What is the basic physics principle used in the generation of this image?

What is the basic physics principle used in the generation of this image?

• A. Travel/transmission of sound waves
• B. Radiotracer uptake/accumulation with increased metabolic activity
• C. X-ray attenuation
• D. Movement of hydrogen ions

Answer: (A)

Sound waves traveling through tissue and their echoes are used to form this image. A transducer emits short pulses of high-frequency ultrasound into the body; when these pulses meet boundaries between tissues with different acoustic impedances, part of the sound energy is reflected back to the transducer. By measuring how long the echoes take to return, the device calculates depth, and the strength of each echo determines how bright that point appears. Scanning across the region builds up a two-dimensional image, with the speed of sound in tissue (about 1540 m/s) used to convert time into distance. Higher frequencies give finer detail but less penetration. This approach is distinct from imaging methods based on X-ray attenuation or radiotracer uptake, and it does not rely on ionizing radiation.

Sound waves traveling through tissue and their echoes are used to form this image. A transducer emits short pulses of high-frequency ultrasound into the body; when these pulses meet boundaries between tissues with different acoustic impedances, part of the sound energy is reflected back to the transducer. By measuring how long the echoes take to return, the device calculates depth, and the strength of each echo determines how bright that point appears. Scanning across the region builds up a two-dimensional image, with the speed of sound in tissue (about 1540 m/s) used to convert time into distance. Higher frequencies give finer detail but less penetration. This approach is distinct from imaging methods based on X-ray attenuation or radiotracer uptake, and it does not rely on ionizing radiation.