Roentgen (unit) absorbed dose in a wide range of matter. When measuring absorbed dose in a human due to external exposure, the SI unit the gray, or the related non-SI rad are used. From these can be developed the dose equivalents to consider biological effects from differing radiation types and target materials. These are equivalent dose, and effective dose for which the SI unit sievert or the non-SI rem are used. The following table shows radiation quantities in SI and non-SI units: Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays
Wilhelm Alexander Freund Wilhelm Alexander Freund Wilhelm Alexander Freund (August 26, 1833 - December 24, 1917) was a German gynecologist who was a native of Krappitz, Silesia. Born into a Jewish family, in 1855 he earned his medical degree at the University of Breslau, afterwards practicing gynecology in the same city. In 1874 he became an associate professor at Breslau. In 1879 he relocated to Strasbourg, where he served as a professor of gynecology and obstetrics. He died in Berlin. In January 1878, Freund performed the first abdominal extirpation of a cancerous uterus. Twenty years later in 1898, Austrian gynecologist Ernst Wertheim (1864-1920)