What is the minimum source-to-skin distance for fixed fluoroscopes?

What is the minimum source-to-skin distance for fixed fluoroscopes?

• A. 15 inches
• B. 12 inches
• C. 10 inches
• D. 18 inches

Answer: (A)

Keeping a minimum source-to-skin distance in fluoroscopy helps limit the radiation dose delivered to the patient’s skin. For fixed fluoroscopes, standards specify a minimum SSD of 15 inches (38 cm). This distance provides enough space to position protective shielding and maintain safe imaging geometry, while acknowledging that dose to the skin rises quickly as the tube gets closer—per the inverse square law, shortening the distance increases skin dose substantially. Mobile fluoroscopy units, by contrast, are allowed a shorter minimum distance (about 12 inches) because they are used in closer, dynamic procedures. Distances greater than 15 inches aren’t required for fixed systems and would not reflect the safety standard, while shorter distances would increase risk.

Keeping a minimum source-to-skin distance in fluoroscopy helps limit the radiation dose delivered to the patient’s skin. For fixed fluoroscopes, standards specify a minimum SSD of 15 inches (38 cm). This distance provides enough space to position protective shielding and maintain safe imaging geometry, while acknowledging that dose to the skin rises quickly as the tube gets closer—per the inverse square law, shortening the distance increases skin dose substantially. Mobile fluoroscopy units, by contrast, are allowed a shorter minimum distance (about 12 inches) because they are used in closer, dynamic procedures. Distances greater than 15 inches aren’t required for fixed systems and would not reflect the safety standard, while shorter distances would increase risk.