What is the minimum required frequency for ultrasound therapy effectiveness?

The minimum required frequency for ultrasound therapy effectiveness is generally around 20 kilocycles per second (20 kHz). This frequency is commonly used in therapeutic ultrasound applications to promote tissue healing, reduce inflammation, and relieve pain. At this frequency, ultrasound waves can effectively penetrate tissues to create thermal and non-thermal effects, which are essential for various therapeutic outcomes.

Higher frequencies, such as those listed in other options, can yield specific therapeutic benefits but are often not necessary for the fundamental effectiveness of ultrasound therapy. Hence, using 20 kHz ensures that practitioners can achieve the desired therapeutic effects while remaining within the range that is safe and effective for treatment.