A New Contrast Echo Imaging Method Using Crossed Beams of Two Ultrasonic Frequencies

Abstract

We propose a novel contrast echo imaging method using crossed beams of two different ultrasonic frequencies as an ultrasound method of diagnostic cancer, which we call the crossed beam contrast echo (CBCE) method. The sum or difference frequency components that are derived from the nonlinear oscillation of the microbubbles driven by dual-frequency ultrasound are used in the CBCE method. The blood flow information can only be obtained in the area of the crossed beams, because no sum or difference frequency components are generated by the propagation of biological soft tissues except in the crossed beam area. We discussed the driving conditions under which the sum frequency component is most efficiently generated, and experimentally confirmed the area in which the sum frequency component is generated. As a result, the sum frequency component was larger than the other harmonic components when its frequency was equal to the resonance frequency of the microbubbles. It was confirmed that the area in which the large sum frequency component is generated was equal to the crossing area of the two beams.