Transmission of 100-MHz-range ultrasound through a fused quartz fiber.
OBJECTIVE
This paper describes an investigation into direct observation of microscopic images of tissue using a thin acoustic wave guide.


METHODS
First, the characteristics of the ultrasonic wave propagated in a fused quartz fiber were measured using the reflection method in order to study the insertion loss and the frequency shift of the ultrasonic wave transmitted from the transducer. Next, a receiving transducer was placed close to the end of the fiber, and the characteristics of the ultrasonic waves propagated through the acoustic coupling medium were measured using the penetration method in order to study the insertion loss and the frequency-dependent attenuation of the penetrated waves. Finally, a C-mode image was obtained by optimizing the measuring conditions using the results of the above measurements and scanning the ultrasonic beams on a target (coin) in water.


RESULTS
A reflected wave with a peak frequency of approximately 220 MHz was obtained from the end of the fiber. The transmitted ultrasonic waves propagated through the acoustic coupling medium were detected with a frequency range of approximately 125-170 MHz, and the maximum detectable distance of the waves was approximately 1.2 mm within the 100-MHz frequency range. Finally, a high-frequency C-mode image of a coin in water was obtained using a tapered fused quartz fiber.


CONCLUSIONS
The results suggest that it is necessary to improve the signal-to-noise ratio and reduce the insertion loss in the experimental system in order to make it possible to obtain microscopic images of tissue.
Graduate School of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo, 191-0065, Japan. irie@microsonic.co.jp.|Research and Development, Microsonic Co., Ltd, Tokyo, Japan. irie@microsonic.co.jp.
Takasuke
T
Irie
Graduate School of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo, 191-0065, Japan.
Norio
N
Tagawa
Graduate School of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo, 191-0065, Japan.
Masayuki
M
Tanabe
Professor Emeritus of Tokyo Metropolitan University, Hino, Tokyo, Japan.
Tadashi
T
Moriya
Monozukukuri Department, Metropolitan College of Industrial Technology, Tokyo, Japan.
Masasumi
M
Yoshizawa
Research Center for Hydrogen Industrial Use and Storage, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
Takashi
T
Iijima
Department of Internal Medicine, Hitachi-Omiya Saiseikai Hospital, Hitachiomiya, Ibaraki, Japan.
Kouichi
K
Itoh
Department of Surgery, Hitachi-Omiya Saiseikai Hospital, Hitachiomiya, Ibaraki, Japan.
Taku
T
Yokoyama
Department of Pediatrics, Hitachi-Omiya Saiseikai Hospital, Hitachiomiya, Ibaraki, Japan.
Hideki
H
Kumagai
Department of Clinical Laboratory, Jichi Medical University, Shimotsuke, Tochigi, Japan.
Nobuyuki
N
Taniguchi
High-frequency ultrasonic wave; Microscopic image; Needle-type ultrasonic probe; Tapered fused quartz fiber