Leukemia and brain tumors among children after radiation exposure from CT scans: design and methodological opportunities of the Dutch Pediatric CT Study

Abstract

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.

Radiation Dose Reduction at Pediatric CT: Use of Low Tube Voltage and Iterative Reconstruction

“…The upcoming European Epidemiologic Study to Quantify Risks for Pediatric Computed Tomography and to Optimize Doses (EPI-CT) study, which was designed to include approximately 1 million children exposed to CT, will offer opportunities to better address these limitations of the uncertainties induced by incomplete dosimetry (21). (20,21). Studies published before 2014 (6)(7)(8) showed potential evidence of a dose-response relationship between pediatric CT and risk for brain tumor and leukemia, which are the most common radiation-induced neoplasms among children (Table 1).…”

Confounding of the Association between Radiation Exposure from CT Scans and Risk of Leukemia and Brain Tumors by Cancer Susceptibility Syndromes

“…Five epidemiologic studies on cancer following radiation exposure from pediatric computed tomography (CT) scans have shown elevated risks of leukemia and brain tumors (1)(2)(3)(4)(5) and other studies are under way (6,7). These studies are record-linkage cohort studies on large numbers of patients collected from existing databases (health insurances and hospitals) with limited or no information on potential confounding factors, which may bias the radiation-cancer association.…”

Calculation of Organ Doses for a Large Number of Patients Undergoing CT Examinations

“…We found our method is highly efficient in large-scale dose calculations for CT patients and is more accurate than the ImPACT dosimetry tool although Monte Carlo transport calculations based on real patient CT images may provide more accurate individualized organ doses. We have successfully applied this method to a variety of CT-related studies including retrospective epidemiological study (1,5,18,19) and CT dose trend analysis studies (3,20). …”