What method is primarily used to describe spatial resolution in CT?

The modulation transfer function (MTF) is primarily used to define spatial resolution in computed tomography (CT). MTF provides a quantitative measure of how well a system can preserve the contrast of an object at various spatial frequencies. Essentially, it evaluates the ability of the CT system to accurately reproduce the various details of an image based on the size and frequency of the structures being imaged.

In CT imaging, higher spatial frequencies correspond to finer details, while lower frequencies represent broader, more uniform areas. The MTF indicates the system's performance in transferring these frequencies from the object being scanned to the final image. If the MTF is high at a specific frequency, the CT system can resolve finer details of that size; if the MTF is low, then those details will be blurred or lost in the image.

Understanding MTF is crucial for imaging professionals, as it helps them evaluate and optimize the performance of CT scanners, ensuring that the resulting images have the highest possible quality for diagnostic purposes. This makes MTF a fundamental concept in imaging science, particularly for assessing spatial resolution in CT.