Radiopharmaceuticals contain a radionuclide and an agent to direct the radionuclide to a receptor, antigen, ionic pump, or other site of interest. Some radiopharmaceuticals are simple, such as the ionic form of the radionuclide, while most radiopharmaceuticals have a complex chemical structure where the radionuclide provides a signal, indicating the site of localization of the carrier molecule. Common single-photon radiopharmaceuticals used for oncological diagnosis include the “so-called” technetiated radoipharmaceuticals such as99mTc-bisphosphonates (that accumulate at sites of bone mineral rearrangement),99mTc-Labeled colloids (that are used for lymphoscintigraphy and for imaging of the liver and spleen),99mTc-Hexakis-methoxyisobutyl-isonitrile and99mTc-tetrofosmin (initially employed for myocardial perfusion imaging, then validatyed also for localization of parathyroid adenomas and for identi fi cation of other malignant tumors). The most commonly used radiopharmaceuticals labelled with radioiodine (123I or131I) include Iodide itself (for localization of thyroid tissue) the (underline – db) and the catecholamine analog Metaiodobenzylguanidine (MIBG, for localizing pheochromocytoma and neuroblastoma).201Tl Ionic thallium can be used for tumor perfusion imaging, while111In-Pentetreotide detects overexpression of somatostatin receptors, especially in neuroendocrine tumors and in lesions arising from the neural crest, such as carcinoid, paragangliomas, and medullary thyroid carcinomas.111In-Capromab Pendetide is a murine monoclonal antibody which recognizes a transmembrane glycoprotein expressed by poorly differentiated and metastatic prostate adenocarcinomas.67Ga-Citrate receptors are overexpressed on membranes of both tumor and in fl amatory cells. Common radionuclides used for radiometabolic therapy include131I,153Sm,89Sr,90Y and177Lu. Therapeutic radiopharmaceuticals are employed for therapy of differentiated follicular thyroid carcinomas, for therapy of pheochromocytoma/paraganglioma/neuroblastomas, for bone pain palliation, for radioimmunotherapy of lymphomas, for peptide radioreceptor therapy of neuroendocrine tumors, and for intra-arterial radioembolization of hypervascularized tumors of the liver. Experimental radionuclides for therapy include89Zr and for radioimmunotherapy and peptide radioreceptor therapy as well as alpha emitters, such as223Ra,211At,212Bi,213Bi, and225Ac for treating intractable bone pain as well as for radioimmunotherapy.
- Nuclear oncology
- Radioimmune therapy
- Single-photon emission imaging
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