Lead Isotopes are used for medical and scientific purposes. Pb-206 and Pb-207 can both be used to produce the medical radioisotopes Bi-205 and Bi-206. Pb-204, Pb-206 and Pb-207 are used to measure lead levels in blood. Pb-208 has been used to produce neutron-rich isotopes of W and Lu. Pb-208 has also been used to study the configuration of neutron stars. Several Lead Isotopes have also been used as target in the production of super heavy elements.