| A | B |
|---|
| mAs | mA X Time |
| Changing from one grid to another | To (GCF)/ From (GCF) x mAs |
| Changing from one screen to another | To (screen)/ From (screen) Flip X mAs |
| Field Size Calculation | D1/D2 = F1/ F2 |
| Changes in Collimation | Size To/ Size From X mAs |
| 15% rule | increase kV 15% to double the density |
| Noticeable difference in density | 30% change in mAs |
| Inverse Square Law | I1/ I2 = SID2^2/ SID 1 ^2 |
| Direct Square Law | mAs1/ mAs2 = D1^2/D2^2 |
| Grid Ratio | h/d |
| Magnification Factor | image/ object or SID/SOD |
| Percent of Magnification | image-object/ object X 100 |
| Going from a Three phase to Single phase | 2 X mAs |
| Going from a Three phase to Single phase | 1/2 X mAs |
| Intensification Factor | exposure without screens/ exposure with screens |
| Geometric Unsharpness | FSS X OID / SOD |
| Find Heat Units | mA X Time X kV X phase |
