What type of imaging uses ionizing radiation to create cross-sectional images of the body?

The correct answer is a CT scan, which stands for computed tomography. This imaging technique uses ionizing radiation to produce detailed cross-sectional images of the body's internal structures. CT scans work by sending a series of X-ray beams through the body at different angles, which are then processed by a computer to create cross-sectional images, allowing for a comprehensive view of organs, tissues, and other structures.

In contrast, ultrasound and MRI do not use ionizing radiation. Ultrasound employs sound waves to create images, making it safe and commonly used for examining soft tissues and monitoring pregnancies. MRI, or magnetic resonance imaging, utilizes powerful magnets and radio waves to generate detailed images of soft tissues without radiation exposure. X-ray imaging uses ionizing radiation as well, but it produces two-dimensional images rather than cross-sectional views, which is why it does not fit the criteria of the question.