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Techniques & Technologies


X-rays for diagnosis and therapy

A child undergoing an x-ray at University Children's Hospital, Vienna, 1921.


Credits:Wellcome Library, London.

X‑rays were discovered by Wilhelm Roentgen in 1895. They are electromagnetic energy waves that are far more energetic than light rays. X‑rays are most commonly used for medical diagnosis, but also for cancer treatment.

The heart of an X‑ray machine is a vacuum-sealed glass cylinder containing a pair of electrodes. When electricity is sent through the tube, X‑rays are released at the positive electrode. The high-energy rays pass through soft body tissue, but get absorbed by dense material such as bone. This creates ’shadows‘ that can be captured with photographic or fluoroscopic techniques. Doctors used X‑rays to see inside living patients’ bodies without having to cut them open.

Military doctors were early converts to X‑rays. They helped the removal of bullets or shrapnel and got soldiers back on the battlefield. Army recruits were X‑rayed for chest diseases such as TB. In the 1940s mass civilian screening for TB took place with portable X‑ray machines.

X‑ray machines were central to hospital diagnosis by the 1930s. They led to specialist radiologists and radiographers. Many techniques and technologies were developed during the 20th century to enhance X‑ray body imaging. X‑ray machines were found to be harmful to practitioners and patients by exposing them to high levels of radiation. As a result, machines were used with protective measures to reduce radiation dosages. However, X‑ray radiation was also a useful cancer treatment known as radiation therapy.

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R Bud and D J Warner (eds), Instruments of Science, An Historical Encyclopaedia (London: Science Museum, 1998)


E Burrows, Pioneers and Early Years: A History of British Radiology, (Aldeney: Colophon, 1986)

A Michetter and S Pfauntsch (eds), X-rays: The First Hundred Years (London: Wiley, 1996)


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