The Dutch study on leukemia among children and young adults after radiation exposure from pediatric computed tomography

Michael Hauptmann, Netherlands Cancer Institute 
Han Lameris, Academic Medical Center 
Jose Meulepas, Netherlands Cancer Institute 
*Cecile M Ronckers, Dutch Childhood Oncology Group 
Anne Smets, Academic Medical Center 
Marcel van Herk, Netherlands Cancer Institute 

Keywords: childhood leukemia, pediatric CT scanning, cohort study, low-dose radiation risk

Computed tomography (CT), a valuable diagnostic procedure, delivers higher radiation doses than most other diagnostic imaging modalities. CT use has increased dramatically in recent years. Ionizing radiation is leukemogenic, but the level of risk associated with low doses is unknown. This is of concern given the extent of CT-use; small individual excess risks may translate into measurable population excesses. Therefore, radiation protection is important, particularly among children, given their sensitivity to radiation-induced cancer and long lifespan to express late effects. Recently, 29,000 lifetime cancers were estimated to be caused by 57 million CT-scans carried out in the US in 2007, including >4,000 excess cancers from pediatric CT scanning.

In 2011, we started a nationwide retrospective record-linkage cohort study in the Netherlands. We plan to include 90,000 children who received one or more electronically archived CT scans in all 59 Dutch hospitals regularly performing pediatric CT scans. We will obtain information on all estimated 160,000 CT scans (1999-2011), including body part scanned, radiology report content, technical parameters and the images for organ dose estimation. Cancer incidence will be obtained by record linkage with the Netherlands Cancer Registry. Information on potential confounders (SES, congenital disorders and history of bone marrow transplantation) will be obtained.

Aims: To: 1. Evaluate the association between radiation exposure from pediatric CT scans and risk of childhood leukemia, 2. Describe nationwide patterns of CT scan use and associated radiation doses in Dutch children, and 3. Contribute data to a European pooled study (EPI-CT) to investigate risk for rarer forms of cancer among children and young adults.

Our study will provide empirical quantitative assessment of CT-related radiation doses and corresponding risk in a nationwide study based on electronic radiology records thus providing safety information for clinical decisions about CT scans and etiologic knowledge about childhood leukemia.