Purpose: Ultrasound is used to see inside of the human body to look for fractures and other bony or soft tissue abnormalities. It has some limitations because of hwo it works. It can’t see past a bone, for example, and it can’t image some deep structures very well.
Issue: Although this machine does not use ionizing radiation or strong magnetic fields, it does use radio frequency energy that can influencethe body.
Frequency: The potential for ultrasonic imaging of objects, with a 3 GHZ sound wave producing resolution comparable to an optical image, was recognized by Sokolov in 1939 but techniques of the time produced relatively low-contrast images with poor sensitivity. Ultrasonic imaging uses frequencies of 2 megahertz and higher; the shorter wavelength allows resolution of small internal details in structures and tissues. The power density is generally less than 1 watt per square centimetre, to avoid heating and cavitation effects in the object under examination. High and ultra high ultrasound waves are used in acoustic microscopy, with frequencies up to 4 gigahertz. Ultrasonic imaging applications include industrial non-destructive testing, quality control and medical uses.
Better option: This one gets sticky to answer…there are some times when an image of what is going on inside of the body is necessary to get a diagnosis or guide a treatment. A good medical intuitive might be a safer option, but is certainly not always available. When you need an image, choose the least harmful image that gives the information required.
Source:
https://en.wikipedia.org/wiki/Ultrasound