 To determine the amount of Pb-210, the alpha radiation emitted by another element, polonium-210 (Po-210), is measured.Thus it is possible to estimate the age of a painting, within a few years' span, by extrapolating the Pb-210 content present in the paint used to create the painting.The white lead in the painting "The Supper at Emmaus" had polonium-210 values of 8.5±1.4 and radium-226 (part of the uranium-238 radioactive decay series) values of 0.8±0.3.