Timeline: a history of medical imaging

Today, medical imaging technologies such as X-ray and MRI machines are so ubiquitous across healthcare settings that it is difficult to imagine a life without them. The contributions of these machines and techniques to the advancement of medicine is undoubtable, from the early days of the humble microscope to the futuristic possibilities of patient-specific 3D modelling, the history of medical imaging is both rich and eventful.

As we look ahead to another year of innovation and developments yet to come, we remember the dedicated few who proved that medicine is more than skin deep, by providing an ever-deeper view into the human body.


Wilhelm Röntgen; current version created by Old Moonraker., Public domain, via Wikimedia Commons

Wilhelm Roentgen accidentally discovers X-rays

Although early references to what we now understand to be X-rays can be traced back to 1785, when the ‘father of modern actuarial science’ – Welsh physician, physicist, and statistician, William Morgan – recorded an “invisible light”, produced when a current is passed through an experimental discharge tube. But it wasn’t until 1895 that this radiation would be given its famed moniker: X-rays.

Official discovery of X-rays is commonly attributed to German physics professor, Wilhelm Roentgen, who – somewhat accidentally – stumbled across the radiation while testing to see whether cathode rays could travel through the glass of Lenard and Crookes tubes. There is some debate as to the specific details of the discovery, as Roentgen instructed that his lab notes be burned upon his death, however, the likely story presented by his biographers is that, during one such experiment, Roentgen noticed that an unidentified ray was escaping from beneath the black cardboard covering his cathode tube, causing a nearby fluorescent screen painted with barium platinocyanide to glow green.

Roentgen dubbed the unknown rays “X” and quickly threw himself into uncovering their scientific secrets. Two months later, he submitted the first paper written on X-rays and submitted it to Würzburg’s Physical-Medical Society journal.

Following his initial discovery, Roentgen went on to identify their potential medical use when he used X-rays to form a picture of his wife’s hand on a photographic plate. It was the first photograph of the human body to be captured using the technique.

Understandably, news of his discovery sent shockwaves across the medical field, and soon physicians around the world were using X-rays to locate injuries, fractures, and foreign objects in the patients. For his work, Roentgen was awarded the Nobel Prize in physics in 1901.


Albert Salomon and the mammogram

Little over a decade after Roentgen received the Nobel Prize, German surgeon Albert Salomon would leverage the capabilities of X-ray imaging to perform his inaugural mammography study. In what would go on to form the foundation of the mammography, Saloman analysed 3,000 mastectomies, where he compared X-rays of breasts to the actual removed tissue, specifically observing microcalcifications.

Through his research with X-ray imaging, Salomon established a difference between cancerous and non-cancerous tumours in the breast. Moreover, he identified the existence of multiple types of breast cancer.

Despite publishing his findings in 1913, patients would have to wait more than 50 years for the clinical use of mammography as a screening tool to become widespread.

Credit: National Cancer Institute, National Institutes of Health


Jmarchn, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Nuclear Magnetic Resonance emerges

Early descriptions of nuclear magnetic resonance can be traced back to the work of American physicist Isidor Isaac Rabi in 1938, when he demonstrated that molecular beams could be made to emit radio waves at specific frequencies when passed through a magnetic field – a feat for which he was awarded the 1944 Nobel Prize in Physics.

After independently discovering nuclear magnetic resonance using different instrumentation and techniques, in 1946 American physicists Edward Purcell and Felix Bloch expanded the technique for use on liquids and solids.

In 1952, Purcell and Bloch were jointly awarded the Nobel Prize in Physics for ‘their development of new methods for nuclear magnetic precision measurements and discoveries in connection therewith’.

While they could not have known it at the time, the work of Rabi, Purcell, and Bloch would become the foundation of a technique that would transform modern healthcare delivery: Magnetic Resonance Imaging.


Discovery of ultrasound for medical diagnosis

The principles of echolocation first identified in 1794 by Italian biologist Lazzaro Spallanzani informed the foundation of today’s ultrasound technology.

Having developed an interest in the possibilities of adapting radar and sonar technology for medical use during the Second World War, Scottish physician Ian Donald began to explore the use of ultrasound to diagnose gynaecological patients. Ultrasonic waves had previously been noted for their use in detecting brain tumours by neurologist Karl Dussick in 1942, however, the use of ultrasound as a diagnosis tool in gynaecology was, at the time, an unknown.

It was during his tenure as professor of regius midwifery at Glasgow University when Donald began to work with T G Brown (a research engineer with from the scientific instrument makers Kelvin & Hughes) to create the first diagnostic ultrasound machine.

In 1956, they were joined by obstetrician John MacVicar and together the team worked to determine the causation behind certain images produced by the scan. Through their research, they identified that an ovarian cyst would result in a clear gap in the image, as well as investigating the shapes of images in the presence of uterine fibroids.

In 1958, Donald, Brown, and MacVicar published their findings in The Lancet.

© Nevit Dilmen, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons


Laskaridis L1, Kampantais S, Toutziaris C, Chachopoulos B, Perdikis I, Tahmatzopoulos A, Dimitriadis G, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Godfrey Hounsfield introduces the CT scan

The concept of tomography was initially introduced in the early 1900s by the Italian radiologist Alessandro Vallebona, however, the use of radiographic film to see a single slice of the body was considered ineffective when it came to capturing soft tissues or larger areas of the body.

The limitations of tomography would continue to impede clinicians until 1967, when Godfrey Hounsfield, an English electrical engineer, and South Africa-born physicist Allan Cormack conceived the idea for the first computed tomography scanner.

Originally, the system focused on head imaging only. In contrast to the highspeed data collection possible with today’s CT imaging, the first scanner developed by Hounsfield and his team at EMI Laboratories in England took several hours to acquire the raw data for a single scan, followed by days of work to reconstruct a single image from this data.

In 1971, the first patient brain CT scan was performed at Atkinson Morley Hospital in Wimbledon, England.


Rise of the MRI body scan

A decade after the first CT scan was recorded in England, Armenian-American doctor and professor at the Downstate Medical Center State University of New York, Richard Damadian, along with Larry Minkoff and Michael Goldsmith, performed the first MRI body scan of a human being.

Their work built upon research from the American chemist Paul Lauterbur. In 1973, Lauterbur developed a way to generate the first MRI images, in 2D and 3D, using gradients.

Across the Atlantic, at the University of Aberdeen, a team led by John Mallard was set up to build the first full-body MRI scanner. In August 1980, the scanner was used to obtain the first clinically useful image of a patient’s internal tissues using MRI, which identified a primary tumour in the patient’s chest, an abnormal liver, and secondary cancer in his bones

It would take a further four years for regulators to give the technology the green light; the US Food and Drug Administration approved the device in 1984.



Sanko, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Total Body PET scanner introduced

Scientists at the University of California-Davis announced the creation ‘EXPLORER’, claimed to be the world’s first medical imaging scanner that can capture a picture of the whole human body at once.

EXPLORER is a combined positron emission tomography (PET) and X-ray CT scanner. Led by scientists Simon Cherry and Ramsey Badawi, the team reported that the scanner captured radiation more efficiently than others, which allowed it to produce an image in one second, dramatically reducing the time required for scans.


A new era of imaging

In late 2021, Siemens Healthineers introduced the world to the first photon-counting CT scanner. The scanner, dubbed Naeotom Alpha, aimed to address limitations in conventional CT scans.

To achieve this, the team behind Naeotom Alpha developed a new detector material: high-purity cadmium telluride (CdTe) crystals. According to Siemens Healthineers, these crystals deliver the highest spatial resolution of any CT imaging system to date and enable pixels nine times smaller than used in conventional CT, without any dose penalty.

With spectral imaging, clinicians can differentiate between calcifications, stents, vessel walls, and contrast media, thereby increasing diagnostic efficiency.


About the author

Eloise McLennan is the editor for pharmaphorum’s Deep Dive magazine. She has been a journalist and editor in the healthcare field for more than five years and has worked at several leading publications in the UK.

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