Читать книгу Essentials of MRI Safety - Donald W. McRobbie - Страница 105

A better‐known effect of the wavelength change in tissue is the creation of standing waves or resonances when a conductor length is close to one half wavelength λ/2. This has particular importance for the avoidance of heating in active implants with lead lengths equal to or close to λ/2. Often the resonant lengths 13 cm and 26 cm are cited, but different tissues have a range of values:

 muscle λ/2 = 14.7 cm at 128 MHz

 fat λ/2 = 33.3 cm at 128 MHz

 cancellous bone λ/2 = 22.9 cm at 128 MHz

 cortical bone λ/2 = 30.6 cm at 128 MHz.