Abstract: A method for attenuating x-rays which is insensitive to the x-ray energy employs forward scattering through a filter element to minimize energy shifts due to Compton scattering. Efficiency can be enhanced by employing a material with a large small angle scattering cross section. Since attenuation in the filter increases rapidly with decreasing x-ray energy, the filter provides larger, thinner scattering areas for low energy x-rays and smaller, thicker scattering areas for higher energy x-rays. By adjusting the relative fractions of the scattering areas and their thicknesses, the total scattering yield through the filter can be made to be essentially independent of x-ray energy over a broad band of x-ray energies.