Milestone-Proposal talk:The Birth of the First CT Scanner

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Introduction and next steps -- John Vardalas (talk) 21:29, 22 May 2020 (UTC)

Dear Proposer:

I am a member of the IEEE History Committee and I will be the Advocate for this proposal. As Advocate, my responsibility is to facilitate the submission of this proposal to a vote by the History Committee. Before I can recommend this proposal to the Committee, at least two external expert reviews are required.

We need to put together a list of possible reviewers. If you have names to recommend, please send them on to me via my email address.

I see that you have not yet checked off the box "Site Owner Permission Letter Received". Have you not yet received this letter?


John Vardalas, Ph.D.

IEEE History Committee

Review from Prof. Hawkes -- John Vardalas (talk) 05:20, 3 September 2020 (UTC)

The following, which I received on 2 Sept. 2020, is Prof. Hawkes's verbatim review of the proposal.

Professor Dave Hawkes founded the Centre for Medical Image Computing (CMIC) at University College London (UCL) in 2005 and has directed it since then. He has been co-Director of the CR-UK, EPSRC and DoH funded joint UCL/KCL Comprehensive Cancer Imaging Centre since 2011. He was Chairman of the Division of Imaging Sciences at KCL between 2002 and 2004 and Director of the £8M EPSRC and MRC funded IRC in Medical Images and Signals from 2003-2007. In 2019 Prof. Hawkes was awarded the Peter Mansfield Medal and Prize by the Institute of Physics for his lifetime contribution to medical imaging research.

"It is an honour to have the opportunity to comment on the proposal to erect a Milestone Plaque at Jupiter House, the site of the old EMI headquarters. I have read the proposal and strongly support the Milestone proposal. The invention of X-ray CT revolutionised radiology and subsequently almost every branch of medicine. There are few medical conditions that do not at some stage require a “scan”.

Early in my career I had the good fortune to work with Dr. John Perry at St. George’s Hospital in South London. John was the medical physicist tasked with checking that the newly invented “EMI-Scanner” was safe to use from a radiation safety perspective. He is the first author of the third of the three landmark papers on the new scanner, published in the British Journal of Radiology in 1973. He had a series of amusing anecdotes of the work he did with Jamie Ambrose, the neuroradiologist at Atkinson Morley Hospital, and Godfrey Hounsfield himself. The initial investment in the project arose from the large sum earned by EMI on the production of the compilation of the Beatles’ songs a year or so earlier. Godfrey Hounsfield, who’s experience was mainly in radar and defence electronics, applied internally within EMI for access to some of these funds to develop the first scanner.

John also spoke of the fortuitous link between Jamie Ambrose and Godfrey Hounsfield and their determination to create a clinically usable system. Godfrey Hounsfield had no medical experience and his early approaches to the established medical engineering industry had been rebuffed. His letter from a well-known medical engineering company, turning down his invention as “having no practical medical application”, was subsequently framed and hung in his office. Jamie Ambrose saw the potential and together they persevered with the first clinical installation at Atkinson Morley Hospital, later to become part of St. George’s Hospital.

The computer used to collect the data on the first clinical scans was not powerful enough to do the reconstructions so the data was stored on magnetic tape and driven to the EMI research labs in Hayes, West London. The reconstructed image data were sent back the next day. There was no screen capable of displaying the images at that time so the integer numerical data was printed out on large format computer paper. Attenuation numbers close to water had short numbers close to zero, bone and lesions within the skull had larger and hence longer numbers. By pinning the print out to the wall and stepping back it was possible to see the bone outline and a lesion (long numbers and appearing darker) within the brain (short numbers and appearing lighter).

I myself met Godfrey Hounsfield a few years later when I set up my lab at Guy’s Hospital. He always maintained an interest in using his CT images to guide surgery and we were developing a project at the time in augmented reality, overlaying CT and MRI renderings in a surgical operating microscope. We visited his facilities at Hayes and he regularly attended our weekly seminars. He was a shy and modest man and always crept in at the back once the talks had started, but asked probing questions at the end. The students enjoyed having him visit.


I have a couple of very minor comments:

Can I suggest inserting the words “clinical” and “X-ray” before “CT” in the title and before “Computerized Tomography” in the Milestone Claim. This distinguishes his work from earlier tomographic reconstruction methods, for example that of Cormack. Godfrey Hounsfield’s major contribution was construction of a clinically usable X-ray CT system that was installed in a hospital and used to generate images on patients. Ultrasound had also been shown to produce images of internal anatomy, but not of the head and not at the detail that X-ray CT could achieve.

I would re-phrase “..that allowed a surgeon to remove a detected cancer” as “.. that allowed a radiologist to locate a cancer and hence guide a surgeon in its removal”. While I am sure it was used by surgeons the initial published work was with a neuroradiologist, Jamie Ambrose.

In the section: “What features set this work apart from similar achievements?” I would rephrase as: “The EMI CT Scanner was the first clinical machine capable of producing high resolution images of X-ray attenuation, allowing depiction of the internal structures and organs of the human body.” MRI is a completely different imaging modality and although it does produce very high quality images, without delivering a dose of ionising radiation, X-ray CT remains the modality of choice for many investigations in for example the lung, vascular systems and the heart etc.

I think it would be appropriate to cite Godfrey Hounsfield’s landmark paper in the British Journal of Radiology. This describes the system.

Computerized transverse axial scanning (tomography): Part 1. Description of system G.N. Hounsfield, 1973, British Journal of Radiology, 46, 1016-1022"

Professor David Hawkes, FMedSci, FREng, FInstP Wellcome/EPSRC Centre for Interventional and Surgical Sciences University College London Charles Bell House 43-45 Foley Street, London, W1W 7TS