Knowing that 6 mAs is appropriate for a knee examination done at 40" SID, how much mAs should be used at 56" SID?

Question

Quizplus · Accepted Answer

The mAs needed for a radiograph is inversely proportional to the square of the distance, so the new mAs needed can be calculated using the following formula: (new mAs/old mAs) = (new SID/old SID)^2.
Plugging in the values: (new mAs/6) = (56/40)^2
Solving for new mAs, we get: new mAs = 12. Therefore, the answer is C (12 mAs).

Knowing That 6 MAs Is Appropriate for a Knee Examination