A technologist standing 6 feet away from the C-arm unit receives an exposure rate of 4 microgray/hour. What will the exposure rate be if the technologist moves back a total of 12 feet?

To determine the exposure rate as the technologist moves away from the C-arm unit, we can apply the principles of radiation exposure and the inverse square law. This law states that the intensity of radiation exposure is inversely proportional to the square of the distance from the source of radiation.

Initially, at a distance of 6 feet, the exposure rate is measured at 4 microgray/hour. When the technologist moves back a total of 12 feet, they are effectively moving to a distance of 18 feet from the C-arm.

Using the inverse square law mathematically, if the original distance is 6 feet and the new distance is 18 feet, we can set it up as follows:

1. The distance factor changes from 6 feet to 18 feet, which is a factor of 3 (18 divided by 6).

2. According to the inverse square law, the new intensity can be calculated by squaring the ratio of the distances:

• (Original Exposure Rate) × (Old Distance/New Distance)² = New Exposure Rate.

• Thus, 4 microgray/hour × (6/18)² = 4 microgray/hour × (1/3)² = 4 microgray/hour