Which of the following is NOT considered one of the three cardinal principles of radiation safety?

Which of the following is NOT considered one of the three cardinal principles of radiation safety?

• A. Time
• B. Distance
• C. Shielding
• D. Inverse square law

Answer: (D)

The three cardinal principles of radiation safety are time, distance, and shielding. These are the practical rules you apply to minimize exposure. Limiting the time you spend near the source reduces the total dose you receive. Increasing your distance from the source dramatically cuts exposure because radiation intensity falls off quickly with distance. Shielding provides a physical barrier that attenuates or blocks radiation before it reaches you. The inverse square law describes mathematically how exposure decreases with distance, which explains why distance helps, but it is not one of the three practical cardinal principles itself.

The three cardinal principles of radiation safety are time, distance, and shielding. These are the practical rules you apply to minimize exposure. Limiting the time you spend near the source reduces the total dose you receive. Increasing your distance from the source dramatically cuts exposure because radiation intensity falls off quickly with distance. Shielding provides a physical barrier that attenuates or blocks radiation before it reaches you.

The inverse square law describes mathematically how exposure decreases with distance, which explains why distance helps, but it is not one of the three practical cardinal principles itself.