Which medical imaging technique uses ionizing radiation?

The correct answer is Computed Tomography (CT) scans, which indeed use ionizing radiation. CT scans work by combining a series of X-ray images taken from different angles and using computer processing to create cross-sectional images of bones, blood vessels, and soft tissues inside the body. The use of X-rays involves ionizing radiation, which has enough energy to produce charged particles by ionizing atoms, potentially leading to tissue damage if exposure is excessive or not managed properly.

While Positron Emission Tomography (PET) scans also involve radiation, they use a radioactive tracer that emits positrons as part of the imaging process and is classified differently because the radiation characteristics differ from those of traditional ionizing radiation techniques such as X-rays. In contrast, Magnetic Resonance Imaging (MRI) utilizes strong magnetic fields and radio waves to generate images of organs and tissues without involving ionizing radiation. Ultrasound imaging relies on sound waves to produce images and is also free of ionizing radiation. Therefore, the only option on the list that definitively uses ionizing radiation as a primary method of imaging is the CT scan.