Beam Intensity

Beam intensity is defined as the product of the quantity and quality of the beam during exposure relative to a specific area. Therefore, the intensity of the beam is affected by beam quality (kVp) as well as beam quantity (mAs). The beam intensity is also affected by the distance between the x-ray tube and the exposed area such that if the distance is increased, the beam intensity decreases following the inverse square low (Figure 7). For example, if the distance between the source and the area of exposure is doubled, the intensity of the beam will be reduced to 25%.1,3,7,8,9,12

Figure 7. Change of beam intensity with distance change.
Change of beam intensity with distance change.