How an eccentric engineer invented the CT scan 50 years ago


By Edmund S. Higgins 6 minute Learn

The potential of valuable objects hidden in secret chambers can actually ignite the creativeness. In the mid-Sixties, British engineer Godfrey Hounsfield contemplated whether or not one might detect hidden areas in Egyptian pyramids by capturing cosmic rays that handed by way of unseen voids.

He held onto this concept over the years, which could be paraphrased as “looking inside a box without opening it.” In the end he did determine methods to use high-energy rays to disclose what’s invisible to the bare eye. He invented a method to see inside the laborious cranium and get an image of the smooth mind inside.

The primary computed tomography picture—a CT scan—of the human mind was made 50 years ago, on Oct. 1, 1971. Hounsfield by no means made it to Egypt, however his invention did take him to Stockholm and Buckingham Palace.


An engineer’s innovation

Godfrey Hounsfield’s adolescence didn’t recommend that he would accomplish a lot in any respect. He was not a very good pupil. As a younger boy his lecturers described him as “thick.”

He joined the British Royal Air Drive at the begin of the Second World Conflict, however he wasn’t a lot of a soldier. He was, nonetheless, a wizard with electrical equipment—particularly the newly invented radar that he would jury-rig to assist pilots higher discover their method dwelling on darkish, cloudy nights.

After the struggle, Hounsfield adopted his commander’s recommendation and bought a level in engineering. He practiced his commerce at EMI—the firm would turn into better known for selling Beatles albums, however began out as Electrical and Music Industries, with a deal with electronics and electrical engineering.

Hounsfield’s pure skills propelled him to guide the crew constructing the most superior mainframe pc out there in Britain. However by the ’60s, EMI wished out of the aggressive pc market and wasn’t certain what to do with the good, eccentric engineer.

Whereas on a pressured vacation to ponder his future and what he would possibly do for the firm, Hounsfield met a doctor who complained about the poor high quality of X-rays of the mind. Plain X-rays show marvelous details of bones, however the mind is an amorphous blob of tissue—on an X-ray all of it appears to be like like fog. This bought Hounsfield interested by his previous thought of discovering hidden buildings with out opening the field.


A brand new strategy reveals the beforehand unseen

Hounsfield formulated a brand new method to strategy the drawback of imaging what’s inside the cranium.

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X-rays beam by way of every ‘slice’ of mind, oriented at every diploma from 1 to 180 in a semicircle. [Image: Edmund S. Higgins, CC BY-ND]

First, he would conceptually divide the brain into consecutive slices—like a loaf of bread. Then he deliberate to beam a collection of X-rays by way of every layer, repeating this for every diploma of a half-circle. The energy of every beam can be captured on the reverse aspect of the mind—with stronger beams indicating they’d traveled by way of much less dense materials.

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Calculating the energy of every X-ray as soon as it’s handed by way of the object, and dealing backward with an spectacular algorithm, it’s attainable to assemble an picture. [Image: Edmund S. Higgins, CC BY-ND]

Lastly, in probably his most ingenious invention, Hounsfield created an algorithm to reconstruct an picture of the mind primarily based on all these layers. By working backward and utilizing one in all the period’s quickest new computer systems, he might calculate the worth for every little field of every mind layer. Eureka!

However there was an issue: EMI wasn’t concerned in the medical market and had no want to leap in. The corporate allowed Hounsfield to work on his product, however with scant funding. He was pressured to scrounge by way of the scrap bin of the analysis services and cobbled collectively a primitive scanning machine—sufficiently small to relaxation atop a eating desk.

Even with successful scans of inanimate objects and, later, kosher cow brains, the powers that be at EMI remained underwhelmed. Hounsfield wanted to search out outdoors funding if he wished to proceed with a human scanner.

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Schematic diagram of the CT scanner included in Hounsfield’s U.S. patent. [Image: Godfrey Newbold Hounsfield]

He knew there have been no grants they might acquire rapidly, however reasoned the U.Okay. Division of Well being and Social Safety might buy gear for hospitals. Miraculously, Ingram bought them 4 scanners earlier than they had been even constructed. So, Hounsfield organized a crew, they usually raced to construct a protected and efficient human scanner.Hounsfield was an excellent, intuitive inventor, however not an efficient communicator. Fortunately he had a sympathetic boss, Invoice Ingram, who noticed the worth in Hounsfield’s proposal and struggled with EMI to maintain the mission afloat.

In the meantime, Hounsfield wanted sufferers to check out his machine on. He discovered a considerably reluctant neurologist who agreed to assist. The crew put in a full-sized scanner at the Atkinson Morley Hospital in London, and on Oct. 1, 1971, they scanned their first affected person: a middle-aged girl who confirmed indicators of a mind tumor.

It was not a fast process—half-hour for the scan, a drive throughout city with the magnetic tapes, 2.5 hours processing the knowledge on an EMI mainframe pc and capturing the picture with a Polaroid digital camera earlier than racing again to the hospital.

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The primary scientific CT scan, with mind tumor seen as darker blob.
[Image: Medical Imaging Systems: An Introductory Guide,’ Maier A, Steidl S, Christlein V, et al., editors., CC BY]

And there it was—in her left frontal lobe—a cystic mass about the dimension of a plum. With that, each different technique of imaging the mind was out of date.

Thousands and thousands of CT scans yearly

EMI, with no expertise in the medical market, out of the blue held a monopoly for a machine in excessive demand. It jumped into manufacturing and was initially very profitable at promoting the scanners. However inside 5 years, greater, extra skilled firms with extra analysis capability comparable to GE and Siemens had been producing higher scanners and gobbling up gross sales. EMI finally exited the medical market—and became a case study in why it may be higher to accomplice with one in all the large guys as an alternative of attempting to go it alone.

Hounsfield’s innovation reworked medication. He shared the Nobel Prize for Physiology or Drugs in 1979 and was knighted by the Queen in 1981. He continued to putter round with innovations till his remaining days in 2004, when he died at 84.


In 1973, American Robert Ledley developed a whole-body scanner that might picture different organs, blood vessels and, in fact, bones. Trendy scanners are sooner, present higher decision, and most essential, do it with much less radiation publicity. There are even cellular scanners.

By 2020, technicians had been performing more than 80 million scans annually in the U.S.. Some physicians argue that quantity is extreme and perhaps a 3rd are pointless. Whereas which may be true, the CT scan has benefited the health of many sufferers round the world, serving to establish tumors and decide if surgical procedure is required. They’re notably helpful for a fast seek for inner accidents after accidents in the ER.

And keep in mind Hounsfield’s thought about the pyramids? In 1970 scientists positioned cosmic ray detectors in the lowest chamber in the Pyramid of Khafre. They concluded that no hidden chamber was present within the pyramid. In 2017, one other crew positioned cosmic ray detectors in the Nice Pyramid of Giza and found a hidden, but inaccessible, chamber. It’s unlikely it will likely be explored anytime quickly.

Edmund S. Higgins is an affiliate affiliate professor of psychiatry & household medication at the Medical College of South Carolina. This text is republished from The Conversation underneath a Artistic Commons license. Learn the original article.