What is the approximate dose rate if a gamma source has a dose rate of 10 mR/h at 12 feet?

To determine the approximate dose rate at varying distances from a gamma source, the Inverse Square Law is commonly applied. This law states that the intensity or dose rate of radiation decreases with the square of the distance from the source.

In this scenario, the original dose rate is given as 10 mR/h at a distance of 12 feet. If we want to find the dose rate at a closer distance, you would calculate how the dose rate changes when the distance is reduced.

The formula derived from the Inverse Square Law can be expressed as:

[ \text{New Dose Rate} = \text{Old Dose Rate} \times \left( \frac{\text{Old Distance}}{\text{New Distance}} \right)^2 ]

In this case, if you hypothetically reduce the distance to a smaller value, for example, half of 12 feet, you can do the calculation to find out how the dose rate increases.

When the distance is halved (from 12 feet to 6 feet), the new dose rate becomes:

[ \text{New Dose Rate} = 10 , \text{mR/h} \times \left( \frac{12}{6} \right)^