by 0.0023 mSv∙mGy−1∙cm−1
The 75th percentile of the effective dose was noted as the threshold for our centre and the mean from this work and two similar works in this environment was recommended as the national threshold
Summary
Computed tomography (CT) is associated with relatively high radiation doses, with a corresponding increased risk of carcinogenesis. Diagnostic reference levels were first mentioned by the International Commission on Radiological Protection, ICRP [2]. They are intended to be a reasonable indication of dose for average-size patients and to provide guidance on what is achievable with current good practice rather than optimum performance [3]. They allow the identification of abnormally high dose levels by setting an upper threshold. Methods: A prospective and cross-sectional study involving 30 conscious paediatrics and adult patients referred for head computed tomography scan. The mean effective dose from this work and two other isolated studies was
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