What absorbs X-rays most effectively?

The most effective X-ray absorbers are materials with high atomic numbers and high density. Lead is a commonly used X-ray absorber due to its high atomic number (82) and high density, making it an efficient barrier against X-ray radiation. Other materials with similar properties, such as tungsten, gold, and depleted uranium, are also effective in absorbing X-rays. When X-rays interact with matter, they undergo various interactions such as photoelectric effect, Compton scattering, and pair production. The probability of these interactions increases with increasing atomic number of the material. Heavy metals, like lead, have a high probability of these interactions, leading to the absorption and attenuation of X-rays.