Dependence of noise on array width and depth in digital radiography

Measurements are reported for the image noise levels in digital radiographs using 256(2), 256(2)-zoom, 512(2), and 1024(2) storage arrays. The noise was essentially the same with 256(2)-zoom or 512(2) arrays, while it was 25% lower for a 256(2) array, and only 15% larger for a 1024(2) array than for a 512(2) array. Compatibility of these results with different models is evaluated. Also the number of bits/pixel was varied to determine the effect on noise; noise before digitization ranged from 4.3 to 0.13 gray levels. The noise level was found to be increased only if the noise was less than approximately one-half of a gray level.