Secondary radiation is produced when primary X-ray photons interact with matter and emerge from the object.

• A. Primary radiation
• B. Secondary radiation
• C. Scatter radiation
• D. Tertiary radiation

Answer: (B)

Secondary radiation comes from the interaction of the primary X-ray beam with matter and is the radiation that exits the object. When the beam hits the patient, photons can scatter (and other secondary photons can be produced) and emerge from the tissues. This distinguishes it from the original primary beam, which is the radiation produced by the tube before any interaction. Scatter radiation is a common form of secondary radiation, but the statement describes the broader concept of secondary radiation itself, including all photons created by the interaction that leave the object. Tertiary radiation would result from secondary photons interacting again, which is not what this describes.