Kalmar "Roentgen" tana nufin Wilhelm Conrad Roentgen, masanin kimiyyar lissafi dan kasar Jamus, wanda ya gano X-ray a shekara ta 1895. Ana amfani da kalmar "Roentgen" a matsayin ma'auni na hasken X-ray da gamma, wanda shine adadin ionizing radiation da ke samar da na'urar lantarki guda ɗaya na caji a cikin cubic centimita na busasshiyar iska a daidaitaccen zafin jiki da matsa lamba.
