The first practical CT scanner is used to diagnose a patient.

The history of X-ray computed tomography (CT) traces back to Wilhelm Conrad Röntgen's discovery of X-ray radiation in 1895 and its rapid adoption in medical diagnostics. While X-ray radiography achieved tremendous success in the early 1900s, it had a significant limitation: projection-based imaging lacked depth information, which is crucial for many diagnostic tasks. To overcome this, additional X-ray projections from different angles were needed. The challenge was both mathematically and experimentally addressed by multiple scientists and engineers working independently across the globe. The breakthrough finally came in the 1970s with the work of Godfrey Hounsfield, when advancements in computing power and the development of commercial CT scanners made routine diagnostic applications possible.