Which of the following are factors affecting scattered radiation?

• A. KVP only
• B. Field Size and Part Thickness only
• C. Tissue Density only
• D. KVP, Field Size, Part Thickness, Tissue Density

Answer: (D)

Scattered radiation is produced by photon interactions inside the patient's tissues, mainly through Compton scattering. The amount of scatter depends on both the energy of the beam and the volume of tissue irradiated. Higher kVp increases photon energy, raising the chance of Compton interactions and the number of photons that scatter out toward the image receptor. A larger field size irradiates more tissue, creating more opportunities for scattering and more scattered photons to exit the patient. Greater part thickness means photons traverse more material, increasing scattering events. Tissue density matters because denser tissues have more atoms per unit volume to scatter photons, boosting scatter production. Together, these four factors determine how much scatter you get, so all of them contribute and the option that includes all four is best.