Which of the following factors influences Modulation Transfer Function (MTF)?

• A. Kilovoltage Peak (kVp)
• B. Milliampere-seconds (mAs)
• C. Spatial frequency
• D. Technologist experience

Answer: (C)

MTF describes how well an imaging system preserves contrast at different levels of detail, which is quantified by spatial frequency. Spatial frequency is the measure of how fine the pattern is (how many line pairs per millimeter). The MTF curve shows that as spatial frequency increases, the system’s ability to transfer modulation declines—higher frequencies (finer details) are reproduced with less contrast due to blur, detector limitations, and sampling. So the factor that directly shapes the MTF value at each point on the curve is spatial frequency itself.

Exposure factors like kVp and mAs affect image appearance through dose, contrast, and noise, but they don’t change the intrinsic transfer ability of the system. Technologist experience can influence practical sharpness through positioning, but the fundamental MTF is a property of the imaging system and its components, not technique.