Safe CT scan for children
X-ray CT is a medical imaging technology that uses computer-processed X-rays to produce tomographic images (virtual 'slices') of the scanned object. This non-invasive technology is used for diagnostic and therapeutic purposes in various medical conditions. Several recent studies suggested a relationship between CT radiation dose and subsequent cancer risk in young people. However, the risks from exposure to low doses of radiation from CT scans are expected to be small. Funded by the EU, the EPI-CT project brings together the national paediatric CT patients' studies already ongoing in Europe and has initiated new studies in five countries (Belgium, Denmark, the Netherlands, Spain and Norway). Scientists from 11 countries with expertise in epidemiology, radiology, molecular biology, biostatistics, clinical medicine and dosimetry will conduct the international cohort study. They will assess cancer risks, particularly leukaemia and brain cancer from radiation exposure. The study already enrolled over 1 million paediatric patients and exceeded the expected cohort size). The automatic extraction of CT scan data from picture archiving and communication systems has started in 54 hospitals in 8 countries. The protocol outlining the EPI-CT methodology for organ dose reconstruction has been developed and published. A specially designed questionnaire aims to obtain historical information on CT scan settings. The consortium has also been working on the methodology for optimising CT image quality while minimising patient radiation dose. Investigation of biological mechanisms showed that cellular repair in young children is impaired at high radiation doses (1 gray (Gy)) as detected by increased cytogenetic damage. However, for low-dose CT exposure (0.04 Gy), no clear statement can be given due to lack of statistical power in the study. These results demonstrate the need for in vitro study with sufficient statistical power to investigate low-dose radiation sensitivity of children using a reliable and sensitive biomarker. Results of the EPI-CT study have been published in seven medical journal papers so far and presented at four conferences and workshops. In the future, project results could be used to optimise image quality and lower CT dose by adjusting scanning parameters.
Keywords
Computed tomography, radiation dose, cancer risk, radiation sensitivity
