Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2002-03-18
2004-01-27
Jaworski, Francis J. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S463000
Reexamination Certificate
active
06684094
ABSTRACT:
The invention concerns an instrument for medical purposes, comprising a housing which can be introduced into an animal or human body, a movably mounted electromagnetic or acoustic transducer unit arranged in the housing, preferably in the distal end thereof, for producing electromagnetic or acoustic waves, in particular ultrasonic waves, and a drive for driving the transducer unit, wherein the transducer unit is connected to at least one first contact element and arranged on the housing is at least one second contact element provided for sliding contact with the first contact element.
BACKGROUND OF THE ART
Such instruments can be introduced into the human body or into cavities of the human body, which are accessible from the exterior, in particular for investigative purposes.
To carry out such an investigation of hollow organs and vessels, use is made in medicine inter alia of ultrasonic instruments, by means of which it is possible to obtain information about the structural makeup of biological tissue. By using sound waves, it is possible to observe structures within a piece of tissue, which are frequently only accessible to visual assessment by means of invasive methods. Within the human body however there are numerous cavities between organs and within bones which shield some regions of the body for the external use of ultrasound. Those regions can only be investigated by means of instruments of the kind set forth in the opening part of this specification, preferably ultrasonic instruments, which are to be introduced into the body. In that respect those instruments should be capable of processing sound waves at least in one plane in space so that a sectional representation of the body structure being investigated can be produced from the sound echoes which are received and evaluated by the instruments.
While there is sufficient space available for the scanning operation when using instruments outside the body, the tight conditions in respect of space in the body to be investigated constitute a problem when using instruments which are to be introduced into the body.
Dutch patent application No. 8700632 describes an ultrasonic instrument having a catheter whose tip either contains a rotatably mounted acoustic mirror or a fixed acoustic mirror and is itself mounted rotatably. A flexible shaft which is coupled to the rotatable mirror or the rotatable catheter tip extends from the distal catheter tip to the proximal end of the catheter and is driven by a drive unit disposed outside the catheter. A transducer is mounted in the catheter tip opposite the rotating acoustic mirror. Rotation of the acoustic mirror produces ultrasonic waves in different directions and the echoes of the sound waves are received again by the acoustic mirror and then by the transducer. As the curvature of the flexible shaft within the catheter is not in one plane, bending of the shaft in a plurality of axes relative to the position of the drive unit is also linked to a rotational movement of the transducer. As a result of this and due to static friction effects the directions of the ultrasonic waves cannot be accurately ascertained so that it is not possible to precisely predict how the image represented by the ultrasonic unit is linked to the position of the structure within the human body. The differing amount of friction which the flexible shaft experiences from one revolution to another also results in statistical modulation of the angular speed of the acoustic mirror, which reveals itself as a lack of definition in the image representation of the sound echoes.
To overcome those disadvantages, U.S. Pat. No. 5,603,327 to Eberle No. 5,603,327 proposes subdividing the fixedly installed ultrasonic converter into a plurality of segments, in respect of which the direction of propagation of the sound waves is achieved by suitable actuation control. That however gives rise to the necessity to provide numerous electrical contacting means in a very small space and in addition to integrate amplifiers for pre-amplification of the really weak echo signals from the numerous sound converter segments, into the instrument. That arrangement entails high manufacturing costs. If the instruments are used only once, which is frequently the case, that results in high consumable item costs on the part of the users.
A further possible option involves continuously measuring the position of the ultrasonic converter, whereby correction of the representation is a possibility. That measure is proposed in PCT publication WO 90/13253, assigned to DU-MED B.V. and published Nov. 15, 1990. For that purpose however it is necessary to use an angular measurement converter which however only permits correction of the visualized echoes, which is complicated and expensive in terms of computing power. Unfortunately complete elimination of the described friction effects is also not possible with such an instrument.
A third possible option involves moving the drive which moves the acoustic mirror or sound reflector into the catheter. Such an instrument is disclosed in European Patent Office application 0 423 895 A1, also owned by DU-MED B. V., which constitutes the most relevant state of the art which the present invention takes as its basic starting point. That known arrangement admittedly avoids the disadvantages of the previously described arrangements, but this arrangement only permits the acoustic wave radiation angle to be fixed in a narrow range. It has been found moreover that the structural factors involved with this arrangement means that it is essentially fixed only to high acoustic frequencies.
The object of the present invention is to improve an instrument of the kind set forth in the opening part of this specification, in such a way that it is possible to operate with the highest possible degree of versatility with a transducer unit which is flexible in particular in terms of frequency and radiation direction of the waves.
SUMMARY OF THE INVENTION
That object is attained in that, in an instrument of the kind set forth in the opening part of this specification, the first and second contact elements jointly form an at least radial mounting for the transducer unit.
Such an arrangement makes it possible to provide a transducer unit which is preferably rotatably mounted and which is substantially directly driven by the drive without the transducer unit requiring a large amount of space. In actual fact, the arrangement according to the invention in which the sliding contacts for contacting the transducer unit at the same time provide for radial mounting of the transducer unit and preferably also axial mounting affords a highly compact and at the same time reliable design configuration. A compact structure increases in particular the large number of possible uses of the instrument which in fact is also to be introduced into narrow natural or artificial openings in the body.
This arrangement also makes it easier for the drive and the transducer unit to be integrated in a compact housing. That affords various advantages. A major advantage is that on the one hand an acoustic mirror or sound reflector and on the other hand force-transmitting means such as for example a shaft are not required, which results in a simplified structure and a perceptible reduction in manufacturing costs. The damped elastic mounting for the transducer unit by the sliding contacts and the substantially direct rigid mechanical coupling of the drive and the transducer unit also reduces oscillations as a consequence of friction, which are superimposed on the movement which is predetermined by the drive, while in addition, by virtue of the very uniform movement of the transducer unit which is achieved in that way, that results in very uniform scanning by the waves generated by the transducer unit.
In addition there is a great deal of scope in regard to the design configuration of the transducer unit, in which respect in particular the frequency and the radiation angle can be virtually freely selected. Finally, the compact structure achieved by means of the arrangement
Lehr Heinz
Niederfeld Gerhard
Grant Stephen L.
Hahn Loeser + Parks LLP
Jaworski Francis J.
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