Thermal Effects (deep tissue) are observed in which frequency range?

Thermal Effects (deep tissue) are observed in which frequency range?

• A. 3 Hz-3 kHz
• B. 3 kHz-5 MHz
• C. 3 GHz-300 GHz
• D. 100 kHz-3 GHz

Answer: (D)

Thermal effects come from energy being deposited in tissue, and how deeply that energy penetrates depends on frequency. Lower frequencies penetrate deeper, while higher frequencies are absorbed more at the surface. For heating that reaches deep tissues, you need RF energy that can travel beneath the skin and fat layers. In biological tissues, this happens roughly from about 100 kHz up to a few gigahertz. Frequencies in this range can cause observable deep-tissue heating (reflected in the SAR you’d measure). Very low frequencies mainly cause stimulation with little heating, and very high microwave frequencies heat mainly the surface. Therefore, deep tissue thermal effects are observed in the range from 100 kHz to 3 GHz.

Thermal effects come from energy being deposited in tissue, and how deeply that energy penetrates depends on frequency. Lower frequencies penetrate deeper, while higher frequencies are absorbed more at the surface. For heating that reaches deep tissues, you need RF energy that can travel beneath the skin and fat layers. In biological tissues, this happens roughly from about 100 kHz up to a few gigahertz. Frequencies in this range can cause observable deep-tissue heating (reflected in the SAR you’d measure). Very low frequencies mainly cause stimulation with little heating, and very high microwave frequencies heat mainly the surface. Therefore, deep tissue thermal effects are observed in the range from 100 kHz to 3 GHz.