What process involves the scattering of photons by electrons resulting in a change of direction and energy transfer?

Compton scattering involves the interaction of photons with electrons, leading to a change in direction and a transfer of energy. This process occurs when an incoming photon collides with a loosely bound outer electron, transferring some of its energy to the electron and changing the photon's trajectory. As a result of this interaction, the photon is scattered at a different angle with reduced energy, while the electron gains kinetic energy.

This phenomenon is significant in the field of medical imaging, including mammography, where understanding photon interactions with tissue is essential for enhancing image quality and optimizing radiation dose. Compton scattering is particularly relevant at the energies used in mammography, as it significantly affects the contrast and appearance of images.

In contrast, the other processes mentioned do not fit the description given. Rayleigh scattering involves the scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light, typically without a transfer of energy. The photoelectric effect refers to the absorption of photons by matter, resulting in the ejection of electrons but not scattering. Refraction involves the bending of light as it passes between different media but does not involve scattering or energy transfer in the same manner as Compton scattering.