Ultrasonic velocity and thickness gage

• US 4,056,970 A
• Filed: 10/30/1975
• Issued: 11/08/1977
• Est. Priority Date: 10/30/1975
• Status: Expired due to Term

• Current Assignee: Yeda Research and Development Co. Ltd. (Weizmann Institute of Science)
• Original Assignee: Yeda Research and Development Co. Ltd. (Weizmann Institute of Science)
• Inventors: Sollish, Bruce D.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Beauchamp, John P.
• Application Number:
  US05/627,386
• Time in Patent Office: 740 Days
• Field of Search: 73/67.7, 73/67.8 R, 73/67.8 S, 73/67.9
• US Class Current: 73/629
• CPC Class Codes: A61B 8/08 Detecting organic movements or changes, e.g. tumours, cysts, swellings A61B8/02 - A61B8/06 take precedence
• CPC Class Codes: G01B 17/02 for measuring thickness
• CPC Class Codes: G01N 2291/02854 Length, thickness
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves

Abstract

An apparatus and method for determining a velocity of propagation and the thickness of different substances such as pipe walls utilizes a transducer connected to an A-scan. This material is placed in a holder between the transducer and a reflecting surface, the holder containing a fluid having a known velocity of propagation. The transducer converts high voltage electrical pulses produced by a generator into ultrasonic vibrations and also converts echo signals received from the reflecting surface and the material back into electrical pulses. A display device connected to the transducer displays these pulses and their exact position on the display device is used to determine the velocity of propagation and the thickness of the material.

Claims

1. A method for determining the velocity of propagation of a particular material, comprising the steps of:

providing a reflecting surface in a fluid medium having a known velocity of propagation;

recording the position in time of an echo received from said reflecting surface utilizing a transducer to create at least one ultrasonic pulse which is reflected off said reflecting surface;

placing the material to be tested in said fluid between said transducer and said reflecting surface;

transmitting at least one ultrasonic pulse from the transducer and receiving echoes of said pulse reflected from said material and from said reflecting surface;

recording the position in time of the echoes corresponding to the anterior and posterior surfaces of said material and the new position in time of the echo from said reflecting surface; and

determining the velocity of propagation of said material by utilizing the positions in time of said echoes, according to the equation

space="preserve" listing-type="equation">V/V.sub.o = 1 - Δ

T.sub.2 /Δ

T.sub.1

where

V is the propagation velocity in the material to be tested,

V_o is the propagation velocity in the fluid medium,

Δ

T₂ is the round trip propagation time from the transducer to the reflecting surface with the material to be tested positioned somewhere in between, minus the round trip propagation time from the transducer to the reflecting surface with said material removed, and

Δ

T₁ is the round trip propagation time between the anterior and posterior surfaces of the material to be tested.

2. A method for determining the thickness of a particular material, comprising the steps of:

providing a reflecting surface in a fluid medium having a known velocity of propagation;

recording the position in time of an echo received from said reflecting surface utilizing a transducer to create at least one ultrasonic pulse which is reflected off said reflecting surface;

placing the material to be tested between said transducer and said reflecting surface in said fluid;

transmitting at least one ultrasonic pulse from the transducer and receiving echoes of said pulse reflected from said material and from said reflecting surface;

recording the positions in time of the echoes corresponding to the anterior and posterior surfaces of said material and the new position in time of the echo from said reflecting surface; and

determining the thickness of said material by utilizing the positions in time of said echoes, according to the equation

space="preserve" listing-type="equation">l = l.sub.o (1-Δ

T.sub.2 /Δ

T.sub.1)

where

l = actual thickness of the material to be tested,

l_o = V_o Δ

T₁ /2, the apparent thickness of the material, as if the propagation velocity were V_o,

V_o is the propagation velocity in the fluid medium,

Δ

T₂ is the round trip propagation time from the transducer to the reflecting surface with the material to be tested positioned somewhere in between, minus the round trip propagation time from the transducer to the reflecting surface with said material removed, and

Δ

T₁ is the round trip propagation time between the anterior and posterior surfaces of the material to be tested.

3. A method for determining the presence of a lesion in a human breast comprising the steps of:

providing a reflecting surface in a fluid medium having a known velocity of propagation;

recording the position in time of an echo received from said reflecting surface utilizing a transducer to create at least one ultrasonic echo which is reflected off said reflecting surface;

placing the breast between said transucer and said reflecting surface;

displacing the transducer in a plane parallel to the reflecting surface in steps;

determining the propagation velocity in the breast at each new position of the transducer according to the equation V/V_o = 1-Δ

T₂ /Δ

T₁, utilizing echoes from the anterior and posterior surface of the breast and the echo from the reflecting surface and repeating the above two steps unitl the entire breast is scanned;

where

V is the propagation velocity in the breast to be tested,

V_o is the propagation velocity in the fluid medium,

Δ

T₂ is the round trip propagation time from the transducer to the reflecting surface with the breast to be tested in between minus the round trip propagation time from the transducer to the reflecting surface with the breast removed from the propagation path, and

Δ

T₁ is the round trip propagation time between the anterior and posterior surfaces of the breast tested;

whereby the presence of one or more lesions beneath a two-dimensional plane can be determined since the velocity of propagation in the lesions differs from that of the remainder of the breast.

4. In an apparatus for measuring characteristics of materials utilizing ultrasound comprising a transducer, means to power said transducer, and means for collecting information concerning the characteristics of the material tested from ultrasound emitted by said transducer, the improvement comprising:

an ultrasound reflector disposed opposite said transducer and at any downstream location from the material to be tested, fluid having a known velocity of propagation between said transducer and said reflector, and wherein said means for collecting include means for determining difference in transit time of ultrasound to and from said reflector with and without the material in said fluid and for determining transit times of ultrasound to and from anterior and posterior surfaces of said material when present in said fluid, according to the equation

space="preserve" listing-type="equation">V/V.sub.o = 1 - Δ

T.sub.2 /Δ

T.sub.1

where

V is the propagation velocity in the material to be tested,

V_o is the propagation velocity in the fluid medium,

Δ

T₂ is the round trip propagation time from the transducer to the reflecting surface with the material to be tested positioned somewhere in between, minus the round trip propagation time from the transducer to the reflecting surface with said material removed, and

Δ

T₁ is the round trip propagation time between the anterior and posterior surfaces of the material to be tested.

5. An improved apparatus according to claim 4, including display means coupled to said transducer for displaying converted mechanical energy received from said reflector and said surfaces of said material.

6. An improved apparatus according to claim 5, further including a recordation means operatively connected to said display means for producing a permanent record of the converted mechanical energy shown on said display means.