BCNP key terms

An unstable form of an element that emits radiation as it decays to a more stable state. In nuclear pharmacy, radionuclides are the radioactive component of radiopharmaceuticals used for imaging or therapy.

A radioactive drug product containing a radionuclide, used for diagnosis or treatment of disease. It may be a simple radionuclide or a radionuclide attached to a targeting molecule.

The time required for half of the radioactive atoms in a sample to decay. Physical half-life is a fixed property of each radionuclide, while biological half-life describes clearance from the body.

The spontaneous transformation of an unstable nucleus into a more stable configuration, accompanied by emission of radiation. Common modes include alpha decay, beta decay, and isomeric transition.

High-energy electromagnetic radiation emitted from an excited nucleus as it transitions to a lower energy state. Gamma photons are highly penetrating and are used for external imaging in nuclear medicine.

A type of beta-plus decay in which a proton-rich nucleus emits a positron and a neutrino. The positron annihilates with an electron to produce two 511 keV gamma photons, enabling PET imaging.

The two 511 keV gamma photons produced when a positron interacts with an electron and both particles are converted to energy. These photons are emitted in opposite directions and are detected by PET scanners.

Atoms of the same element that have the same number of protons but different numbers of neutrons. Isotopes share chemical properties but may differ in nuclear stability and radioactivity.

A metastable nuclear state in which a nucleus remains in an excited energy level for a measurable time before decaying. Technetium-99m is a medically important isomer that emits gamma radiation without changing its proton or neutron number.

A metastable isomer of technetium-99 with a 6-hour physical half-life that emits a 140 keV gamma photon. It is the most widely used radionuclide in diagnostic nuclear medicine because of its favorable imaging properties and availability from generators.

A device containing molybdenum-99 adsorbed on a column, which decays to technetium-99m. Saline elution removes the technetium-99m while the parent molybdenum-99 remains on the column for continued production.

The process of removing a daughter radionuclide from a generator column by passing a suitable solvent through it. In a technetium-99m generator, sterile saline is used to collect the sodium pertechnetate solution.

The solution that emerges from a generator column after elution. It contains the daughter radionuclide, such as sodium pertechnetate Tc-99m, along with any impurities that were not retained on the column.

The chemical form of technetium-99m obtained from a generator, written as Na99mTcO4. It is used directly for thyroid, salivary gland, and gastric imaging, and as the starting material for preparing technetium-99m radiopharmaceuticals.

A sterile, nonradioactive vial containing the chemical ingredients needed to prepare a radiopharmaceutical when mixed with a radionuclide solution. The kit typically contains a reducing agent, ligand, buffer, and stabilizer.

The process of incorporating a radionuclide into a molecule or particle so that it can be used as a radiopharmaceutical. For technetium-99m, radiolabeling usually involves reduction of pertechnetate and binding to a ligand.

The fraction of the total radioactivity in a radiopharmaceutical that is present in the desired chemical form. It is assessed by methods such as thin-layer chromatography or high-performance liquid chromatography.

The fraction of the total radioactivity in a preparation that comes from the intended radionuclide. It is determined by gamma-ray spectrometry or by measuring the half-life and comparing it with the expected value.

The fraction of the total mass in a radiopharmaceutical that is the desired chemical substance, excluding nonradioactive impurities. It is distinct from radiochemical purity, which considers only the radioactive species.

The presence of molybdenum-99 in the technetium-99m eluate, which is an unwanted radionuclidic impurity. It is measured with a dose calibrator or gamma spectrometer and must not exceed regulatory limits.

The presence of aluminum ions in the technetium-99m eluate, which can interfere with radiolabeling. It is tested by spotting the eluate on indicator paper and comparing the color change with a standard.

An instrument used to measure the radioactivity of a radiopharmaceutical before administration. It is an ionization chamber that must be calibrated for each radionuclide and checked for accuracy and constancy.

An imaging device that detects gamma photons emitted from a patient and produces planar images. It uses a collimator, scintillation crystal, photomultiplier tubes, and electronics to localize the source of radioactivity.

Single-photon emission computed tomography, a nuclear imaging technique that produces three-dimensional images by detecting gamma photons from multiple angles around the patient. It commonly uses technetium-99m radiopharmaceuticals.

Positron emission tomography, an imaging technique that detects annihilation radiation from positron-emitting radionuclides to produce three-dimensional functional images. Common PET radionuclides include fluorine-18 and gallium-68.

A positron-emitting radionuclide with a 110-minute half-life, commonly used in PET imaging. Fluorine-18 fluorodeoxyglucose is the most widely used PET radiopharmaceutical for assessing glucose metabolism.

A glucose analog labeled with fluorine-18 that is taken up by cells and trapped after phosphorylation. It is used in PET imaging to evaluate glucose metabolism in tumors, brain, and heart.

The time required for the amount of radioactivity in a biological system to decrease by half due to both radioactive decay and biological elimination. It is calculated from the physical and biological half-lives.

The time required for half of a substance to be eliminated from the body by biological processes such as metabolism and excretion. It is independent of radioactive decay and varies with the chemical form and patient.

The pattern of distribution of a radiopharmaceutical within the body over time. It is influenced by the drug's chemical properties, route of administration, and physiological factors such as blood flow and organ function.

The process by which a radiopharmaceutical accumulates in a specific organ or tissue. Mechanisms include active transport, receptor binding, phagocytosis, and compartmental sequestration.

The amount of energy from ionizing radiation deposited per unit mass of tissue, usually expressed in gray or rad. In nuclear medicine, it is estimated using models that account for the radiopharmaceutical's biodistribution and decay.

The calculation and measurement of radiation dose delivered to tissues. In nuclear pharmacy, dosimetry is used to estimate patient dose, optimize therapy, and ensure compliance with radiation safety limits.

As Low As Reasonably Achievable, a radiation safety principle that requires minimizing radiation exposure to workers, patients, and the public while considering economic and social factors. It is implemented through time, distance, and shielding.

Material placed between a radiation source and a person or detector to reduce exposure. In nuclear pharmacy, lead or tungsten shields are used for syringes, vials, and radiopharmaceutical storage areas.

The practices and regulations designed to protect people and the environment from unnecessary exposure to ionizing radiation. It includes facility design, monitoring, waste management, and worker training.

Material that contains or is contaminated with radionuclides and must be managed according to regulations. In nuclear pharmacy, waste includes decay-in-storage items, contaminated supplies, and unused radiopharmaceuticals.

A method of radioactive waste management in which short-lived waste is stored until its radioactivity has decayed to background levels. It is permitted for certain radionuclides with short half-lives, such as technetium-99m.

A United States Pharmacopeia chapter that sets standards for compounding sterile radiopharmaceuticals. It addresses facility requirements, personnel training, environmental monitoring, and quality assurance for nuclear pharmacy practice.

The set of procedures used to verify that a radiopharmaceutical meets established specifications for identity, purity, potency, and safety. It includes tests such as visual inspection, pH, radiochemical purity, and radionuclidic purity.