Which imaging technique specifically utilizes ionizing radiation?

The imaging technique that specifically utilizes ionizing radiation is X-ray imaging. This method involves the use of X-rays, which are a form of high-energy electromagnetic radiation. When X-rays pass through the body, they can create images of internal structures on a film or digital detector. The contrast in images is due to different absorption rates of various tissues – for instance, bones absorb more X-rays than muscles or organs, allowing for clear delineation between them.

CT scans, while also using ionizing radiation, fall under a different category and can be considered a more advanced form of X-ray imaging that provides cross-sectional images of the body. MRI and ultrasound do not use ionizing radiation; MRI uses magnetic fields and radio waves to generate images, while ultrasound employs sound waves. Thus, while both CT scans and X-ray imaging involve ionizing radiation, X-ray imaging is the specific answer requested in the question, solely focusing on the technique in its most common form.