A method, a system, and a non-transitory computer readable medium for evaluating x-ray signals. The method may include calculating an estimated field for each of multiple non-perturbed objects, the multiple non-perturbed objects represent perturbances of the perturbed object; the perturbances are of an order of a wavelength of the non-diffused x-ray signals; and evaluating the non-diffused x-ray signals based on the field of the multiple non-perturbed objects.