Beam Intensity

Beam intensity is defined as the product of both the quality and the quantity of that beam during the exposure relative to a specific area. Therefore, the beam's intensity is affected by beam quality (kVp) and beam quantity (mAs). The distance between the x-ray tube and the exposed area is a factor which affects the beam intensity. If we increase the distance, the beam intensity decreases following the Inverse Square Law (Figure 7). For example, if we double the distance between the source and the area of exposure, we will be reducing the intensity of the beam by 25%.^1,3,7,8,9,12

Figure 7. Change of beam intensity with distance change.

Figure 7. Change of beam intensity with distance change.