ULTRASONIC DIAGNOSTIC DEVICE

摘要

High-sensitivity and safety are needed to be considered in radiation force elastography technology for diagnosing hardness by transmitting an ultrasonic focused beam into a subject. As a means for displacing a tissue and exciting shear waves, a focused beam is transmitted to two places. The transmitted beam is time-controlled so as to become a burst chirp signal, and ultrasonic wave transmission and reception are carried out while sweeping transmission frequencies. In this case, when the distance between two focal points and a transmission frequency become an integer multiple of a wavelength, two waves interfere with each other and a large amplitude is obtained. When the transmission frequency matches a resonance frequency specific to a tissue, a large amplitude is also obtained. These make it possible to improve the sensitivity with the strength of a small transmission waveform. Further, since the transmission using the burst chirp facilitates widening the transmission frequency band, it is possible to use a frequency having a high sensitivity to a region to be measured. A wide area is covered by allowing the number of focal points and the positions thereof to be arbitrary.