Computed tomography (CT) scans are indispensable in modern medicine; however, the spectacular rise in global use coupled with relatively high doses of ionizing radiation per examination have raised radiation protection concerns. Children are of particular concern because they are more sensitive to radiation-induced cancer compared with adults and have a long lifespan to express harmful effects which may offset clinical benefits of performing a scan. This paper describes the design and methodology of a nationwide study, the Dutch Pediatric CT Study, regarding risk of leukemia and brain tumors in children after radiation exposure from CT scans. It is a retrospective record-linkage cohort study with an expected number of 100,000 children who received at least one electronically archived CT scan covering the calendar period since the introduction of digital archiving until 2012. Information on all archived CT scans of these children will be obtained, including date of examination, scanned body part and radiologist’s report, as well as the machine settings required for organ dose estimation. We will obtain cancer incidence by record linkage with external databases. In this article, we describe several approaches to the collection of data on archived CT scans, the estimation of radiation doses and the assessment of confounding. The proposed approaches provide useful strategies for data collection and confounder assessment for general retrospective record-linkage studies, particular those using hospital databases on radiological procedures for the assessment of exposure to ionizing or non-ionizing radiation.
Computed tomography Cohort study Leukemia Children Methodology Low dose radiation
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We sincerely thank all hospitals who provided and will provide data for our study. Without the dedicated support by numerous professionals in the participating radiology departments, this study would not be possible. This study was funded by the European Community Seventh Framework Programme (FP7/2007–2013) under Grant Agreement Number 269912—EPI-CT: ‘Epidemiological study to quantify risks for paediatric computerized topography and to optimise doses’ and by the Association for International Cancer Research (AICR) with Grant 12-1155. Dr. Ronckers is supported by the Dutch Cancer Society. Funders had no involvement in the study design, data collection, analysis and interpretation, the writing of the report, or the decision to submit the paper for publication.
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