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
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