Which of the following factors influences MTF?

• A. Technical experience
• B. kVp
• C. mAs
• D. Spatial frequency

Answer: (D)

MTF describes how well an imaging system preserves contrast for different sizes of detail, so it is fundamentally a function of spatial frequency. Spatial frequency is the rate at which image features repeat per unit distance; low frequencies correspond to coarse, large features, while high frequencies correspond to fine detail. The MTF curve shows how transfer efficiency changes as you move to higher spatial frequencies, and in general the system preserves less contrast as frequency increases due to blur from finite focal spot size, detector blur, sampling limitations, and motion. This is why spatial frequency is the key factor: the whole purpose of MTF is to quantify the system’s ability to transfer contrast across a range of detail sizes. Exposure factors like kVp or mAs affect image brightness and noise, not the intrinsic transfer properties of the system itself.