If the exposure rate of a fluoroscopy tube is 50 R from the tube focus, what will the exposure rate be at a distance of 4 inches?

To determine the exposure rate from a fluoroscopy tube at a distance, the inverse square law is applied. This law states that the intensity of radiation from a point source is inversely proportional to the square of the distance from the source.

Starting with an exposure rate of 50 R at the tube focus, let's calculate the exposure rate at a distance of 4 inches. The exposure rate will decrease as the distance from the tube increases.

If we consider the distance from the tube focus to be halved (for example, from one distance to half that distance), the exposure rate will actually quadruple, owing to the inverse square relationship. Therefore, if you move away from the source, you can find the new exposure rate by dividing the initial exposure by the square of the factor by which the distance has changed.

At 4 inches, to find the reduction in exposure rate, consider that the initial distance is effectively 0 inches (the focal point) and now extending to 4 inches. Generally speaking:

• At 1 inch (which is a common baseline for calculations), the exposure rate might be at 50 R.

• At 2 inches, it would be 50/(2^2) or 50/4 =