John Joly

John Joly (/ˈdʒoʊli/; 1 November 1857 – 8 December 1933) was an Irish geologist and physicist known for his development of radiotherapy in the treatment of cancer. In 1914, he worked with Walter Stevenson to establish the Irish Radium Institute, where they jointly developed the "Dublin method" for deep radiotherapy using hollow needles. He is also known for developing techniques to more accurately estimate the age of a geological period, based on radioactive elements present in minerals, the uranium–thorium dating.