敷波 保夫, 安原 正樹
Yasuo SHIKINAMI, Masaki YASUHARA
Takiron Co., Ltd., Medical Div.
Ultrasonographic acoustic characteristics, Liquid poly(alkylene oxide)s, Attenuation, Specific acoustic impedance, Coupler
Ultrasonic characteristics such as sound velocity (c), acoustic impedance (ρc), and attenuation (α)
of liquid poly(alkylene oxide)s (PAOs) were measured at 25°C and 3.5, 5.0, and 7.5 MHz in an attempt to
use them as acoustic couplers for ultrasonography of superficial diseases. The PAOs used included
homopolymers of poly(ethyleneglycol) (PEG), poly(propylene glycol) (PPG), poly(butylene glycol)
(PBG), block and random copolmers of ethylene oxide (EO) and propylene oxide (PO), ether compounds
of these PAOs and glycerin, and mono and dimethyl ethers of PEG. The c and α values were calculated
from the waveforms of the reflected signals. The acoustic characteristics were found to be affected by the
molecular weight, branching of chains, and structure of the end groups of molecular chains. The liquid
PAOs at low molecular weight region, have c and ρc similar to those of water and soft tissues of living
body (skin, muscle, spleen, liver, kidney, fat and brain). The liquids demonstrated low attenuations. In
particular, PPG with a molecular weight of 200-400, bifunctional EO/PO copolymers, trifunctional
glycerin PAO ethers excluding EO, and mono and dimethyl PEG ethers demonstrated low attenuations.