Exposure linearity between adjacent mA stations must be within what tolerance?

• A. +/- 10%
• B. +/- 1%
• C. +/- 2%
• D. +/- 5%

Answer: (A)

Exposure linearity checks how the X-ray output responds to changing the mA setting while keeping other factors the same. When you compare two adjacent mA stations with the same kVp, distance, and filtration (and adjust the time so that the mAs matches), the resulting image receptor exposure should be essentially the same. Small differences are expected due to slight variations in tube current regulation, timer accuracy, and other system tolerances, so a tolerance of plus or minus 10 percent is allowed. This makes sense because real-world equipment isn’t perfectly linear, but it should stay within that 10% window. Tolerances like ±1%, ±2%, or ±5% are too strict given typical generator and tube variability.