Typical Radiation Doses for children undergoing common Computed Tomography examinations at Uganda Cancer Institute
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Background Optimization of radiation during medical exposures is a principal of radiation protection. It is of more importance in children as they have more sensitivity to radiation, more effective doses, and higher life expectancy. One way of achieving radiation optimization is by setting local, national or regional diagnostic reference levels (DRLs). Uganda and its imaging facilities lack local and regional DRLs respectively. We determine the typical radiation doses, a type of local DRL, in terms of age and body weight of children who underwent common CT examinations and attended at Uganda Cancer Institute. General objectives The aim of this study was to determine typical radiation doses for common computed tomography (CT) scans among children who attended at Uganda Cancer Institute. Methodology This was a cross-sectional study carried out at Uganda Cancer Institute among children who underwent the institute’s common computed tomography (CT) examinations (head, chest and abdomen, and abdomen) from November 2018 to February 2019. Demographic data, clinical indications, and anatomic site examined of 109 patients were collected from the request forms. The CT scan machine specifications, specific type of CT examination, and acquisition doses were collected from the CT scan console. The data was analyzed to determine the median of the total dose-length-product (DLP) and average volume computed tomography dose index (CTDIvol) to establish typical radiation doses of the commonly performed examinations at Uganda Cancer Institute as a function of age or body weight. Relationship between acquisition doses, examination phases, patient age and body weight were evaluated. The DRLs were compared with international published pediatric CT scan dose values. Results A total of 109 participants were included: 40 underwent head CT scans, 49 underwent chest and abdomen CT scans, and 20 had abdomen CT scans. The median age was 6 years and 51% were 2 male. The typical radiation dose of CTDIvol for head CT scan across all age groups was 42.5mGy. Similarly, the typical radiation value of CTDIvol for chest and abdomen CT scan was constant across weight groups with a value of 7.1mGy. The typical radiation doses of CTDIvol for abdomen in children with a body weight of 5-14kg, 15-29kg, and 30-49kg were 9.45mGy, 11.8mGy, and 10.15mGy respectively (p-value=0.745). The typical radiation doses of DLP for head increased as the age increased ranging from 1879.9mGy.cm to 2359.6mGy.cm (p value=0.017). The typical radiation doses of DLP for chest and abdomen increased as the body weight increased ranging from 600.6mGy.cm to 935mGy.cm (p value=0.00). The typical radiation doses of DLP for abdomen ranged from 577.85mGy.cm to 1241.5mGy.cm (p value=0.131). The median or 75th percentiles of CTDIvol, total DLP, and scan length for head, chest and abdomen, and abdomen at UCI were higher in comparison with other similar published local and international values in Kenya, Australia and Europe. Conclusion The radiation delivered to pediatric patients during head, chest/abdomen, and abdomen CT examinations across various age and body weight groups was high. There was a difference between the DRLs obtained from UCI and other published radiation doses in Uganda, Kenya, and Europe. Recommendation There is an urgent need to establish pediatric CT examination protocol and imaging guideline for CT examinations on children at UCI. Further study including all anatomic sites and with bigger sample size is recommended in orders to set CT DRLs of all anatomic sites imaged and representing all age groups, and body weight groups.