The influence of a malignant nodule on resonance frequencies of the thyroid gland

The thyroid is investigated as a resonant cavity. A number of 16 eigenfrequencies and eigenmodes are evaluated for a thyroid geometric model excited by ultrasounds. The malignant tissue was modelled by spheres with different diameters. The spatial distributions of the acoustic eigenmodes are in accordance with blood supplier positions. Blood supplier efficiency and local temperature will decrease as a result of nodules or cysts. The acoustic field eigenfrequency for the same propagation mode is bigger when thyroid has a malignant nodule. Efficiency of ultrasound diagnosis and thyroid treatment will be increased by knowing these modes and frequencies.