Note: Descriptions are shown in the official language in which they were submitted.
6~3
ABSTRAC~ OF THE DISCLOSURE
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Pulsed real-time B-scan ultrasonic method and apparatus are
disclosed together with pulsed Doppler Ultrasonic method and ap-
paratus. The s-scan apparatus includes a pulse operated transmit-
ter and receiver operating at a first frequency, and the Doppler
apparatus includes a pulse operated transmitter and receiver op-
erating at a second frequency sufficiently far xemoved from the
B-scan frequency to avoid interference therebetween. Asynchronous
pulse operation of the B-scan and Doppler systems is provided.
The system includes a visual display means to which the receiver
outputs are connected through a multiplexer operated to pass the
B-scan receiver output to the visual display means whenever such
B-scan output is present. The Doppler apparatus includes means
for temporarily storing the Doppler receiver output, which
stored Doppler signals subsequently are read out through the
multiplexer to the visual display means between select lines of
B-scan display. A simultaneous display of the B-scan image and
a Doppler profile is provided when desired. A control stick unitr
under one-hand control of the operator, is used to select the
position of the line along which the Doppler profile is obtained
and displayed. A cursor generator, under con-trol stick control,
is used to generate a cursor signal for display of a cursor along
which the Doppler proflle is displayed. The B-scan apparatus is
operable with a normal or magnified display of a section of the
object under investlgation. Also, a reticle signal generator is
; ~ included for the display of tick marks at the visual display means.
ORIGIN OF INVENTION
The invention described herein was made in the course of
a contract wlth the Department o~ ~ealth, Education and Welfare.
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BACKGROUND O~ THE INVENTION
Thls invention relates to ultrasonic imaging method and
apparatus and in particular to pulsed real-time B-scan, pulsed
Doppler, and a combination pulsed s-scan and pulsed Doppler
imaging and motion detecting means for use in the simultaneous
display of a B-scan image and blood-flow profile.
The capacity of ultrasonics to differentiate tissues on the
basis of their ability to propagate ultrasound, the lack of toxic
effects at energy levels required for diagnostic use, and the
fact that there is no requirement for invasive technlques with
; their attendant disadvantages and dangers make ultrasonic visual-
ization a particularly effective and an attractive d~agnostic
tool. A variety of ultrasonic techniques have been demonstrated,
including Doppler and B-scan methods.
The well known pulsed B-scan method employs a narrow beam
transducer to project a short ultrasonic pulse into the tissue
and to detect the reflec-ted pulses. With B-scan, a two dimen-
sional lmage is produced by moving the transducer past the area
of interest and recording and/or displaying the reflected pulse
train at closely spaced intervals. The well known pulsed
Doppler method also employs a narrow beam transducer to project
a short ultrasonic pulse into moving tissue or particles, such
as blood cells, and to detect the frequency of the reflected
signal, which frequency is related to the movement or flow of
the tissue or particles. By sequentially sampling the reflected
Doppler signal a ~elocity profile along the line of propayation
of the transmitted pulse may be obtained. A combined B-scan and
Doppler profile display greatly enhances the detection and
visualization of the structure under investigation.
30~ A discussion of various ultrasonic techniques, including
the well known B-scan method, is found in the INTERNATIONAL
~; ~ JOURNAL OF NONDESTRUCTIVE~TESTING, Vol. 1 (1969), pp 1-27,
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"Methods of Acoustic Visualization", by Philip S. Green, one o~
the present inventors. Ultrasonic pulsed Doppler velocity detec-
tion means also are well known as disclosed, for example, in
U.S. Patent No. 3,777,740 bv ~avid E. Hokanson, issued December 11,
1973, and in the article entitled, 'Pulsed Ultrasonic ~oppler Blood~
flow Sensing' by Donald W. Baker in IEEE TRAMSACTIONS ON SONICS
AND ULTRASONICS, vol. SU-17, No. 3, July 1970. Additionally, a
system for manually switching between B-mode and Doppler displays
is contained in an article in IEEE TRANSACTIONS ON BIO-MEDICAL
ENGINEERING, vol. BME-21, No. 2, March 1974 entitled 'Ultrasonic
Duplex Echo - Doppler Scanner' by Frank E. Barber et al. Similar-
ly a combined B-scan and Doppler display is suggested in a report
entitled 'Development of High Resolution Ultrasonic Imaging
Techniques for Detection and Clinical Assessment of Cardiovascular
Disease' dated 9/5/74 by Titus C. Evans, Philip S. Green and
James F. Greenleaf, Report No. N01-HT-4-290~-1 available from
National Technical Information Service, 5285 Port Royal Road,
Springfield, Virginia, 22151.
SUMMARY OF THE INVENTION AND OBJECTS
An object of this invention is the provision of improved
method and apparatus for the diagnosis of cardiovascular diseases,
particularly in the carotid and femoral arteries.
.
An object of this invention is the provision of an improved
pulse B-scan ultrasonic imaging method and apparatus for display
:
of a real-time B-scan image of physical characteristics of a
section of the interior o~ the body.
An object of this invention is the~provision of an improved
easily operated, pulsed Doppler blood flow profiling method and
apparatus;for display o~ a blood-flow proflle.
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An object of this invention Is the provision of an improved
combination pulsed B-scan and pulsed Doppler system for the simul-
taneous display of a real-time ~-scan image of physical character-
istics of a section of the interior of a body and of a superimposed
Doppler profile along a line of desired length and location sub-
stantially in said imaged section.
An object of this invention is the provision of improved
method and means for real-time display of ultrasonic B-scan and
Doppler information to provide significant clinical data for
visualization of the interior of an artery, localization of
atheromatous plaque, quantification of the luminal geometry and
dimensions detection of atherosclerotic plaque, differentiation
of non-calcified plaque from calcified plaque and from normal
tissue, flow velocity, and the like.
The above and other objects and advantages of this invention
are achieved by use of separate focused B-scan and Doppler
transducers within a mounting head containing a suitable acoustic
~ 20 transmission medium, such as water, and having a liquid-tight
: acoustic window therein for coupling to the subject under inves-
tigation. Asynchronously operating B-scan and Doppler signal
transmitters supply recurrent different-frequency pulses to the
.
transducers for launching pulses of ultrasonic waves into the
subject. The B-scan transdueer is supported for .recurrent scanning
movement across the section of the interior of the objact to be
: imaged, and the Doppler transducer is supported for movement
along a parallel path under control of an output from a control
: stick unit manually controlled by the operator. Separate B-scan
and Doppler signa:L receivers are provided for processing the
: received B-scan and Doppler pulse signals reflectad from dis-
: continuities, particles, and the like, within the subject~ The
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s-scan receiver output is connected to a visual display means
through a mul-tiplexer to provide a real-time B-scan image thereat
as video signals are developed at the receiver output. The Doppler
receiver, on the other hand, effectively stores electrical analog
signals proportional to the Doppler frequency of the echo signal
received by the Doppler transducer from along the transducer axis.
The analog Doppler proportional signals are sequentially read
out through the multiplexer to~the visual display means between
selected lines of the B-scan frame for the simultaneous display
of the B-scan image and Doppler profile. A Doppler cursor signal,
to identify the line along which the Doppler profile is obtained,
is generated and displayed during alternate Doppler display periods.
Once each frame of B-scan operation simultaneous initiation of B-
scan and Doppler operations is effected, and first and second de-
flection voltage levels axe established and held, between which
levels the Doppler profile and cursor are displayed for assuring
proper registration of the B-scan and Doppler displays. Also,
the B-scan system functions in different operating modes for dis-
play of an image of a section of the subject or for the display
of an enlarged image of a portion of said section, both of which
displays include the same number of scan lines per frame. During
display of the normal size image, tick marks may be provided at
the visual display means for indicating the extent of the section
imaged when switching to the enlarged image operating mode. The
tick marks are supplied by a reticle generator which also is oper-
able between selected B-scan display lines for the display of
calibrated tick marks at the margins of the visual display means
Por tissue metrology.
More particularly, there is provided:
~anually operated mechanism for one-hand control of a plurality
of vàriable electrical means comprising,~`a pivotal control stick
which includes an outer end which is rotatable about the control
stick axis, first, second and third manually variable potentiometers
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included in an ultrasonic pulsed Doppler profile system comprising
pulsed Doppler transmitter/receiver means connected to a movable
ultrasonic transducer, and visual display means for the visual
display of Doppler profile signals, means connecting said first
potentiometer to said control stick ~or control thereof upon
pivotal movement of said control st:ick in a first direction,
means connecting said second potent:iometer -to said control stick
for control thereof upon pivotal movement of said control stick
;n a second direction orthogonal to said ~irst direction, and
means connecting said third variable electrical means to said
control stick for control thereof upon rotation o~ the outer end
of the control stick about the control stick axis, said ultrasonic
pulsed Doppler profile system including, means under control of
said first potentiometer for controlling the position of said
ultrasonic transducer, means under control of said second potentio-
meter for controlling the delay between operation o~ said pulsed
Doppler transmitter and Doppler receiver means, and means under
control of said third potentiometer for controlling the length
of time operation of said Doppler receiver means.
There is also provided:
In ultrasonic apparatus for displaying a Doppler profile
along a line from within an object comprising,
: : a pulsed Doppler system including transducer means for
obtaining Doppler profile signals comprising a plurality of
~ ~ analog signal levels,
: means for visual display of said Doppler pro~ile slgnals,manually controlled:means for positioning said transducer
means along a linear pathj said manually controlled means com-
: prising,
a control stick which is movable in one direction for con-
trolling the transducer posltion, is movable in another direction
for controlllng the depth~at which said Doppler profile signal
~egins, and lS rotatable for controllin~ the Doppler profile length.
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The invention and the above and other objects and advantages
thereof will become apparent from the following detailed descrip-
tion when considered with the accompanying drawings.
BRIEF DESCRIPTION OF THE DR~WINGS
In the drawings, wherein like reference characters refer to
the same parts in the several views:
Figs. lA, lB, lC and lD, taken together as shown in Fig. lE,
lQ show a simplified combination block and schematic diagram embodying
a real-time ultrasonic B-scan/Doppler imaging system and method of
this invention;
Fig. 2 is a diagrammatic view of the face of the visual display
means showing a B-scan image of a longitudinal section of an artery
with the system operating in the lX mode and with a reticle display;
Fig. 3 is a diagrammatic view of the face of the visual display
means which is similar to that of Fig. 2 but showing a cross section
of an artery, and simultaneously displaying a 2X indicator together
with a Doppler cursor and Doppler profile along said cursor;
Fig. 4 is a view which is similar to that of Fig. 3 but showing
the artery at two-times (2X) magnification;
Fig. 5 is a view of the front panel of the imaging system
showing varlous control elements;
Figs. 6 and 7 are waveform diagrams of electrical signals
developed at various locations within the system for use in e~plain-
ing the operation of tlle B-scan portion of the system, the time
scale employed in the Fig. 7 waveforms being much shorter than that
in Fig. 6;
Figs. 8, 8A, and 8B show waveform diagrams for use in explana-
~30 tion of the Doppler portion of the system during acquisition of
Doppler signals;
Fig. 9 are waveform diagrams for use in explanation of the
operation of the Doppler profile and cursor signal display means;
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Figs. 10A and 10B are waveform diagrams for use in explana-
tion of the timing system for assuring proper registration of
the Doppler and B-scan displays; the time scale employed in Fig.
10B being much shorter than that in Fig. 10A; and
Fig. 11 are waveform diagrams for use in explanation of the
operation of the reticle generator.
Reference first i5 made to Fig. lA wherein s-scan and Doppler
transducer means 20 and 22, respect:ively, are shown mounted within
a scanning head 24 carried at the end of an articulated arm, not
shown, for the support thereof over a subject or patient ~6. The
head contains a suitable acoustic transmission medium, such as
water r for the support of acoustic waves produced by the transducer
means 20 and 22. A liquid tight acoustically transparent window
closes the lower end of the scanning head, through which window
ultrasonic compressional waves generated by the transducer means
are coupled to the subject 26, and through which reflected acous-
tical signals returned from the subject are coupled to the
transducer means.
- For purposes of description, and not by way of limitation,
focused transducer means 20 and 22 are employed comprising, for
example, lens-focused transducers. The acoustic axes of the
transducers 20 and 22 are generally parallel. In the illustrated
arrangement, during B-scan operation, the acoustic axis 30 of
the B-scan transducer 20 recurrently intersects the acoustic axis
32 of the Doppler transducer 22 within the subject. Also,
~where the system is employed for the diagnosis and assessment of
atherosclerosis oE the common carotid artery, for example, Lenses
which provide focusing at a depth of approximately 1.5 centimeters
beneath the skin of the subjèct 26 and which have a one (1) centi-
.
meter depth of focus may be employed. Obviously, the system isnot limited to such fixed lens-focused transducers. If desired,
the transducers may compris~e an array of transducer elements op-
erated so as to provide a variable focus for focusing at different
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depths .~or imaging di.f~erent body parts.
Linear scannin~ of the s-scan acoustic axis 30 along the
subject is provided. In the illustrated arrangement scan opera-
tion of the B-scan transducer 20 back and forth across the sub-
ject in the direction of the double-headed arrow 34 provides such
scanning action. The mechanism for scanning operation of the B-
scan transducer is diagrammaticall.y shown comprising mechanical
linkage 36 which may include, for example, a crank or eccentric
for connection of the transducer 20 to the shaft 38 of a motor 40.
Operation of the motor 40 at a constant speed results in a sub-
stantially sinusoidal scanning rate of the B-scan transducer 20
across the subject. In the waveforms of Fig. 6, the sinusoidal
scanning action of the B-scan transducer is identified by the
waveform 600. The ends of the scanning aGtion where the trans-
ducer 20 changes direction of movement occur at the peaks and
~alleys of the waveform 600. The transducer 20 moves at a
maximum rate at a point midway between the scan ends at the
steepest portion of the sinewave. In practice, the linkage 36
may include, for example, a pantograph-type mechanism driven by
the motor 40 for linear traversal by the transducer 20 of the
field at a rate of, say, 15 fields (or 7.5 frames) per second.
Again, such rates are for purposes of illustration only and not by
way of limitation.
The Doppler transducer 22 is movable across the subject
26 in the direction of double-headed arrow 42 along a path
parallel with the B-scan transducer 20 and closely spaced there-
from. In accoxdance with one feature of this invention, posi-
tioning of the Doppler transducer 22 along said parallel path
is under control of a manually operated control stick type of
3Q control unit 44, shown in Fig. lC. One output from the control
unit 44 (the horizontal or X-axis, position output) is supplied
to a servo drive mechanism 46 which, in turn, is connected to
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the Doppler transducer 22 through a mechanical linkage 36A. Themechanical linkage may be of -the same pantographic-type as -the
linkage 36 used to support the s-scan transducer 20 for movement
along a substantially straight line path under control of the
servo drive mechanism. As seen in Fig. lC, the control unit 44
includes a control stick 48 pivotally mounted by a ball and
socket mounting means 50 for mo~ement in any pivotal direction.
The control stick is mechanically connected to movable arms of
Doppler transducer horizontal (X) and vertical (Y) position
control potentiometers 52 and 54, respectively, to position
the same in accordance with the X and Y positions of the control
stick. The potentiometers are supplied with a suitable refer-
ence potential, and Doppler horizontal and vertical position
potentials are obtained from the movable arms thereof over
leads 56 and 58. The lead 56, as noted above, is connected to
the servo drive mechanism 46 for horizontal position control of
the Doppler transducer 22. The vertical control potential at
lead 58 is used to control the vertical position, or depth,
~ithin the subject 26 at which Doppler detection along the
transducer axis 32 is to begin.
The control unit 44 is provided with a third potentiometer
60 having a mo~able arm which is mechanically connected to a
rotatable knob 62 on the control stick 48 fox control of the
potentiometer setting by rotation of the knob. The potentiometer
60 provides a Doppler length control potential therefrom over
lead 64 for the control of the length of the line at the trans-
ducer axis 32 aIong which Doppler information is acquired or
subsequent display of a Doppler profile at the face of a cathode
ray tube 66 (Fig. lB3. It will be understood, then, that the
information or the Doppler proile display is obtained along a
line within the subject 26 determined by the setting o the
control unit 44 ~mder one-hand control o the operator. A Doppler
prOfile 68 is shown in the combined s-scan and Doppler displays
illustrated in Figs. 3 and 4. Doppler signal transmitting, re-
ceiving and display means are described in detail hereinbelow.
For present purposes it will be noted that a cursor 70 is included
in the display with the Doppler profile to indicate the line
along which the Doppler signal is acquired for such display and
to provide a reference for the Doppler profile. The cursor
ends are marked by horizontal marks 70A and 70B at the opposite
ends thereof.
As noted above, the system may be employed for the
diagnosis and assessment of atherosclerosis of the common
carotid artery, and generally diagrammatic views o~ different
B-scan and combination B-scan and Doppler displays of the artery
of the type which may be provided at the face of the cathode ray
tube 66 are shown in Figs. 2, 3 and 4. Fig. 2 shows a B-scan
longitudinal sectional image of the common carotid artery 72,
with the artery bifurcation 73 at the left of the display. The
skin 74 also is seen in Fig. 2, and clearly appears on the screen
since the reflection therefrom is large. As is well understood,
the transmitted ultrasonic wavefield is reflected by irregulari-
ties and discontinuities encountered thereby, and the discontinuity
provided by the skin is great. Blood, however, is more homo-
geneous than the surrounding tissue and substantially no re-
flected B-scan signals are obtained therefrom. Consequently,
the arterial lumen appears as a light area in the drawings. In
practice, the light and dark areas of the drawing would be
reversed unless the intenslty control signal is inverted to pro-
vide for the illustrated type of display. That is, the arterial
lumen would appear as a dark area on the screen since substantially
no reflected B-scan signaIs are obtained therefrom. Sof-t
atherosclerotic lesions also may produce relatively low back-
scattering, making their detection and identification difficult.
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In Figs. 2, 3 and 4, plaque 76 is shown fain-tly at the arterial
wall. With the addition of the pulsed Doppler display 68, for
the illustrated simultaneous B-scan and Doppler display as shown
in Figs~ 3 and 4, the moving blood i.s readily distinguished from
the nearly stationary arterial walls and from lesions protruding
into the lumen. The luminal area and shape can be assessed by
displaying blood-flow-velocity profi.les in relation to their loca-
tion within the artery.
With the present arrangement/ either normal (lX) or two times
normal (2X) B-scan image and associated Doppler display may be
provided at the face of the cathode ray tube 66, and the labels
lX and 2X are employed hereinbelow to identify components, circuitry,
waveforms, illustrative material, and the like, associated with the
production and display of the normal and enlarged images, respec-
tively. Fig. 3 illustrates a lX B-scan display, with Doppler pro-
file, of a cross-section of the artery 72/ and Fig. 4 illustrates
a 2X display obtained along the same cross-section. Generally, in
practice, the system is operated in the lX mode for locating the
area to be investigated, and then is switched to the 2X mode for
more detailed investigation.
The svstem includes a reticle generator used to provide cali-
brated tick marks along the display marglns. For 1~ operation
~Figs. 2 and 3) the tick marks are identified by the reference
characters 80-1 through 80-60, and for 2X operation (Fig. 4) they
are identified by the reference characters 82-1 through 82-28.
For purposes of illustration, a 3.0 centimeter by 3.0 centimeter
section may be imaged under lX operating conditions for the
visual display of the carotid arteries in the neck. For convenience
in operation, the ~spacing between adjacent tick marks identi~ied
the same distance ~for both the lX and 2X operating conditions which,
in the illustrated arrangement comprises 2 centimeters. For such
operation, substantially one-half as many tick marks are required
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for the 2X display as ~or the lX display.
As will become apparent hereinbelow, the section imaged under
2X operating conditions is centrally located with respect to that
section imaged under lX operating cc,nditions. During lX operating
conditions, a 2X field indicator may be provided at the display to
indicate the extent of the 2X field when switching from the lX to
the 2X operating mode. Such marks assist the operator in locating
the area to be displayed before switching from the lX to the 2X
operating mode. In Fig. lA, the sections imaged by B-scan operation
under lX and 2X operating conditions are identified by the refer-
ence characters 85-lX and 85-2X, respectively.
System operating controls are included at the front panel 86
of the novel apparatus of this invention shown in Fig. 5 where,
separate s-scan, Doppler, and Display control sections are shown.
The Display control section includes a pushbutton switch 90 for
selection of either the lX or 2X display at the cathode ray tube.
A pushbutton operated reticle display switch 92 also is provided
for display of the tick marks 80-1 through 80-60 and 82-1 through
~82-28 for the lX and 2X operating modes, respectively. The 2X
field indicator tick marks 83-1 through 83-4 are displayed under
control of the 2X field indicator switch 94. The Display control
section also includes a multiposition display mode selector switch
96 for the display of B-scan only, Doppler only, combined B-scan
and Doppler, or for the display of the time gain control profile
of time gain control means included in the B-scan system. At
; another setting of the mode selector switch 96, labeled 'R~wave
sync', a synchronization signal derived from a cardiac R-wave
detector is supplied to a camera control system for obtaining
photographs of the visual display at selected points in the sub-
ject's cardiac cycle. The operator may choose the appropriate
point in the cardiac cycle by potentiometer control means 98 at
the Display control panel~for adjusting a delay triggered from
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the R-wave detector. The control stick 48 with length control.
potentiometer 62 ls shown at the Doppler control section of the
front panel. Other front panel controls are described herein-
~elow with the description of the associated operating systems.
Many of the panel switches include a plurality oE switch sections
for different functions at various points within the system, and
such sections sometimes are individually identified by the use of
suitable suffixes in conjunction with the above identified
reference numerals.
As described above with reference to Fiy. lA, the B-scan
transducer 20 is swept back and forth in the direction of the
arrow 34 with a sinusoidal motion. The pulsed B-scan transmitting
and receiving apparatus is operated at a generally sinusoidally
. varying pulse rate in synchronism with the sinusoidal scan rate
of the transducer 20 there~y providing for a raster of evenly
spaced scan lines across the face of the cathode ray tube 66 to
avoid variations in the intensity of the display~which would
otherwise result. Master timing pulses for use in control of the
B-scan imaging and display operation are provided by timing means
associated with the B-scan transducer drive mechanism. In the
exemplary arrangement shown in Fig. lA such timing means includes
a timing plate 100 attached to the reciprocating B-scan trans-
ducer 20, and a timing disk 102 attached to the motor shaft 38
for synchronous operation of the plate and disk with the trans-
ducer. The plate 100 is formed with a plurality of parallel,
evenly spaced stripes, or lines, and a photocell 104 adjacent
thereto produces signals in response to the lines as the plate
reciprocates. For purposes of description only, the plate may
be provided with 400 evenly spaced lines for the production o~
30~ 400 output pulses from the photocell 104 during travel of the
transducer 20 from one end of the scan to the opposite end
there~f. The pulses are produced, of course, at a sinusoidally
15-
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varying rate in synchronism with the sinusoidal scan rate of the
transducer 20. In Fig. 6, the master timing pulse outpu-t from
the photocell 104 is identified by the reference numeral 602. For
clarity, only about l/20th of the total num~er of pulses produced
are shown.
During travel of the transducer 20 from one end of the line
of scan to the opposite end thereof, one field (one-half frame) of
B-scan information is produced and displayed. However, only one-
half of the timing pulses produced are used for timing the opera-
tion of the B-scan transmitting and receiving operations in both
the lX and 2X operating modes. Consequen-tly, as will become ap-
parent hereinbelow, the B-scan display comprises 200 evenly spaced
scan lines per field, or 400 per frame. The scanning sequence is
vertically from top to bottom, and hori~ontally from left to right
to left for a complete picture frame of 400 lines, during which
the B-scan transducer is mechanically driven back and forth
through a complete scanning cycle.
As noted abo~e, timing means includes also the disk 102
attached to the motor shaft 38. In the illustrated arrangement
one-half of an annular track on the disk is of one color and the
other one-half is of another color. A photocell 106 located
adjacent the track produces an output signal in response to one
of the colors for the generation of ~ series of puls~s of equal
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1 "on" and "off" time periods. For each complete scan cycle of
2 the B-scan transducer 20 a symmetrlcal squarewave signal 604 i5
3 produced having leading and -trailing edges at the ends of travel
4 of the B-scan transducer 20, i.e. at the peaks and valleys of the
sinewave 600, as seen in Fig. 6. Generation of such a square-
6 wave signal 604 at the appropriate times simply is achie~ed by the
7 proper physical positioning of the photocell 106 with respect to
8 the rotating disk 102.
9 The timing signals 602 and 604 from the photocells 104 and
106, respectively. are used in the produc-tion of pulses ~or the
11 time control of the B-scan transmitting, receiving and display
12 operations in a manner now to be described. ~irst, it will be
13 noted that with the illustrated arrangement the mechanical drive
t4 system for the B-scan transducer 20 operates the same in both the
lX and 2X operating modesO That is, the mechanical drive system
16 for scan operation of the B-scan transducer 20 operates to drive
17 the transducer at the same rate along the same path in both the
18 lX and 2X B-scan operatin~ modes. As noted above, for carotid
19 artery visualization. the B-scan transducer 20 may be periodically
dri~en back and forth alon~ a 3.0 centimeter path ~t the rate of
21 7.5 cycles per second. Consequently, the master timing pulse
22 output 602 from the photocell 104 is the same in both the lX and
23 2X operating modes. As seen in Fig. lA, the timing pulse output
24 from the photocell 104 is supplied, inter alia, to a ~lip-flop
108 included in the 3-scan Timing Unit 109 which deliYers as
26 output one-half the number of input pulses supplied thereto.
27 Consequently, the 400 pulses produced at the photocell 104 output
28 per pass of the ]3-scan transducer in either direction are reduced
29 to 200 pulses at the output from the divîde-by-two flip-flop 108.
3;
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The pulse output from the divide-by-two flip-flop 108 is
supplied as one input to a transmission gate 110, which gate has
as a second input the photocell 104 output. The gate is set Eor
lX or 2X operation under control of the output from selector
switch 90 (Fig. 5). With the gate 110 in the illustrated lX
position the output pulses from the di-vided-by-two flip-flop
108 are coupled to line 112 for B-scan timing control. In the 2X
position of selector switch 90 the photocell 104 output is
connected to the line 112 through the gate 110 and a logic network
121, operated in a manner described below, for supply of the same
number of timing pulses to the line 112, but in a diferent timing
sequence. In Fig. 6 the IX output from the gate 110 at line 112
provided by the divide by two circuit 108 isidentified by the
reference numeral 606, and the 2X output from the logic network
121, also at line 112, is identified by the reference numeral 608.
For simplicity, the transmission gate 110 is shown symbolically
as a double-pole double-throw switch but in practice such gate
comprises suitable combinations of AND, OR, NAND, and/or NOR gates.
In the lX position of switch 90 no energizing signal is supplied
to the gate 110, and the divide-by-two 108 output is connected
directly to line 112 therethrough. In the 2X switch position of
switch 90 an energizing signal is supplied to the gate 110 for
direct connection of the photocell 104 output to the input of a
gate network 114 lncluded in the logic network 121 without division.
Operation of the gate network 114 is under control of the out-
put from flip-flops 116-1 and 116-2 which serve to periodically
open and close the gate for passage of selected photocell 104 out-
put pulses 602 therethrough for 2X tim1ng control~ The flip-flops
116-1 and 116-2 a:re operated in such a manner to control the gate
network 114 for passage of 200 photocell output pulses produced
,
~ ~18-
~
- : '. - -: .. . ~ . - ' : . .. . . . .
~during B-scan transducer travel along the center of ~the sweep.
~¦¦At opposi.te ends of the B-scan sweep the gate networX 114 is
3 disabled -to~prevent passage of photocell 104 output pulses there
4 through. In Fig. 6 the flip-flop 116-1 and 116-2 outputs are
~ identified by the reference characters 610-1 and 610-2, respective
6 ly, and the output from the gate networX 114 is identified by the
7 reference numeral 608. It will be seen that 2X timing pulses 608
8 are provided at the output from the gate network 114 whenever
9 a control pulse is supplied thereto from either one of the ~lip-
flops 116-1 or 116-2 to AND gates 114-1 or 114-2, respectively,
11 included in the gate network. An OR gate 115 connects the out-
12 puts from the AND gates to the line 112,
13 Operation of the flip-flops 116-1 and 116-~ is under control
14 of the fast and slow timing pulses 602 and 604 from the photocells
-15 104 and 106, respectively9 through use of an up-down counter 118
16 and decoders 120-1 and 120-2. The photocell output pulses 602
~ 17 and 604 are supplied as input and up-down control signals, re-
: 18 spectively, to the counter 118 for up-counting during travel of
19 the B-scan transducer in one direction and down-counting during
tra~el thereof in the opposite direction. ~he counter output is
1 21 supplied to the decoders 120-1 and 120-2 and as seen in Fig. 6,
22 an output pulse 612-1 from the decoder 120-1 is provided whenever
23 the count from counter 118 passes 101. Similarl~, wheneYer the
24 count passes 300 J an output pulse 612-2 is provided from the
decoder 120-2.
26 The decoder 120-1 and 120-2 outputs are supplied to the
~7 flip-flops 116-1 and 116-2 through transmission gate~ 122-1 and
~28 122-2. The slow clock signal 604 from the photocell 106 and zn
29~ inverted slow clock signal ~ from the photocoll 106 through an
30 inver~- 124 are ~upplied -s contrcl signals to the ga~es 122-1 !
~ 32 ~
l ~
1 ¦ and 122-2 for alternately enabling -the same during scan operation
2 ¦in one and the opposite direction, respectively. During B-sc~n
3 transducer iravel in one direction the decoder 120-1 output, ~t
4 the count of 101, is passed through the enabled gate 122-1 to the
~ reset terminal of the flip-flop 116~1 to reset the same. At -the
6 count o~ 300, the decoder 120-2 output is passed through the
7 enabled gate 122-1 to the set terminal o~ the flip-flop 116-1 to
8 set the same. During scan operation in the opposite direction
9 the transmission gate 122-2 is enabled by the signal ~ rom the
inverter 124 while gate 122-1 is disabled. Now, at the count of
11 300, the decoder 120-2 output is passed through the enabled gate
12 122-2 to the reset terminal of the flip-~lop 116-2 to reset the
13 same. When the count of 101 is reached, while counting down, the
14 decoder 120-1 output is pa5sed through the gate 122-2 to the set
terminal of the flip-flop 116-2 to set the same.
16 ~s noted above, the flip-flop 116-1 and 116-2 outputs 610-1 1
17 and 610-2 (from the Q terminals) are supplied as control signals
18 to the transmission gate 114 to enable the same during the center
1~ 200 fast clock puls~s during B-scan operation in the 2X operating
mode to pass the same during both back and forth scanning. The
21 fast clock pulses from the periodically enabled gate 114, which
22 pulses are generated at a sinusoidally varying rate when the gate ¦
23 is ena~led, are supplied to line 112 for periodic recurrent pulse
24 operation o~ the B-scan system in the 2X operat;ng mode.
Except for the novel lX and 2X timing operation thereof, the
26 B-scan transmitting and receiving means may be o~ substantially
27 conventional design. In the illustrated arrangement, as seen in
28 Fig. lA, the B-sc:an transmitter is shown comprising a pulser 126
29 which is supplied with recurrent timing pulses (either pulses 606
31
~0
for lX operation or periodic recurrent pulses 608 for 2X operation)
over line 112 for on-of~ control thereof. When the pulser is
turned on a high frequency energy pulse is generated which is
supplied through transmit-receive switch 128 and over line 130
to the s-scan transducer 20 for pulse genera~ion of ultrasonic
waves within the transducer head 24V which waves are focused
within the subject 26. The B~scan operating frequency differs
sufficiently from the Doppler operating frequeney to avoid inter-
ference therebetween. For purposes of illustration only, the
B-scan unit may operate at a center frequency of, say, 10 MHz
whereas the ~oppler unit may operate with pulse Doppler signals
at a frequency of, say, 5MHz. By operating at such widely
different frequencies asynchronous pulse B-scan and Doppler
operation is possible and is employed in the illustrated arrange-
ment.
Continuing the description of the B-sean operation, refleeted
ultrasonic signals from discontinuities within the subject 26
are reeeived by the transdueer 20 and supplied over line 130 and
through the transmit-receive switch 128 to a preamplifier 132.
; 20 The transmit-receive switch 128 functions to isolate the trans-
mitted signal from the input to the preamplifier 132. The pre-
amplifier is of the low-noise, broad-band, high-dynamic range
type having a good linear gain charaeteristic over a wide input
signal strength range.
The preamplifler output is supplied to a time variable gain
ampli~ier 136 having a gain eharaeteristie whieh varies as a
funetion of time. With B-sean operation, wherein return signals
reeeived from seatterers furthest within the subjeet 26 experienee
the greatest attenuation, it is eommon praetiee to eompensate for
3~ sueh differenees in attenuation by time variable gain ampli~ieation
-21-
:
89~
1¦ Of the received signal. In -the illus-tra-ted arrangemen-t the gain
2¦¦of the variable gain amplifier 136 is varied in accordance wi~h
3 the output from a gain function generator 138. Operation o~ the
4 generator is started ~ollowing transmission of an ultrasonic
~ pulse, with start of the generator ope~ation being under control
6 of a timing pulse supplied thereto from line 112 through an OR
7 gate 140, a delay unit 174, a normally enabled AND gate 1~1, and
8 a one-shot 142. With this arrangement, the same delay time is
9 provided between the presence of a pulse at line 112 and the
triggering of the gain ~unction generator 138 for both lX and 2X
11 operations.
12 The gain function generator 138 simply may comprise a ramp
13 generator with an output signal which ~unctions to increase the
14 gain of the amplifier 136 in proportion to range in a manner to .
o~fset the loss o~ signal caused by acoustic absorption within .
16 the subject. In the present.arrangement, an adjustable function
17 generator 138 is used having a plurality of controls 144,
18 accessible at the front panel 8,6 (see Fi~. 5) ~or control o~ the . . .
19 shape of the generator output~ The settin~ o~ each of the fiYe
contrlS 144 (comprising potentiometers, for example) determines.
21 the ampli~ier 136 gain during one-fifth of the echo signal dura- :
22 tion thereby permitting the operator to tailbr the B-scan display
23 as desired, or required. Adjustable gain function generators
: Z4 for control o~ variable gain amplifiers are well known and require
no detailed description- It here will be noted ~that the gain
function generator output, before triggering, is such as -to sub- :
1 27 stantially disable operation of the amplifier 136. Gonsequently,. i
28 the generator 138 must be triggered by an output ~rom the one-
29 shot 142 to enable operation o~ the amplifier 136. ~
. .` ` .
~3~
32 I ...
~: ! 22
-: "
. .,: ~ . : .
.
~ 3
The output from the time varia~le gain controlled amplifier
136 is applied to a broad band compression amplifier 146 com-
prising, for example, a DC coupled log amplifier with a compres-
sion factor of, say, 40 to 60 dB. The compression amplifier 146
is followed by a variable gain amplifier 148 having a gain control
150 for setting the gain thereof.
The variable gain amplifier 148 output is detected by an
envelope detector 152 comprising, for example, a full wave recti-
fier followed by a low pass filter; the detector output signal
being related to the envelope of the broad band high frequency
signal output from the amplifier 148. The envelope detector
output is supplied to a compression amplifier 154 for matching
the detected signal with characteristics of the cathode ray tube
66, to which the signal is fed, for proper display of the entire
signal range at the cathode ray tube. The compression amplifier
154 output is connected through lead 155 (from Fig. lA to Fig. lB)
and applied as an input to the Z-axis section 156Z of a multi-
plexer 156, the output from which multiplexer section is
connected to the control grid 158 of the cathode ray tube 66 to
intensity modulate the electron beam thereof. It here will be
noted that X-axis and Y-axis multiplexer sections 156~ and 156Y,
respectively, are included through which beam deflection signals
are supplied to the cathode ray tube for deflection of the beam
in orthogonal directions across the face 159 of the tube. Such
multiplexing means are included for the simultaneous display
~` of B-scan, Doppler and reticle signals in a manner described below.
For B-scan operation, cathode ray tube beam deflection
in the X, or horizontal r direction is proportional to the position
of the B-scan transducer 20 along the scan path, and deflection
`
~ "w
~ 23-
:: . :
.
~ 6~3
1 in the Y, or vertical, direction is proportional to the time
2 elapsed since the last B-scan pul~,e was transmitted. A9 noted
3 auo~c, signals from ~ha photocc' ~ arc usad to corl',ol ~he
4 ¦timing of the B-scan transmitter operation and, therefore, may
5 ¦be used in deriving the B-scan Y-axis deflection signal. Since
6 ¦the photocell 104 output signals are derived from the timing plate
7 ¦100 included in the mechanical scanning mechanism for the B-scan
8 ¦transducer 20, the signals therefrom also ma~ be employed as
9 ¦synchronizing signals in derivin~ the B-scan X-axis deflection
10 ¦signal.
11 ¦ The horizontal, or X-axis circuit used to produce a deflection
12 ¦signal for deflection o~ the electron beam across the face of the
13 ¦cathode ray tube in synchronization with the position of B-scan
14 ¦ transducer 20 includes an up-down master counter 160 (Fig. lA) -to
15¦ which the master timing pulses 606 or 608 ~Fig.- 6)~ for lX or 2X
16¦ operation, respectively, at line 112 are supplied. Up-down
17¦ counting control of the counter is provided by an output from
18¦ photocell 106, which output, as noted above, switches at opposite
19¦ ends of the transducer 20 sweep. The photocell 106 output also
20¦ is used to trigger a one-shot 162 having an output connected to
21 ¦ the reset terminal o~ the master counter 160. With this arrange~
22 ment one output pulse is obtained from the one-shot 162 ~or each
23 complete back-and-~orth scan of the transducer 20 for synchron-
24 ization of the up/down counting and transducer position once a
?5 frame.
26 The output from the master counter 160 is supplied to a
27 digital to analog (D/A) converter 168 for conversion of the digita~
28 counter output to an analog signal for use as the B-scan X-axis
29 (horizontal) deflection signal. For lX operation, the master
3 counter 160 operates at the sinusoidally ~arying rate of the
31 pulses 606 (Fig. 6) suppIied thereto from the photocell 104
I 24
~ ~ . , .
1 ~ ~ "
- -: : . - - , . . - . :
through the divide-by-two clrcui-t 108. Consequently, the D/A
converter output comprises a step sinewave 620-1 as shown in
Fig. 6. For 2X operation, input pulses 608 are periodically
supplied to the counter from the photocell 104 through the gates
110 and 114. Now, the D/A converter output comprises, essentially
a stepped sinewave 620-2 wlth its positive and negative crests
clipped (Fig. 6). The stepped sinewave signal 620-1 or 'clipped'
stepped sinewave signal 620-2 output from the D/A converter 168
is connected over line 170 from Fig. lA to Fig. lB and supplied
as one input to the X-axis multiplexer 156X section. The multi-
plexer section 156X output, as noted above, is supplied to the
horizontal deflection system of the cathode ray tube 66 for hori-
zontal deflection of the electron beam in accordance with the
multiplexer output.
Vertical, or Y-axis, deflection of the cathode ray tubP
beam for B-scan operation is provided by ramp signals generated
following B-scan transmitter operation. A time delay is provided
between the transmitter pulse and initiation of the vertical
deflection ramp signal, the amount of which delay is dependent up-
on the transit time of the pulse in traveling from the transducer20 to the section to be imaged, and the return of the reflected
signal to the transducer therefrom. As seen in Fig. lA, and
described above, the imaged section 85-lX for lX opera~ion begins
at a lesser depth and extends to a greater depth than the 85-2X
section for 2X operation. Thus, a shorter time delay before
initiation of the vertical deflection ramp signal for lX opera-
tion is required than for 2X operation. As seen in Fig. lA,
the master timing pulses on line 112 (either pulses 606 from
gate 110 for lX operation, or pulses 608 from gate 114 for 2X
operation) are supplied through the OR gate 140 to the time delay
.
~,`r ~ 25--
, ~ . . ., , . . . . . ,:
... . . .
l~unit 174, for lX operation, and to a time delay unit 176, ~or 2X
2 ¦¦ operation. The delay uni~ts 174 and 176 simply may comprise one-
3 shots which produce output signals o~ fixed duration upon receipt
4 of a master timing pulse at the in;puts thereto. The outputs from
delay units 174 and 176 ~re shown in Fig. 7 and identi~ied by
6 reference numbers 704 and 706, respectively.
7 The trailing edge of the pulses 704 and 706 are used to
8 trigger ramp generators 178 and 180, respectively. (In addition,
9 the ~railing edge of the lX delay pulse 704 also tri~gers the one-
shot 142 which triggers operation of the gain function generator
11 138 which, in turn, controls operation of the ampli~ier 136 in
12 the B-scan receiver unit, in the manner described above.) The
13 ramp signal outputs from the generators 178 and 180 are identified
14 by reference numerals 708 and 710, respectively9 in Fig. 7. The
generators 178 and 180 also produce square wave pulses 712 and
16 714 of a duration equal to the ramp signals 70~ and 710, respec-
~7 tively, for use in control o~ the multiplexer 156 during B-scan
18 operation, in a manner described below. (It will be apparent,
19 with suitable switching and ampli~ier m~ans ~or selectively
amplifying the output from, say, the ramp generator 178, that
21 only the one ramp generator would be needed ~or use in the gener-
22 ation o~ both of the ramp signal outputs 178 and i80 required for
23 the lX and 2X operations, respectively,~ Also, in the illustrated
24 arr2ngement the delay units 17~ and 176 provide for fixed time
delays. However, it will be apparent that adjustable delay
26 units may be employed for imaging different depth sections, if
27 desired, to accommodate dif~erent sonic pulse times as required.
28
3~
~26
-
.. . .. , , . :
.
D~86~3
1~ A transmission gate 182, under control of lX-2X switch 90 at
21 the ~ront panel ~ (Fig- 5) and illustrated symbolically as a
3 double-pole double-throw swi-tch for simplicity, but comprising a
4 network of gates, is used for selec-ting either the lX or 2X ramp
and square wave signals ~o~ use in the B-scan receiver opera-tion.
6 The selected ramp si~nal 708 or 710 is supplied over line 184
7 (from Fig. lA to Fig. lB) to -the input of the Y-axis mul-tiplexer
8 section 156Y ~or use as the Y-axis deflection signal during B-scan
opera-tion. The selected square wave signal 712 or 714 is
supplied over line 186 (from Fig. lA to Fig. lB) as one input to
11 a logic network 190 described in detail hereinbelow following
12 a description of the source of Doppler and reticle control signals
13 which also are supplied thereto. For present purposes, it will
14 be understood that the logic network prevents such Doppler and
reticle control signals from switching the multiplexer 156 during
16 the presence of the B-scan control signal (712 or 714) on line 186.
17 The sguare wave signal 712 or 714 essentially is passed
18 directly through the logic network 190 and supplied over line 188
19 as a B-scan control signal for the multiplexer 156. B~scan
horizontal deflection si~nal 620-1 or 620-~ (Fig. 6), vertical
21 de~lection signal 708 or 710, and the B-scan receiver output from
22 ampli~ier 154 are simultaneously supplied to the cathode ray ~ube
23 for the generation of a ~ertical line o~ B-scan signal information
24 during the presence of the B-scan channel control signal to the-
25 multiplexer over line 188. With the display mode switch 96
26 (Fig. 5) in the illu8trated B~scan position, or in either of the
27 two B + Doppler ~ositions; a B-scan line o~ in~ormatîon is gener-
28 ated and displayed for each B-scan transmitter pulse produced,
29 (except one during which various operating levels are~established
30 to assure that the Doppler display i~ properly located with
3! ~
321 ~ ~ ~7
- ~ ~ . .
1 jrespect to the B-scan display). For lX operation, the ~ertical
2 B-scan hnes are generated at a sinusoidally varying rate, in
3 synchronism with the sinusoidal scanning operation o~ the trans-
41 ducer 20 for the production of evenly spaced vertical sweep lines
51 at -the face of the cathode ray tube 66. With 2X operation, the
6 transmitting and receiving units are periodically operated during
7 the central portion of the transducer 20 scan. During such 2X
8 operating periods, the transmittin~r and receiving units are
9 operated at a ~inusoidally varying rate in synchronism with the
central portion of the transducer 20 scanning operation ~or -the
11 production of evenly spaced vertical scan lines. The same number '
~ of scan lines are produced during operation over the central
13 portion of the scan of the transducer 20 in -the 2X::operating mode
14 as are produced during a complete scan thereof in the lX setting.
For lX operation, wherein, say, 400 ultrasonic pulses at a sinu-
16 soidàlly varying rate are produced during each complete (back
17 and forth) cycle of transducer 20 operation, the time between
18 pulses may vary from a minimum of, say9 220 microseconds to a
19 maximum of one ~l) millisecond.
With the present inventionj B-scan operation and display in
21 the manner described above without Doppler operation and display,
22 and without reticle display, is provided under operator control by
~23 simply setting the Display Mode selector switch 96 to the B-scan
24 position. With the switch 96 set ~or the B-scan mode, and the
~5 switch 90 in the lX setting, the tran~ducer-containing head 24
26 may be moved along the patient t~ any desired section to be imaged.
27 When an area o~ interest is located, the operation may be switched
28 to the 2X sstting to provide the operator with an enlarged image
of the central portion of the selected area. If the area of
31
32l
`28
" .
:, ' : ':' . '" " ' ' ' ' .. .
. .. . , : . . : - ~
36~3
1 in-terest is not readily locatable using B-scan alone, the Doppler,
2 or the combined B-scan and Doppler operating mode may be selectedO
3 With Doppler operation, movement or flow is readily detected.
4 Blood flow, fo~ example, within an arter~ may be detected using
the Doppler display, or multiplexed B-scan and Doppler display,
6 to aid the operator in the initial location of the artery. The
7 transducer head 24 then may be oriented to provide B-scan imaging
8 of the desired section thereof. In any event, it here will be
9 understood that the novel B-scan method and apparatus above-
described has application separate and apart from the Doppler
11 and reticle systems described below.
12 From the above description, it will be apparent tha-t signals
13 are displayed at the cathode ray -tube 66 as they become available
14 from the B-scan receiver. The Doppler transmitting and receiving
1~ system, which operates asynchronously wi-th the B-scan system, in-
16 cludes low pass filters which function, essentiall~, as Doppler
17 pro~ile signal storage means for the storage of the Doppler pro~
18 file signals, which signals subsequently are read out to the
19 cathode ray tube 66 through the display multiplexer 156 between
selected B-scan vertical sweeps. Also, generated reticle signals
21 are displayed, by use of the multiplexer, between other selected
22 B-scan vertical sweeps. Since the B-scan ver-tical lines are
23 generated and displayed at a sinusoidally varying rate, the
24 Doppler and reticle displays are provided where the B-scan ~er-
~5 tical sweep rate is slowest, which is adjacent the opposite ends
26 of the field.
27 Similar reticle and Doppler display timing units 200 and 202
28 ~Fig. lB) are employed. The reticle timing unit 2~ comprises an
29 up-down counter 204 to which the slow timing control signal 604
(Fig. 6) from the photocell 106 is supplied ouer line 206 from
31 Fig. lA to Fig. lB. Also, a reset signal 866 (Fig. lOA) ~rom the
~ I
1 ~9
li
: : . . ..
- ~ , , - - . ..
- - . .
- ~ ~ . . .. . . .
~ 3
1 one-shot 162 is supplied -to the counter over line 208 from Fig.
2 lA to Fig. lB to assure synchronization of the up/down coun-ting
3 and transducer scanning direction. The counter output is used to
4 address a programmable read only memory (PROM) 210 having an out-
5 put which identifies B-5can lines ~ollowing which a reticle sig-
6 nal is to be displayed. The output from the PROM is coupled to
7 a comparator 212 having as a second input the output from the
8 mas-ter counter 160 connec-ted thereto over line 213 ~rom ~ig. lA
9 to Fig~ lB. The comparator 212 compares the count from the PROM
210 with the count ~rom the master counter 160 and provides an
11 output pulse when the counts are equalO
12 The comparator output trlggers a one-shot 214 having an output
13 which is applied both to the clock input to the counter 204 to
14 step the same and -to the reticle generator 510 to trigger opera-
tion thereof. It will be seen, then, that the counter 204 is
16 stepped to change the address to the PROM only when the count
from the master counter 160 equals the count ~rom the PROM. The
18 PROM is programmed to provide for a pulse output from the com-
19 parator 212 at any desired master counter output. For example,
outputs may be provided at -the counts of 2, 4, 6, 8, 10, 190, 192,
21 194, 196, and 198, i~ desired, for sub~eguent reticle display.
~2 The comparator 212 output also is supplied as another input to
23 the logic network 190 whichl in turn, controls the operation of
24 the multiplexer 156 in the manner described below. For present
purposss it will be under~tood that with an input signal to the
26 logic network from the comparator 212, an output 764 (Fig~ 6~ is
27 produced~at line 218 therefrom which is supplied as a reticle
28 channel~control signal to the multiplexer 156 for a reticle dis-
29 play. The logic net~ork 190 simply delays switching the multi-
plexer to the re~ticle channel until the end of an~existing B-scan
31 channel control signal. The logic network 190 operation is
32 described ~eloN~ ~
~ ~ 3 `
- : ~
The Doppler display -timing uni-t 202 is of substantially
identical design as the reticle display timing unit 200 described
a~ove. Briefly, the Doppler display timing unit 202 comprises
an up-down counter 220 to which the same up/down and reset
signals are supplied as are provided the up-down counter 204.
The counter output addresses a PROM 222, the output from which
identifies those B-scan lines following which a Doppler signal
(either a Doppler cursor or Doppler profile signal) is to be
displayed. The PROM output is compared with the master counter
160 output at comparator 224 which supplies an output whenever
the counts are equal. Obviously, the PROM 222 is programmed
differently than the PROM 210 for the provision of output signals
from the comparator at different times. The comparator 224
output is supplied as an input to the logic network 190, and to
a one-shot 226. The one-shot 226 output steps the counter 220
and is supplied as a timing signal over line 228 from Fig. lB
to Fig. lD for use in timing the Doppler profile and cursor dis-
plays in a manner described below.
LOGIC NETWORK 190
The logic network 190 for channel control of the multiplexer
156 now will be described. The square wave output 712 or 714
from one of the ramp generators 178 or 180~ depending upon the
setting of the transmission gate 182, is connected over line
186 (Fig. lA to Flg. lB) to the input terminal of a flip-flop
240 included in the logic network 190. The flip-flop 240 is set
; by the leading edge of squarewave signal 712 or 714 to provide
an output 754 (Figs. 6 and 73 therefrom over line 188 to the
multiplexer 156 tc> control the same for transmisslon of B-scan
input signals therethrough to the cathode ray tube. The trail-
ing edge of the square wave signal 712 or 714 triggers a one-
short 242, the output 752 from vhich resets the flip-flop 240
tv terminate the square wave pulse 754.
-31-
- , ' :
- . . . .
Assume now that a signal 756 (Fig. 7) is provided at the out-
put from the Doppler comparator 224 signifying that a Doppler
display is to be effected. This signal 756 is supplied as an
input to a flip-flop 244 to set the same. The flip-flop 244
output 758 is connected to an AND gate 246, the other input to
which is obtained from the one-shot 242. The output from the AND
gate therefore remains low until the output 752 from the one-
shot is applied thereto. When the gate is enabled, the output
therefrom is connected as a reset signal to the flip-flop 244 -to
reset the same and thereby terminate the pulse 758. The output
760 from the gate 246 also serves to set a flip~flop 248. The
flip-~flop 248 output 762 (lX) or 762 (2X) is connected over lead
250 as a channel selector signal to the multiplexer 156 to con-
dition the same for passage of Doppler input signals at the
input thereof to the cathode ray tube. The flip-flop 248 is reset
by the square-wave output 712 or 714 at line 186 when the next
B-scan line of information is to be transmitted to the cathode
ray tube. It will be seen that the multiplexer is conditioned -
for passage of Doppler signals (either a Doppler cursor or a
Doppler profile) for substantially the entire time period be-
tween pulses 712, with lX operation, or between pulses 714, with
2X operation. In Fig. 6, the reference numeral 762 identifies
; either the 762 (lX) or 762 (2X) output of the flip-flop 248,
depending upon the selected operation.
The reticle comparator 212 output is employed in the same
manner as the Doppler comparator 224 output to control the
multiplexer 156 for a reticle displa~. In brief, the comparator
212 output sets a flip-flop 254. The flip-flop 254 output, to-
gether with the one-shot 242 output, are supplied as inputs to
an AND gate 256, the output from which sets a 1ip-flop 258. The
output from the 1ip-flop 258 is connected over line 218 to
the multiplexer 156 as a channel control signal for passage of
reticle input signals therethrough to the cathode ray tube 66.
-32-
~¢3 ca~36~3
The flip-floP 258 is reset by the next pulse 712 or 714 to occur
which, as described above, initiates a B-scan multiplex operation.
From the above description, it will be seen that through use of
the logic network 190, the multiplexer 156 is controlled for
transmission of B-scan signals for the 'real time' display thereof
as they become available from the B-scan receiver. Reticle
signals produced by the reticle signal generator 510 are displayed
between selected lines of the B-scan display as determined
by the programming of the PROM 210. Doppler profile signals from
the Doppler receiver and Doppler cursor signals from the cursor
generator also are displayed between selected lines of B-scan
display as determined by the programming of the PROM 222.
DOPPLER TRANS~IIII-O A~D ~OE lVI ~ SYSTEM
The pulse Dopp~er transmitting and receiving system operates
asynchronously with respect to the operation of the above-
described real-time pulse B-scan system~ Asynchronous transmitting
operation is made possible by the use of widely different B-scan
and Doppler frequency pulse signals so as to avoid interference
~etween the acoustic wave fields. For example, as noted above,
the pulsed B-scan system may operate at a relatively high
- frequency of, say, 10MHz, whereas the pulsed Doppler system may
be operated at a much lower frequency of, say, 5MHz. By use
of such frequencies, the simultaneous presence of the pulsed
signals within the subject, and simultaneous B-scan and Doppler
receiver operation~is possible without mutual interference.
Except for the timing of the Doppler display means, which is
time division multiplexed with the real-time B-scan display,
substantially any suitable puIsed Doppler transmltting and re-
ceiving system may be employed in the arrangement of thisinvention. The i:Llustrated Doppler system is of the general type
disclosed in the above-mentioned article entitled, "Pulsed Ultra-
~ -33-
: - ~ -. . . , . -
1il3
,~
sonic Doppler Blood-Flow Sensing" IEEE Transactions on Sonics
and Ultrasonics, STJ-17, pp. 170-~185 (1970) by D.W. Baker.
Referriny to Fig. lC, on-off control of the Doppler system is under
control of a transmission ~ate 290 ~which, in turn, is controlled
by the display mode switch 96 (Fig. S) for closure thereof when
the display mode switch is either in the Doppler or in either of
the B ~ Doppler switch positions. For simplicity, the gate 290
simply is shown as a single pole single throw switch in Fig. lC.
With the gate 290 in the enabled condition, a clock signal 800
(F;g. 8) from Doppler cloclc 292 is supplied therethrough to first
and second one-shots 294 and 296, respectively. The output 802
(Fig. 8) from the first one-shot is used as a control signal to
gate on a transmit/receive (T/R) switch 298 in preparation for
the transmission of a transmit pulse therethrough. The other
one-shot 296 serves as a delay unit for delayed triggering of a
one-shot 300. In Fig. 8 the output from one-shots 296 and 300
are shown by waveforms 804 and 806 respectively. The delayed
output 806 controls the opening and closin~ of an RF gate 308
which gate, when enabled, passes the output signal ~rom an RF
signal generator 310 to a power amplifier 312. The amplified
signal from the power a~plifier 312 passes through the now
enabled T/R switch 298 and thence through lead 316 to the Doppler
transducer 22 in the head 24 (Fig. lC to Fig. lA). The ~F gate is
opened and closed, under cloc~ 292 control, to provide the
transducex 22 with phase-coherent 5MHz bursts of, say, 1 micro~
second duration at a pulse repetition frequency of, say 10,000
pulses per second.
The Doppler transducer 22 is located adjacent the path
traversed of the E-scan transducer 20, and may be positioned at
any point along a parallel path under control of the horizontal
output signal at line 56 rom the control stick unit 44 in the
; -3~-
manner described above. A focused transducer 22 may be employed
for focusing of the ultrasonic beam therefrom at a dep-th sub-
stantially equal to the center oE the dep-th range of the B-scan
system. Ideally, the beam axis for the Doppler transducer would
be in the plane of the section imaged by the B-scan system so that
the resultant Doppler display would provide an indication of
Doppler response from points within the imaged section 85-lX or
85-2X shown in Fig. lA. However, since separate B-scan and
Doppler transducers 20 and 22, respectively, are employed, align-
ment of the Doppler axis 32 in the plane of the B-scan imaged
section extended is not practical and, is not required. The
parallel paths along which the transducers move are closely
positioned to minimize the angle at which the Doppler axis 32
intersects the image plane. If desired, the transducers 20 and
22 may be arranged to provide for parallel acoustic axes 30 and
32.
Following transmission of the ultrasonic pulse by the Doppler
transducer 22, echo signals from scatterers within the subject
26 are received by the transducer and electrical signal output
therefrom is supplied over line 316, and through the transmit-
receive switch 298 (now in the'receive' condition) to a preamp- -
lifier 318. The signals from the preamplifier are further ampli-
fied by an RF amplifier 320, and the output from the RF amplifi-
er is supplied as one input to a demodulator 322 which has a
voltage output related to the Doppler frequency shift of the echo
signal. It will be understood that echo signals include those
~rom both stationary and movin~ scatterers, and that the return
signals from moving scatterers, such as ~lood cells flowing within
a vein or artery, are shlfted in frequency due to Doppler ef~ects.
3~ Depending upon the direction of motion, the signal may undergo
an increase or decrease in frequency. Here, a reference signal
is supplied to the demodulator from the RF signal generator 310
35-
through a frequency offset circuit 324 and RF ampli~ier 326.
Such a reference signal, which ;s offset from the transmitted
frequency, and phase coherent therewith, is employed to bias
the zero flow output voltage position so that reverse flow can
be detected and subsequently displayed. The amplitude of the
demodulator output siynal varies with the relative phase of the
echo and reference signals supplied to the demodulator. In Fig.
8A the Doppler transmitter signal 880, the amplified Doppler
echo signal 882 from amplifier 320, and the demodulator output
signal 884 are shown.
The Doppler signal 884 from the demodulator 322 is amplified
by driver amplifier 328 and supplied to a series of sample and
hold circuits 330-1 through 330-20 in parallel. Control inputs
to the sample and hold circuits are obtained from a shift regis-
ter 334 for the sequential sampling of the Doppler signal. In
the illustrated arrangement a 32-bit serial shift register is
employed of which twenty output bits are employed in the control
of the twenty sample and hold circuits. Obviously, fewer or
additional Doppler channels than the twenty illustrated may be
employed. Both the time delay between the transmission of a
Doppler pulse signal and the initiation of operation of the shift
register 334, and the rate at which the shift register is clocked
are under control of the manually operated control unit 44 for
setting the Doppler "window". Doppler window control is described
below following a description of the operation of the remainder
of the Doppler receiver.
Referring again to Fig. 8At echo signals from the patient's
skin and artery wall are identified in the waveform 882 of the
amplified echo signal. Also in Fig. 8A, twenty points on the
demodulator output 884 are marked to identify the times at which
the twenty sample and hold circuits 330-1 through 330-20 are
sequentiaIly operated to sample the demodulator output. It will
-36-
36~L3
be seen that -the Doppler window is posltioned for operation
within the artery walls for blood flow detection. Note that the
demodulator output 884 is only a function of the phase difference
between the received rf signal 882 and the offset frequency and
not a function of the rf signal amplitude.
The outputs from the sample and hold circuits 330-1 through
330-20 are fed through notch filters 332-1 through 332-20 to fre~
quency-to-voltage converters ~F/V) 344-1 through 3~4-20. The
filter notch for filters 332-1 through 332-20 is set at the
difference frequency (fo) between the rf signal frequency and the
offset frequency supplied to the demodulator 322 from the frequency
offset 324 through the amplifier 326, to prevent most of the
difference frequency signal from passing therethrough to the
frequency to voltage converters. Filtering at the notch fo is
not complete, and a small portion of such signal is allowed to
pass through the filter. In the absence of a Doppler frequency
echo signal (for example, between the skin and artery) the small
difference frequency signal is detected by the frequency to
voltage converters for conversion to an analog signal level
indicative of zero Doppler return. Also, the filter has low
and high cu-t off frequencies of, say, fo-3KHz and fo+3KH~ to
eIiminate high frequency noise, such as that produced by switch-
ing of the sample and hold circuits. In Fig. 8B, outputs 886-1
and 886-10 from two channels of the sample and hold circuits
330-1 and 330-10 are shown, with spikes of noise produced when
switching the same. The corresponding filtered outputs 888-1
and 888-10 from~the filters 332-1 and 332-10 also are shown in `
Fig. 8B.
A higher Doppler fre~uency signal is returned from blood flow
near the center of the artery than adjacent the artery wall, and
the different Doppler frequency signals are indicated by the
different frequency signals from the filters 888-1 and 888-10 in
: : : : :
~ 37-
Fig. 8s. The frequency to voltage converters 344-1 through 344-20,
which are of the zero-crossing type, convert the signals to cor-
responding analog signals, two of which 890-1 and 890 10 are shown
in Fig. 8B. The analog voltage signals are supplied through a com-
mutator 346 to the cathode ray tube for horizontal deflection
during Doppler display.
DOPPLER 'WINDO~' CONTROL
.
Operating controls for the shift register 334 for setting
the Doppler window now will be described.
The RF gate control pulse 806 (Fig~ 8), from the one-shot 300
(Fig. lCl which triggers generation of a Doppler transmitter signal,
also is supplied as an input to a voltage controlled delay unit
336 comprising, for example, a one-shot. The output pulse 808
from the voltage controlled delay unit has a duration dependent
upon the magnitude of a control voltage supplied thereto over
line 58 by the Doppler Y-axis control output from the control
stick unit 4~, described above. The trailing edge of pulse 808
is used to trigger a one-shot 338, the output 810 from which is
supplied to the data input terminal of the shift register 334.
-38-
:. . . . . . .
.
.
:~'a8~i~3
1 The shift register 334 subsequently is clocked by the out~ut
2 814 ~rom a gatable, programmable frequency clock 340. The
3 ¦frequency, or clock rate, is set by the Doppler length control
4 ¦output ~rom the~ control stick unit 44 connected thereto over
5 ~lead 64~ A gate signal 812 for on-off control o~ the clock 3!~o
~ ¦is provided by the output from a ~lip-~lop 342. The flip-~lop
7 ¦is set by the trailing edge of the pulse 808 from the vol-tage
~¦ controlled delay unit 336 for initiating clock operation. The
9¦ flip-~lop 342 is reset by an output from the shift register 334
10¦ when the register input pulse supplied thereto *rom the one-shot
11 ¦ 338 is shifted out o~ the register. As mentioned above, only
12 ¦ twenty of the 32 bit outputs from the register 234 (identified
13¦ by reference character 815) are employed in controlling the
14¦ operation o~ the sample and hold circuits 332-1 through 332-20.
The clock, however, continues to run until the input bit to the
I6 register is shifted out o~ the register and to the ~lip-~lop 342
17 to reset the same. It will be seen, then, that the time at
18 which the clock 340 is gated on is determined by the Doppler
19 vertical control voltage on line 58, and the ~requency at which
the clock operates is determined by the Doppler length control
21 voltage on line 64. As described above,these Doppler vertical
22 and length control voltages serve to posi-tion the ~oppler
23 receiver "window", during which time the Doppler echo signal is
24 gated by the sample and hold circuits to the fr0~uency to
25 voltage converters. These Doppler control voltages, together
26 with the Doppler X-axis, or horizontal, control voltage at line
27 56 are selectively set by the operator by use of the control
28 RtiCk unit 44 in the manner described above.
. .
31
32
39
.
.. . . .
a~
1 DOPPLER DISPLAY
2 As seen in Fig. lC, the frequency to voltage converter out-
3 Iputs are connec-ted to a commutator, or analog multiplexex.
4 Operation of the commutator 346 for the sequential connection
of the fre~uency to voltage converter output slgnals to the
6 commutator output line 348 is controlled by the output from
7 counters 350 (Fig. lD), the commutator control signals from the
8 counters to the commu-tator being supplied over lead wires 352
9 from Fig. lD to Fig. lC. Timing of the operation o~ the
commutator 346 is controlled in a manner described below to
11 assure proper registration of the Doppler profile display 68
12 with both the cursor 70 display and the B-scan display. For
13 present purposes it will be noted that when the commutator 346
14 is clocked the Doppler profile signal at the commu-tator output
1~ is connected over line 348 to the summing junction J at the
16 input to an ampli~ier 3~6. - ~
17 The Doppler profile ~ignal from the commutator 346 is ;
18 supplied as one of three inputs to the amplifier 356. The
19 Doppler hori20ntal, or X-position, control signal at line 56
from the control stick unit 44 also is supplied there-to and
21 functions as an ampli~ier offset signal to establish the refer-
22 ence level for the Doppler profile display, and to establish
23 the lateral po~ition o~ the cursor 70 during cursor display~
24 the cursor and Doppler profile being displayed during alternate
Doppler display periods in the manner described below. The
26 cursor 70, as seen in Figs. 3 and 4, is provided with horizontal
27 end segmen~s 70A and 70B to clearly mark the cursor ends, and
28 tha necessary horizon~tal deflection signals to produce such
29 end segments are supplied as a third input signal to the
ampli~ier 356 over line 360 ~rom the cursor generator ~hown-
31 in Fig. lD.
~2
.
~:
~0~6~3
The horizontal deflection signals ~or Doppler display from
amplifier 356 are connected to an amplifier 364 having a vol-tage
gain of two (2). The ampli~ier is included in the circuit in
the 2X operating condition, and is bypassed, by transmission gate
366 in shunt therewith, in the lX operating condition. The out-
put from the amplifier 364, or from amplifier 356 through
enabled gate 366 , is connected over line 368 (from Fig. lC to
Fig. lB through Fig. lA) to the multiplexer 156 as the Doppler
X--axis input signal thereto for connection to the horizontal
deflection circuit of the cathode ray tube 66 when a Doppler
multiplexer channel control signal is supplied thereto over line
250. For present purposes, it will be understood that a
Doppler multiplexer channel control signal 762 is present at
line 250 for switching to Doppler display whenever a Doppler
profile or Doppler cursor signal is provided at the multiplexer
input.
Vertical deflection signals for Doppler display are provided
~y a ramp signal generator 380 in conjunction with outputs from
sample and hold circuits 382 and 384, all of which are shown
in Fig. lD. As seen in the displays of Figs. 3 and 4, both the
Doppler profile 68 and cursor 70 are displayed between the same
vertical deflection levels and consequently, the ramp signal for
vertical deflection during Doppler display is required to operate
only between such levels. Once each B-scan frame the Doppler
and B-scan transmitters are simultaneously operated, and the
sample and hold circuits 382 and 384 subsequently are controlled
to sample and hold the B-scan defLection signal present at the
beginning and endt respective~ly, of the Doppler signal storage
sequence executed by the sample and hold circuits 330-1 through
330-20 (Fig. lC). The output signals 818 and 820 from the sample
and hold circuits 382 and 384, respectively, are show~ in Figs.
9 and 10B and the means for controlling the sample and hold circuits
-41-
,: - . ~, :, - -
. . - ., . : , . . .
- , : . ~ .. : . . . . :
136~L3
382 and 384 are described below. For present purposes it will be
understood that the sample and hold circuit outputs 818 and 820
are established at the required levels, identified as Vl and V2,
once every s-scan frame and remain therea-t during the remainder of
the B--scan cycle for use in controlling the rate of operation of
the commutator 346 and for use in generating Doppler ~ertical de-
flection signals.
As described above, a Doppler display sequence is initiated
with an output 756 (Fig. 7) from the comparator 224 (Fig. lB)
which output conditions the multiplexer 156 for Doppler transmission,
through use of the logic network 190, and which also triggers the
one-shot 226. The one-shot 226 ou-tput 822 (Fig. 9) is supplied
over line 228 (from Fig. lB to Fig. lD) as a clock input to a
flip-flop 388. The Q output terminal of flip-flop 388 is connected
to the data terminal for toggle operation of the flip-flop. A
Doppler signal profile display is initiated when the Q output
terminal switches to a low level, and a Doppler cursor display is
initiated when the Q output terminal switches high. It will be
apparent then that a Doppler profile is displayed on alternate
outputs from the comparator 224~
DOPPLER PROFILE - X-AXIS
Assume, now that the Q output from the flip-flop 388
switches from high to low to initiate a Doppler profile display.
The flip-flop 388 output 824 is supplied as the data input to a
flip-flop 390, to which clock pulses are supplied from a voltage
controlled oscillator (VCO) 392. The flip-flop 390 thereby also
switches states upon receipt of a clock pulse from the VCO 392
following a c,~hange in state of the input to the D terminal.
~Y -42-
~1 ~09~36~3
l The falling edge of the flip-~lop 390 output 826 at output ter-
2 minal Q -triggers a one-shot 391 having an output pulse 823. The
3 pulse ~2~ from the one-shot 391 is supplied as a reset signal
4 to counter 350 to reset the same, and is connec-ted through an
OR gate 394 to the control input of the ramp generator 380 -to
~ trigger on the same. The Q terminal output from the flip-flop
7 390 is connected as one input to an AND gate 396 to enable the
8 same for passage of clock pulses from the VCO 392 there-thrcugh.
9 The clock pulses 830 from the AND gate 396 clock the counter 350
and, as described above, the commutator 346 (Fig lC) switches
1~ under control of signals from the counter 350 ~or passage of the
12 Doppler profile signals from the frequency to voltage converters
13 344-l through 344-20 to the horizontal deflection circuit of the
14 cathode ray tube 66. The VCO 392 frequency is controlled by the
1~ voltage output from a difference amplifier 398 having input
16 signals Vl and V2 supplied thereto from the sample and hold
17 circuits 382 and 384, respectively. Consequently, the clock rate
18 is determined by the difference in the voltages Vl and V2,
19 with the output frequency o~ the clocX decreasin~ with an increase
in the voltage difference between Vl and V2. It will be seen,
21 then, that the rate at which the counter 350 is clocked, and the
22 commutator 346 is stepped, is inversely proportional to the
23 difference between the voltages Vl and V2~
24 Although the AMD gate 396 ramains enabled for passage of
clock pulses from the VCO 392 until the flip-flop 390 changes
~6 state, it will be apparent that only the first twenty (20) clock
~7 pulses are~employed by the counter 350 for stepping the commutator
28 346 to read out the analog Doppler profile signals ~rom the
29 twenty (20) frequency to voltage converters. In Fig. 9~ the
first, twenty clock pulses are shown produced between times T6
3l and T7.
32
43
.,
36~3
1 For proper display of these signals, a ver-tical deflection signal
2 must be supplied to the cathode ray -tube which signal r~nps
3 between the Vl and V2 levels between the times T6 and T7.
~ DOPPL R PROFILE - Y-AXIS
6 A vertical ramp signal, for both Doppler profile and Doppler
7 cursor display, is supplied to the multiplexer section 1~6Y over
8 line 410 from an ampli~ier 402 (Fig. lD to Fig~ lB). The
9 amplifier 402 and its associated input and feedback resistors
comprise a summing circuit for summing the input potential~
11 supplied thereto. The amplifier 402 is provided with a ~irst
12 input Vl from th~ sample ahd hold circuit 382. A second input
13 for the amplifier is supplied from either the ramp generator 380
14 or sample ahd hold circuit 384, depending upon the condition of
transmission gates 400 and 404 connecting the ramp generator
16 and sample and hold circuit outputs to the ampli~ier input.
17 The ramp generator 380 and sample and hold 384 outputs 831 and
18 820, respectively alternately are supplied to the ampli~ier 402
19 by operating the transmission gates 400 ~nd 404 in ~uch a manner
that one is enabled while the other is disabled. Control signals
21 ~or the gates 400 and 404 are obtained from a comparator 406.
2~ The output from the co~arator is directly connected to the gate
23 400, and is connected through an inverter 408 to the other gate
24 such that when one gate is enabled the other gate is disabled.
~51 Comparator inputs are provided by the ramp generator 380 and
26 sample ahd hold circuit 384 outputs~
27 In operation, as described above, the ramp generator 380 is
28¦ gated on by ~e ou-tput 828(Fig. 9) from the one-shot 391
29¦ connected thereto through the OR gate 394 at the same time that
301 the AND gate 396 is enabled for passage of VCO output cloc~ pulse
31
32 ~
44 `
.
. . .
~ . . . . ..... . .. .. . . .
. . . : ..
6~3
1 ¦830 therethrough. When -the generator 380 is enabled, the ramp
2 ¦signal output 831 -therefrom rises from a zero level. Upon reach-
~ ing tne level OI the signal ouiput 82u Irom the sample and hold
4 circuit 384, at V2, the comparator 406 produces an output 832
which switches the transmission gat;es 400 and 404 to disable the
~ gate 400 and to enable the gate 404. Now, the signal ou-tput V2
7 from the sample and hold circuit 384 is supplied as a second
8 input to the amplifier 402, rather than the ramp signal generator
9 380 output. Wi-th the use of proper scaling resistors at the
inputs to the ampli~ier 402 the output 834 therefrom (Fig~ 9)
11 ramps between voltage levels Vl and V2 between times T6 and T7
12 during which the commutator 346 (Fig. lC) is being stepped to
13 read the Doppler profile information from the frequency to
14 voltage converters 344-l through 344-20 out to the X-axis input
to the cathode ray tube 66 through the amplifier 356.
1~ . .
17
18 DOPPIER Z-AXIS
~ 19
Z-axis control during Doppler pro~ile and cursor displays is
21 provided by square wave outputs ~rom ramp generator 380 and
22 a ramp generator 418 (for cursor generation. described below)
23 which square wave outputs are connected through an OR gate 411
24 and over line 413 (Fig~ lD to Fig, lB) to the Doppler Z-axis
input to the multiplexer 156 for connection to the control grid
26 ¦158 o he cathod~ ray tube 66.
29
31
32
-
.
CURS~R GENERATIO~
As noted above, the Doppler profile and cursor signals are
supplied to the cathode ray tube on alternate Doppler display
periods. The flip-flop 388 is triggered by the output 822 from
the one-shot 226, and a Doppler profile signal is displayed when
the Q output thereof switches from high to low, in the manner
described above. (See Fig. 9). When the flip-flop 388 is next
triggered by the one-shot output 822, and the output therefrom
goes from low to high, a Doppler cursor signal is generated and
displayed at the cathode ray tube 66. The rising edge of wave-
form 824 from flip-flop 388 triggers a one-shot 414, and the
output pulse 836 therefrom (Fig. 9) is connected through an OR
gate 416 to a ramp generator 418 to trigger the same. The ramp
signal generator 418 is used in the generation of the horizontal
end sections 70A and 70B of the Doppler cursor. The generator
418 has both ramp 838 and square wave 840 outputs which are pro-
duced when the generator is triggered by the one-shot 414. The
ramp signal output is connected through a first transmission gate
420 to the s~ming junction J to the amplifier 356 (Fig. lC)
over line 360. A DC potential, from a DC source and a potentiometer
422, ~Fig. lD) is connected to the summing junction through a
second transmission gate 424. The potentiometer 422 is adjusted
to provide a DC potential to the gate 424 which is substantially
equal to the mldpoint potential of the ramp signal 838, for
reasons which will become apparent hereinbelow.
The gates 420 and 424 are gated on and off by use of the
squarewave output~840 from the ramp generator, with the square-
wave gating signal being supplied to the gate 420 through an
inverter 426 so that the one gate is enabled while the other
gate is disabled. ~In Fig. 9, the outputs from the gates 420 and
4~4 are identified by the~reference numerals 842 and 844,
respeotively. The gate 424 normally is enabled for connection
-46-
, .
:: :
of the constant DC potential therethrouyh to the amplifier 356.
The DC potential from the gate 424 essentia]ly adds a constant
DC value to the horizontal position control signal supplied to
the amplifier 356 from the control unit 44 (Fig. lC). When the
ramp signal generator 418 is enabled, the square wave output
therefrom disables -transmission gate 424, for removal of the DC
source therefrom, and enables transmission gate 420, for connect-
ing of the ramp signal therethrough. The combined outputs from
gates 420 and 424, identified by reference numeral 846 in Fig. 9,
;ncludes first and second offset ramp sections 846A and 846B for
generation of the cursor end sections 70A and 70B, respectively.
The second end section 70B is generated following generation of
a vertical ramp signal for -the vertical portion of the cursor 70
in a manner now to be described.
The trailing edge of the squarewave 840 from the generator
418, at time T 12, triggers a one-shot 428, and the output 848
from the one-shot is connected through the OP ga-te 394 to the
ramp generator 380 to enable the same. The operation of the
ramp generator 380 and sample and hold circuits 382 and 384 in
the generation of the vertical deflection signal 834 for Doppler
profile display was described above. Here the ramp generator is
gated on by the pulse output 848 from the one-shot 428 rather
than by the pulse output 828 from the one-shot 391. As described
above, when the ramp signal 831 from ramp generator 380 reaches
the level V2 from the sample and hold circuit 384, an output 832
is produced by the comparator 405 which is used to switch the
transmission gates 400 and 404. It here will be noted that the
comparator output 832 also lS connected to a one-shot 430 to
trigger the same. The one-shot 430 output 850 is connected to
the ramp generator 418 through the OR gate 416 to enable the same.
The lower cursor end signal, designated 846B is thereby produced
at the combined outputs from the transmission gates 420 and 424
47~
in the manner de~cribed above, for generation of ~he cursor end
70B.
ESTABLISHING DOPPLE~ VERTICAL SCAN LEVELS
Periodically, the sample and hold circuits 382 and 384 are
operated to establish and to periodically update the Vl and ~2
signal levels, respectively, necess:Ltated, for example, by
initial turn-on of the equipment, by changes in the Doppler length
and/or vertical settings of the control stick 48, by decay in
the output voltage of the sample and hold circuits with time in
the hold mode, and the like. It will be apparent that the voltage
levels Vl and V2 from the sample and hold circuits 382 and 384
must i.dentify the levels from which the first and last Doppler
echo signal stored by the sample and hold circuits 330-1 and 330-20
are acquired for proper display of the stored Doppler profile sig-
nals. The B-scan vertical deflection signal, in timing and slope,
is: correct, of course, for proper display of the B scan signals.
With the present arrangement, the B-scan and Doppler transmitters
periodically are simultaneously operated and, with the B-scan
vertical deflection signal supplied as an input to the sample and
hbld circuits 382 and 384, the deflection signal is sampled by the
sample and hold circuits 382 and 384 at the instants that the
first and last Doppler signal are stored by the respective sample
and hold circuits 330-1 and 330-20. In the illustrated arrange-
ment the first timing pulse from the photocell 104 generated each
frame is used to control the B-scan and Doppler units for the simul-
taneous generation of ultrasonic pulses by the B-scan and Doppler
: transducers 20 and 22. The tlming means for effecting the simul-
taneous B-scan and Doppler transmitting operations includes a flip-
flop 480.shown in Fig. lD. The R terminal input of the flip-flop
480 is connected to the output from a one-shot 482 which, in turn
is triggered~by the photocell 104 output connected thereto over
line 484 from Plg. lA to Fig. lD through Fig. lC. Output
: -48-
''
9~3
pulses from the one-shot 482 therefore are produced at the same
sinusoidally varying rate as photocell 104 pulses 602 shown
in Fig. 10A. ~rhe S input terminal of the flip-flop 480 is con-
nected to the output 866 from the one-shot 162 over line 486 from
Fig. lA through Fig. lC to Fig. lD. The one-shot 162 is triygered
once per cycle of the output 604 from the photocall 106 at one
end of the B-scan sweep to set the flip-flop 480. A reset signal
-occurs a short time later, upon occurrence of the first fast tim-
ing pulse from the photocell 104, to reset the flip-flop. In
Fig. 10~ the flip-flop 480 output is identified by the reference
numeral 868. Other fast timing pulses from the photocell 104 have
no effect upon the operation ~ the flip-1Op 480 until the flip-
flop is again set at the beginning of the next B-scan cycle.
The trailing edge of the flip-flop output 868, which corres-
ponds in time to the first timing pulses from the photocell 104,
is used to trigger a one-shot 488 which, in turn, sets a flip-
flop 490. The flip-flop 490 output 870 is connected as one in-
put to an AND gate 492. The other AND gate input comprises the
-; Doppler transmit/receive control pulse 802 from one-shot 294
connected thereto over line 494 from Fig. lC to Fig. lD. The
Doppler system may operate at a repetition rate of, say 10,000
pulses per second, and only approximately 1/30 of the transmit/
; ~ receiver control pulses 802 are shown for clarity in FLg. 10A.
The gated signal 872 from AND gate 492 triggers a one-shot 496,
the inverted signal output from~which is connected as~ a reset
signal to the flip-flop 490 to reset the same in preparation for
the next output~pulse from the one-shot 488. The other one-shot
496 output 874 lS used to~trigger operation of the B-scan~system
for simultaneous operat~on thereof with~the Doppler system.~
To thi~s end the~output~874 i~s connected through lead 498 (from
30~ Flg.~lD~ to F~g.~lA through F~q~. ;lC) and through the~OR gate~l~40 anddelay units 174 and 176~ to the ramp signal generators 178 and 180.
As described~above,~the~ramp~ generator outputs;are employed
49-
, ~ . ~ . . . .. .
~136~3
as vertical deflection signals for the B-scan display, and the
selected ramp generator output is obtained at line 184 from
the transmission gate 182.
With the Doppler system operat:ing at a pulse repetition rate
of 10,000 pulses per second, it will be understood that a delay of
up to 100 microseconds may exist between the triggering of the
one-shot 496 (upon occurrence of the first B-scan timing signal
from the photocell 104) and the triggering of the B-scan system.
secause of such improper timing the first line of B-scan informa-
tion is not displayed. Display of this line of information at the
cathode ray tube 66 is prevented by any suitable means. In the
illustrated arrangement, the gain function generator 138 is dis-
abled to disable operation of the time variable gain amplifier 136
at this time. To this end the signal 874 from the one-shot 496 is
connected to a delay unit 502 (FigO lA) such as a one-shot, having
an output with a pulse period which exceeds the period of the
pulses from the delay units 174 and 176. The one-shot 502 output
is connected through an inverter circuit 504 to the AND gate 141
to keep the output therefrom low during the presence of the output
pulse from the delay unit 174 thereby preventing triggering opera-
tion of the gain function generator 138. Without triggering the
gain function generator, the amplifier 136 remains disabled and no
B-scan line of information is obtained fxom the compression ampli-
fier 154 at the B-scan receiver output. Also, means not shown may
~e used to prevent triggering of the pulser 126 at this time to
avoid transmission of a B-scan pulse.
The vertical deflection signal for B-scan operation at line
184 from the transmission gate 182 is supplied over line 436
from Fig. lA to Fig. lD through Pig. lB, as an analog input
signal to the sample and hold circuits 382 and 384. Control signals
are supplied to the sample and hold circuits 382 and 384 for
momentarily switching the same to the sampling mode from the hold
~5 0 ~:
. . . . . . . . .
:, ~ . . . .
363L3
mode when the first and last sample and hold circuits 330-1
and 330-20 respectively (Fig. lC) are actuated during Doppler
receiver operation. In the illustrated arrangement the control
signals are obtained by use of the clock signals 814 (Fig. 8)
from the programmable frequency clock 340 (Fig. lC). The clock
si~nals, in addition to clocking the shift register 334, are
connected over line 442 to a counter 444. The counter may com-
prise, for example, a pair of binary coded decimal up counters
connected in cascade in the ripple mode. The "1" output terminal
of the counter is supplied as a reset signal to a flip-flop 446.
The "4" and "16" output terminals are connected to the input of
an AND gate 448 to provide an output therefrom at the count of
"20", which output is used to reset a second flip-flop 450. The
counter 444 is reset and the flip-flops 446 and 450 are set
by the pulse output 874 from the one-shot 496 once every B-scan
frame immediately prior to above-described counting operation
of the counter 444 and resetting of the flip~flops 446 and 450.
The flip-flop 446 and 450 outputs designated 876 and 878,
respectively are shown in Fig. lOB. These flip~flop outputs
are supplied as control signals to the sample and hold circuits
382 and 384 for switching the same to the sample, or tracking,
mode while the flip-flops are in the set condition. Consquently,
it will be seen that the B-scan vertical deflection signal sup-
plied as an input to the sample and hold circuits 382 and 384
is sampled and held at the beginning and at the end of the
acquisition of the Doppler profile signal. The outputs from the
sample and hold circuits 382 and 384 during such periodic
updating thereof are identified by reference numerals 818 and
820, respectively, in Fig. lOB. The signal levels Vl and V2
held by th~ sample and hold circuits 382 and 384 are used both
in the generation of the cursor 70 to set the end levels thereof
and, in the display of the Doppler profile 68 to set the vertical
end levels and to establish the rate at which the individual
,, ~ ~ , .
, --51--
` - ' ' ' - . . :
-- . .
6~3
segments thereof are displayed, in the manner described above.
RE T I CLE S I GNAL GENE RATOR
An electronic reticle signal generator 510, shown in Fig. lB,
is included to provide cali~rated tick marks along the margins
of the display for use in tissue metrology, and the like. As men-
tioned above, and as seen in Figs. 2 and 3, tick marks for the
lX operation are identified by the reference characters 80-1
through 80-60, respectively. For the 2X display, as shown in
Fig. 4, the tick marks are identified by the reference characters
82-1 through 82-28. Also as described above, 2X field indicator
marks 83-l through 83-4, as seen in Fig. 3, may be provided with
the lX display to indicate the 2X boundries when switching from
the lX to the 2X dispiay. In Fig. 5, the reticle on-off and 2X
field indicator switches 92 and 94, respectively, are shown.
Referring to Fig. lB, the reticle signal generator 510 is
shown comprising a decoder 512 comprising, for example, eight 4
lines to 1 decoders. The decoders are provided with some hard-
wired inputs and some switchable inputs -through the lX, 2X switch
section 90-l and 2X field indicator switch 94. The switches 90-l
and 94 are shown comprising single pole double throw switches,
each with one terminal connected to a high level input and the
other connected to a low level inpuk. The output from switch
90-1 is connected as an input to selected decoder input terminals
and to an AND~gate 514. The output from the 2X field indicator
switch 94 provides a second input to the gate 514. In -the il-
lustrated arrangement, for purposes of description only, decoder
binary outputs of 0, 64, and 128 are provided with switch 90-l
and 94 settings of lX, 2X and lX with 2X field indicator,
respectively.
~ The decoder 512 outputs are supplied as input signals to a
presettable counter 516~, whereby the counter is preset to the
:
~-52-
'
36~3
count provided from the decoder 512 output upon receipt of a load
signal from the one-shot 214. The one-shot 21~ is triggered when~
ever a signal input thereto is provided from the comparator 212,
in the manner described above, whenever a reticle cycle is to be
performed. It will be understood then, that with the switch 90-1
in the lX position and the switch 94 open, the counter 516 is
loaded with a count of zero upon receipt of a load signal thereto;
that with the switch 90-1 in the 2X position, the counter 516 is
loaded with a count of sixty four (64) when the load terminal is
energized; and that with the switch 90-1 in the lX position and
the switch 94 in the closed position, the counter 516 is loaded
with a count of 128 when the enable terminal is energized. As is
understood, upon receipt of clock pulses at the clock input to
the counter counting proceeds from the preselected, or preloaded,
value of zero, sixty four or one hundred twenty eight, in the
illustrated arrangement.
The one-shot 214 output 900 (Fig. 11) for loading of the
counter 516 also is supplied to a delay unit 518 comprising, for
example, a one-shot having an output 902. As described above,
the comparatOr 212 output, through the logic network 190, is
used for multiplexer channel control to switch the multiplexer
156 for reticle display. The delay provided by the one-shot 518
allows for settling of the multiplexer 156 before transmission
of reticle signals therethrough after switching channels.
The one-shot 518 output 902 is connected to the reset ter-
minal of a flip-flop 52Q which is reset by the trailing edge
thereof. The flip-flop 520 output 904 serves as a gating signal
which is connected on a free running clock~522 for on-off control
~ thereof. The cloc~c output 906 is connected both to the input o~
the counter 516 to drlve the same~ and through a NOR gate 523~to
the input of a delay unit 524 to trigger the same. The reticle
on-off control switch 92 is shown included in the DC supply circuit
53-
-
. - . . :
for the delay unit 524 for on-off control of the reticle generator~
Other locations for such on--off control of the reticle generator will
be apparent. In Fig. 11, the one-shot 524 output is identified by
the reference numeral 907.
The contents of the counter 516 are supplied to a programmable
read only memory (PROM) 526 having first and second outpu-ts (Y-out
and X--out) which, in turn, are connected as inpu-ts to digital to
analog. (D/A) converters 528 and 530. The analog outputs 908 and
910 from the D/~ converters 528 and 530 are connected through the
multiplexer 156 to the respective vertical and horizontal deflection
circuits of the cathode ray tube 66 for positioning of the tick
marks at the face of the screen. After the counter 516 is stepped,
the delayed clock pulse from the above-mentioned delay unit 524
triggers a one-shot 532 having an output which is connected through
the multiplexer 156 to the control grid of the cathode ray tube 66
for on-off Z-axis control thereof. The delay provided by delay
unit 52~ allows for settling of the vertical and horizontal deflec-
tion voltages from the D/A converters 528 and 530 before the Z-axis
is turned on, or enabled, by the output of the one-shot 532. With
the present arrangement the PROM 526, in effect, converts the counter
516 output to digital number representations of the Y and X axis
coordina-tes of reticle tick marks, which digital signals then are
convertea by the D/A converters 528 and 530 to analog vertical and
horizontal deflection signals for the cathode ray tube.
At the end of the reticle display (e.g. at count 61 of the
counter 516 for lX display, at count 93 for 2X display, and at
count 193 for lX with 2X field indication display), the PROM
526 is programmed to provide the same output. ~he PROM output
is decoded by a decoder 533, and the decoder output 912 is
supplied to the fllp--flop 520 to set the same, thereby stopplng
the clock 522. The~decoder output also is applied to the reset
terminal of the one-shot 532 to prevent output pulses therefrom.
It will be seen, then, that when the counter 516 is clocked by the
; ~ ~: ': , ~ ... .
.54-
~lnal clock pulse in the cycle, no z-axls signal is supplied to
the cathode ray tube since the one-shot 532 is disabled before the
delayed clock pulse reaches the same. The reticle generator
remains in this quiescent condition until actuated ~y another
pulse from the one-shot 214 when an output is provided from
the comparator.
For convenience in use of the reticle, the spacing between
adjacent tick marks identifies the same distance for both lX and
2X operating conditions which, in the illustrated arrangement,
comprises a distance of 2 millimeters. It will be seen, then,
that substantially twice as many tick mar~s are required for lX
operation as for 2X operation. Since the clock 340 operates at
the same rate for both lX and 2X operation, a reticle cycle of
a dlsplay of the tick marks for 2X operation requires approximately
one-half the time required for the lX reticle display. A some-
what longer period is required where the 2X field indicator is
included with the lX display.
OPERATION
Although the operation of the ultrasonic B-scan/Dopplex
~o imaging system is believed to be apparent from the above
description, a brief description thereof with reference to the
waveforms of Figs. 6 through 11 now is given. As the motor 40
- drives the focused broadband B-scan transducer 20 back and forth
across the subject 26 at a generally sinusoidally varying rate
~Fig. 6, waveform 600), timing pulses 602 are produced by the
photocell 104, which pulses occur at the sinusoidally varying
:
rate of movement of the transducer. During such scanning opera-
tion, a symmetrical squarewave 604 is produced at the photocell
106 output which switches signal levels at opposite ends~o~ the~
`~30 transducer 22~travel.
. ~
The fast and~slow master timing signals 602 and 604 are used
to~control B-scan transmittlng~;and receiving-operations. For ~lX
operation the~fast master timing signal 602 is divided by a
; 5
~ca8~;~3
divide-by-two circuit 108 CFlg. lA) and supplied through gate
110 to the pulser 126. Impulses from the pulser are supplied to
the transducer 20, and the resultant short, focused, ultrasonic
pulses travel into the subject to be reflected from internal
discontinuities therewithin. For the lX operation an area 85-lX
~Fig. L~) is scanned, which area li.es along the transducer axis
30. Both the B-scan and Doppler transducers 20 and 22 are
focused at substantially the midpoi.nt depth of the imaged area.
The B-scan receiver is recurrently operated, following B-scan
pulse transmission, for the reception c)f echo signals received
between the upper and lower levels of the section imaged, and
the simultaneous display thereof. To this end, the master timing
pulse output from the divide-by-two circuit 108 is delayed by
delay unit 174, and subsequently triggers operation of the receiver
gain function generator 138 and a vertical ramp signal generator
178. The ramp signal 708 from generator 178, for lX operation is
connected through multiplexer section 156Y to the vertical deflec-
tion circuit of the cathode ray tube 66 for vertical deflection in an amount
dependent u~on the time lapsed fran the preceding transmitter pulse. The
generator 178 also includes a squarewave output 712 which, through logic net-
work 190, is connected as a channel control signal to the multiplexer for pas-
sage of B-scan signals therethrough. The B-scan display at the cathcde ray tuke
66 is intensity modulated~by connection of the B-scan receiver
~; output from compression amplifier 154, through line 155 and multi-plexer 156, to the control grid thereof. The X axis deflection
` ~ signal for the B-scan dlsplay, which is proportional to the
transducer 20 position, is ~provided by use of a master up-down
counter 160 to wh:Lch the ~fast~ master timing signals ~02 are~ supplied
~ ~ to step the same, and to which the slow master timing signals 604
;~ ~ 30 are suppli~sd;~for ~up-down control.~ The digital count output is
convsrtsd~ by `a dlgltal to analog convsrter 168 to analog form
620~ for connection to~ the horizontal de~lection circuit of
the cathode~ ray tube thr;ough the multiple~er. It will be seen,
.. ..
then, that the B-scan signals from the B-scan receiver are displayed
as they become available at the receiver output at a rate dependent
upon the master timing pulses from the divide-by-two circuit 108,
with lX operation.
For 2X B-scan display, only the master timing pulses produced
during the central portion of the B-scan transducer 20 sweep are
employed. Those pulses produced at the opposite ends of the sweep,
during travel along the initial and final quarters of the path
length, are blocked and, therefore, do not function to trigger the
pulser 126 or the delay unit 176. The circuit for passing only
the master timing pulses generated during the central portion of
the B-scan sweep includes an up-down counter 118 which is stepped
by the master timing pulses 602 from the photocell 104. Up-down
counter control is provided by the slow clock pulse 604. Decoders
120-1 and 120-2, responsive to the count from the counter 118
provide outputs 612-1 and 612-2 when the count passes 101 and 300,
respectively. Logic means 121, responsive to the decoder outputs
612-l and 612-2, in effect~ serves to pass master counter pulses
to trigger the B-scan transmitter between the counts at which the
decoders 120-l and 120-2 are designed to operate. The pulse output
6a8 from the log;c network 121 triggers the pulser 126 to produce
a transmitter pulse, and triggers a 2X delay unit 176 for delay
triggering of the 2X ramp generator 180. The ramp generator output
710 rises at twice the rate of the lX ramp generator output 708
to vertically sweep the cathode ray tube electron beam the same
vertical distance but in substantially one-half the time required
for lX display. (As noted above, a slngle ramp generator may be
employed, with the generator output amplified by diferent amounts
to provide for the different ramp signal slopes.) The timing pulses
3~ 6Q8 also are supplied to the master counter 160 ~or gener~ation of
the stepped horizontal deflection signal 620-2 from the D/~ converter
168 in the same manner descrlbed above for lX operationO Both the
; ~,
i
; ~ ~ -57-
-
:
horizontal and vertical deflectîon signals ~or 2X display operate
between the same levels as the horizontal and vertical deflection
signals for lX display, but change at substantially twice the
rate, for display of the imaged section 85-2X over the same screen
area as the lX display~ In -this manner an enlarged view o~ the
central portion of the lX display is provided. There is no
appreciable change in picture quality in switching between lX to
the 2X operating modes since -the display is made up of the same
number of lines for both the lX and 2X operating conditions.
Except for the one timing pulse per B-scan frame used in the
establishment of the upper and lower levels for the Doppler verti-
cal deflection signal, the above-described B-scan transmit, receive,
and display operations take place independently of the Doppler sys-
tem operation. Also, the Doppler transmit and receive operations
are performed asynchronously with respect to the B-scan operation.
Doppler display, as well as reticle generation and display, on the
other hand, are timed for execution between selected B-scan dis-
plays. In particular, they are executed adjacent the opposite ends
of the B-scan where the operating rate is a minimum.
The Doppler transmit and receive operations include the use
of the clock signal 800 (Fig. 8) for producing a pulse 802 for
periodically conditioning the T/R switch 298 for a transmit opera-
tion and for producing another slightly delayed pulse 805 for en-
abling the ~F transmission gate 308. Phase-coherent 5MHz bursts
880 (Fig. 8A) from the RF signal generator 310 and gate 308 are
amplified by power amplifier 312 and delivered to the Doppler
transducer 22 through the T~R switch 298. Received signals 882~
including signals;reflected from moving interfaces and particles
within the subject 26, are connected as one input to a demodulator
30~ 322 through the T/R switch 298, the preamplifier 318, and~the
amplifier 320. An offset frequency version of the RF signal
generator 310 output is~supplied as a second input to the~demodu-
lator. ~The amplitude of the demodulator ou~put signal 884 at any
-58-
,
"
given time in the Doppler return is proportional to the phase
(relative to the second input signal) of the waves reflected from
a small volume (e.g. one-cubic mi]limeter volume) of the subject
at a proportional distance from the transducer; the volume being
related to the pulse length and the focusing; or collimation, of
the transmitted acoustic wave. For re-turn signals from particles
or interfaces having a component of movement along the transducer
axis 30, the relative phase changes with time. For stationary
objects, the relative phase is unchanged with time.
The signal 884 from the demodulator 322 is sequentially sampled
by the sample and hold circuits 330-1 through 330-20. The sampled
voltages held by the sample and hold circuits are proportional to
the signal phase at successive points along the transducer axis 32.
The sampling is effected by use of the gateable clock 340, the
output from whicb is used to clock a shift register 334 which,
in time, sequentially operates the sample and hold circuits. The
clock 340 is gated on, i.e. enabled by the output from voltage
controllèd delay unit 336, with the delay being adjusted by the
vertical output from the control stick unit 44 as determined by
the vertical setting of the control stick. The clock rate is
established by the length control output of the control stick 44
which controls the length of the Doppler axis 30 along which the
return signals are sampled. The position of the Doppler trans-
ducer 22 along its path of travel is adjustably set by the hori-
zontal, or X-axis, output from the control stick unit. Complete
one hand control of the line along which the Doppler return sig-
nals are obtained is provided with this arrangement.
The sample and hold outputs 886 (Fig. 8B) are filtered by
notch filters 332-1 through 332-20 to substantially, but not
completely, remove therefrom~the difference frequency signal (fo),
produced at the output~of demodulator 322. Sample and hold
switching transients also nre removed.~ The~signals 888 from the
notch filters are converted to equivalent analog signals 890
5 9_
' ~ ~
~8~L3
representative of the Doppler signal frequency by frequency to
voltage converters 344-1 through 344-20. The frequency to
voltage converters are of the zero crossing type which include
low pass filters in the output circuits thereof for maintenance
of levels between zero crossings of the input signal~.
The analog Doppler signal levels from the frequency to ~ol-
tage converters 3~4-1 through 344-20 are displayed between
pre-established B-scan line displays; the Doppler profile and
the Doppler cursor signals being displayed on alternate Doppler
display periods. Timing for Doppler display is provlded by the
output 756 (Fig. 7) from the logical comparator 224 (Fig. lB).
The master up-down counter 160 (Fig. lA), having an output
indicative of the B-scan line, provides one input to the compara-
tor. A second comparator input is provided by the output from
the PROM 222. With e~ual logical inputs there-to, an output is
obtained therefrom which is used to trigger -the Doppler display.
Address select signals for the PROM are supplied from the Doppler
counter 220, which is stepped by the comparator output. The
PROM is programmed to provide outputs which will result in com-
parator ol'tputs between selected B-scan lines.
The comparator 224 output 756 (Fig. 7) through logic networ~
190, conditions the multiplexer 156 for Doppler channel trans-
mission. The comparator output also triggers the one-shot 226
which, in turn, triggers the toggled flip-flop 388 (Fig. lD)
having an output 82~ (Fig. 9). When the flip-flop 388 is toggled
high the Doppler cursor 70 is displayed, and when toggled low,
the Doppler profile 68 ~is displayed. The low output signal
from the~Q termin~al of the flip-flop 388 is applied to the data
input terminal of the fllp-flop 390 whlch then changes state upon
receipt of the first clock pulse to arrive thereat from the VC0 392.
The Q output Erom the flip-flop, now hlgh, enables the AND gate
~; 396 for passage of clock~pulses from the V~0 392 therethrough to
.
~ 60-
the counter 350. The counter 350 is connected over line 352 to
the commutator 346 wnich sequentially samples the outputs 890
from the frequency to ~oltage converters 34~-1 through 344-20.
The commutator output, comprising the Doppler profile signal,
is connected through the amplifier 356, the amplifier 364 for 2X
operation of the gate 366 for lX operation, and the multiplexer
156, to the horizontal deflection circuit of the cathode ray tube
66 for Doppler profile display.
The ramp vertical deflection signal for Doppler display
operates between upper and lower deflection voltaye limits
related to the timing of the initiation and termination of the
sample and hold functions of the sample and hold circuits 330-l
through 330-20 during Doppler receiver operation. The upper and
lower deflection voltage limits for Doppler display are established
recurrently (i.e., once each B-scan frame) by the simultaneous
actuation of the B-scan and Doppler systems. The signal for such
simultaneous actuation is produced by setting the flip-flop 480
(Fig. lD) by the output 866 (Fig. lOA) from the one-shot 162 which,
in turn, is triggered once each B~scan frame by the photocell 106
output 604. The flip-flop 480 is reset by the first fast clock
pulse 602 to occur at the beginning of the B-scan frame, and the
trailing edge of flip-flop 480 output 868 triggers a one-shot
488 which, in turn, sets the flip-flop 490. The flip-flop 490
output 870 enables the gate 492 for passage of a signal from the
one-shot 2~4 which is triggered by the Doppler clock 292. The
one-shot output signal 872 from the AND gate 492 triggers a one-
shot 496 which resets the flip-flop 490 and triggers operation
of the lX and 2X delay circuits 174 and 176 included in the B-scan
~ receiver. The trailing edge of the pulse outputs from the delay
units 174 and 176 trigger ramp generators 178 and 180, and the
selected ramp signal output, depending upon the setting of gate 182
(Fig. lA), is connected to the input terminals of sample and hold
.
-61-
-
. , .
circuits 382 and 384 over line 184 from Fig. 1~ to Fig. lB, and
line 436 from Fig lB to Flg. lD.
The ra~p signal lnputs are sampled at the beginning and end
of the Doppler receiver storage operation, when sample and hold
circuits 330-1 and 330-20, respectively, are operated to sample
the Doppler signal. To this end, control signals ~or the ~ample
and hold circuits 382 and 38~ are obtained from the clock 340
output 814 (Fig. 8) which drives the counter ~44. At the counts
of 1 and 20, outputs from the counter reset flip-flops 446 and
450 having outputs which control the sample and hold circuits 382
and 384, respectively. The sample and hold outputs 818 and 820
(Fig. 9) identify the vertical levels between which the Doppler
profile signals are acquired during Doppler receiver operation.
Vertical deflection for the Dopplerprofile display now is
described. The Q output of flip-flop 390 enables gate 396 for
passage of clock pulses from the VCO 392 to the counter, in the
manner described above, for stepping the same and actuating the
commutator 346. The Q output 826 (Fig. 9) of the flip-flop 390
triggers the one-shot 391, and the one-shot output 828 is con-
nected to the ramp generator 380 through OR gate 394 to trigger
operation thereof. The ramp signal output 831 is connected
through the transmission gate 400 to the input of the amplifier
402, together with the sample and hold 382 output Vl.
The amplifier output 834 is connected through the multiplexer
156 to the vertical deflection circuit of the cathode ray tube
66. When the verticaL deflection signal from the ramp generator
380 reaches the level of V2 from the sample and hold circuit 382,
an output 832 is produced from the comparator 406 which opens
(disables)~ the gate 400 and closes (enables) the gate 404,
connecting the sample and hold 384 output V2 to the amplifier.
The VCO 392 operating frequency is con-trolled by the difference
between the outputs ~2 and V1 from the sample and hold circuits
: :
~ 62-
384 and 382 through use o~ di~ference ampll~ier 398 in a manner
such that the commutator 346 is operated at the proper rate to
read out the values from the frequence to vol-tage converters 344-1
through 344-20 while the vertical deflection signal ramps from the
Vl to the V2 level. Z-axis control for the Doppler display is
provided by the output at line 413 from gate 411 connected to the
cathode ray tube 66 through the multiplexer 156.
~ hen the flip-flop 388 is next toggled by an output 822
(Fig. 9) from the one-shot 226 (which i5 triggered by the
comparator output in the manner described abo~e) the Doppler cursor
70 is displayed. The leading edge of the Q output 824 from flip-
flop 388 triggers the one-shot 414, and the one-shot 414 output
(836) through OR gate 416, triggers operation of the ramp genera-
tor 418. The ramp signal output 838 from the ramp generator is
connected as an input to the transmission gate 420. The ramp gen-
erator also has a square wave output 840 comprising a control signal
for the gate 420 and, a second transmission gate 424, which are
switched in a manner such that one gate is closed while the other
is open. The input to the gate 424 comprises a DC potential at
a level which is intermediate the end levels of the ramp signal
from the generator 418. The gate 424 normally is closed (enabled)
for connection of such DC poten-tial to the input to the ampli-
fier 356. As described above, the amplifier 356 output is connected
through amplifier 364 or gate 366 to the horizontal deflection
circuit of the cathode ray tube through the multiple~er 156 during
Doppler display~ The DC signal from the gate 424 together with
the horizontal signal from the control stick unit 44 which also
is connected to the amplifier 356, establish the X-axis position
of the cursor 70 and reference for the Doppler profile display.
The ramp signal output 838 from the generator 418 when connected
to the amplifier 356 during ramp generation functions to horizon- -
tally sweep the electron beam of the~cathode ray tube 66 to oppo-
`
-63-
~.~i
.
: . . : - .
site sides o~ the normal position for generation of the end mark
70A.
The trailing edge of the squarewave output 840 (Fig. 9) from
the ramp signal generator 418 triggers a one-shot 428. The one-
shot output 8~8, through OR gate 394, triggers operation of the
ramp generator 380 which, as described above, provldes for a ramp
signal 831 at the transmission gate 400 output which extends
between the Vl and V2 levels supplied by the respective sample
and hold circuits 382 and 384. When the ramp signal output 831
reaches the V2 level from the sample and hold circuit 384, the
comparator 406 operates (output 832) to trigger the one-shot 430.
The one-shot output 850 is connected through OR gate 416 to the
ramp generator 418 for generation of the lower cursor end mar~ 70B
~igs. 3 and 4). When the flip-flop 388 is next toggled the
Doppler profile is displayed in the manner described above, for
the alternate display o~ Doppler profile and cursor signals~
depending upon which direction flip-flop 388 is toggled. With the
present arrangement proper registration of the Doppler and B-scan
displays is assured by the above~described pexiodic simultaneous
operation of the B-scan and Doppler receiver systems for updating
the Vl and V2 levels held by the sample and hold circuits 382 and
384.
Reticle generation and display, when switched on by closure
of switch 92, is provided between other selected B-scan lines as
determined by the contents of PROM 210. The reticle counter 204,
PROM 210, comparator 212 and one-shot 214 are similar to and
operate in a manner slmilar to the above described operation
of the Doppler counter 220, PROM 222, comparator 224 and one-shot
~226, and such operation is~not repeated here. An output from~the
comparator 212 sets the flip-flop 25~4 in the logic network l90,
the output~from which 1ip-fl~op-is~ suppli~ed as a gate~enable sig- -
nal to gate~256. ;~he trailing edge of tne~square wave output 712
Fig. 7)-~from lX~of 2X~ramp genera-tor 178 or 180, depending upon
64-
. ,. .. -. .. . ........ , , ~ . -
: : . . . . ~ .
the setting of gate 182, triggers the one-shot 242 in the
logic network 190, and the one-shot output 752 is transmitted
through the enabled gate 256 to set the flip-flop 258 for
reticle channel control of the mult:iplexer 156.
The reticle comparator 212 out:put also triggers the one-shot
214 the output 900 (Fig. 11) from which, in turn, triggers a delay
unit 518 to allow for settling of the multiplexer 156 before
passing reticle signals therethrough. The trailing edge of the
delay unit output 902 resets a flip-~lop 520 and is fed through
OR gate 523 to trigger a delay unit 524. The delayed pulse 907
from the delay unit 52~ triggers a one-shot 532 having an output
connected to the Z-axis control of the cathode ray tube 66 through
the multiplexer. Subsequent triggering of the one-shot 532
by pulses from the delay unit 524 are obtained from the clock 522
which is enabled when the flip-flop 520 was reset.
X-Y positioning of the reticle marks at the face of the screen
is under control of output signals 908 and 910 (Fig. 11) from D/A
converters 528 and 530 connected to the cathode ray tube deflection
circuits through reticle channels of the multiplexer 156. Inputs
for the D/A converters are obtained from the PROM 526 which is
addressed by the counter 516 output. With the illustrated arrange-
ment the counter 516 is preset to begin counting at any one of
three starting positions depending upon the reticle to be displayed,
i.e. lX, 2X, or lX with 2X field indicator. Signals for presetting
the counter are obtained from the decoder 512, and the counter is
; preset upon receipt of a load signal 900 from the one-shot 214 at
~` ~ the start o~ tha reticle cycle. One of three different inputs is
supplied to the decoder to provide one of three outputs therefrom,
~ dependent upon the settings of the lX-2X~and 2X field indicator
switches 90-l and~94. D/A 528 and 530 outputs soa and 910 for lX
:
and 2X operation are shown in Fig. 11. At the end of the reticle
display the PROM 526 cutputs the~same X-Y signals which are decoded ~-
by decoder 533, the output 912 from which sets the ~lip flop 520 to
6~-
stop the clock 522, and disables -the one-shot 532 to prevent the
las-t clock pulse from triggering the one-shot.
The invention having been described in de-tail in accordance
with the requirements of the Pa-tent Statutes, various changes
and modifications will sugyest themselves -to those skilled in this
art. With the present arrangement, 'real-time' ultrasonic s-scan
image and Doppler profile displays are provided whereby a motion
display of interfaces and scatterers is provided. It will be ap-
parent, however, that the system output may be supplied to video
signal storage means, such as video tape, or may be connectedthrough a scan converter, or the like, before display of the siy-
nals. The use of the term real-time herein is not intended to
preclude such arrangements. Also, with the present arrangement
periodic updating of the sample and hold circuit 382 and 384
during the time normally employed to acquire and display one line
of B-scan display is shown. Obviously, such updating may be
performed between selected B-scan lines, if desired. It is intended
that the above and other such changes and~modifications shall fall
within the spirit and scope of the invention as defined in the
appended claims.
-66-
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