If the dose rate from a gamma source is 100 mR/hour at 12 feet, what is the approximate dose rate at 6 feet?

To determine the dose rate at a closer distance from a gamma source, the inverse square law is used. This principle states that the intensity of radiation is inversely proportional to the square of the distance from the source.

In this scenario, the dose rate is measured at 12 feet and found to be 100 mR/hour. When the distance to the source is halved, from 12 feet to 6 feet, the intensity of the radiation increases significantly. Calculating using the inverse square law, the ratio of the distances squared is 12 feet squared divided by 6 feet squared, which equals 2 squared or 4. This indicates that the radiation dose rate will be four times greater at 6 feet than at 12 feet.

Therefore, the dose rate at 6 feet can be calculated by multiplying the dose rate at 12 feet (100 mR/hour) by 4, leading to an approximate dose rate of 400 mR/hour. This illustrates the impact of distance on radiation exposure and aligns with the principles outlined in radiation safety protocols.