Ultrasonic scanner - Patent Review 4241608

Claims

The claimed invention is:

1. An ultrasonic receiving system comprising:

an array of transducer elements operable in a plurality of groups for receiving echoes from ultrasonic waves, each group producing electrical signals corresponding to the echoes from each of the ultrasonic waves which impinge thereon, wherein the signals from the echoes from each of the ultrasonic waves form one of a plurality of data lines, and each of the groups have a characteristic center position relative to an end of the array, whereby each data line corresponds to one of the center positions;

ordering means operably connected with the transducer array for arranging the data lines into a set of data lines in order of increasing distance from said end to the array of the corresponding center position;

interpolator means for averaging adjacent data lines in the set to produce at least one interpolated data line corresponding to a center position between the center positions corresponding to the adjacent data lines; said interpolator means comprising a first latch means for receiving a first data line, second latch means for receiving a second data line, averaging means connected to said first latch means and said second latch means for averaging the data line received in the first latch means with the data line received in the second latch means and producing at least one interpolated data line;

third latch means for receiving the interpolated data line, first multiplexor means connected to said averaging means and said third latch means for arranging each interpolated data line within the set in order between the data lines which were averaged to produce each interpolated data line.

2. The receiving system of claim 1 wherein the interplator further includes:

second multiplexor means for receiving serially each data line of said set,

memory means connected to said second multiplexor means for storing the data lines in said set and for supplying data lines to said first latch means and said second latch means.

3. The receiving system of claim 2 further including a visual display means for transforming each data line of said set into one line of a visual display.

4. An ultrasonic diagnostic apparatus comprising:

an array of transducer elements for converting electrical signals into ultrasonic waves upon actuation and for converting ultrasonic waves into electrical signals, said array being divisible into at least two sections, each section being composed of transducer elements disposed at section positions within that section, the section positions in each of said sections corresponding to the section positions in the other of the sections;

means for selecting groups of transducer elements, each of the groups comprising one or more transducer elements which are actuated proximate in time to generate an ultrasonic wave; said selecting means comprising section position means for providing an indication of the section positions for each of the groups, section means for providing an indication of the sections for each of the groups, and actuating means responsive to the section indication and section position indication from said section position means and section means for actuating the transducer elements comprising each of the groups, said actuating means being operatively connected with said section position means, said section means and said transducer array whereby the actuating means determines the transducer elements which constitute each group based on the section and section position indications; and

means for processing electric signals produced by the transducer elements upon receiving ultrasonic echoes said processing means comprising means for receiving the electrical signals; delay means for adjusting the signals to compensate for a longer path travelled by parts of the echo received by some transducer elements, the adjusted signals produced by the echoes from each transmitted ultrasonic wave forming a data line; means for sorting the data lines according to the position along the array of the center of the corresponding transmitted wave; means for storing the sorted data lines; and means for interpolating the stored data lines to increase the number of data lines; and video display means for displaying the stored and interpolated data lines as an image indicative of acoustically reflective interfaces in an examined object.

5. An ultrasonic diagnostic apparatus comprising:

an array of transducer elements for generating ultrasonic waves when activated with an electrical pulse and for generating an electrical signal upon receiving an incident ultrasonic echo;

means for serially activating pluralities of transducer elements, each activated plurality generating an ultrasonic wave front, said activating means activating said pluralities in such an order that each activated plurality has no transducer elements in common with the preceding activated plurality;

means for receiving electrical signals generated by said array upon receiving ultrasonic echoes from each wave front, the electric signals produced the the echoes from each wave front forming a data line;

means for sorting said data lines according to the position of the center of the corresponding wave front; and means for storing the sorted data lines.

6. The apparatus as set forth in claim 5, wherein the activating means activates unique pluralities of transducer elements until wave fronts are generated having centers displaced by the spacing between adjacent transducer elements.

7. The apparatus as set forth in claim 5 wherein the activating means activates unique pluralities of transducer elements until wave fronts are generated having centers displaced by not more than half the spacing between adjacent transducer elements.

8. The apparatus as set forth in claim 5 further comprising interpolating means for interpolating adjacent data lines stored in said storing means to produce intermediate data lines, said interpolating means being operatively connected with said storing means, whereby the number of data lines is increased.

9. The apparatus as set forth in claim 8 further comprising a video monitor for displaying the data lines, said monitor operatively connected with said interpolating means.

10. An ultrasonic diagnostic apparatus comprising:

an array of A transducer elements, wherein A is an integer;

driving pulse generator means for generating a pulse of a predetermined amplitude and duration for actuating a transducer element;

means for enabling groups of G driving pulse generator means to cause G of the transducer elements to be actuated to form an ultrasonic wave front, where G is an integer; and

delay means having a non-delay path and D delay increments having different delays, where D is an integer less than (G/2)-1, said delay means operatively connected between said enabling means and said driving pulse generator means for delaying the enabling of some of the driving pulses generated by D different delays whereby the ultrasonic wave front is focused.

11. The apparatus as set forth in claim 10 further comprising:

second delay means operatively connected with said array for receiving electrical signals produced by the transducer elements upon the transducer elements receiving ultrasonic echoes, said second delay means comprising a non-delay means comprising a non-delay path and E delay paths, where E is an integer less than (G/2)-1;

means for selectively channeling each electrical signal through one path of the second delay means;

means for combining the electrical signals from each path of the second delay means; and

means for transforming the combined signals into a representation of a visual display.

12. The method of scanning an object with ultrasonic waves from an array of transducer elements to produce a representation of a region of the object comprising:

actuating a first group of transducer elements to generate an ultrasonic wave and allowing the transducer elements to receive echoes from the ultrasonic wave to produce signals indicative thereof;

actuating subsequent groups of transducer elements of the array one group at a time to generate ultrasonic waves, each subsequent group having no transducer elements in common with the immediately preceding group and allowing the transducer element to receive echoes from each ultrasonic wave to produce signals indicative thereof;

sorting the signals in order by the position of the center of the corresponding ultrasonic wave; and

processing the signals indicative of the echoes from ultrasonic waves to produce said representation.

13. The method as set forth in claim 12 wherein each group consists of a unique plurality of transducer elements.

14. The method as set forth in claim 12 wherein each group consists of N or N+1 transducer elements, where N is an integer.

15. The method as set forth in claim 14 wherein subsequent groups are actuated until all unique groups are actuated.

16. The method of scanning an object with ultrasonic waves to form a representation of an image of the interior of the object comprising:

causing a plurality of groups of 2N+1 transducer elements of an array of transducer elements to transmit an ultrasonic wave front, one group at a time, where N is an integer;

after each transmission allowing the groups of transducer elements to receive echoes from the ultraonsic wave front and produce electric signals in response to the received echoes; and

processing the electric signals from 2N of the 2N+1 transducer elements which transmitted the ultrasonic wave from which the electric signals were produced by combining the signals from pairs of transducer elements to produce N time varying signals; subjecting the N signals each to one of less than N delays; and combining the delayed signals to produce a data line, whereby the data line comprises a series of pulses, the amplitude of the pulses being indicative of the reflectivity of an interface in the object and the time between the beginning of the data line and a pulse being indicative of the depth of the interface and whereby the plurality of data lines from the plurality of groups taken together from the representation.

17. An ultrasonic diagnostic apparatus comprising:

an array of electroacoustic transducers for converting electric signals into ultrasonic waves and converting ultrasonic waves into electric signals, transducers in the array being adapted to be actuated in groups sufficiently proximate in time to coact in generating the ultrasonic waves, each group comprising one or more transducers;

location selecting means for serially producing location signals, each location signal being indicative of a location relative to the array of a preselected position in a group of transducers to be actuated to transmit an ultrasonic wave, whereby the location means selects the location of groups relative to the array for serial actuation;

width selecting means for producing width signals, the width signal being indicative of the number of transducers per group;

group selecting means for selecting from the location signals and width signals the transducers in the array to be actuated to form each group, said group selecting means being operatively connected with said location selecting means and said width selecting means; and

pulsing means for actuating the transducers in each selected group, said pulsing means being operatively connected with said group selecting means and said array of transducers.

18. The apparatus as set forth in claim 17 further comprising:

focus selecting means for producing timing signals for indicating the relative timing between actuation of transducers in each group, the relative timing being selected to focus and aim the ultrasonic waves relative to the array, said focus selecting means being operatively connected with said group selecting means; and wherein said group selecting means further selects the relative timing between actuation of specific ones of the transducers forming each group in accordance with the timing signals.

19. The apparatus as set forth in claim 18 wherein said location selecting means comprises a programmable read only memory adapted to be programmed with a series of location signals and a counter means to address the memory for serially producing the location signals.

20. The apparatus as set forth in claim 18 wherein said focus means comprises a plurality of delay means for delaying a control signal, the control signal and delayed control signals being the timing signals.

21. The apparatus as set forth in claim 18 wherein said group selecting means further comprises means for gating each of said enable signals, said gate means being controlled by said timing signals, said gate means being operatively connected with said decoder means and said pulsing means.

22. The apparatus as set forth in claim 18 wherein said pulsing means comprises a plurality of pulsers, each of the pulsers being connected with one of the transducers in the array.

23. The apparatus as set forth in claim 18 further comprising means for processing the electrical signals produced by the transducers upon receiving ultrasonic echoes, said processing means being operatively connected with said array, and display means for displaying an image indicative of acoustially reflective interfaces in an examined object, said display means being operatively connected with said processing means.

24. The apparatus as set forth in claim 18 wherein each of said transducers comprises two tranducer means and electrical means for connecting the two tranducer means whereby the two transducer means operate in unison to convert electrical signals into ultrasonic waves and to convert ultrasonic waves into electrical signals.

25. The apparatus as set forth in claim 24 wherein each of said transducers is divided into two connected parts by a slot extending at least half way through the transducer, each of said connected parts being a transducer means.

26. The apparatus as set forth in claim 24 wherein said each of said two transducer means is a generally rectangular crystal of electro-acoustic material.

27. The apparatus as set forth in claim 17 wherein said preselected position which is indicated by the location signal is the center of the group.

BACKGROUND OF THE INVENTION

The present invention relates to ultrasonic diagnostic equipment. In particular, the invention relates to a hand-held array of ultrasonic transducers which are positioned over the object, such as a human body, to be examined and to the associated signal producing, processing and display equipment which provides the operator with an output indicative of the cross section of the body below the hand-held device. Although ultrasonic diagnostic equipment has been used for several years, the present invention is an improvement over previous units because it has much greater versatility, resolution, and freedom from distortion.

Twice the horizontal resolution of the earlier units is made possible in the present invention by using a unique method of actuating odd and even numbers of transducer elements. This method provides twice as many lines of data for each view of the object examined.

To reduce spurious signals resulting from grating-lobe responses, the present invention uses a novel structure for transducer elements. Each transducer element is divided in half or comprised of two transducer elements coupled in parallel at each transducer element position. This parallel transducer arrangement achieves a significant reduction in spurious responses.

The present invention provides for more precise focusing than previous machines. One way is by allowing the user to select any one of a number of apertures, i.e. select the number of transducer elements which will be pulsed as a group. By making the size of the aperture variable, the present machine has better resolution at both shallow and deep depths. Because pulsing larger numbers of transducer elements per group will produce the best focusing and depth of field at greater depths within the object to be examined, whereas pulsing a relatively small number of transducer elements will produce the best focusing at depths closer to the surface of the object being examined, previous fixed aperture machines are not able to match the present resolution over the full shallow to deep range. Although others have devised transducer probes which actuate different numbers of transducer elements at the same time, for example see U.S. Pat. No. 3,911,730, the invention herein recognizes the relationship between the length (number) of the group of transducer elements pulsed and the focus of the resulting picture at the depth of interest.

Another way in which the focusing is improved is by shaping the transmitted signal from the ultrasonic probe into a generally arc-like wave which converges at the depth of interest by using a number of delay circuits to modify the relative actuation time of each element within the group of transducers being activated in such a manner that each point on the resulting wave front reaches a point at the depth of interest at the same time. U.S. Pat. No. 3,919,683 illustrates the use of delay circuits to help focus the wave front, but unlike the present invention it requires a separate delay circuit for every pair of elements within each group of transducers. The present invention does not use a fixed ratio of delay circuits to elements within the group. Instead it recognizes that a small number of delay circuits which can be programmed for different delay periods can produce the same results with less hardware, i.e. cost.

Analogously, the present invention uses small numbers of programmable delay circuits to bring echo signals received by the transducer elements into coincidence before processing them to form the visual display.

Simplification of the post processing of the echo signals is achieved by using a log compression system. In the log compression system, the amplitudes of the echo signals are transformed into their logarithmic equivalents. This allows the system to handle a wide echodynamic range and reduces the equipment necessary to transform these signals into a video picture. Logarithmic intensity modulation circuits per se are not new, for example see U.S. Pat. No. 3,881,466 which uses logarithmic intensity modulation circuitry in conjunction with an oscilloscope display.

Another unique feature of the present invention is its display format. The display is such that it can be produced on a standard TV screen. This is accomplished first because the invention doubles the number of data lines produced without increasing the number of transducer elements, and second because the interpolation system of the present invention increases the number of data lines still more. In this manner, a small hand-held array, such as one with sixty-four transducer elements, can produce a sufficient number of different data lines to equal the number of raster scan lines being used.

A digital memory for the data allows the picture on the TV screen to be frozen, allows easy interfacing with video tape and photograph equipment, allows instant storage of any image regardless of transducer movement, and allows a variable gray scale display.

Another advantage of the present invention is that it is able to make a split screen presentation of the data. That is to say, part of the screen can be used to show one representation, such as the cross sectional picture of the examined object, and another portion of the screen can be used to produce an ECG signal, an A scan, a time gain compensation curve, time motion, or any one of a number of other related or independent representations. Both displays can then be photographed in a single frame of film with a camera, such as the DELTA-MAT manufactured by Ohio-Nuclear, Inc.

A unique method of dual encoding minimizes hardware required. In the present invention each transducer element requires two enable signals in order to be activated. The same hardware can be used to determine the timing and sequencing and provide a first enable signal to a plurality of elements and the second enable signal to select among this plurality of elements. This reduces the timing and sequencing hardware to a fraction of the hardware needed in a single encoding system.

A PROM based scan generator enables the present invention to select groups of transducer elements which can be activated from left to right, right to left, or most importantly, in a non-sequential manner. By activating the groups in a non-sequential manner, the present invention is able to improve picture quality by reducing spurious echoes and signals from the preceding ultrasonic pulse and decrease the time between actuating subsequent groups. Further, the PROM based scan generator allows the invention to alternate between different modes of activating the transducer elements and group of elements. The invention can alternate between the modes of actuation needed to produce selected displays of the split screen format.

Additionally, the present invention includes an improved display format for one dimensional displays, such as an A scan. The data received by the transducers would normally produce a series of discrete data values which would show up on a cathode ray tube, such as a TV screen, as a series of dots. To overcome this, the present invention includes a further interpolation possessing means which functions to connect the dots and turn the display into a continuous line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate the relationship between the transducer elements and the data line;

FIG. 2 is a diagram of focusing beam paths;

FIG. 3A shows the split transducer element and FIG. 3B the coupled transducer elements;

FIG. 4 is a schematic diagram of the data line interpolation scheme;

FIGS. 5 and 6 are a block diagram of the overall circuit of the preferred embodiment;

FIGS. 7A and 7B are two halves of a more detailed block diagram of the pulser/receiver circuitry of FIG. 5;

FIG. 8 is a block diagram of the analog processor module of FIG. 6;

FIG. 9 is a block diagram of the memory module of FIG. 6;

FIG. 10 is a block diagram of the A-mode/TGC Generator of FIG. 6 and of the interpolator module of FIG. 6;

FIG. 11 is a block diagram of the dot connector of FIG. 6;

FIG. 12 is a block diagram of the post processing steering and composite video steering module of FIG. 6;

FIG. 13 is a block diagram of the digital video control module of FIG. 6; and

FIG. 14 is a block diagram for a test pattern generator.

DESCRIPTION OF THE PREFERRED EMBODIMENT

By way of very basic background, some ultrasonic viewing instruments have an array of transducer elements. This array may be linear, as in the preferred embodiment, or it may take some other form, such as matching the external contour of the object to be examined. The transducer elements, of course, are small crystals which when subject to an electrical impulse can be caused to oscillate at a known frequency, and conversely when the crystals are subject to sound oscilations of the same frequency they will produce small electric