1989-10-12
1993-11-30
Jaworski, Francis
Surgery
Truss
Pad
12866301, A61B 800
Patent
active
052656144
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
a. Field of the Invention
The present invention relates to an acoustic coupler provided between an ultrasound probe and a surface of a body to be diagnosed.
b. Description of the Related Art
An ultrasound probe including an ultrasonic transducer is used for diagnosing an affected part in a human body by holding the probe to a surface of the human body. During holding the probe to the body, the ultrasonic transducer transmits an ultrasonic wave which is formed into an ultrasonic beam for scanning the body, and receives ultrasonic echoes from the body along the beam.
As well known, the ultrasonic transducer has two types, a single type having a single ultrasonic transducer and an array type having plural ultrasonic transducers arranged either in a line an in a matrix. Therefore, the size and shape of the ultrasound probe is varied in accordance with the type of the ultrasonic transducer.
When the surface of the body is soft so that the ultrasound probe can be tightly fitted to the surface of the body and when the affected part is located from the surface of the body as deeply as the ultrasonic echoes can be focused well with a sufficient depth of field, the probe can be used in a state being directly held to the surface of the body through a thin layer of water, vegetable, oil, glycerin or liquid paraffin. The thin layer prevents multi-reflection caused by an air gap between the probe and the surface of the body.
On the other hand, when the surface of the body is not soft or not flat to the ultrasound probe as in a case that the thyroid gland or the carotid artery is diagnosed by the ultrasound probe, it is hard to hold the probe to the surface of the throat tightly without leaving the air gap. Furthermore, when the affected part is located near the surface of the body as in a case of diagnosing the thyroid gland, carotid artery or mamma cancer, it is hard to detect ultrasonic echoes from the affected part with sharp resolution, because the echoes are focused within a thin depth of field. In these cases, an acoustic coupler having a thickness of approximately 1 to 10 cm is used between the ultrasound probe and the surface of the body. The thickness of the acoustic coupler is varied in accordance with the flatness of the surface of the body and/or the location of the affected part from the surface of the body.
The material of the acoustic coupler must have low acoustic attenuation and acoustic impedance required to be equal to the surface of the human body. This kind of material will be called an "acoustically transparent material" or simply a "transparent material" hereinafter. As the transparent material for the acoustic coupler, water put in a bag has been used, using a transparent elastic material such as silicon rubber for the bag. Water is easily obtained and can be used in a hygienic condition so there is no worry of making the body dirty. However, there were problems that the bag would have been broken, resulting in splashing water on the body. This problem has been solved by using a gelled material for the acoustic coupler. A gelled material can be made so as to be acoustically transparent. Further, it is easy to apply to the surface of the body without leaving an air gap, and it is easy to remove from the surface, leaving no fragment of the gel material. Such gelled material will be simply called a "gel" hereinafter.
In regard to the gel and its application to the acoustic coupler, there have been many patents (Japanese laid opened patents). For instance: SHO 59-11708 to IMAI on Jan. 25, 1984 discloses a gel applicable to the acoustic coupler, such as a silicon rubber gel, a water gel, an oil gel or a gel mixed with water and oil; SHO 59-49750 to MIYAMOTO et al. on Mar. 22, 1984 discloses a gel called a poly vinyl alcohol (PVA) gel which a kind of a hydrated gel containing approximate 80% of water content, having large elasticity and hardness and very small acoustic attenuation. The elasticity and the hardness depend on a refrigerating temperature and a frequency of repe
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International Search Report for International Application No. PCT/JP89/00881, European Patent Office, Nov. 22, 1989.
Hayakawa Kenichi
Kawabe Kenji
Matsui Kiyoto
Shimura Takaki
Takeda Shiro
Fujitsu Limited
Jaworski Francis
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