A system and method for adjusting or selecting the treatment parameters for HIFU signals to treat a target treatment site, and/or to aid in visualizing the likely degree and location of HIFU effects on patient tissue. The system transmits one or more test signals into patient tissue and receives signals created in response to the test signals. The signals are analyzed to determine a response curve of how a characteristic of the signal varies with the one or more test signals. The response curve of the detected signals is used to select a treatment parameter.