Which type of radiation shielding is most effective for high-energy X-rays?

Lead is considered the most effective type of radiation shielding for high-energy X-rays due to its high density and atomic number. The primary factor in shielding against X-rays is the material's ability to absorb or attenuate the radiation. Lead's dense composition allows it to effectively attenuate high-energy photons, reducing the amount of radiation that can pass through. This is particularly important in radiography where high-energy X-rays are used for imaging, as exposure to these rays can pose health risks.

While aluminum, concrete, and water can provide some level of shielding, they are generally less effective than lead for high-energy X-rays. Aluminum has a lower atomic number, which makes it less efficient at stopping X-rays, especially at higher energies. Concrete can offer some shielding but is bulkier and requires larger thicknesses to achieve comparable attenuation as lead. Water, while useful for certain applications, has a low density and is less effective against high-energy radiation compared to lead. Thus, in contexts where optimal protection from high-energy X-rays is required, lead is the preferred choice.