roentgen
/ˈrɒntgən/(缩略词：R)
noun
- a unit of ionizing radiation, the amount producing one electrostatic unit of positive or negative ionic charge in one cubic centimetre of air under standard conditions伦琴（X辐射或γ辐射的照射计量单位）。
词源
1920s: named after Wilhelm Conrad Röntgen （1845-1923）, German physicist, discoverer of X-rays.