Ultrasound Physics

HIFU: Depends on application, low than half of the diagnostic frequency.
Abdominal imaging: 3.5 ~ 5 MHz.
Cardiovascular imaging: 2.5 ~ 3.5MHz.
Ophthalmology, eye application: 15 ~ 50MHz.
Dermatology, skin application: 15 ~ 50 MHz.
Small organ: 5 ~ 12MHz.
Peripheral vascular: 5 ~ 10 MHz.
Intravascular (IVUS): 10 ~ 50 MHz.
Frequency, Penetration, and spatial resolution: Higher frequency gives better resolution, and less penetration. The transmitted power of ultrasound pulse for imaging is regulated by FDA. The highest energy within FDA regulation is always used for the best signal to noise ratio. As long as the signal from the farthest depth has enough SNR, the highest frequency is always the first choice.