Portugal: António Caetano de Abreu Freire Egas Moniz

(29^th November 1974 – 13^th December 1955)

Better known as Egas Moniz, this Portuguese neurologist was born in Avanca, 300 km north of Lisbon. He is known for developing the technique of cerebral angiography and in 1927 he became the first person to successfully image the human brain using radiopaque substances. This was achieved by injecting his patients with 25% sodium iodide solution which shows up clearly in an X-ray as it absorbs the radiation – allowing the visualization of blood flow and tumours within the brain. Cerebral angiography is still used now but in 1975 the more popular Computed Tomography (CT) was introduced into clinical practice.

Moniz’s ground-breaking medical imaging technique helped lay the foundations for more sophisticated methods of understanding and imaging the human brain. 90 years on, Positron Emission Tomography (PET) is regularly used to characterize brain activity. This time a positron-emitting isotope is injected into the blood stream of the patient. When it reaches the brain, positrons are emitted that very quickly collide with electrons in the atoms there. This causes annihilation which leads to the release of gamma rays detected by a machine outside of the body, creating the image.

An even newer technique being investigated is Neutron Stimulated Emission Computed Tomography (NSECT). This uses a beam of fast neutrons to generate the gamma rays that create the image, this time representing the elemental composition of body tissue, perhaps enabling the identification of malignant tumours, see Physics in Medicine & Biology.

Thanks to creative pioneers like Egas Moniz, medical imaging has come a long way over the last century; providing humans with safe, non-invasive techniques that can save lives.

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