How is the spatial resolution of a radiographic system measured?

The spatial resolution of a radiographic system is measured in line-pairs per millimeter (lp/mm) because this unit reflects the system's ability to distinguish between two closely spaced objects. Spatial resolution pertains to how well the details of an image can be resolved, which is crucial in radiography where clarity is essential for accurate diagnoses.

Line-pairs represent the smallest distance between two lines that can be distinguished as separate, making lp/mm a direct measure of the capability of the imaging system to provide detailed information. A higher value of line pairs indicates better resolution, meaning the system can capture finer details.

In contrast, other units of measurement listed, such as pixels per inch (ppi), primarily pertain to digital imaging clarity but do not effectively represent the actual resolving power in terms of radiographic systems. Similarly, contrast percentage and exposure time do not relate to spatial resolution directly. Contrast percentage deals with the difference in density between areas of an image, while exposure time refers to the duration of radiation exposure, neither of which measures the sharpness or detail-resolving ability of the imaging system.