For mobile equipment, which provisions are correct?

• A. Exposure switch can be dead-man type
• B. Distance between operator and patient at least 6 feet away from the useful beam
• C. Source-to-skin distance is 12 inches
• D. All of the above

Answer: (D)

Operator safety and exposure control when using mobile X-ray units. A dead-man exposure switch ensures that the operator must actively keep the switch pressed to expose, preventing accidental or prolonged exposure if the operator loses contact. Standing at least six feet away from the patient or the primary beam reduces the dose received by the operator, thanks to the inverse-square relationship between distance and exposure. Maintaining a source-to-skin distance of at least 12 inches keeps the skin dose within safer limits and complies with safety guidelines for portable imaging. Taken together, these provisions reflect standard protective practices for mobile radiography, so all of the listed provisions are correct.