Figure 1
Diagram of the experimental vibro-acoustography system for in vitro thyroid imaging. The thyroid sample in the gel block is placed inside a water tank and is then scanned by the dual-beam ultrasound from the confocal transducer focused at the desired depth inside the sample. The difference frequency (Δ f) between the two ultrasound beams (f 2 and f 1) is represented as Δ f = f 2- f 1. The hydrophone receives the acoustic field at the Δ f from the sample. This signal is then processed and mapped into an image.