Ultrasound and computed tomography: spin-offs of the world wars.
Important losses to the ships of the allied troops by the attacks of the German submarines during World War I led researchers to find specific detecting devices as a means of defence. In 1880 Pierre Curie and his brother, discovered the production of ultrasound waves. Langevin, their student, applied this invention to the localisation of boats. At the end of WWI, research and results ended up being forgotten, but gained attention again with the sonar when WWII loomed on the horizon. At the end of the war, a former military medical doctor, G. Ludwig (US Navy), tried to localize gallstones with a left-over sonar apparatus. This definitely led to firm conclusions. Other researchers in several countries contributed to refining this new imaging technique which is nowadays widely applied. During WWII, the American and British army developed considerable research in the field of the calculator (computer) to speed up deciphering the secret codes. Coupling the principles of tomography discovered during WWI with the computing capability of the calculators developed during WWII, computerized axial tomography could be obtained. This new technology, which is used daily, probably is one of the greatest acquisitions of the 20th century in the field of medical imaging.