Good Evening Everyone,
One of our most utilized tests in the emergency department is the CT scan. CT scan use in the emergency department has risen disproportionately (330%) in comparison to the increase in ED visits (30%) between 1996 and 2007. In the back of most EM physician’s minds is typically whether radiation is necessary or not, particularly when a patient is young. Today, I’ll be discussing circumstances that have led to rising CT scan usage, evidence for projected malignancy risk, and interventions to address CT overuse.
What are the circumstances causing increased CT usage?
A systematic review in the American Journal of Emergency Medicine in 2018 examined studies between 1998-2017 and identified determinants associated with increased CT usage in the emergency department.
Increase in defensive medicine practice by physicians
Trauma patients that are transferred from a local ED to a level 1 trauma center are often re-imaged
Lack of integration between electronic medical records when patients are transferred between EDs
Rising elderly patient population with more medical comorbidities
ED crowding resulting in less time at the bedside to educate patients on risks of radiation from CT scans
How much do CT scans increase the risk of malignancy?
A landmark study published in JAMA Internal Medicine in April 2025 established future risk of malignancy with the current rise in CT scan usage using a validated predictive radiation risk tool developed by the National Cancer Institute.
In the study, 61.5 million patients underwent 93 million CT scans from 2023-2024 with the following demographics:
25.7 million (4.2%) children
58.9 million (95.8%) adults
32.6 million (53%) female
28.9 million (47%) male
There could be 103,000 projected lifetime cancers from radiation-induced malignancy (could account for 5% for all future cancer)
Higher CT utilization in adults accounted for most projected radiation-induced cancers (93,000)
The CT Abdomen Pelvis is projected to be the cause of the majority of future cancers (37%) followed by the CT Chest (32%) in adults
Most common projected malignancies in adults include lung cancer, colon cancer, leukemia, and bladder cancer
Radiation risk is higher in children due to increased physiologic sensitivity to radiation, but projected cancer numbers are lower compared to adults (9700)
CT Head contributes to the largest number of cancers in children (53%), greatest at age <1 with risk decreasing with age
Most common projected malignancies in children include thyroid, lung, and breast cancer
In female patients, lung and thyroid cancer are predicted to have a higher incidence and breast cancer is the second most common projected cancer from CT scan overuse
Interventions to Address CT Overuse In the ED:
A 2022 systematic review in the Annals of Emergency Medicine identified successful and less successful interventions to address CT overuse in the ED.
Successful interventions without compromising patient safety:
diagnostic pathways
alternative imaging options
involving consultants early
Less successful interventions not backed by evidence:
family/patient education
passively disseminated guidelines
clinical decision support tools
All in all, the information above may not come as a surprise to many of us, but it provides us with concrete evidence demonstrating that CT overuse in the ED may have serious consequences for our population (103,000 predicted cancer diagnoses accounting for 5% of all future cancers). Consider the data when ordering your next CT scan and the suggested interventions above so that we may mitigate malignancy risk in the future.
Best,
Lekha Reddy
