Nuclear stability forms the foundation of radionuclide imaging. In nuclear medicine, the diagnostic and therapeutic properties of an isotope depend entirely on the structure and stability of its nucleus. Understanding why certain nuclei are stable while others undergo radioactive decay is essential for selecting appropriate radioisotopes and for interpreting their behaviour in imaging and therapy.

Nuclear stability is governed by binding energy, mass defect, nuclear forces, and the neutron-to-proton ratio. Concepts such as the valley of stability, pairing effects, and the semi-empirical mass formula explain patterns of decay and isotopic abundance. These principles underpin why isotopes such as technetium-99m are suitable for imaging, while others decay via alpha, beta, or positron emission. Nuclear stability is a high-yield topic in FRCR Part 1 Physics and ABR Core examinations, particularly in questions linking atomic structure to decay mechanisms.

This section contains structured nuclear medicine physics questions covering binding energy calculations, nuclear mass relationships, stability curves, and applied exam scenarios. The questions are designed to consolidate core theory while reinforcing clinical relevance in radionuclide imaging.

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