In accordance with its missions in the “Code de la santé publique” (French Public Health Code), the French Institute for radiation protection and nuclear safety (IRSN) periodically analyses the exposure of the French population to ionising radiation due to diagnostic medical imaging procedures. To complete the "ExPRI 2017" study on exposure to ionising radiation of the general population due to diagnostic procedures in France in 2017, a specific study was conducted about CT (computed tomography) scan procedures in children under 16 years of age in France over the period 2012-2018 and the associated radiological exposure.
This study was based on CT scan procedures in children extracted from a representative sample panel of health insurance beneficiaries. The year-by-year analysis (i.e., without individual follow-up of the children from one year to the next) made it possible to evaluate, among other things, the evolution over the period studied of:the frequency of CT scan procedures (number of procedures per 1,000 children) per year;
the proportion of children who had at least one CT scan procedure per year.
Over the period 2012-2018, the annual frequency of CT scan procedures was relatively constant (across all ages and sexes) and fluctuated around 13.7 procedures per 1,000 children.
On average over the same period, the annual frequency of CT scan procedures varies greatly according to the age of the child: about 15 ‰ for children under 1 year old, less than 10 ‰ between 1 and 9 years old, then increasing to more than 35 ‰ at 15 years old.
Over the period studied, 1.1% of children under 16 years of age had at least one CT scan procedure per year. Among this population, the average number of CT scan procedures per year per child was 1.23; 11% to 16% of these children had 2 or more CT scan procedures depending on the year considered.
Since CT and MRI (magnetic resonance imaging) have a large number of common indications and the recommendations of professionals are moving towards a transfer of some procedures to MRI, a study of the evolution of MRI procedures was also carried out. This study shows that, unlike in CT, the annual frequency of MRI procedures increased significantly (+59%) over the period studied.
According to the paediatric data analysed in the Diagnostic Reference Level (DRL) system managed by IRSN, the doses received by children for a CT scan (for the brain, abdomen-pelvis and thorax) show a decreasing trend between the periods 2011-12 and 2016-18. This decrease should be interpreted with caution due to the small amount of data collected during these periods. A new order on DRLs, published in May 2019, has strengthened the provisions for sending dose assessments to IRSN in paediatrics and has made it possible to obtain more data over the period 2019-2021. Analysis of these data in the next DRL review, to be published, will provide more precise information on changes in ionising radiation doses received by children.