What is secondary radiation?

• A. X-radiation that is created when the primary beam interacts with matter.
• B. Radiation produced by radioactive isotopes outside the body.
• C. Light emitted from the imaging receptor.
• D. A type of shielding material around the patient.

Answer: (A)

Secondary radiation is the X-radiation created when the primary X-ray beam interacts with matter, such as the patient’s tissues. As the beam enters the body, some photons are scattered (often via Compton scattering) and exit the tissue in directions away from the original path. These scattered photons are the secondary radiation. They have lower energy than the primary beam and can contribute to both patient dose and occupational exposure, which is why techniques like shielding and proper collimation are important. This type of radiation is distinct from radiation from external radioactive sources, light from the imaging receptor, or shielding material.