Which statement best describes modulation transfer function (MTF)?

• A. It measures the brightness of the image.
• B. It measures the color depth.
• C. It measures the accuracy of reproduction across spatial frequencies.
• D. It measures the patient dose.

Answer: (C)

MTF shows how well an imaging system preserves image contrast for patterns with different levels of detail. As you test finer and finer details (higher spatial frequencies), MTF measures the fraction of the original contrast that makes it to the image. A higher MTF at a given frequency means the system can reproduce that level of detail more faithfully; a falling MTF indicates blur or loss of contrast for finer features. In practice, you plot MTF against spatial frequency, and values range from 0 to 1 (or 0% to 100%), with 1 meaning perfect transmission of contrast at that frequency. This concept is precisely what describes the accuracy of reproduction across spatial frequencies, not brightness, color depth, or patient dose.