How is a contact shield positioned relative to the patient?

• A. Flat or shaped and placed directly on patient.
• B. Suspended over region of interest.
• C. Mounted on wall.
• D. Attached to ceiling.

Answer: (A)

Contact shielding is most effective when the shield is placed directly on the patient, flat or shaped to conform to the body. Keeping the shield in direct contact minimizes the distance between the shield and the skin, so it attenuates the x-ray beam before it reaches sensitive tissues and before scatter is produced. Any air gap would reduce shielding effectiveness and can allow scatter or primary radiation to reach the patient tissue or degrade the image due to misalignment. Shields that are suspended over the region or mounted on walls or ceilings are designed to protect staff from scatter, not to shield the patient in close contact, and introduce gaps or geometry that make them less suitable for this purpose.