What characteristic distinguishes ultrasound from other imaging modalities?

Ultrasound is distinguished from other imaging modalities primarily because it utilizes sound waves instead of ionizing radiation. This characteristic is significant because it makes ultrasound safer for patients, particularly in sensitive populations such as pregnant women and children. Unlike modalities such as X-rays and CT scans, which use ionizing radiation that can pose risks with excessive exposure, ultrasound employs non-ionizing sound waves to create images of internal structures. This method allows for the visualization of soft tissues and organs in real-time, aiding in the assessment of various medical conditions without the radiation-related concerns associated with other imaging techniques. Thus, the use of sound waves is a defining feature that sets ultrasound apart in the field of medical imaging.