What imaging technique utilizes ionizing radiation?

The correct answer is X-rays, which utilize ionizing radiation. Ionizing radiation is capable of removing tightly bound electrons from atoms, thus creating ions. In the context of medical imaging, X-rays use this type of radiation to penetrate the body and create images of structures inside, such as bones and certain organs. This imaging technique is invaluable in diagnosing fractures, infections, and other pathologies.

While CT scans also utilize ionizing radiation, they are a more advanced application of X-ray technology and can be considered as a specific type of X-ray imaging that provides detailed cross-sectional images of the body. Therefore, although CT scans use ionizing radiation, X-rays fundamentally represent the primary imaging technique that directly introduces ionizing radiation as its standard modality.

MRI and ultrasound, on the other hand, do not use ionizing radiation. MRI employs strong magnetic fields and radio waves to produce images, while ultrasound uses high-frequency sound waves to generate images of soft tissues. This distinction is important when considering the safety and applications of various imaging techniques.