Table 1. Classifications and applications of ultrasound waves.

Ultrasound waves	Classifications	Applications
Ultrasound intensity	Low-intensity ultrasound (<3 W/cm2)	Therapeutic medicine, imaging medicine, medical diagnosis, and drug delivery
	High-intensity ultrasound (≥3 W/cm2)	Surgery, cancer ablation, and palliative treatment
Ultrasound frequency	Low frequency ultrasound (20–200 kHz)	Drug delivery, surgery, cancer ablation, and palliative treatment
	Medium frequency ultrasound (0.7–3.0 MHz)	Therapeutic medicine, such as bone-fracture healing, soft-tissue lesions healing, inhibiting inflammatory responses, and erectile dysfunction treatment
	High frequency ultrasound (1–20 MHz)	Imaging medicine and medical diagnosis