The phenomenon of X-ray absorption refers to the process by which X-ray photons passing through a material are absorbed by the atoms in that material, transferring their energy to the electrons.
When an X-ray photon enters a substance, it can interact with the electrons in the inner shells of atoms. If the photon’s energy is equal to or greater than the binding energy of an electron, it can eject that electron from its shell. This process is called the photoelectric effect.
The amount of absorption depends on factors such as:
- Atomic number (Z) of the material — higher-Z materials like lead absorb X-rays more effectively.
- X-ray photon energy — lower-energy X-rays are absorbed more strongly than higher-energy ones.
- Density and thickness of the material — denser and thicker substances absorb more X-rays.
This phenomenon is crucial in medical imaging, material analysis, and X-ray spectroscopy because the differences in absorption between different tissues or materials create contrast in the resulting images.