Example 1: Determine mAs with SID changed from 40″ to 44″. (Look down the 40″ column to the 44″ box, and locate 1.2 as the conversion factor.) Original mAs = 8.

Answer: 8 × 1.2 = 9.6 or 10 mAs

Example 2: A chest technique @ 72″ is 6 mAs @ 90 kVp. If the SID needs to be decreased to 60″, what mAs should be used if other factors remain unchanged?

Answer: Conversion factor is 0.7. 6 mAs × .7 = 4.2 mAs