Roentgen (unit) Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays and gamma rays. It is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air. In 1928 it was the first international measurement quantity for ionising radiation to be defined for radiation protection, and was an easily replicated method of measuring air ionization directly by using an ion chamber. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays. Although relatively easy to measure, it had
Albany Medical College co-founder of the American Medical Association. AMC is attributed as the site where David S. Sheridan perfected the modern-day disposable catheter, among other major discoveries and innovations. Among AMC alumni accomplishments include the discovery of the hormone leptin, the invention of computed tomography, and the discovery of oral rehydration therapy. There are multiple courses of study at the College, with tracks that end in an MD degree, as well as a Graduate Studies program with the following departments: AMC sponsors medical residency programs in anesthesiology; emergency medicine; family medicine; internal medicine; medicine/pediatrics; neurology; obstetrics, gynecology, and reproductive sciences; ophthalmology; pathology;