Which shielding materials are commonly used for gamma radiation and what are their typical medical applications?

• A. Water, air, foam; used for packaging.
• B. Lead, concrete, tungsten; used for walls, doors, aprons, containers.
• C. Aluminum, copper, steel; used for plumbing, medical devices.
• D. Plastic, wood, glass; used for floors, ceilings, chairs.

Answer: (B)

Dense, high-atomic-number and high-density materials are chosen for gamma shielding because gamma rays interact with matter in ways that are more effectively attenuated by dense, high-Z substances. For medical shielding, lead, concrete, and tungsten are standard. Lead provides strong attenuation for a broad range of gamma energies and can be easily formed into walls, doors, protective aprons, and containers for radioactive sources. Concrete is widely used for shield walls and room barriers due to its thickness, ease of construction, and cost, making it practical for creating substantial shielding in radiology and nuclear medicine facilities. Tungsten offers similar attenuation in a much thinner profile than lead, which is advantageous in tight spaces or around equipment where space is limited, such as around certain interventional devices or compact shielding needs. In medical settings, these materials are used to line walls and doors of imaging and treatment rooms, to fabricate staff protective aprons and shields, and to contain sealed radioactive sources and waste.

Other materials like water, air, or foam provide much weaker gamma attenuation unless built as impractically thick shields, so they are not used for primary shielding. Aluminum, copper, and steel can attenuate gamma rays but require much greater thickness to achieve the same protection as lead, making them less practical for standard shielding. Plastic, wood, and glass offer minimal gamma shielding and are not suitable as primary barriers.