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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally, to ultrasonic transducer probes,
more especially to continuous wave ultrasonic transducer probes, and most
particularly to such a transducer probe for medical diagnostic procedures
wherein the probe is positioned within the suprasternal notch of a human
patient in order to insonify the ascending aorta.
2. Description of the Background Art
Insonification of mammalian organs as a medical diagnostic technique has
come to the fore within the last decade. Ultrasonic energy is transmitted
into a body and reflected energy from object organs, tissues, or the like
within an insonified region or field is received, processed, thence
analyzed as an indication of extant conditions thereof. Ultrasonic
diagnostic procedures are now relatively commonplace in the examination of
human patients to identify a wide range of physical conditions and/or
disorders; ranging, e.g., from prenatal examinations of a fetus to the
measurement of cardiac output. As will be appreciated more fully as this
description ensues, it is to devices for use within the latter class that
the invention is most particularly related.
Substantial attention has been paid in the art of ultrasonic diagostics to
improvements in the systems employed for generating and receiving the
ultrasonic energy and methods and means for analysis of the results
obtained thereby. Only scant attention has been paid to the design of the
transducer probe utilized in conjunction with these systems. For those
systems destined for examination, e.g., of prenatal conditions where the
ultrasonic transducer is applied to the abdominal region of a patient,
there are very few limiting geometrical constraints on the size and shape
of the transducer probe. Contrariwise, important considerations of patient
comfort and operator efficiency obtain in respect of ultrasonic
examination via insonification through the suprasternal notch, as is the
case where cardiac output is being examined by insonification of the
ascending aorta. Within that context, the patient may be in a supine
position, perhaps partially elevated, while the system operator places the
head of the transducer probe within the suprasternal notch and is required
to manipulate that probe in order to effectuate beam steering for the
purpose of positioning the transducer elements properly relative to the
cardiac region. The transducer head is usually at least partially obscured
from view of the operator by virtue of its disposition within the
suprasternal notch. Typically, the operator is observing an output device,
usually a graphic output such as a CRT, to achieve appropriate positioning
of the probe; attention thus diverted from the physical placement of the
probe within the notch of the patient under examination. On the other
hand, the patient must remain reasonably still while the operator
manipulates the probe and, accordingly, patient comfort is a requirement
which should not be underestimated lest patient movement in response to
discomfort may contribute to erroneous data.
To date, the art has yet to respond to the combined needs for an ultrasonic
transducer probe which assists in positioning by the operator without the
need for direct visual observation during manipulation while allowing for
improved patient comfort during necessary manipulation while the probe is
disposed within the suprasternal notch.
SUMMARY OF THE INVENTION
The present invention advantageously provides an improved ultrasonic
transducer probe particularly adapted for insonification of a human
patient by disposition thereof within the suprasternal notch. The improved
design of the instant transducer probe presents tactile positioning means
whereby the system operator may achieve appropriate positioning of the
transducer head, usually at least partially obscured within the patient's
suprasternal notch, while focusing attention on whatever equipment is
associated with the system. Yet an additional benefit of the present
design is minimization of patient discomfort otherwise heretofore
associated with that type of operator manipulation, fostering a more
relaxed atmosphere for the test and, in turn, enhanced reliability of the
results thereof.
The foregoing, and other, advantages and benefits are realized in an
ultrasonic transducer probe comprising an elongate handle member with a
proximal and a distal end, having a non-circular peripheral
cross-sectional geometry including at least one longitudinal edge or
raised rib to yield a gripping surface providing tactile positioning means
for the transducer and a transducer head extending from the distal end of,
and generally normal to, the handle, wherein the head has a generally
arcuate cross-sectional geometry and a generally trapezoidal profile. The
non-circular cross-sectional geometry of the handle member, and most
notably the edge(s) or rib(s) thereon, provide(s) the system operator with
a sensory indication of the position of the transducer head even though
the same is at least partially obscured within the patient's suprasternal
notch, greatly facilitating beam steering during the insonification
procedure. The generally arcuate cross-sectional geometry of the head,
with rounded corners and the lack of edges, allows rotational manipulation
of the probe within the suprasternal notch without accompanying discomfort
experienced by the patient; while the generally trapezoidal profile
permits lateral movement without objectionable probing discomfort.
Furthermore, the juncture of the transducer head and handle member, in
concert with the aforementioned geometrical configurations, yields a
hook-like conformation greatly facilitating placement of the probe
properly within the suprasternal notch.
In a preferred form of the present invention, the handle member has a
quadrilaterial cross-sectional geometry such as a rectilinear or
trapezoidal cross section; and most preferably a generally square cross
section with a very slight downward and inward taper along the side edges
with respect to the longitudinal axis thereof. Further along these lines,
the transducer head may take any of a number of arcuate forms, the
preferred being either ovate or circular as may be required by or
depending on the transducer crystal array selected.
A particularly preferred transducer crystal array for a continuous wave
ultrasonic probe is comprised of a transmitter cyrstal and a receiver
crystal, wherein each is of a generally "D"-shape directed outwardly from
the bottom face of the transducer head. In that embodiment, the two
crystals are disposed in spaced relationship along the respective linear
legs thereof and the same are pitched one with respect to another in order
to achieve a desirable focal length. In another aspect, a single
transducer crystal is employed, e.g., where the procedure utilizes a pulse
echo transducer system, in which case the single crystal is preferably
disposed within a transducer head having a generally circular cross
section.
Other advantages, and a fuller appreciation of the construction and mode of
operation of the present invention, will be gained upon an examination of
the following detailed description of preferred embodiments, taken in
conjunction with the figures of drawing, wherein:
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an ultrasonic transducer embodying the
features of the present invention;
FIG. 2 is a side elevational view of the ultrasonic transducer shown in
FIG. 1;
FIG. 3 is a bottom plan view of the transducer shown in FIG. 1, here
illustrating the exemplary transducer as a continuous wave ultrasonic
transducer of the type having a transmit crystal and a receive crystal;
FIG. 4 is a sectional view taken substantially along the line 4--4 of FIG.
2 and illustrating details of an illustrative mounting arrangement for the
transmit and receive crystals in a continuous wave ultrasonic transducer
and, illustrating also in broken lines, the focal point and focal zone
established with the exemplary focused beam continuous wave transducer;
FIG. 5 is a sectional view taken substantially along the line 5--5 of FIG.
2, and illustrating particularly the non-circular and peferably
rectilinear configuration of the transducer handle which serves to provide
a sensory input for the medical practitioner assisting in aiming the
ultrasonic beam;
FIGS. 6 and 7 are, respectively, bottom and side isometric views
illustrating the recommended procedure for holding the ultrasonic
transducer of the present invention;
FIG. 8 is a diagrammatic frontal elevational view illustrating generally a
human heart and certain of the major arterial vessels, and particularly
ilustrating the relative positions of the patient's suprasternal notch and
ascending aorta with the transducer of the present invention positioned in
the suprasternal notch and directing a focused ultrasonic beam
substantially axially along the ascending aorta;
FIG. 9 is a highly diagrammatic side elevational view of the upper chest
and lower neck portion of a patient in a supine position and illustrating
particularly proper placement of the ultrasonic transducer of the present
invention within the patient's suprasternal notch with a focused
ultrasonic beam being directed substantially axially along the ascending
aorta which is here illustrated diagrammatically; and,
FIG. 10 is a bottom plan view similar to FIG. 3, but here illustrating a
modified pulse-type ultrasonic transducer of the type employing only a
single crystal which is energized to alternately function as a transmit
crystal and as a receive crystal.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates, generally, to ultrasonic transducer probes,
more especially to continuous wave untrasonic transducer probes, and most
particularly to such a transducer probe for medical diagnostic procedures
wherein the probe is positioned within the suprasternal notch of a human
patient in order to insonify the ascending aorta. Accordingly, the present
invention will now be described with reference to certain preferred
embodiments within the foregoing contexts; albeit, those skilled in the
art will appreciate that such a description is meant to be exemplary only
and should not be deemed limitative.
Turning to the figures of drawing, in each of which like parts are
identified with like reference characters, an ultrasonic transducer probe,
designated generally as 10, is shown to be comprised of an elongate handle
designated generally as 12 having a proximal end 14 and a distal end 16,
and a transducer head designated generally as 18 depending from the
latter. As best viewed in FIGS. 1-3 (collectively) the head 18 has a
generally arcuate cross section defined by an arcuate sidewall 20 tapered
along the leading edge at a sloping top face 22; thereby yielding a
generally trapezoidal profile as best viewed in FIG. 3. The transducer
head 18 extends generally normal to the longitudinal axis of the handle 12
and projects slightly downward therefrom at a common juncture 24 in the
form of a step. As will be described more fully hereinbelow, the overall
geometry of the head 18 and its disposition relative to the handle 12
materially facilitates the use of the probe 10 in its most preferred
environment within the suprasternal notch of a human patient.
The transducer head 18 (as is conventional) houses transducer crystal means
designated generally as 26. In a highly preferred embodiment, the
transducer cyrstal means 26 is composed of an array of a transmitter
crystal 28 and a receiver crystal 30 generally flush with the bottom face
32 of the transducer head member. As viewed best in FIGS. 3 and 4, each of
the transducer cyrstals 28 and 30 is in the general shape of a "D", where
the two crystals are disposed in spaced relationship along their
respective linear legs, separated by an intermediate marginal element 34
of the transducer head. Further, the bottom face 32 is formed with a
slight outward bevel along the line of the marginal separator 34, as best
viewed in FIG. 4. Consequently, the two transducer crystals assume a
cooperative, angular relationship as respects the line of propagation of
outgoing ultrasonic energy for insonification and the line of reception
from the insonified region. More specifically, and with particular
reference to FIG. 4, the bevel of face 32 presents the transmitter crystal
28 at an angle toward the transverse centerline 36 along a transmitter
path 38 represented, for simplicity sake, by the single propagation line
40. When the transmitter crystal 28 is energized by a suitable voltage
pulse via wiring leads 42, an ultrasonic wave will progress along
propagation line 40 and insonify a region within the patient's body
designated generally as 44. Likewise, the bevel on face 32 presents the
receiver crystal at an angle with respect to the transverse centerline 36,
defining a receiver path 46 represented again for simplicity sake by the
single receiver line 48. Reflected sound energy from the region 44 will
return along the receiver line 48 to the crystal 30, wherein the
mechanical movement of the crystal is reconverted to an electrical signal
conducted outwardly of the probe via receiver wiring 50. As is evident
from the intersection of the propagation and receiver lines 40 and 48,
respectively, along the transverse centerline 36, a focal point 52 is
defined within the insonified region 44 (corresponding to the focal zone);
the depth of focus being dictated, inter alia, by the pitch of face 32 and
the spacing between the transducer crystals across the marginal element
34. For insonification of the ascending aorta through the suprasternal
notch in order to measure cardiac output, the focal zone is preferably
from about 6 to about 8 centimeters from the face 32 with a focal point
midway (i.e., about 7 centimeters). A bevel angle on the order of about
3.degree., yielding an included angle between crystals 28 and 30 of about
174.degree., optimizes this focal depth.
A principal ramification of the foregoing is the importance of positioning
the transducer head 18 properly within the suprasternal notch of a patient
in order to present the focal point 52 within the region of the ascending
aorta as best viewed in FIGS. 8 and 9. Those figures illustrate (in a
highly diagrammatic form) a heart designated generally as 54 disposed
within the chest cavity posterior of a sternum designated generally as 56.
For purposes of the present discussion, the important anatomical structure
is the aorta, identified generally as 58, is comprised of the aortic root
60, the ascending aorta 62, the transverse aorta 64 and the descending
aorta 66. A probe 10 in accordance with the present invention, like that
described above with reference to, e.g., to FIG. 4, is disposed within the
suprasternal notch 68 for insonification of the ascending aorta shown to
be within the focal zone of the transducer. In order for the operator to
locate the ascending aorta 62 properly within the focal zone of the
device, the transducer probe must be manipulated within the notch 68.
Usually, the operator's attention is on a visual display during this
procedure limiting the ability to pay strict visual attention to the
location of the probe which, as can be seen with reference to FIGS. 8 and
9, is at least partially obscured within the patient's suprasternal notch.
Of equal importance during the physical manipulation of the transducer
probe 10 is patient comfort. The configuration of the probe 10
accommodates these two objectives. Initial positioning of the transducer
probe 10 within the suprasternal notch and subsequent, necessary
manipulation is facilitated by the shape of the elongate handle member,
and its cooperative interrelationship with the head 18 at the step 24,
when the device is held properly by the operator. As best viewed with
reference to FIGS. 1-3 and 5, the handle 12 has a non-circular peripheral
cross-sectional geometry--in this exemplary embodiment, a quadrilateral
shape. Thus, the handle includes a top face 70, a bottom face 72 and
opposed side faces 74 and 76. By virtue of a quadrilateral configuration,
longitudinal edges 78 are yielded at the juncture of adjacent faces which
aid in grasping and positioning the probe properly. FIGS. 7 and 8
illustrate the proper grip of the probe 10, with the operator's hand
grasping the proximal end of the probe, the forefinger resting proximate
the merger of the top face 22 of the transducer head with the top face 70
of the handle, and the thumb applying gripping pressure to the sidewall
74. When so grasped, the flat surfaces of the quadrilateral cross section
in combination with the longitudinal edges provide the operator with a
sensory perception of the position of the transducer head through the
operator's sense of touch; the configuration, therefore, defining tactile
positioning means facilitating proper orientation of the transducer when
disposed within the suprasternal notch 68. In turn, accordingly, the
operator need not pay close visual attention to the transducer, allowing
that attention to be focused on whatever display is associated with the
overall system.
The most preferred quadrilateral cross section for the handle 12 is best
viewed in FIG. 5 to be approximately square, but tending to trapezoidal in
the sense that the side faces 74 and 76 have a very slight inward and
downward taper. The slight taper has been determined to be preferable for
accentuating the ability of the geometry to provide both tactile sensing
means for positioning the probe and also added operator comfort. However,
strictly rectilinear cross sections might be employed to equal advantage
(e.g., square or rectangular), as might other polyhedral geometries. In
further point of fact, some individuals may find that the simple inclusion
of one or more longitudinal, raised edges or ribs formed along the handle
will suffice for this functional objective. Accordingly, a generally
circular cross section including one or more longitudinal ribs--to yield
an overall non-circular peripheral geometry--might be utilized to this
same end.
Regardless of the selection from among those cross-sectional configurations
noted above to provide tactile positioning means for the probe, the head
itself is configured with patient comfort in mind. Looking to FIGS. 1-3
and 8-9, it can be seen that the head 18 has a smooth, overall rounded
geometry lacking distinct sharp edges. The lack of edges per se and the
arcuate cross section permits rotation of the head 18 within the
suprasternal notch 68 very smoothly. The trapezoidal profile, eliminating
material from the extreme distal end of the probe, permits the same to
nestle within the suprasternal notch and be manipulated to the proper
anterior/posterior declination either without or only at the experience of
minimal protrusion beyond the notch 68 into the patient's throat region.
The overall arcuate cross section shown in the embodiment of FIGS. 1-9 is
generally ovate, accommodating the pair of transducer crystals 28 and 30.
However, it is equally well envisioned to form the transducer head in a
generally circular cross-sectional configuration as viewed in FIG. 10. In
that embodiment, the probe, designated generally as 80 is comprised of an
elongate handle member 82, preferably of the same quadrilateral cross
section as the embodiment of FIGS. 1-5. A transducer head 84 depends from
the distal end of handle 82 and is formed to possess the same generally
trapezoidal profile as shown in FIGS. 1 and 2. However, in this embodiment
only a single transducer crystal 86 is included and, in this case, has a
generally circular shape. The circular crystal is, thus, accommodated
within a generally circular transducer head as opposed to the ovate head
best viewed, e.g., in FIG. 3. The probe 80 is otherwise positioned and
manipulated the same as the probe 10 discussed in detail above.
While the invention has now been described with reference to certain
preferred embodiments, those skilled in the art will appreciate that
various substitutions, modifications, changes and omissions may be made
without departing from the spirit thereof. Accordingly, it is intended
that the foregoing description be construed simply as illustrative of
embodiments of the present invention and not be deemed limitative of the
scope of the claims appended hereto.
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