What is the maximum leakage radiation quantity permitted for a diagnostic x-ray tube housing when measured 1 meter from the housing?

• A. 1000 mGya/hour.
• B. 10 mGya/hour.
• C. 100 mGya/hour.
• D. 1 mGya/hour.

Answer: (D)

Leakage radiation must be kept very low to protect anyone nearby. The standard limit for a diagnostic x-ray tube housing is 1 mGya/hour at a distance of 1 meter from the housing. This means the rate at which energy is deposited in air by stray radiation outside the useful beam cannot exceed 1 milli-Gray per hour at that distance. Measuring at 1 meter provides a practical check of how much radiation could escape into surrounding areas where staff might be exposed during setup or operation. If the leakage were higher than this limit, the housing shielding wouldn’t meet safety requirements and would need maintenance or replacement. The other higher values would not satisfy the safety standard, which is why 1 mGya/hour is the correct limit.