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
Anton Wilhelm Plaz Anton Wilhelm Plaz Anton Wilhelm Plaz (1 January 1708, Leipzig – 26 February 1784, Leipzig) was a German physician and botanist. From 1723 he studied medicine at the universities of Leipzig and Halle, receiving his doctorate at the latter institution in 1728. In 1733 he became an associate professor of botany at Leipzig, where afterwards, he successively served as a full professor of botany (1749–54), physiology (1754–58), anatomy and surgery (1758), pathology (1758–73) and therapy (1773–84). From 1773 to 1784 he was dean to the medical faculty at the university. He was a member of the Römisch Kaiserlichen Akademie der