In radiography, the patient is the main source of which type of radiation?

• A. Primary radiation
• B. Scattered radiation
• C. Leakage radiation
• D. Thermal energy

Answer: (B)

Primary radiation is the deliberately created beam from the x-ray tube that travels toward the patient and ultimately forms the image after passing through tissues. The patient themselves is not the source of this primary beam; instead, they act as the medium that the beam traverses. When those photons interact with tissue, especially through Compton scattering at diagnostic energies, photons are deflected in various directions. This scattered radiation emerges from the patient and is a major source of stray exposure to staff and to the image receptor, contributing to fog in the image as well. Leakage radiation comes from the tube housing and is not produced by the patient, and thermal energy refers to heat produced by the exposure, not a form of radiation. So the patient is the main source of scattered radiation.