These are superb compensating filters, specially designed for digital "run off" (DA) and digital subtraction arteriography (DSA) of the lower extremities including the feet. They make for much more homogeneous density up to a width of 35 cm, thereby avoiding saturated signals that cause halation. Moreover, during bilateral examinations, the central sensors of a large fluoroscope are able to select technical factors that are reliably applicable to the periphery. Finally, these ridges contribute greatly to immobilization. Here are a number of helpful suggestions.