Rethinking Head Computed Tomography (CT) in the Emergency Department: From Reflex Imaging to Reasoned Care

Head computed tomography (CT) is among the most frequently ordered tests in emergency care, yet its use for mild traumatic brain injury (mTBI) remains highly variable. Contemporary practice patterns reflect this: head CT is obtained in >80% of emergency department (ED) evaluations for suspected mTBI, and in older adults presenting after a fall, approximately half undergo cranial CT in routine practice (49% in a UK ED cohort aged ≥65 years). Ageing societies bring more older fallers to the ED, often with incomplete histories and widespread use of anticoagulants or antiplatelets. These realities lower imaging thresholds and can turn CT into a default substitute for clinical reasoning. This editorial argues for a reframing: head CT should be positioned as a decision-support tool within a broader diagnostic strategy, not as the endpoint of thinking. We highlight recurrent pitfalls: misunderstanding what decision rules, such as the Canadian CT Head Rule (CCHR), are designed to predict; applying CCHR outside its intended population; equating "any radiographic abnormality" with clinically important injury; and underestimating the diagnostic and therapeutic value of time, serial neurologic assessment, and high-quality discharge planning. Integrating evidence from decision rules, observational data in older fallers, and qualitative research on physician decision-making, we propose a practical approach: align imaging with the outcome of interest, respect rule assumptions and exclusions, and deliberately "use time" when immediate imaging is unlikely to change management. Ultimately, reducing unnecessary CT is not merely an educational problem; it requires a sustainable clinical ecosystem that supports judgment under uncertainty.