Roentgen equivalent man has been defined since 1976 as equal to 0.01 sievert, which is the more commonly used SI unit outside the United States. A number of earlier definitions going back to 1945 were derived from the roentgen unit, which was named after Wilhelm Röntgen, a German scientist who discovered X-rays. The acronym is now a misleading historical artifact, since 1 roentgen actually deposits about 0.96 rem in soft biological tissue, when all weighting factors equal unity. Older units of rem following other definitions are up to 17% smaller than the modern rem. One rem carries with it a 0.05% chance of
Abraham Roentgen Abraham Roentgen Abraham Roentgen (30 January 1711 – 1 March 1793) was a German Ébéniste (cabinetmaker). Roentgen was born in Mülheim am Rhein, Germany. He learned cabinet making from his father. At age 20, he traveled to Den Haag, Rotterdam and Amsterdam, learning from established cabinet makers. He became known for his marquetry work, and worked in London (in the workshop of William Gomm) until 1738. On 18 April 1739, he married Susanne Marie Bausch from Herrnhut. His son, David Roentgen, was born on 11 August 1743. In 1753 they migrated to the Moravian settlement at Neuwied, near Coblenz, where