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
David Roentgen David Roentgen David Roentgen (1743 in HerrnhaagFebruary 12, 1807), was a famous German cabinetmaker of the eighteenth century, famed throughout Europe for his marquetry and his secret drawers and mechanical fittings. His work embraces the late Rococo and the Neoclassical styles. In 1753 his father Abraham Roentgen, who had trained in London in the workshop of William Gomm, migrated to the Moravian settlement at Neuwied, near Coblenz, where he established a furniture factory. David learned his trade in his father's workshop, inherited the paternal business in 1772, and entered into partnership with the clockmaker Kintzing. By that time, the name