The photoelectric effect is most dangerous to which party?

• A. Operator
• B. Patient
• C. Bystander
• D. Technician

Answer: (B)

In diagnostic X-ray exposure, the photoelectric effect means photons are absorbed by atoms in the patient’s tissues, ejecting inner-shell electrons and depositing energy locally. That energy deposition is the patient’s radiation dose, so the patient carries the main risk from this interaction. The operator and bystander mainly receive scattered radiation, which is much lower thanks to shielding, distance, and proper beam filtration. The effect is more likely in high‑Z tissues like bone, which boosts image contrast but also concentrates dose in those areas. So, the person most at risk from this interaction during imaging is the patient.