Automatic correction of x-ray scatter and veiling glare in simulated fluoroscopic images

Abstract

Fluoroscopic images are degraded by scattering of x-rays from within the patient and by veiling glare in the image intensifier. Both of these degradations are well described by a response function applied to the primary intensity. If the response function is known, than an estimate of the primary component of the image can be computed by applying the inverse operation. However, the response function is actually variable, with dependence on such factors as patient thickness and imaging geometry. We describe a technique for estimating a parameterized response function so that a good estimate of the subject density profile can be recovered even if the response function parameters are not known in advance. Our method uses a partially absorbing filter with spatially varying density as a reference object which enables us to compute good estimates of the parameterized response function. We use simulated images to evaluate our method for a wide range of conditions. Our simulation results show that this technique can greatly reduce densitometric errors in fluoroscopic images.