CT scanning and cancer risk
Myron Yaster MD, Eddy Zandee van Rilland MD, and Genie Heitmiller MD
“Unlike imaging studies in adults, children often require general anesthesia or deep sedation to achieve the immobility required for successful imaging, exposing pediatric anesthesiologists to more ionizing radiation from X-rays than those who provide anesthesia primarily to adult patients.”1 In today’s PAAD,2 Richman et al review the risks of computerized tomography (CT) to patients. As way of background, CT scans are roughly equivalent to 100-250 chest X-rays! I think you will find the results of today’s PAAD shocking and it doesn’t address the risks of radiation exposure to us. In a survey study performed several years ago, my study group found that “few pediatric anesthesiologists had ever received formal training in radiation safety and few routinely adhered to preventative strategies to minimize the risk of radiation-induced injury, particularly the routine use of dosimeters, lead glasses, and thyroid and lead acrylic shields.”1 Five years later, the need to improve radiation safety education, to change the safety culture surrounding radiation safety, and to more fully investigate the utility of dosimeters and barriers to routine use of lead shielding and eyeglasses in pediatric anesthesia practice remain the same as it was then. Myron Yaster MD
Editorial
Richman IB, Katz MH. Balancing Computed Tomography's Benefits with Radiation Risks. JAMA Intern Med. 2025 Apr 14. doi: 10.1001/jamainternmed.2025.0514. Epub ahead of print. PMID: 40227674.
Original article
Smith-Bindman R, Chu PW, Azman Firdaus H, Stewart C, Malekhedayat M, Alber S, Bolch WE, Mahendra M, Berrington de González A, Miglioretti DL. Projected Lifetime Cancer Risks from Current Computed Tomography Imaging. JAMA Intern Med. 2025 Apr 14:e250505. doi: 10.1001/jamainternmed.2025.0505. Epub ahead of print. PMID: 40227719; PMCID: PMC11997853.
“Computed tomography (CT) is an indispensable and widely performed medical imaging test. Ongoing technological advancements expand its capabilities and popularity, and utilization continues to rise. While CT aids diagnosis, leading to improved outcomes, it also exposes patients to ionizing radiation at levels known to be associated with increased cancer risk (1 CT scan = 100-250 chest X-rays). Several large retrospective cohort studies have shown that childhood exposure to CT is associated with increased risk of hematologic malignant neoplasms and brain cancer.”2 “This study updates previously projected lifetime cancer incidence associated with CT using the most recent utilization numbers available, empirical data on CT type by age and sex, and organ doses estimated directly from examination-level clinical data across the United States using best-practice methods. The purpose is to understand the public health impact of current CT use and to identify the highest risk examination types, age, and sex groups.”2
What did they find? “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 (90% UL, 96 400-109 500) radiation-induced cancers were projected to result from these examinations. Estimated radiation-induced cancer risks were higher in children and adolescents, yet higher CT utilization in adults accounted for most (93 000; 90% UL, 86 900-99 600 [91%]) radiation-induced cancers. The most common cancers were lung cancer (22 400 cases; 90% UL, 20 200-25 000 cases), colon cancer (8700 cases; 90% UL, 7800-9700 cases), leukemia (7900 cases; 90% UL, 6700-9500 cases), and bladder cancer (7100 cases, 90% UL, 6000-8500 cases) overall, while in female patients, breast was second most common (5700 cases; 90% UL, 5000-6500 cases). The largest number of cancers was projected to result from abdomen and pelvis CT in adults, reflecting 37 500 of 103 000 cancers (37%) and 30 million of 93 million CT examinations (32%), followed by chest CT (21 500 cancers [21%]; 20 million examinations [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.”2
For pediatric anesthesiologists, the take home message is that “projected cancer risks per CT examination were estimated to be highest among children who underwent CT at younger than 1 year and decreased with age at exposure. For example, cancer risk in girls younger than 1 year were 20 cancers per 1000 examinations (1900 of 97 000) versus 2 per 1000 in girls aged 15 to 17 years (1100 of 483 600).” (figure below)2
Does this increased cancer risk mean we should abandon CT scanning? Of course not! CT scanning is often lifesaving and provides important information to guide therapy. It should give us pause, however, when scans may be unnecessary and are obtained when physical history, physical examination, and other imaging studies that do not require radiation could be used.
A question I (MY) have always wondered about is: “If the radiation is so high, why aren’t children undergoing a CT scans routinely shielded with lead while in the scanner?” It turns out that the CT scanner may see lead shielding as part of the body and calculates the body to be denser than it is, thus delivering a higher amount of radiation than is needed. If the lead shield enters the imaging field of view, imaging artifacts related to the lead shield may significantly degrade image quality, potentially requiring repeat imaging and additional radiation exposure to the patient. So, the recommendation is no patient shielding for CT scan. That being said, if you need to be in the scanner room during a scan, YOU and anyone else in the room who is not the patient, like a parent, SHOULD BE WEARING LEAD!
Send your thoughts and comments to Myron who will post in a Friday reader response.
References
1. Whitney GM, Thomas JJ, Austin TM, Fanfan J, Yaster M. Radiation Safety Perceptions and Practices Among Pediatric Anesthesiologists: A Survey of the Physician Membership of the Society for Pediatric Anesthesia. Anesthesia and analgesia 2019;128(6):1242-1248. (In eng). DOI: 10.1213/ane.0000000000003773.
2. Smith-Bindman R, Chu PW, Azman Firdaus H, et al. Projected Lifetime Cancer Risks From Current Computed Tomography Imaging. JAMA internal medicine 2025 (In eng). DOI: 10.1001/jamainternmed.2025.0505.