Derating method for therapeutic applications of high intensity focused ultrasound

A derating method, comprising:

• selecting a focal waveform and a corresponding first voltage (Vw) of an ultrasound source that generates the focal waveform in water, wherein the focal waveform is nonlinear;
• selecting an attenuation of a tissue;
• calculating a second voltage (Vt) that generates the focal waveform in the tissue according to
• Vt=Vwexp(αL)
• where α is an attenuation coefficient of the tissue at the frequency of the ultrasound source, and L is a focal length of the ultrasound source;
• and
• at least one of modeling and irradiating a nonlinear ultrasound wave with the ultrasound source set at the second voltage, wherein the nonlinear ultrasound wave forms the focal waveform in the tissue.

An ultrasound system, comprising:

• an ultrasound source configured to propagate nonlinear acoustic waves;
• and
• a controller having instructions for
• generating a nonlinear acoustic wave from the ultrasound source in water, wherein the ultrasound source is set to a first source voltage (Vw);
• determining a focal waveform of the nonlinear acoustic wave;
• and
• determining a second source voltage (Vt) of the ultrasound source according to
• Vt=Vwexp(αL),
• where α is an attenuation coefficient of a tissue at the frequency of the ultrasound source and L is a focal length of the ultrasound source;
• and
• wherein the ultrasound source is configured to generate the focal waveform in the tissue when the ultrasound source is set at the second voltage (Vt).