3 MHz gets warm faster due to which characteristic?

3 MHz gets warm faster due to which characteristic?

• A. Superficial treatment
• B. Deeper heating
• C. Higher energy conversion
• D. Lower impedance

Answer: (A)

The key idea is that frequency sets how deep ultrasound energy is absorbed in tissue. A higher frequency like 3 MHz is absorbed more rapidly and over a shorter distance, so most of the energy is deposited in superficial layers. That means the superficial tissues heat up faster with 3 MHz than deeper tissues, making it a choice for near-surface targets. In contrast, deeper heating would come from a lower frequency, such as 1 MHz, which penetrates further before being absorbed. The heating pattern isn’t primarily about more energy being produced; it’s about where the energy is absorbed. Impedance affects coupling at boundaries, but it doesn't determine the depth of heating.

The key idea is that frequency sets how deep ultrasound energy is absorbed in tissue. A higher frequency like 3 MHz is absorbed more rapidly and over a shorter distance, so most of the energy is deposited in superficial layers. That means the superficial tissues heat up faster with 3 MHz than deeper tissues, making it a choice for near-surface targets. In contrast, deeper heating would come from a lower frequency, such as 1 MHz, which penetrates further before being absorbed. The heating pattern isn’t primarily about more energy being produced; it’s about where the energy is absorbed. Impedance affects coupling at boundaries, but it doesn't determine the depth of heating.