A radiograph of the abdomen is underexposed and must be repeated.The original analog exposure factors used were 65 kV with 25 mAs.The technologist decides to keep the mA at the same level but change the kV to increase radiographic density.How much of an increase is needed in kV to double the density?

Question

Quizplus · Accepted Answer

To double the radiographic density, we need to use the inverse square law: if we keep the mA constant (25 mA), doubling the density requires quadrupling the mAs (50 mAs). Since we want to keep the mAs constant, we can double the density by doubling the exposure time or doubling the radiation intensity. Doubling the radiation intensity requires increasing the kVp by 15% or 10 kV (according to the 15% rule). Therefore, we need to increase the kV from 65 to 75, which is an increase of 10 kV. Choice B is the only option close to this value.

A Radiograph of the Abdomen Is Underexposed and Must Be