11/06/2025
The "first, do no harm" principle, or “primum non nocere” in Latin, is an ethical principle in medicine and healthcare that emphasises the importance of avoiding harm to patients. This fundamental principle can be overlooked in practice, particularly in the context of diagnostic tests and procedures. Approximately 93 million computed tomography (CT) examinations are performed on 62 million patients annually in the United States, and ionising radiation from CT is a known carcinogen.
A study was published in the Journal of the American Medical Association (Internal Medicine) to determine the number of future lifetime cancers in the US population associated with CT imaging use in 2023.
The scientists used the IMV Medical Information Division CT Market Outlook Report, based on a national annual survey of 235 hospitals and 78 imaging facilities, to quantify the number of CT examinations performed in the United States in 2023. Lifetime radiation-induced cancer incidence and 90% uncertainty limits (UL) were estimated by age, s*x, and CT category using National Cancer Institute software based on the National Research Council's Biological Effects of Ionizing Radiation VII models and projected to the US population using scaled examination counts.
An estimated 61,510,000 patients underwent 93,000,000 CT examinations in 2023, including 2,570,000 (4.2%) children, 58,940,000 (95.8%) adults, 32,600,000 (53.0%) female patients, and 28,910,000 (47.0%) male patients. Approximately 103,000 radiation-induced cancers were projected to result from these examinations over a person’s lifetime. Estimated radiation-induced cancer risks were higher in children and adolescents, but the higher CT utilisation in adults accounted for most (93,000) radiation-induced cancers. The most common cancers estimated to be caused were lung cancer, colon cancer, leukaemia and bladder cancer overall, while in female patients breast cancer was second most common. The largest number of cancers was projected to result from abdomen and pelvis CT in adults, reflecting 37% of cancers, followed by chest CT (21%). Estimates remained large over a variety of sensitivity analyses, which resulted in a range of 80,000 to 127,000 projected cancers across analyses.
The authors provided the following context: if the number of new cancer diagnoses in the United States remains stable (1.95 million in 2023) and both the utilisation and radiation doses from CT remain unchanged in future decades, CT could be responsible for approximately 5% of all cancers diagnosed each year. This would place CT on par with other significant risk factors, such as alcohol consumption (5.4%) and excess body weight (7.6%). The projected number of radiation-induced cancers in this analysis is 3 to 4 times higher than earlier assessments for several reasons. First, while the growth in utilisation has slowed, CT use is 30% higher today than in 2007. This is largely due to the growth in low-value, potentially unnecessary imaging as well as population ageing. Second, dose modelling in this study accounted for multiphase scanning, which occurs in 28.5% of examinations but was not modelled previously. Third, the substantially higher organ doses in this study were reconstructed using newer dosimetry methods.
Artificial intelligence (AI) has emerged as a transformative solution to this problem, enabling low-dose CT imaging protocols that enhance image quality while significantly reducing radiation doses. We can only wait for the widespread adoption of these advances.
For more information see: https://pubmed.ncbi.nlm.nih.gov/40227719/
