Lutitium-177 (Lu-177) is a beta emitter (0.5 MeV) with a half-life of 6.73 days and gamma photopeaks of 113 (3%) keV and 210 (11%) keV, respectively. It can be produced to a high specific activity and has a half value layer (HVL) of 0.6 mm of lead. It has a range of several millimeters in tissue. Antibodies have been successfully labeled with it (e.g., CC49) for intraperitoneal treatment of ovarian cancer (18) or peptides (e.g., octreotate) for treating somatostatin-expressing tumors (19,20). It is commercially available in the United States in pharmacologic grade and is usually labeled using macrocyclic compounds such as tetraazacyclododecane-tetraacetic acid (DOTA). The higher absorbed doses and the lower tissue penetration range of 177Lu has been shown to be advantageous for treating small tumors. Cumulative doses of 600-800 mCi have resulted in partial remissions of 30% in patients with neuroendocrine tumors (19).

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