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Pixels, matrix, bit depth and Nyquist
Smaller detector elements give finer detail; more bits give more shades of gray; more photons give less noise.
Pixels and matrix
A digital image is a grid, or matrix, of picture elements called pixels, arranged in rows and columns. In a flat-panel detector, each pixel comes from a detector element (DEL), which has its own sensing area and thin-film transistor. Pixel pitch is the distance from the center of one pixel to the center of the next, typically about 100 to 200 micrometers in radiography. Pixel size equals the field of view divided by the matrix size. For a set field of view, a larger matrix means smaller pixels and finer detail. In a flat-panel detector, the DEL size is fixed, so collimating to a smaller area does not make the pixels smaller.