Which imaging modality lacks ionizing radiation?

• A. MRI
• B. CT
• C. X-ray
• D. Nuclear medicine

Answer: (A)

Magnetic resonance imaging uses strong magnetic fields and radiofrequency pulses to produce images, and it does so without ionizing radiation. That’s why it lacks the radiation dose associated with X-ray and CT scans, as well as the radiotracer–based emissions used in nuclear medicine. X-ray and CT rely on ionizing X-ray photons, while nuclear medicine uses radioactive tracers that emit ionizing radiation. Because MRI avoids ionizing radiation, it’s the modality best suited when minimizing radiation exposure is a priority, though it has its own considerations like longer scan times and compatibility with implants.