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Yoshizawa M.,Tokyo Metropolitan College of Industrial Technology | Irie T.,Tokyo Metroplitan University | Irie T.,Microsonic Co. | Itoh K.,Hitachi Omiya Saiseikai Hospital | Moriya T.,Tokyo Metroplitan University
Japanese Journal of Applied Physics | Year: 2010

In this paper, we propose a robust sensing system that protects a thin rod sensor used in the measurements of acoustic impedance in puncture needle-type ultrasonography. In this ultrasonograpy, an ultrasonic interference method using the thin rod sensor is applied. Since the thin rod made of fused quartz is not robust, a protector is required for the thin rod sensor in in vivo measurement. Therefore, the sensing system has consisted of a thin rod sensor and a hollow pipe with a top cover to protect the sensor. For the observation of a low-impedance material such as biological tissue, the measurement method requires an impedance-transforming layer as the top cover. However, since the optimum thickness of the layer decreases as the measurement frequency increases, the decrease in the thickness causes deformation of the layer. The deformation introduces an error in the measurement. To avoid such a problem, we developed a robust sensing system. The system consists of a quarterwavelength layer that functions as an impedance transformer and a half-wavelength (or multiple times of a half-wavelength) layer that provides the robustness of the system. We confirmed experimentally the effectiveness of the robust sensing system for acoustic impedance measurement of a tissue sample by the acoustic impedance difference method. The experimental results show that the robust sensing system is useful for puncture needle-type ultrasonography. © 2010 The Japan Society of Applied Physics.

Fujii Y.,Jichi Medical University | Yoshizawa M.,Tokyo Metropolitan College of Industrial Technology | Emoto R.,Tokyo Metropolitan College of Industrial Technology | Haruyama N.,Tokyo Metropolitan College of Industrial Technology | And 2 more authors.
Journal of Medical Ultrasonics | Year: 2012

To clarify the potential of a novel system using the acoustic impedance difference imaging (AIDI) method for diagnosis of skin disorders, we used it on a coin and swine skin. An ultrasound wave with a central frequency of 20 MHz, emitted from a fused quartz rod with a diameter of 1.25 mm, was focused on the surface of the coin and skin samples. The difference in acoustic impedance was determined by the reflection-type interference-based acoustic impedance measurement method. The processed data were produced as greyscale images on which the maximum measured amplitudes were mapped. We applied the method to a coin. Swine skin, burned and covered with an acrylic sheet with a thickness of 0.2 mm (a few times the half-wavelength) to eliminate the undulations of the skin surface, was employed to obtain processed images from which undulation data were excluded. All the processed images obtained corresponded almost exactly with the magnified optical ones. In the processed images of swine skin, a marked difference was found after the burning procedure. The processed images obtained using the AIDI method reflected not only the undulations but also other information such as elasticity. In conclusion, our system using AIDI has the potential to become a useful modality for the diagnosis of skin disorders. © 2011 The Japan Society of Ultrasonics in Medicine.

Irie T.,Tokyo Metroplitan University | Irie T.,Microsonic Co. | Tagawa N.,Tokyo Metroplitan University | Yoshizawa M.,Tokyo Metropolitan College of Industrial Technology | Moriya T.,Tokyo Metroplitan University
2015 IEEE International Ultrasonics Symposium, IUS 2015 | Year: 2015

We have studied transmission methods of high-frequency ultrasonic waves through a thin fiber for direct observation of the microscopic image of the tissue. We reported previously that the C-mode images of the tissue on the glass placed in water were obtained by penetration method using a fused quartz fiber as the probe. In this paper, we describe that the B-mode image of a sample tissue in water was obtained by reflection method using the focused ultrasonic beam. © 2015 IEEE.

Yagi S.-I.,Meisei University | Yokoyama R.,Meisei University | Tamura K.,Aloka Co. | Sato M.,Microsonic Co.
Japanese Journal of Applied Physics | Year: 2011

A strategic synthetic aperture radar (SAR) along a flight path has been developed including a potential extensibility in a wide-range target area and an excellent spatial resolution by utilizing two-way range stacking, matched filtering, and chirp signal transmission. For the simultaneous ultrahighframe-rate ultrasonic imaging of microdynamics in a living tissue, a one-way synthetic aperture array processing of a real-time-received two-dimensional (2D) echo signal followed by a successive transmission is indispensable, in which the range stacking in SAR should be modified toward the pulsed ultrasonic irradiation generated by the array transducer. Therefore, the modification of the range stacking was proposed for pulsed radiation from a flexible point ultrasonic source. Firstly, a one-way receiving range stacking algorithm was described in a spatiotemporal frequency domain, and it was consequently extended to account for the forward-range- and cross-range- dependent time delay of the 2D echo signal in each range bin for the reconstruction of the target area. The overall system performance for the linear array transducer having 256 elements with a 3.0 MHz center frequency and a 0.25 mm pitch was verified for the reconstructed images in a numerical simulation and a hardware experiment. © 2011 The Japan Society of Applied Physics.

Irie T.,Tokyo Metroplitan University | Irie T.,Microsonic Co. | Koumoto K.,Tokyo Metroplitan University | Tanabe M.,Tokyo Metroplitan University | And 4 more authors.
Japanese Journal of Applied Physics | Year: 2010

The purpose of the study is to diagnose bone diseases using the ultrasonic image. We investigate the broadband transducer with a 0.5-5 MHz frequency range. We fabricated two types of transducers with a thin piezoelectric plate bonded with a thick plate resonator. One is an acoustic lens transducer made of flat lead zirconate titanate (PZT) material, and another is a concave transducer made of PZT rod-polymer 1-3 composite material. The application of the transducers to clinical diagnosis involves the measurement of frequency-dependent characteristics of bone by the penetration method. We measured ultrasonic waves radiated from the transducer at the focal point, and performed frequency analysis. As a result, a flat frequency characteristic of the concave transducer was obtained. © 2010 The Japan Society of Applied Physics.

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