What is effective dose and why is it used? Effective dose is a calculated quantity that reflects the overall risk of stochastic effects (primarily cancer induction) from radiation exposure to the whole body. It accounts not only for the absorbed…
What is absorbed dose in nuclear medicine? Absorbed dose is the amount of energy deposited by ionising radiation per unit mass of tissue. It represents the physical energy transferred from radioactive emissions to matter and is measured in gray (Gy),…
What determines radiation dose in nuclear medicine? Radiation dose in nuclear medicine is determined by the amount of administered activity, the physical half-life of the radionuclide, the biological clearance of the radiopharmaceutical, the type and energy of emitted radiation, and…
What is receptor imaging in nuclear medicine? Receptor imaging in nuclear medicine refers to the use of radiopharmaceuticals that bind specifically to cellular receptors, allowing in vivo visualisation of receptor expression. Rather than demonstrating perfusion or metabolism alone, receptor imaging…
What is target-to-background ratio in nuclear medicine? Target-to-background ratio (TBR) describes the relative concentration of a radiopharmaceutical within a region of interest compared with surrounding normal tissue. It is the fundamental determinant of image contrast in nuclear medicine. The higher…
What determines organ uptake of a radiopharmaceutical? Organ uptake of a radiopharmaceutical is determined by a combination of blood flow, cellular transport mechanisms, receptor expression, metabolic trapping, and clearance pathways. While biodistribution describes the overall distribution pattern in the body,…
What is chelation in nuclear medicine? Chelation in nuclear medicine is the process by which a radionuclide, typically a metal ion, is bound securely within a specialised chemical structure called a chelator. The chelator forms multiple bonds with the metal…
What is labelling efficiency in nuclear medicine? Labelling efficiency refers to the proportion of a radionuclide that successfully binds to the intended pharmaceutical compound during preparation of a radiopharmaceutical. It is usually expressed as a percentage of total radioactivity that…
What is the difference between carrier-added and no-carrier-added radionuclides? The difference between carrier-added and no-carrier-added radionuclides relates to whether stable (non-radioactive) atoms of the same element are present alongside the radioactive isotope. In a carrier-added preparation, the radioactive isotope is…
What determines biodistribution of a radiopharmaceutical? The biodistribution of a radiopharmaceutical is determined primarily by the chemical structure of the carrier molecule, as well as physiological factors such as blood flow, membrane transport, receptor expression, metabolism, and excretion pathways. The…