Links & GlossaryNuclear Med. Glossary P-RThe Nuclear Medicine Glossary by Richard Zimmerman, IBA Letters P to R PET:positron emission tomography. Imaging modality based on the detection of the two gamma photons generated by a positron emitter. PET/CT:imaging technology combining positron emission tomography and X-ray analysis. Positron:see Beta-plus. Posology:dosage and procedures for administering a medicine. Prevalence:total number of patients at a given time for a defined disease. It is an estimation of how common a disease is in a population. Proton:a positively charged elementary particle, constituting the nucleus of the atom together with the neutron. Proton therapy:method of external radiotherapy using a proton beam. Rad:see Gray. Radiation:a beam of invisible particles or waves emitted by a source. Also, it corresponds to the process of transmission of energy in corpuscular (α, β- particles, etc.) or electromagnetic form (visible light, ultraviolet, infrared, X, γ, etc.) Radioactive half-life (or period):time at the end of which half the atoms initially present in a radioactive element have disappeared through spontaneous transformation. This period (half-life) is different for each radionuclide, but is a precise physical constant for a given radionuclide and is influenced by neither temperature or pressure. Radioactivity:property of certain radionuclides which emit particles spontaneously (electrons, protons, neutrons, nuclei) and/or α-, β-, γ-, or X-rays. Radiochemical:a radioactive substance not intended for human use. Radiochemist:a chemist specializing in the manufacture of radioactive substances; therefore, in the field of nuclear medicine, a specialist in the development of labeling, and in the field of nuclear physics, a specialist in the chemistry of radionuclides. Radiochemistry:chemistry of substances incorporating a radioactive element. Radioelement:an element where all the isotopes are radioactive, e.g., those of the plutonium or uranium groups (term often used wrongly in the place of radionuclide or radioisotope). Radioisotope:an unstable isotope that decays over the course of time, emitting radiation (see Radionuclide). Radiologist:specialist in X-ray imaging. Radionuclide:radioactive atomic nucleus. Two radionuclides compared with each other are called radioisotopes if they belong to the same family of atoms (e.g. the radioisotopes of iodine, such as iodine-123, -124, or -131) and radionuclides in other cases. The word in the plural, ‘radioisotopes,’ is frequently used wrongly to designate all radionuclides. Radiopharmaceutical:radioactive medication intended for diagnosis or therapy in the field of nuclear medicine. Radiopharmacist:a hospital pharmacist specializing in the labeling and handling of radiopharmaceutical preparations intended for administration to a patient. Radiopharmacy:a laboratory, principally located in a hospital, equipped to handle radioactive substances for injection into patients. Radiophysician:physician specializing in the handling and production of radionuclides. Radiotherapist:physician specializing in treatment by external radiotherapy. If the radioactive substance has to be injected into a patient, this task is entrusted to the nuclear physician. Radiotherapy:method of therapy (treatment of a disease) based on the use of radiation, of whatever sort (X-, α-, or β-rays, neutrons, etc.). Rem:see Sievert. |