The encyclopedia · Engineering & Operations · Technical decision · 1968–1979
EMI's Hounsfield rebuilt X-rays as math and gave medicine the CT scan
Hounsfield at music company EMI swept X-rays around a patient's head and let a computer solve for the slice, clearing the fog that hid the brain.
EMI (Electric and Musical Industries)
The solution
Conventional X-rays project a three-dimensional body onto a two-dimensional film, so everything along the beam overlaps; the brain appeared as a grey, undifferentiated fog. Godfrey Hounsfield, head of medical research at EMI — better known for records — filed a patent for a complete computed-tomography system in 1968, granted in 1972.
His machine swept an X-ray tube around the skull, replaced film with sensitive crystal detectors, and let a computer reconstruct the cross-section by solving thousands of equations. The Nobel committee later noted the detectors were more than 100 times as sensitive as film, giving exceptional density resolution.
The first clinical scanner went to work in 1971; when Hounsfield published images in 1972 they stunned the medical world — grey and white matter and fluid-filled cavities suddenly visible. CT was introduced into medical care within six years of the first scans and won Hounsfield (with Allan Cormack) the 1979 Nobel Prize in Physiology or Medicine.
Why it worked
- Crystal detectors beat film sensitivity by over 100x
- Computer reconstruction removes overlapping structures
- Slice images made the brain's soft tissue visible
- A music company's research division funded the breakthrough
What can be applied
When direct observation can't see inside, take many partial measurements and reconstruct: more angles plus computation beats trying to see the whole thing at once.
Aftermath
CT scanners spread to every organ system within a few years, becoming one of radiology's most-used tools; EMI itself failed to hold the scanner market against GE and Siemens. Hounsfield shared the 1979 Nobel Prize in Physiology or Medicine with Allan Cormack.
Sources
- The Nobel Prize in Physiology or Medicine 1979 — Press release
- The Nobel Prize in Physiology or Medicine 1979 — Speed read: Clearing the fog
spotted an error? The archive wants to know.