Are high-dose CT examinations on the rise?

To analyse high-dose CT examinations (≥50 mSv) over a 10-year period to study temporal changes and identify causes.

CT dose provided by the dose management system (Radimetrics) was assessed for the years 2013-2022. CT protocols that led to ≥50 mSv exams were identified. Using body mass index (BMI), patients were classified into underweight, normal weight, overweight, and obese, and correlation with dose was studied. Stratified analysis was performed for diagnostic and interventional examinations according to procedure type, patient age, and protocol.

Over 10 years, 1 353 168 consecutive CTs were performed on 381 790 patients. From 2017 to 2022, exams with doses ≥50 mSv increased by 244% (0.25% to 0.86%), despite introduction of new scanners. In the 4991 CTs for which BMI was available, about 80% pertained to overweight or obese patients. These groups showed nearly 7 times the increase (250 exam increase per year from 2018-2022 versus 39) of underweight and normal weight patients. Common protocols for these high-dose exams included CT angiography of the aorta, coronary arteries, head and neck, and thorax-abdomen/abdomen (for aortic aneurysm/dissection and aortic valve replacement planning).

The rise in ≥50 mSv CTs aligns with newer scanners having powerful X-ray tubes, but with insufficient safeguards, notably for overweight and obese patients.

The awareness of exams with ≥50 mSv and their increased frequency in recent years, with some newer scanners and in patients with high BMI and in multiphase imaging, necessitates actions by manufacturers, policymakers, regulators, and users.