Physics for IGCSE & O level - Waves And Sounds (Section 2 - No. 32)
Why is ultrasound preferred over X-rays in some medical applications?
Ultrasound is less expensive.
Ultrasound can cause cell damage inside a growing baby.
Ultrasound uses ionizing radiation.
Ultrasound can distinguish between different layers of soft tissue.
Explicació
Ultrasound is preferred because it can distinguish between different layers of soft tissue, and is much safer than X-rays. X-rays, and therefore will not cause damage to the baby.