JPH06277219A - Medical ultrasonic converter assembly - Google Patents

Abstract

PURPOSE: To obtain an ultrasonic-converter assembly which is free from generation of large distortions or other deterioration in ultrasonic images by structuring an interface means to conduct to a patient's body ultrasonic energy which is received/transmitted from/to the ultrasonic converter and by equipping with an ultrasonic element consisting of a rigid material of a lower-sonic velocity. CONSTITUTION: An ultrasonic converter 10 having an ultrasonic transmission element manufactured from a rigid lower sonic-velocity material is installed within a probe housing 12. The converter 10 has an array of converter elements so arranged as to meet the flat plane of the figure at right angles and an ultrasonic lens 14 has a flat plane and a convex outer plane installed to the converter 10. The convex outer plane of the lens 14 is a cylindrical shape in the direction to meet the flat plane of the figure at right angles and normally, is manufactured from such elastic lower-sonic velocity materials as silicone rubber, etc. Further, as a protective cover 20 manufactured from a rigid lower sonic-velocity material covers the outer plane of the convex shape of the lens 14, having a uniformly matched form with the convex outer plane, it is arranged that no air is present between the elements.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to transducer assemblies for medical ultrasonic devices, and more particularly to interfacial elements for providing ultrasonic energy coupling between the transducer and the body of a patient.

[0002]

Ultrasonic transducers are frequently used in various medical applications. The converter can comprise a converter element or a series of converter elements. The transducer is typically part of an ultrasound imaging system for producing an image of the desired area within the patient's body. For many applications, the transducer is mounted within a handheld probe. The handheld probe is positioned adjacent a selected external region of the patient's body, for example, adjacent the chest wall for scanning the heart. In another example, the transducer is mounted in a probe that can be placed in a cavity or pathway in the body. Transducers are often equipped with ultrasonic lenses to focus the ultrasonic energy.

When an ultrasonic transducer is used in medical imaging, it ensures that the material between the transducer and the area of the patient's body being imaged does not distort or interfere with the image. This is very important. In particular, when ultrasonic energy encounters the interface between materials of different sound speeds, some of the energy is reflected or refracted. Since the speed of sound in air (about 332 m / sec) is significantly different from the speed of sound in the human body (about 1540 m / sec), it is important to exclude air between the ultrasonic transducer and the patient's body. For this reason, it is common to use acoustic gel between the transducer and the patient's body.

[0004]

Single piece ultrasonic lenses for flat piezoelectric crystals usually have a convex outer structure. This allows good contact between the transducer and the body part on which the image is formed. In order to provide a lens for focusing ultrasonic energy with a flat inner surface contacting the transducer and a convex outer surface, the speed of sound in the material must be slower than the speed of sound in the human body. A typical material with such a low speed of sound is silicone rubber, which is relatively soft, poorly durable, extremely dampening and must be constructed on an ultrasonic transducer. . It is desirable to provide a protective cover on this silicone rubber lens. However, the cover should not cause a large distortion in the ultrasonic image or attenuate the ultrasonic energy.

Another ultrasonic transducer configuration is described in US Pat.
There is a transesophageal probe described in 5,127,410 (issued July 7, 1992) that uses a rotary transducer and a lens. Such transducers and lenses are placed behind a sealed window and rotate with respect to that window. The lens comprises internal elements made of silicone rubber and external elements made of urethane rubber. Acoustic lubricant is filled in the gap between the lens and the window. The urethane rubber lens element is relatively soft and is unable to provide adequate mechanical support to the window when an object is pressed or impacted on the window.

[0006]

In accordance with the present invention, a medical ultrasonic transducer assembly is provided. The transducer assembly transmits and receives ultrasonic energy to an ultrasonic transducer, conducts ultrasonic energy transmitted from the transducer to a patient's body, and receives ultrasonic energy received from the patient's body. Interface means for conducting to the converter. The interface means comprises at least one ultrasonic transmission element made of a rigid, low sonic material. The material preferably has a speed of sound that closely matches the speed of sound in human tissue. The ultrasonic transducer can consist of a single transducer element or a series of transducer elements.

A rigid low sonic material is preferably
A material suitable for use in the human eye as a contact lens. The rigid low-sonic velocity material of the present invention has durability and can be machined or shaped into a desired shape. The velocity of sound in a rigid, low sonic material is approximately the same as the velocity of sound in the human body, so that distortion of the ultrasound image and reflection of ultrasound energy is minimized.

In a first embodiment of the invention, the interface means comprises an ultrasonic lens and the ultrasonic transmission element comprises a protective cover provided on said ultrasonic lens. Its protective cover is
Contact the patient's body while using the transducer.

In a second embodiment, the transducer assembly comprises a fixed window and means for rotating the transducer with respect to the fixed window. The ultrasonic lens is attached to the transducer,
Rotate with the transducer. The ultrasonic transmission element comprises a protective cover attached to the ultrasonic lens and disposed between the ultrasonic lens and the window and made of a rigid, low sonic material.

In a third embodiment, the transducer assembly comprises a fixed window and means for rotating the transducer with respect to the fixed window. The window is made of a rigid, low sound velocity material.

In a fourth embodiment, the transducer assembly comprises a fixed window and means for rotating the transducer with respect to the fixed window. The ultrasonic lens is attached to the transducer,
Rotate with the transducer. The ultrasonic transmission element comprises the outer element of the ultrasonic lens, made of a rigid, low sonic material.

[0012] In a fifth embodiment, an ultrasonic transmission element made of a rigid, low sonic material comprises an acoustic conduit that provides ultrasonic energy coupling between the transducer and the patient's body. . The acoustic conduit includes an isolation to separate the transducer from the patient's body. The acoustic conduit may also include a surface that redirects ultrasonic energy by total internal reflection within the acoustic conduit.

In accordance with another aspect of the present invention, there is provided an element for providing ultrasonic energy coupling between an ultrasonic transducer and a patient's body. The element is composed of a member made of a rigid, low sonic material.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel interface element for use between an ultrasonic transducer and a patient's body. The present invention is based on the discovery that rigid breathable materials, which are commonly used in the human eye as contact lenses, have properties that make them very suitable for the transmission of ultrasonic energy. Such rigid breathable materials are used to fabricate various ultrasonic transmission elements that are placed between the ultrasonic transducer and the patient's body.

The most important requirement for such an ultrasonic transmission element is the speed of sound in the material. The speed of sound in this material preferably approximately matches the speed of sound in the human body (about 1540 m / sec).
This ensures that the transmitted or received ultrasound energy does not experience significant distortion or other degradation in the ultrasound image as it passes through the element. It is desirable that the speed of sound in this material be as close as possible to the speed of sound in the human body.
However, sound speeds in the range of about 950-2000 m / sec are considered acceptable. Materials with sonic velocities in this range are mostly flexible and therefore lack durability.

Another requirement is that the acoustic impedance of a rigid material is the acoustic impedance of the human body (1.
54Mrayls) should almost match. Acoustic impedances in the range of about 1.0-2.1 Mrayls are considered acceptable.

It has been discovered that the rigid breathable materials commonly used for contact lenses have a velocity of sound very close to the velocity of sound in the human body. Further, such materials are relatively hard, durable and can be machined or shaped into the desired shape. Another advantage of such materials is the acoustic damping (typically
It is possible to have a sound attenuation (generally 20 dB / cm) lower than 30 dB / cm). Thus, this rigid breathable material can be used to make a variety of ultrasonic transmission elements that can be placed between the ultrasonic transducer and the patient's body. The breathability required for contact lenses is not required for ultrasonic transmission elements. Therefore, it is believed that rigid materials having sonic velocities in the range of 950 to 2000 m / sec (hereinafter referred to as rigid low sonic velocity materials) can be used to manufacture the ultrasonic transmission element according to the present invention.

A suitable rigid low sonic material is "Equalens I
The product name is "Polymer Technology Corporatio"
n ”(Wilmington, Massachusetts). The measured sound velocity of this material is within the above range. Other breathable contact lens materials are available from Ellis et al., May 1979 1
Published U.S. Pat.No. 4,152,508, Ellis et al., January 1984 3
Published U.S. Pat.No. 4,424,328, Ellis et al., July 1984 3
1-day U.S. Pat.No. 4,463,149, Ellis et al. August 1986
U.S. Pat.No. 4,604,479 issued 5th, Ellis et al. 1986 11
U.S. Pat.No. 4,625,007 issued May 25, Ellis et al., 1987
U.S. Pat.No. 4,686,267, issued August 11, 1989, Ellis et al.
U.S. Pat.No. 4,826,889, issued May 2, 1989, Ellis et al. 1989
U.S. Pat.No. 4,826,936, issued May 2, 1991, Ellis et al.
U.S. Pat. No. 4,996,275, issued February 26, 2010, and Baron
Et al., U.S. Pat. No. 5,032,658, issued Jul. 16, 1991. Generally, this rigid low sonic material has a composition containing polymethylmethacrylate and silicon or silicon fluoride.

A first embodiment of an ultrasonic transmission element made of a rigid low sonic material is shown in FIG. The ultrasonic transducer 10 is mounted inside the probe housing 12. Transducer 10 has an array of transducer elements in a direction orthogonal to the plane of FIG. The ultrasonic lens 14 has a flat surface attached to the transducer 10 and a convex outer surface. The convex outer surface of the lens 14 has a cylindrical shape in a direction orthogonal to the plane of FIG. The lens 14 is typically made of a low acoustic velocity flexible material such as silicone rubber. A protective cover 20 made of a rigid low sonic material as described above covers the convex outer surface of the lens 14. The cover 20 has a shape that conforms to the convex outer surface of the lens 14 so that there is no air between the elements. The thickness of cover 20 can generally be about 0.5 mm. However, it will be appreciated that other thicknesses are available. The cover 20 prevents the ultrasonic lens 14 from being damaged and does not cause distortion or other interference in the obtained ultrasonic image. The protective cover 20 is typically placed in contact with the patient's body using acoustic gel.

Another embodiment of an ultrasonic transmission element made of a rigid low sonic material will be described with reference to FIG. The ultrasonic transducer probe 30 is placed in contact with the patient's body 32. The probe 30 includes a phased array ultrasonic transducer 36 formed of a piezoelectric material. The transducer 36 is rotated by a mechanism 38 that directly or indirectly rotates the transducer using a reciprocating motor or other suitable means.
The compound lens 40 has a convex cylindrical lens element 46 and a concave element 48 that joins with this convex element 46. Lens element 46 is typically silicone rubber such as RTV. Lens element 48 is typically made of urethane rubber. The window assembly is mounted in a housing 41 covered by an epoxy seal 42. The window assembly comprises a thin polyester film window 45 and a back layer 47. This back layer 47 can be manufactured from urethane rubber. This back layer 47 is RFI
A screen 49 can be included. An acoustic lubricant 51, such as silicon fluoride oil, is disposed between the lens 40 and the back layer 47 to allow the transducer 36 and lens 40 to rotate with respect to the window assembly. Such a probe assembly is described in more detail in the above-referenced US Pat. No. 5,127,410.

According to a second embodiment of the present invention, a protective cover 60 made of a rigid low sonic material is attached to the outer surface of the lens element 48. This protective cover 60 prevents the flexible urethane lens element 48 from being physically damaged as the transducer rotates. Further, the cover 60 protects the urethane lens element 48 from deterioration due to the acoustic lubricant 51. Finally, the cover 60 provides a mechanical backing for the window assembly, which reduces the potential for damage to the window due to pressure or shock from external objects.

Preferably, the cover 60 is compatible with the acoustic lubricant 51 and maintains the acoustic lubricant 51 in place to evaporate or form air pockets during rotation of the lens 40. Try not to. This requirement is probably met by the breathing properties of the rigid low sonic material.

In a third embodiment of the invention, a transducer probe
The thirty windows 45 are manufactured from a rigid low sonic material. In conventional transducer assemblies, the window 45 was very thin to reduce refraction and reflection of ultrasonic energy, and the back layer 47 was made of urethane rubber. Therefore, such window assemblies were susceptible to damage by external objects. On the other hand, if the window 45 is made of a rigid low acoustic velocity material, it can be made relatively thin. This is because the acoustic characteristics are very close to the acoustic characteristics in the human body. Therefore, the potential for damage to the probe assembly is reduced without affecting the ultrasound image. The protective cover 60 and the rigid low sound velocity window 45 can be used separately or in combination in the transducer assembly of FIG.

FIG. 3 shows a fourth embodiment of the present invention. The ultrasonic transducer probe 30 in the figure has the same structure as the probe shown in FIG. The same elements in FIGS. 2 and 3 are designated by the same reference numerals. In the embodiment of FIG. 3, lens element 62, which couples to convex lens element 46, is made of a rigid low sonic material according to the present invention. The lens element 62 has the same advantages as the protective cover 60 shown in FIG. 2 and described above. The lens element 62 prevents physical damage to the convex element 46 and is not degraded by the acoustic lubricant 51. In addition, the lens element 62, made of a rigid, low sonic material, provides a mechanical backing for the window assembly, which reduces the potential for damage to the window.

FIG. 4 shows a fifth embodiment of the present invention. The acoustic conduit 70 is used to transmit ultrasonic energy between the ultrasonic transducer 72 and the patient's body 74. The acoustic conduit is made of a rigid low sonic material and is configured to redirect the ultrasonic energy transmitted or received by the transducer 72. The surface 75 of the acoustic conduit 70 makes an angle of 45 ° with the direction of transmitted and received ultrasonic energy. This surface 75 contacts the air or another material whose acoustic impedance is sufficiently different from the rigid low sonic material of the acoustic conduit 70. As a result, ultrasonic energy is reflected from the surface 75 by total internal reflection and the coherent state is maintained.

A simpler version of this acoustic conduit consists of a straight section made of a rigid, low sonic material, which acts as an isolation to keep the ultrasonic transducer away from the patient's body. . The rigidity of this acoustic conduit allows the construction of clip-on devices for imaging with narrow limbs, such as fingertip transducers. This rigid low sonic material can be machined to follow the curvature of the imaged organ.

Above, several embodiments of ultrasonic transmission elements made from rigid low sonic materials have been shown and described. It will be appreciated that the present invention includes any ultrasonic transmission element made from a rigid low sonic material.
Such elements provide structural rigidity and have a speed of sound that facilitates transmission and reception of ultrasonic energy to and from the human body while minimizing reflection and refraction of ultrasonic energy.

While the presently preferred and preferred embodiment of the invention has been illustrated and described, those skilled in the art can make various changes and modifications without departing from the scope of the invention as defined in the claims. It will be clear that modifications are possible.

[0029]

Since the present invention is constructed as described above, it is possible to provide a transducer assembly for a medical ultrasonic device which does not cause a large distortion or other deterioration of an ultrasonic image.

The embodiments of the present invention will be listed below.

1. An ultrasonic transducer that transmits and receives ultrasonic energy, conducts the ultrasonic energy transmitted from the transducer to the body of the patient, and transmits the ultrasonic energy received from the body of the patient to the transducer. An interface means for conducting, said interface means comprising at least one ultrasonic transmission element made of a rigid, low acoustic velocity material, further comprising an ultrasonic lens, The ultrasonic transducer assembly according to claim 1, wherein the ultrasonic transmission element comprises a protective cover provided on the ultrasonic lens.

2. An ultrasonic transducer that transmits and receives ultrasonic energy, conducts the ultrasonic energy transmitted from the transducer to the body of the patient, and transmits the ultrasonic energy received from the body of the patient to the transducer. An interface means for conducting, said interface means comprising at least one ultrasonic transmission element made of a rigid, low sonic material, and further comprising means for rotating said transducer, An ultrasonic lens, wherein the interface means is attached to the transducer and rotates with the transducer;
A fixed window positioned between the ultrasonic lens and the patient's body, the ultrasonic transmission element comprising a protective cover attached to the ultrasonic lens and extending from the ultrasonic lens to the window A medical ultrasonic transducer assembly, comprising:

3. An ultrasonic transducer that transmits and receives ultrasonic energy, conducts the ultrasonic energy transmitted from the transducer to the body of the patient, and transmits the ultrasonic energy received from the body of the patient to the transducer. An interface means for conducting, said interface means comprising at least one ultrasonic transmission element made of a rigid, low sonic material, and further comprising means for rotating said transducer, The interface means comprises an ultrasonic lens attached to and rotating with the transducer, and the ultrasonic transmission element comprises a fixed window positioned between the ultrasonic lens and the patient's body. A medical ultrasonic transducer assembly, comprising:

4. An ultrasonic transducer that transmits and receives ultrasonic energy, conducts the ultrasonic energy transmitted from the transducer to the body of the patient, and transmits the ultrasonic energy received from the body of the patient to the transducer. An interface means for conducting, said interface means comprising at least one ultrasonic transmission element made of a rigid, low sonic material, said ultrasonic transmission element further comprising: A medical ultrasonic transducer assembly, comprising an acoustic conduit for ultrasonic coupling between a patient and the body of a patient.

5. The medical ultrasonic transducer assembly of claim 4, wherein the acoustic conduit comprises a surface that redirects ultrasonic energy within the acoustic conduit by total internal reflection.

6. An ultrasonic transducer that transmits and receives ultrasonic energy, conducts the ultrasonic energy transmitted from the transducer to the body of the patient, and transmits the ultrasonic energy received from the body of the patient to the transducer. An interface means for conducting, said interface means comprising at least one ultrasonic transmission element made from a rigid, low sonic velocity material, and further comprising said rigid, low sonic velocity material The sound velocity inside is about 950 (m / sec) to 2000
A medical ultrasonic transducer assembly characterized by being in the range of (m / sec).

7. An ultrasonic transducer that transmits and receives ultrasonic energy, conducts the ultrasonic energy transmitted from the transducer to the body of the patient, and transmits the ultrasonic energy received from the body of the patient to the transducer. An interface means for conducting, said interface means comprising at least one ultrasonic transmission element made of a rigid, low sonic material, and further comprising means for rotating said transducer, An ultrasonic lens, wherein the interface means is attached to the transducer and rotates with the transducer;
A medical ultrasonic transducer assembly, comprising: a fixed window positioned between the ultrasonic lens and a patient's body, the ultrasonic transmission element comprising a component of the ultrasonic lens.

8. An ultrasonic transducer that transmits and receives ultrasonic energy, conducts the ultrasonic energy transmitted from the transducer to the body of the patient, and transmits the ultrasonic energy received from the body of the patient to the transducer. Comprising: an interface means for conducting, said interface means comprising at least one ultrasonic transmission element made of a rigid, low acoustic velocity material, the ultrasonic transmission element further comprising an ultrasonic lens Or a medical ultrasonic transducer assembly, characterized in that it consists of its components.

9. An element comprising a member made of a rigid, low sonic material, characterized by providing an ultrasonic energy connection between the ultrasonic transducer and the patient's body.

[Brief description of drawings]

1 is a partial cross-sectional view of a transducer assembly according to the present invention with a flexible ultrasonic lens and a protective cover made of a rigid, low sonic material.

FIG. 2 is a cross-sectional view showing an example of a transducer assembly that employs a rotary transducer and a lens.

FIG. 3 is a cross-sectional view illustrating an embodiment of a transducer assembly that employs a rotary transducer and a lens.

FIG. 4 is a side view showing a schematic of a transducer assembly that employs an acoustic conduit to provide ultrasonic energy coupling between the transducer and the patient's body.

[Explanation of symbols]

 10: Ultrasonic transducer 12: Probe housing 14: Ultrasonic lens 20: Protective cover

Claims (1)

[Claims] 1. An ultrasonic transducer for transmitting and receiving ultrasonic energy, conducting ultrasonic energy transmitted from the transducer to a body of a patient, and transmitting ultrasonic energy received from the body of the patient. Medical device, characterized in that it comprises an interfacial means for conducting to said transducer, said interfacial means comprising at least one ultrasonic transmission element made of a rigid, low acoustic velocity material. Ultrasonic transducer assembly.