福喜多 博, 植野 進一郎, 橋本 雅彦, 屋野 勉

Hiroshi FUKUKITA, Shin-ichiro UENO, Masahiko HASHIMOTO, Tsutomu YANO

松下技研株式会社

Matsushita Research Institute Tokyo, Inc.

キーワード : Ultrasound, Pulse reflection method, Tissue characterization, Nonlinearity parameter, Attenuation coefficient

A new method for obtaining the depth distribution of the nonlinearity parameter (B/A) and the frequency-dependent attenuation coefficient is given. In this method, the higher frequency probe pulse wave, which is superposed coaxially on the lower frequency pump pulse wave, is modulated nonlinearly due to its propagation, and is received as an echo signal. The relationship between these acoustic parameters and the modulation characteristics of the probe pluse wave is found by dividing the spectra of the modulated echo signals with each other. The possibility of canceling out of bias error factors such as the frequency dependent acoustic reflection coefficient of random scattering media, at the above dividing process is discussed. Preliminary evaluation of this method is made by using an experimental system. B/A values are obtained for various kinds of sponge phantom immersed in water, 1-propanol, 2-propanol, ethylene glycol, or diethylene glycol, and for agar graphite phantom for excised pig and human liver. The correction of the experimental data for human liver obtained through the abdominal wall is discussed by analysing the reflection of pump waves at the boundaries between the tissues.