Given an original technique of 30 mAs and 80 kVp, which would produce an image with double the receptor exposure?

Given an original technique of 30 mAs and 80 kVp, which would produce an image with double the receptor exposure?

• A. 60 mAs, 90 kVp
• B. 30 mAs, 92 kVp
• C. 15 mAs, 80 kVp
• D. 30 mAs, 70 kVp

Answer: (B)

Receptor exposure responds strongly to mAs and also to kVp because higher kVp increases photon penetration. A practical rule is that increasing kVp by about 15% while holding mAs constant roughly doubles the exposure at the image receptor. Here, raising kVp from 80 to 92 while keeping mAs at 30 does exactly that: the mAs stays the same, but the beam is more penetrating, so about twice as many photons reach the receptor. The other options either raise or lower exposure in ways that don’t produce the target doubling: increasing mAs would raise exposure, but changing kVp as well can push it beyond a simple double; lowering mAs or lowering kVp reduces exposure. So keeping mAs fixed and increasing kVp to 92 achieves the doubling most directly.

Receptor exposure responds strongly to mAs and also to kVp because higher kVp increases photon penetration. A practical rule is that increasing kVp by about 15% while holding mAs constant roughly doubles the exposure at the image receptor. Here, raising kVp from 80 to 92 while keeping mAs at 30 does exactly that: the mAs stays the same, but the beam is more penetrating, so about twice as many photons reach the receptor.

The other options either raise or lower exposure in ways that don’t produce the target doubling: increasing mAs would raise exposure, but changing kVp as well can push it beyond a simple double; lowering mAs or lowering kVp reduces exposure. So keeping mAs fixed and increasing kVp to 92 achieves the doubling most directly.