Why is noise proportional to √N in nuclear medicine imaging? In nuclear medicine imaging, noise is proportional to the square root of the number of detected counts (√N) because radioactive decay follows Poisson statistics. For a Poisson process, the variance…
What is the Poisson distribution in nuclear medicine? The Poisson distribution describes the statistical variation in the number of radioactive decay events detected over a given time interval. In nuclear medicine, radioactive decay is a random process, and the number…
What is transient and secular equilibrium in radionuclide generators? Transient and secular equilibrium describe the relationship between the activity of a parent radionuclide and its radioactive daughter in a decay chain, particularly when the parent has a longer half-life than…
How does a Tc-99m generator work? A Tc-99m generator is a system that produces technetium-99m (Tc-99m) from the radioactive decay of its parent isotope, molybdenum-99 (Mo-99). Mo-99 decays by beta minus emission to form Tc-99m, which can then be chemically…
Why is Tc-99m ideal for radionuclide imaging? Technetium-99m (Tc-99m) is ideal for radionuclide imaging because it has a combination of physical and radiological properties that optimise image quality while minimising radiation dose. It emits a single gamma photon of 140…
What is radioactive activity and how is it measured? Radioactive activity is the rate at which unstable nuclei in a sample undergo radioactive decay. It represents the number of nuclear disintegrations occurring per unit time. The SI unit of activity…
What is effective half-life? Effective half-life is the time required for the activity of a radionuclide within the body to fall to half its initial value, taking into account both radioactive decay and biological clearance. It represents the combined effect…
What is biological half-life? Biological half-life is the time required for half of a substance to be eliminated from the body due to biological processes such as metabolism and excretion. Unlike physical half-life, which depends on nuclear decay, biological half-life…
What is physical half-life? Physical half-life is the time required for half of the radioactive nuclei in a sample to undergo decay. It is a fixed property of a given radionuclide and does not depend on external conditions such as…
Why does PET not require a collimator? PET does not require a physical collimator because it uses electronic collimation through coincidence detection. When a positron annihilates with an electron, it produces two 511 keV photons that travel in nearly opposite…