Radiopharmacy MCQs
Practice questions on radiopharmaceutical production, quality control, and preparation.
What is the parent isotope in a standard Technetium-99m generator?
Explanation: Molybdenum-99 (Mo-99) is the parent isotope which decays into the daughter isotope Tc-99m. The half-life of Mo-99 is 66 hours.
Which quality control test detects Alumina breakthrough in the Tc-99m eluate?
Explanation: Chemical purity testing detects Aluminum (Al3+). This is typically doing using a colorimetric spot test with specialized test paper compared to a standard standard solution (< 10 µg/mL).
The limit for Molybdenum-99 breakthrough in Tc-99m eluate at the time of administration is:
Explanation: The NRC limit is 0.15 µCi of Mo-99 per 1 mCi of Tc-99m at the time of administration.
Radiochemical purity refers to:
Explanation: Radiochemical purity is the fraction of total radioactivity in the desired chemical form (e.g., bound Tc-99m MDP vs. free pertechnetate). It is usually tested with thin-layer chromatography (TLC).
Which radiopharmaceutical is used for renal cortical imaging?
Explanation: Tc-99m DMSA (Dimercaptosuccinic acid) binds to the renal cortex and is used for static renal imaging to evaluate for scarring or pyelonephritis. MAG3 and DTPA are used for dynamic functional studies.
The physical half-life of Fluorine-18 is approximately:
Explanation: F-18 has a half-life of roughly 110 minutes (1.83 hours), making it suitable for distribution from regional cyclotrons.
Stannous ion (Sn2+) in cold kits acts as a:
Explanation: Stannous ion is a reducing agent. It reduces Technetium from the +7 valence state (in pertechnetate) to lower states (e.g., +4) so it can chelate with the pharmaceutical ligand (e.g., MDP, HIDA).
Particle size is critical for which radiopharmaceutical mechanism?
Explanation: Tc-99m MAA (Macroaggregated Albumin) relies on capillary blockade in the lungs. Particles must be large enough to trap (10-90 µm) but not so large as to block larger vessels.
Which agent is used to label Red Blood Cells via the ‘in vivo’ method?
Explanation: Stannous pyrophosphate (PYP) is injected first to ’tin’ the RBCs, followed by Tc-99m pertechnetate which then binds to the beta chain of hemoglobin.
Hydrolysis of reduced Technetium results in the formation of:
Explanation: Hydrolyzed-Reduced Tc (HR-Tc) is a common radiochemical impurity that behaves like a colloid, often showing uptake in the liver and spleen (reticuloendothelial system).
Which of the following requires heating during preparation?
Explanation: Tc-99m Sestamibi (and Mertiatide/MAG3) requires a boiling water bath step during preparation to facilitate the complexation reaction.
Tc-99m Sulfur Colloid is cleared from the blood by:
Explanation: Phagocytosis by the reticuloendothelial system (Kupffer cells in liver, spleen, bone marrow).
The biological half-life refers to:
Explanation: The time required for the body to eliminate half of the administered substance via biological processes (excretion, metabolism).
Mo-99 is produced primarily by:
Explanation: Nuclear fission of Uranium-235 targets in a nuclear reactor is the primary method for producing Mo-99.
What is the expiration time for most Tc-99m labeled kits?
Explanation: Most prepared Tc-99m kits have a shelf life of 6-12 hours, after which radiochemical purity may degrade due to radiolysis or oxidation.