OAR 333-106-0315: Additional Requirements for Radiographic Machines: Exposure Reproducibility

The coefficient of variation of exposure shall not exceed 0.05 when all technique factors are held constant. This requirement shall be deemed to have been met if, when four exposures are made at identical technique factors, the value of the average exposure (E) is greater than or equal to five times the maximum exposure (Emax) minus the minimum exposure (Emin). E >5 (Emax - Emin).