Ultrasound examinations utilize _______________ and the attenuation properties of different body tissues to produce images.

• A. Sound waves
• B. Magnetic fields
• C. Radioactive isotopes
• D. Ionizing radiation

Answer: (A)

Ultrasound imaging relies on sound waves. The transducer emits high-frequency sound waves into the body, and these waves travel through tissues, becoming weaker as they are absorbed, scattered, or reflected—a process called attenuation. Different tissues attenuate sound to different extents, so the returning echoes vary in strength and timing. The ultrasound system uses these echoes to build an image, mapping where echoes come from and how strong they are. This is possible because ultrasound uses non-ionizing mechanical energy, unlike imaging methods that rely on magnetic fields, radioactive isotopes, or ionizing radiation.