In radiation shielding, what is the role of a secondary barrier?

• A. Protects against the direct beam
• B. Protects against scatter or leakage
• C. Is used to store shielding materials
• D. Provides structural support

Answer: (B)

Secondary barrier is designed to protect against scatter and leakage radiation. The direct beam is extremely intense and is stopped by the primary barrier, which faces the X-ray tube and patient. But radiation that bounces off the patient or room surfaces (scatter) and any radiation that leaks from the tube housing can reach areas off to the side or behind the operator. The secondary barrier is placed to attenuate this secondary radiation so occupational exposure stays within safe limits. It’s not meant to block the direct beam, store shielding materials, or provide structural support—the latter roles lie with other elements of the room design.