How does increasing the atomic number of the material affect x-ray absorption?

Increasing the atomic number of a material leads to an increase in x-ray absorption. This is due to the higher likelihood of interactions between x-ray photons and the electrons present in materials with higher atomic numbers.

Materials with higher atomic numbers have more protons in their nuclei and subsequently more electrons surrounding them. When x-ray photons pass through these materials, they are more likely to be absorbed because the increased number of electrons provides more opportunities for interactions like photoelectric absorption and Compton scattering. Consequently, as the atomic number rises, the absorption coefficient increases, which means that a greater proportion of the x-rays are absorbed rather than transmitted through the material.

This concept is particularly significant in dental radiography, where different tissues (like bone, enamel, and soft tissue) have varying atomic numbers. Understanding this principle allows dental professionals to interpret radiographs accurately, as denser materials with higher atomic numbers will appear more radiopaque (lighter) on the x-ray image, while less dense materials will appear more radiolucent (darker).