Which of the following lists all factors affecting scattered radiation?

• A. KVP; Field Size; Part Thickness; Tissue Density
• B. KVP; Field Size; Part Thickness
• C. Field Size; Part Thickness; Tissue Density
• D. KVP; Tissue Density

Answer: (A)

Scattered radiation depends on factors that change how many photons interact and how many of those interactions send photons toward the image receptor. Raising kilovoltage peak increases photon energy and the likelihood of Compton scattering, so more scatter is produced. Increasing the field size irradiates a larger tissue volume, producing more scatter events overall. Greater part thickness means more tissue for photons to traverse and interact with, again boosting scatter. Tissue density affects scatter because denser tissues have more electrons to scatter photons off, increasing scatter probability. Since all four factors—KVP, field size, part thickness, and tissue density—influence scatter, the option that includes all of them is the best choice.