Method and apparatus for visual imaging ultrasonic echo signals utilizing multiple transmitters for reduced specular reflection effects

Claim 2

Apparatus for providing a visual display of ultrasonic echo signals reflected from an object and its internal acoustic heterogeneities comprising a plurality of acoustic transmitters oriented about an object being examined and controllably operated for sequentially generating periodic pulsed ultrasonic frequency pressure wave signals in a liquid medium which are directed at the object from a plurality of directions, means for directing the periodic ultrasonic signals at the object, a plurality of closely spaced simultaneously responsive acoustic detectors arranged in a single row along an axis perpendicular to the centerline axis of the apparatus for detecting uLtrasonic echo signals reflected from the object in response to each periodic ultrasonic signal incident thereon and for converting the detected ultrasonic signals to equivalent electrical signals, acoustic image focussing means for imaging the ultrasonic echo signals onto said acoustic detectors, the centerline axis of the apparatus being defined by the centerline axis of said focussing means and the center of the row of detectors, a like plurality of amplifying means connected to outputs of associated said acoustic detectors for amplifying the electrical signals developed by said detectors, means in communication with outputs of said signal amplifying means for providing a visual display of the detected echo signals wherein each line of the visual display is associated with a corresponding acoustic detector, means in communication with inputs of said acoustic transmitters for generating periodic short duration electrical pulses which sequentially trigger the generation of the periodic pulsed ultrasonic signals from said transmitters and also establishes a periodic zero reference time of operation of said apparatus, and means having an input connected to an output of said periodic short duration electrical pulse generating means and an output connected to inputs of said signal amplifying means for simultaneously gating all of the signal amplifying means periodically on and off at desired time intervals corresponding to the depth of field in the object being examined, each line of the visual display depicting the echo signals reflected from the object and its internal heterogeneities and detected by the associated acoustic detector within the depth of field defined by said gating means whereby the display represents a visualization in depth of a planar slice of the object wherein the slice lies in a plane defined by the centerline axis of the apparatus and the axis of the single row of detectors, the echo signals resulting from the sequential operation of the transmitters and received by said detectors being sequentially displayed on said visual display means wherein the echoes originating from the same points in the object appear at corresponding same points on said visual display means to thereby substantially reduce loss of image resolution due to the effects of specular reflection off the object.

Claim 3

The apparatus set forth in claim 1 and further comprising means connected between an output of said gating means and an input of said visual display means for correcting the visual display to compensate for echo time shifts caused by said transmitters which are located off-axis wherein off-axis is defined as nonaligned with the apparatus centerline axis.

Claim 4

The apparatus set forth in claim 2 wherein said plurality of transmitters are located in a plane perpendicular to the axis of said detectors and containing the centerline axis of the apparatus.

Claim 5

The apparatus set forth in claim 2 wherein said plurality of transmitters are oriented about the object at various angles and substantially equally spaced therefrom.

Claim 6

The apparatus set forth in claim 3 wherein said plurality of transmitters are oriented about the object at various angles and substantially equally spaced therefrom.

Claim 7

The apparatuo set forth in claim 2 wherein said plurality of transmitters are distributed along approximately a 180* arc about the object.

Claim 8

The apparatus set forth in claim 2 wherein said plurality of transmitters are distributed along an arc less than 180* about the object.

Claim 9

The apparatus set forth in claim 2 wherein said plurality of transmitters are distributed in spaced apart relationship along an arc about the object.

Claim 10

The apparatus set forth in claim 8 wherein said plurality of transmitters are distributed in equal spaced apart relationship along the arc.

Claim 11

The apparatus set forth in claim 2 wherein said off-axis compensation means comprises adjustment means for increAsing the sweep speed of said visual display means with increasing off-axis angle of orientation of the transmitters.

Claim 12

The apparatus set forth in claim 2 and further comprising means connected between outputs of said periodic short duration electrical pulse generating means and inputs of said transmitters for correcting the visual display to compensate for echo time shifts caused by said transmitters being nonequidistant from the center of the field of view in the object.

Claim 13

The apparatus set forth in claim 11 wherein said nonequidistant from center compensation means comprises time delay circuits for adjustment of the times between each transmitter pulsing and commencement of the corresponding visual display.

Claim 14

The apparatus set forth in claim 1 wherein said ultrasonic signal directing means consists of said transmitters being oriented such that the outputs thereof are directed toward the object being examined whereby the sequentially generated pulsed ultrasonic signals propagate directly from said transmitters to the object.

Claim 15

The apparatus set forth in claim 1 wherein said acoustic image focussing means is a plurality of concave type acoustic reflectors equAl in number to the plurality of transmitters, each reflector associated with a corresponding transmitter and aligned with the centerline axis of signal propagation therefrom, said ultrasonic signal directing means consists of said acoustic reflectors and the outputs of said transmitters being directed toward said acoustic reflectors whereby the generated pulsed ultrasonic signals propagate from said transmitters to said acoustic reflectors and are reflected therefrom toward the object being examined.

Claim 16

The apparatus set forth in claim 2 wherein said acoustic image focussing means is of the reflective concave type and is aligned with the centerline axis of the apparatus whereby the ultrasonic echo signals are reflected from said acoustic image focussing means for imaging onto said acoustic detectors.

Claim 17

The apparatus set forth in claim 1 wherein said acoustic image focussing means consists of a converging type acoustic lens positioned between said acoustic detectors and the object being examined and aligned with the centerline axis of the apparatus.

Claim 18

The apparatus set forth in claim 1 wherein said acoustic image focussing means consists of a concave type acoustic reflector aligned with the centerline axis of the apparatus, said acoustic detectors positioned between said acoustic reflector and the object being examined and spaced from said reflector beyond the focal point thereof.

Claim 19

The apparatus set forth in claim 1 and further comprising means connected between outputs of said amplifying means and an input of said visual display means for temporarily storing the amplified electrical signals, and means in communication with said gating means for periodically generating sequential signals which are applied to said signal storage means to provide periodic sequential read-out of the amplified electrical signals to said visual display means to thereby develop the image on said visual display means wherein serial scans are formed and intensity modulated by the echo signals resulting from the sequential operation of the transmitters.

Claim 20

The apparatus set forth in claim 18 wherein said visual display means is a cathode ray tube.

Claim 21

The apparatus set forth in claim 18 wherein said visual display means is a cathode ray tube provided with a single signal input connected to a common output of said signal storage means.

Claim 22

The apparatus set forth in claim 1 wherein said visual display means is a parallel input device having a like plurality of inputs connected respectively to separate outputs of said amplifying means whereby the outputs of said amplifying means are simultaneously applied to the plurality of inputs of said visual display means.

Claim 23

The apparatus set forth in claim 21 wherein said visual dispLay means is a multi-input cathode ray tube wherein the sweep lines are simultaneously generated to thereby provide a more rapid display of the detected echo signals.

Claim 24

The apparatus set forth in claim 21 wherein said visual display means is a plasma display panel containing an array of rows and columns of gas discharge devices, the gas discharge devices being connected row-by-row respectively with the outputs of said amplifying means, and the columns being sequentially energized by signals generated in a range timing circuit triggered by said gating means.

Claim 25

The apparatus set forth in claim 21 wherein said visual display means is an array of rows and columns of liquid crystals, the crystals being connected row-by-row respectively with the outputs of said amplifying means, and the columns being sequentially energized by signals generated in a range timing circuit triggered by said gating means.

Claim 26

The apparatus set forth in claim 21 wherein said visual display means is an array of rows and columns of light emitting diodes, the diodes being connected row-by-row respectively with the outputs of said amplifying means, and the columns being sequentially energized by signals generated in a range timing circuit triggered by said gating means.

Claim 27

The apparatus set forth in claim 1 wherein said acoustic transmitters, said acoustic detectors and the object being examined are immersed in the liquid medium.

Claim 28

The apparatus set forth in claim 1 wherein said plurality of acoustic detectors are of number in the range of 20 to 1,000.

Claim 29

The apparatus set forth in claim 1 wherein said acoustic transmitters are piezoelectric transducers for converting electrical exciting waves into equivalent ultrasonic pressure waves in the liquid medium in which said transmitters, detectors and object being examined are positioned.

Claim 30

The apparatus set forth in claim 1 wherein said acoustic transmitters and detectors are each piezoelectric transducers, the minimum spacing between adjacent acoustic detectors is one half the wavelength of the ultrasonic signal in the liquid medium.

Claim 31

The apparatus set forth in claim 29 wherein said acoustic detectors are equally spaced apart.

Claim 32

The apparatus set forth in claim 14 wherein said row of acoustic detectors are spaced approximately mid-way between a center-most of said acoustic reflectors and the object being examined.

Claim 33

The apparatus set forth in claim 1 wherein the wavefront pattern of periodic ultrasonic pressure wave signals generated by said acoustic transmitters is sufficiently broad to illuminate the entire object being examined, and the periodic short duration electrical pulses are repeated approximately every 10 milliseconds and a complete display period rate of slightly less than 15 per second does not present a flicker problem since each complete display is a plurality of frames forming a composite of the visual displays resulting from a sequential operation of the plurality of transmitters.

Claim 34

Apparatus for providing a visual display of an object undergoing motion and its internal acoustic heterogeneities by means of ultrasonic echo signals reflected therefrom and comprising a plurality of acoustic transmitters controllably operated for sequentially generating periodic pulsed ultrasonic frequency pressure wave signals in a liquid medium which are directed at an object being examined from a plurality of directions, the wavefront pattern of each ultrasonic signal being sufficiently broad to be incident on the entire area of interest on the object being examined, a plurality of at least 20 closely spaced acoustic detectors arranged in a single row within the liquid medium along an axis perpendicular to the centerline axis of the apparatus, said detectors being simultaneously responsive for detecting ultrasonic echo signals periodically reflected from the object in response to the periodic generated ultrasonic sIgnals incident thereon and for converting the detected ultrasonic echo signals to equivalent periodic electrical signals, each detector being sensitive to a broad ultrasonic pressure wavefront pattern to thereby receive multidirectional reflections from a particular echo producing region in the object being examined, a concave acoustic reflector located within the liquid medium and aligned with the center of the row of detectors which together determine the centerline axis of the apparatus, said detectors located between said acoustic reflector and the object being examined, said transmitters oriented in an arc extending partially around the object in a plane perpendicular to the axis of the row of detectors and including the centerline axis of the apparatus, a like plurality of amplifiers connected to outputs of associated said acoustic detectors for amplifying the electrical signals developed by said detectors, means in communication with outputs of said amplifiers for providing a visual display of the detected ultrasonic echo signals, an electronic synchronizing generator for periodically generating short duration electrical pulses which inititate the periodic operation of said ultrasonic transmitters and also establishes a periodic zero reference time of operation of said apparatus, means in communication with an output of said synchronizing generator for sequencing the operation of said transmitters in accordance with a particular logic, an electronic range gating pulse generator having an input connected to an output of said synchronizing generator and a first output connected to inputs of said amplifiers for simultaneously gating all of the amplifiers periodically on and off at the repetition rate of generation of the short duration electrical pulses, the gating on time corresponding to the range of the object being examined and the time interval between gating on and gating off corresponding to the depth of field in the object being examined to thereby obtain a time domain discrimination of the ultrasonic echo signals, a second output of said range gating pulse generator providing a periodic synchronizing signal to a sweep generator which provides the scan input to said visual display means, said sweep generator further provided with an input from an output of said transmitter operation sequencing means, each scan line of the visual display depicting the superimposed echo signals resulting from the sequential operation of the transmitters and detected by an associated acoustic detector within the depth of field defined by said range gating pulse generator whereby the display represents a moving visualization in depth of a planar slice of the object while it is undergoing motion whrein the slice lines in a plane defined by the centerline axis of the apparatus and the axis of the single row of detectors, and means for adjusting the sweep speed of said sweep generator in accordance with the orientation of each transmitter located off the centerline axis of the apparatus to thereby compensate for echo time shifts on the visual display caused by the off-axis transmitters.

Claim 35

Apparatus for providing a visual display of an object undergoing motion and its internal acoustic heterogeneities by means of ultrasonic echo signals reflected therefrom and comprising a plurality of acoustic transmitters controllably operated for sequentially generating periodic pulsed ultrasonic frequency pressure wave signals in a liquid medium which are directed at an object being examined from a plurality of directions, the wavefront pattern of each ultrasonic signal being sufficiently broad to be incident on the entire area of interest on the object being examined, a plurality of at least 20 closely spaced acoustic detectors arranged in a single row within the liquid medium along an axis perpendicular to the centerline axis of the apparatus, said detectors being simultaneously responsive for detecting ultrasonic echo signals periodically reflected from the object in response to the periodic generated ultrasonic sIgnals incident thereon and for converting the detected ultrasonic echo signals to equivalent periodic electrical signals, each detector being sensitive to a broad ultrasonic pressure wavefront pattern to thereby receive multidirectional reflections from a particular echo producing region in the object being examined, a concave acoustic reflector located within the liquid medium and aligned with the center of the row of detectors which together determine the centerline axis of the apparatus, said detectors located between said acoustic reflector and the object being examined, said transmitters oriented in an arc extending partially around the object in a plane perpendicular to the axis of the row of detectors and including the centerline axis of the apparatus, a like plurality of amplifiers connected to outputs of associated said acoustic detectors for amplifying the electrical signals developed by said detectors, means in communication with outputs of said amplifiers for providing a visual display of the detected ultrasonic echo signals, an electronic synchronizing generator for periodically generating short duration electrical pulses which inititate the periodic operation of said ultrasonic transmitters and also establishes a periodic zero reference time of operation of said apparatus, means in communication with an output of said synchronizing generator for sequencing the operation of said transmitters in accordance with a particular logic, an electronic range gating pulse generator having an input connected to an output of said synchronizing generator and a first output connected to inputs of said amplifiers for simultaneously gating all of the amplifiers periodically on and off at the repetition rate of generation of the short duration electrical pulses, the gating on time corresponding to the range of the object being examined and the time interval between gating on and gating off corresponding to the depth of field in the object being examined to thereby obtain a time domain discrimination of the ultrasonic echo signals, a second output of said range gating pulse generator providing a periodic synchronizing signal to a sweep generator which provides the scan input to said visual display means, said sweep generator further provided with an input from an output of said transmitter operation sequencing means, each scan line of the visual display depicting the superimposed echo signals resulting from the sequential operation of the transmitters and detected by an associated acoustic detector within the depth of field defined by said range gating pulse generator whereby the display represents a moving visualization in depth of a planar slice of the object while it is undergoing motion whrein the slice lines in a plane defined by the centerline axis of the apparatus and the axis of the single row of detectors, and means for adjusting the sweep speed of said sweep generator in accordance with the orientation of each transmitter located off the centerline axis of the apparatus to thereby compensate for echo time shifts on the visual display caused by the off-axis transmitters.

Claim 36

The apparatus set forth in claim 33 and furthter comprising memory means connected between outputs of said amplifiers and a single signal input of said visual display means for temporarily storing the amplified electrical signals, the output of said range gating pulse generator providing the gating on and gating off signals to said memory means whereby the amplifiers may be continually responsive, and means having an input in communication with an output of said range gating pulse generator and having outputs connected to inputs of said memory means for periodically generating signals for sequentially reading out the memory means and thereby serially supplying the read out amplified electrical signals to the single signal input of said visual display means, said visual display means being a serial input device.

Claim 37

The apparatus set forth in claim 33 Wherein said visual display means being a parallel input device having a like plurality of signal inputs connected to the outputs of associated said amplifiers, the periodic synchronizing signal from the second output of said range gating pulse generator providing a simultaneous synchronization of all the scan lines on said visual display means with the gating on of said amplifiers.

Claim 40

The method set forth in claim 36 and further comprising the steps of temporarily storing the amplified electrical signals prior to supplying them to the visual display device, and sequentially reading out the stored amplified electrical signals and serially supplying them to a single signal input of the visual display device which is of a serial input type, the periodic sweep speed signals supplied to the scan input of the visual display device providing synchronization of a line-by-line scan On thhe visual display device with the sequential reading out of the stored amplified electrical signals.

Claim 41

The method set forth in claim 36 wherein the step of supplying the amplified electrical44 signals to the visual display device consists of simultaneously supplying the outputs of the amplifiers to a plurality of signal inputs of the visual display device equal in number to the number of acoustic detectors In response to the gating on of the amplifiers, the periodic sweep speed signals supplied to the scan input of the visual display device which is of a parallel input type provides simultaneous synchronization of all the scan line on the visual display with the gating on of the amplifiers.

Claim 42

The method set forth in claim 36 and further comprising the step of increasing the resolution of the display on the visual display device along a vertical direction corresponding to the axis of the single row of acoustic detectors by more closely spacing of adjacent detectors, the limit of spacing being half a wavelength of the ultrasonic pressure wave signal in the liquid medium, and increasing the resolution of the display along a horizontal direction corresponding to the depth of field in the object being examined by utilizing a higher frequency of the ultrasonic frequency of excitation of the acoustic transmitter, the ultrasonic frequency being in a range of 1 to 10 megahertz.