What is the recommended size for the treatment area in ultrasound therapy relative to the effective radiating area (ERA)?

In ultrasound therapy, the effective radiating area (ERA) refers to the portion of the transducer that actually emits ultrasound waves and contributes to the therapeutic effect. The recommended size for the treatment area should indeed be 2-3 times the size of the ERA to ensure effective coverage and therapeutic benefit.

Choosing a treatment area that is 2-3 times the size of the ERA allows for a more comprehensive application of ultrasound energy to the target tissues. This range facilitates an adequate overlap of the ultrasound waves, ensuring that the therapeutic benefits extend beyond the immediate area directly under the transducer. It helps in maintaining uniform heating and effective treatment of the tissues impacted by the condition being treated.

While a treatment area the same size as the ERA would limit the therapeutic effects to a small area, thus possibly not addressing surrounding tissues adequately, a size larger than 3 times the ERA would be inefficient and may lead to unnecessary treatment of areas that do not need therapy. Therefore, selecting a treatment area that correlates optimally with the ERA, as indicated in the correct answer, is essential for maximizing the efficacy of ultrasound therapy.