Palladium

The isotope-amount ratio n(¹⁰⁷Pd)/n(¹⁰⁷Ag) is used in geochronology to help date major thermal events in the Solar System. Although ¹⁰⁷Ag is naturally occurring, ¹⁰⁷Ag is also the daughter product of the beta decay of ¹⁰⁷Pd. If both excess ¹⁰⁷Ag and ¹⁰⁷Pd (with a half-life of 6.5×10⁶ years) are present in a sample of extraterrestrial origin, then the material would have formed sometime after ¹⁰⁷Pd decayed. The n(¹⁰⁷Pd)/n(¹⁰⁷Ag) amount ratio can be measured to help determine when the ¹⁰⁷Pd decay process began and how much time has elapsed since the material was formed [344], [345], [346], [347], [348].

Seeds of the radioactive isotope ¹⁰³Pd are internally placed in the body to fight prostate and other cancers locally. ¹⁰³Pd has a half-life of 16.99 days and releases energy at about 80 X-rays and 186 Auger electrons per 100 decays of ¹⁰³Pd. Therefore, this makes this isotope an ideal candidate for internal radiotherapy for the treatment of cancers [349]. The radioisotope ¹⁰⁹Pd (with a half-life of 13.5 h) can be used as a form of cancer therapy. For example, ¹⁰⁹Pd-labeled porphyrins or porphyrin-like substances are used as diagnostic and therapeutic techniques to help locate and address areas of tumorous growth. Porphyrins accumulate in tumors of the body and when radiolabeled porphyrins are introduced to the body, the X-rays and energy released can help determine the location and even treat the cancerous tumors [350].