Roentgen (unit) One roentgen deposits of absorbed dose in dry air, or in soft tissue. One roentgen of X-rays may deposit anywhere from in bone depending on the beam energy. This tissue-dependent conversion from kerma to absorbed dose is called the F-factor in radiotherapy contexts. The conversion depends on the ionizing energy of a reference medium, which is ambiguous in the latest NIST definition. The roentgen has its roots in the Villard unit defined in 1908 by the American Roentgen Ray Society as "the quantity of radiation which liberates by ionisation one esu of electricity per cm of air under normal conditions
Friedrich Wilhelm Theile Friedrich Wilhelm Theile Friedrich Wilhelm Theile (11 November 1801, in Buttstädt – 20 October 1879, in Weimar) was a German physician and anatomist. In 1825 he received his medical doctorate from the University of Jena with the dissertation-thesis "De Musculis nervisque laryngeis". From 1828, with Heinrich Wilhelm Ferdinand Wackenroder, he was in charge of the pharmaceutical institute at Jena. In 1831 he became an associate professor, and three years later relocated to the University of Bern as a full professor of anatomy. From 1853 he practiced medicine in Weimar, during which time, he largely concerned himself with literary activities. In