AI Summary
5 min readEvery time you order a CT scan, you are effectively giving a patient the equivalent of 500 chest X-rays of radiation if it’s an abdomen-pelvis study, or 100 chest X-rays for a CT head. And each scan carries a cumulative DNA damage risk. In 2023, 93 million CTs were ordered in the United States alone, and a paper in JAMA Internal Medicine estimated that those scans will cause roughly 103,000 future cancers—about 5 percent of all new cancers. Yet CT is also one of the most powerful diagnostic tools in emergency medicine. The tension between these facts is the central problem of imaging decisions in the ED, and Dr. Ahmed Shaw, an emergency physician and regional lead for Ontario Health, walks through four cases that show how to navigate it.
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What you'll learn
- 1 (04:43) **The CT Overuse Problem** - Dr. Shaw introduces the staggering scale of CT utilization and its associated cancer risk
- 2 (07:33) **Shared Decision-Making Language for Imaging** - Dr. Shaw’s exact script for discussing radiation risk with patients who insist on a CT
- 3 (11:08) **Reclaiming “Tincture of Time”** - Serial re-examination as an underutilized alternative to immediate CT in low-risk patients
- 4 (15:47) **Appendicitis: CT Now vs. Ultrasound in the Morning** - How to decide whether to image a suspected appendicitis patient overnight
- 5 (20:22) **Antibiotics for Suspected Appendicitis: To Give or Not to Give** - The evidence on empiric antibiotics while awaiting imaging
- 6 (22:44) **Head Injury in a Remote Nursing Station** - The high-stakes decision of whether to fly out a patient for a CT head
- 7 (27:25) **Nuance in the Vomiting Criterion** - When isolated vomiting after head injury does not require a scan
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Show Notes
When to image, when to wait, and what to do when the ideal test isn’t available are often far more nuanced than they appear. In this EM Cases episode, Dr. Amit Shah joins Anton to tackle some of the toughest everyday imaging decisions: How much should cumulative radiation exposure influence our decision to order another CT? In suspected appendicitis, when is it safe to wait for ultrasound rather than obtain CT overnight? Can the emerging traumatic brain injury biomarkers GFAP and UCH-L1 help avoid CT, particularly in rural and remote settings? And in suspected cauda equina syndrome, how can PVR and CT lumbar spine be combined to risk-stratify patients when MRI isn’t immediately available—and when should a reassuring PVR or CT not reassure us? Plus, practical shared decision-making strategies, the role of the “tincture of time,” and much more...
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