(12) United States Patent
`Berman et al.
`
`USOO6315724B1
`(10) Patent No.:
`US 6,315,724 B1
`(45) Date of Patent:
`Nov. 13, 2001
`
`(54) 3-DIMENSIONAL ULTRASONIC IMAGING
`
`(75) Inventors: Michael Berman, Har Adar (IL);
`James Gessert, Colorado Springs;
`Wayne Moore, Lyons, both of CO
`(US); Rachel Nechushtai, Motza Elit
`(IL); Hillel Rom, Bet Zait (IL); Ziv
`Soferman, Givatayim (IL)
`(73) Assignee: Biomedicom LTD, Jerusalem (IL)
`
`5,764,014
`5,817,022
`5,836,869
`5,875.257
`
`6/1998 Jakeway et al. ..................... 318/587
`10/1998 Vesely .................................. 600/443
`11/1998 Kudo et al. ..
`600/173
`2/1999 Marrin et al. ........................ 382/107
`OTHER PUBLICATIONS
`
`c:
`
`s
`
`“Efficient Ray Tracing of Volume Data”, M. Levoy, ACM
`Transactions on Graphics, vol. 9, No. 3, pp. 245-261, 1990.
`AC3C61-“Curved Array General Imaging Scanhead”,
`Specifications, Acoustic Research Systems, Inc., Longmont,
`Colorado. 1999.
`(*) Notice: Substylisher's Sonora Medical Systems, “RT 3200 Advantage II Ultra
`p
`sound System for Obstetrics and Gynecology”, 1999.
`U.S.C. 154(b) by 0 days.
`Rafael “Two-Axis Angular-Rate Gyro-System Descrip
`(21) Appl. No.: 09/421,046
`tion', Haifa, Israel.
`(22) Filed:
`Oct. 19, 1999
`Primary Examiner Francis J Jaworski
`(74) Attorney, Agent, or Firm Abelman, Frayne &
`(51) Int. Cl." .................................................... A61B 8/00
`Schwab
`(52) U.S. Cl. ........................... 600/443; 128/916; 600/459
`5
`(58) Field of Search ..................................... 600,437,443,
`(57)
`600/447, 459; 128/916
`An ultraSonic imaging System including a probe containing
`at least one ultraSonic transducer and at least one inertial
`References Cited
`Sensor as well as electronic circuitry connected to the probe
`U.S. PATENT DOCUMENTS
`for causing the at least one ultraSonic transducer to transmit
`ultraSonic energy into a region and to receive reflected
`7/1984 Ahn et al. .............................. 73/652
`4,458,536
`ultraSonic energy therefrom, creating a plurality of generally
`E. 3.9. st et al, al.
`"136. two-dimensional imageS whose geometrical relationship is
`5,039,035
`8/1991 Fitzpatrick .....
`... 224f122
`indicated by outputs from the at least one inertial sensor.
`5,071,160
`12/1991 White et al. ...
`... 280/735
`5,398,691
`3/1995 Martin et al. ................... 128/662.06
`
`ABSTRACT
`
`(56)
`
`2 - - 12
`
`Olea e a
`
`-
`
`35 Claims, 10 Drawing Sheets
`
`132
`
`RACK BAL
`CONTROLLER
`
`EXISTING SYSTEMTTTT -
`
`106
`WIDEO
`MONITOR -1.
`
`PRINTER
`
`134
`
`VIDEO SWCHNC
`
`IMAGE OUTPU
`SYSTEM
`ELECTRONICS
`
`
`
`
`
`
`
`- - - - - - - - - - - - - - -
`114
`116
`f
`SWITCH
`
`
`
`INERTIA
`SENSOR
`
`INERTIAL PROBE
`ASSEMBLY
`
`3D IMAGE
`CENERATOR
`
`CARTESIAN IMAGE
`VOLUME ARRAY
`130-
`E WOME
`VISUALIZER
`
`------------
`
`3D IMAGING
`
`-
`
`3SHAPE EXHIBIT 2004
`Exocad v. 3Shape
`IPR2018-00785
`
`

`

`U.S. Patent
`
`Nov. 13, 2001
`
`Sheet 1 of 10
`
`US 6,315,724 B1
`
`- - - - - - - - - - - - - - -
`EXISTING SYSTEM
`
`F.G. 1
`
`132
`
`VIDEO
`MONTOR
`
`106
`
`108
`
`WCR
`
`110
`PAGE
`PRINTER
`
`IMAGE OUTPUT
`
`SYSTEM
`ELECTRONICS
`
`TRACK BALL
`CONTROLLER
`
`124
`ST
`
`um am am m air - - - as
`
`VIDEO CAPTURE)
`
`CARTESLAN MAGE
`VOLUME ARRAY
`
`INERTIAL PROBE
`ASSEMBLY
`
`N
`112
`
`-
`3D IMAGING
`-------------- |-
`
`
`
`
`
`
`
`
`
`
`
`

`

`U.S. Patent
`US. Patent
`
`Nov. 13, 2001
`
`Sheet 2 of 10
`
`US 6,315,724 B1
`US 6,315,724 B1
`
`02530;
`
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`m_Mi_2_m_02359:_s182%.$2ZOEMEO"29:22
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`
`
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`
`
`
`
`
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`
`
`
`
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`
`

`

`U.S. Patent
`US. Patent
`
`Nov. 13, 2001
`Nov. 13, 2001
`
`Sheet 3 of 10
`Sheet 3 0f 10
`
`US 6,315,724 B1
`US 6,315,724 B1
`
`
`
`
`
`

`

`U.S. Patent
`
`Nov. 13, 2001
`
`Sheet 4 of 10
`
`US 6,315,724 B1
`
`F.G. 5
`
`POSITION ULTRASONIC MAGING
`PROBE ASSEMBLY 1 12 WITH INTEGRATED
`ANGLE TRACKER 204 TO PREPARE
`FOR 3D ACQUISITION
`
`
`
`PRESS SWITCH 206 ON PROBE, WAIT FOR
`LED 208 AND ROTATE PROBE ABOUT FIXED
`AXIS THROUGH A DESIRED RANGE
`
`IN PARALLEL DURING ROTATION
`
`- -
`
`- - - - - - - - - - - - - - - - - - - - - - - - - - -
`
`- -
`
`- -
`
`
`
`ACQUIRE 2D IMAGES
`
`
`
`
`
`
`
`
`
`
`
`- - - - - - - - - - -
`
`INTEGRATE ANGULAR VELOCITIES
`DERVED FROM TRACKER 204 AND
`OBTAIN RELATIVE
`ANGULAR POSITION
`
`
`
`
`
`TAG 2D IMAGE WITH RELATIVE
`ANGULAR POSITION AND SAVE
`IN A BUFFER
`
`PRESS SWITCH AGAIN TO
`STOP "3D" ACQUISITION
`
`EMBED TAGGED 2D IMAGES IN
`3D VOLUME
`
`SELECT VOLUME OF INTEREST FROM ARRAY
`
`GENERATE WIDEO IMAGE OF WOLUME
`RENDERED FROM SELECTED VIEWPOINT
`
`

`

`U.S. Patent
`
`Nov. 13, 2001
`
`Sheet 5 of 10
`
`US 6,315,724 B1
`
`F.G. 6
`(PRIOR ART)
`
`SELECT SUBSET OF 128 TRANSDUCER
`ELEMENTS VIA MULTIPLEXING ELECTRONICS
`
`PULSE SELECTED TRANSDUCER
`ELEMENTS WITH APPROPRIATE DELAYS
`TO FORM A FOCUSED ACOUSTIC BEAM
`
`AMPLIFY RECEIVED ECHOES DELAY AND SUM TO
`FORM A LINE OF FOCUSED ACOUSTIC DATA
`
`DIGITALLY SAMPLE THE RECEIVED LINE OF
`INFORMATION AND SAVE IN BUFFER
`
`SELECT ANOTHER SUBSET OF 128
`TRANSDUCER ELEMENTS TO MOVE THE
`"BEAM" TO A NEW DIRECTION AND REPEAT
`TRANSMIT/RECEIVER CYCLE
`
`REPEAT THE ABOVE STEPS UNTIL 128 LINES
`OF DATA ARE COLLECTED, SUFFICIENT
`TO FORM A 2D IMAGE
`
`SCAN CONVERT THE 128 LINES OF ACOUSTIC
`DATA INTO A 2D WIDEO IMAGE
`
`
`
`CAPTURE 2D IMAGES
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`

`

`U.S. Patent
`
`Nov. 13, 2001
`
`Sheet 6 of 10
`
`US 6,315,724 B1
`
`FIG. 7
`
`INPUT: 2D IMAGES AGGED
`WITH RELATIVE ANGULAR POSITION
`
`FOR EACH VOXEL IN THE 3D
`CARTESIAN GRID OF THE VOLUMETRIC
`OUTPUT IMAGE IN THE DOMAIN
`COVERED BY THE FAN:
`
`INTERPOLATING IMAGE VALUES FOR THE WOXEL
`FROM THE STORED 2D IMAGES WHOSE PLANES
`ARE CLOSEST TO THE WOXEL
`
`
`
`
`
`
`
`OUTPUT: VOLUMETRIC IMAGE IN CARTESIAN COORDINATES
`
`

`

`U.S. Patent
`US. Patent
`
`US 6,315,724 B1
`US 6,315,724 B1
`
`
`
`
`
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`
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`
`

`

`U.S. Patent
`US. Patent
`
`Nov. 13, 2001
`Nov. 13, 2001
`
`Sheet 8 of 10
`Sheet 8 0f 10
`
`US 6,315,724 B1
`US 6,315,724 B1
`
`
`
`
`
`3L]—E
`
`LL
`li
`O
`v S, S2
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`LLJU
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`

`

`U.S. Patent
`
`Nov. 13, 2001
`
`Sheet 9 of 10
`
`US 6,315,724 B1
`
`FG.
`
`11
`
`POSITION ULTRASONIC IMAGING
`PROBE ASSEMBLY 112 WITH INTEGRATED
`MULTI DEGREE OF FREEDOM
`TRACKER 304 TO PREPARE
`FOR 3D ACQUISITION
`
`
`
`
`
`
`
`PRESS SWITCH 306 ON PROBE, WAIT FOR
`LED 308 AND MOVE PROBE
`ALONG A DESIRED
`IMAGE ACQUISTION PATH
`
`- -
`-
`-
`- -
`- - - - - - - -
`IN PARALLEL DURING
`PROBE ASSEMBLY MOTION
`
`
`
`ACQUIRE 2D IMAGES
`
`
`
`
`
`- - - - - - - - - - -
`
`EMPLOY POSITION INFORMATION
`DERVED FROM TRACKER 304
`TO OBTAIN RELATIVE POSITION
`
`
`
`
`
`TAG 2D IMAGE WITH RELATIVE
`POSITION AND SAVE
`IN A BUFFER
`
`
`
`PRESS SWITCH ACAIN TO
`STOP "3D" ACQUISTION
`
`EMBED TAGGED 2D IMAGES IN
`3D VOLUME
`
`SELECT VOLUME OF INTEREST FROM ARRAY
`
`CENERATE WIDEO IMAGE OF VOLUME
`RENDERED FROM SELECTED WIEWPOINT
`
`

`

`U.S. Patent
`
`Nov. 13, 2001
`
`Sheet 10 Of 10
`
`US 6,315,724 B1
`
`F.G. 12
`
`INPUT: 2D IMAGES TAGGED
`WITH RELATIVE POSITION
`
`----------------------------
`CALCULATE DISTANCE BETWEEN THE WOXEL AND EACH
`OF THE IMAGE PLANES
`
`
`
`
`
`
`
`
`
`CONSIDER ALL N
`PLANES WHOSE
`DISTANCE TO THE
`VOXEL S LESS THAN
`A THRESHOLD. IS THERE
`AT LEAST ONE
`
`NO
`
`SET VOXEL VALUE
`TO BE ZERO
`
`FOR EACH SUCH PLANE, FIND
`THE PROJECTION OF THE VOXEL
`ON THE PLANE
`
`YES
`
`LET THE DISTANCE
`OF THE VOXEL TO THE i-TH PLANE
`BED AND THE PROJECTION OF
`THE VOXEL ON THE PLANE BEAT
`THE COORDINATES (X,Y);
`
`
`
`
`
`
`
`DETERMINE THE WALUE V AT EACH
`PROJECTION (XY). BY BLINEAR
`INTERPOLATION
`
`DEFINED AS THE
`SUM OF ALL DISTANCES Di,
`i=1,2,5,...,N
`
`CALCULATE VOXEL VALUE V
`SUM OVER ALL i=1,2,...,N OF
`
`OUTPUT: VOLUMETRIC IMAGE
`
`

`

`1
`3-DIMENSIONAL ULTRASONIC IMAGING
`
`US 6,315,724 B1
`
`2
`Additionally or alternatively the inertial Sensor includes a
`micro-mechanical device. Furthermore, the inertial Sensor
`may also include a Sensor employing the Coriolis force.
`Additionally in accordance with a preferred embodiment
`of the present invention the gyroscope is capable of Sensing
`Velocity having one angular degree of freedom.
`Further in accordance with a preferred embodiment of the
`present invention the gyroscope is capable of Sensing motion
`having more than one degree of freedom.
`Preferably the micro-mechanical device is capable of
`Sensing motion having one degree of freedom. Additionally
`the micro-mechanical device is capable of Sensing Velocity
`having one angular degree of freedom. Preferably the micro
`mechanical device is capable of Sensing motion having more
`than one degree of freedom.
`Still further in accordance with a preferred embodiment of
`the present invention the inertial Sensor is capable of Sensing
`motion having one degree of freedom. Additionally the
`Sensor is capable of Sensing Velocity having one angular
`degree of freedom. Preferably the sensor is capable of
`Sensing motion having more than one degree of freedom.
`Still further in accordance with a preferred embodiment of
`the present invention the electronic circuitry includes video
`capture circuitry for capturing individual two-dimensional
`Video images and an image organizer, combining the indi
`vidual two-dimensional Video images into a three
`dimensional image based on information from the at least
`one inertial Sensor.
`Additionally in accordance with a preferred embodiment
`of the present invention the electronic circuitry includes
`Video capture circuitry for capturing a time Series of two
`dimensional Video images of a Video Stream and an image
`organizer, combining the individual two-dimensional video
`images into a three-dimensional image based on information
`from the at least one inertial Sensor.
`Further in accordance with a preferred embodiment of the
`present invention the electronic circuitry includes Video
`capture circuitry for capturing individual two-dimensional
`Video images, an image organizer, combining the individual
`two-dimensional Video images into a three-dimensional
`image based on information from the at least one inertial
`Sensor, and a three-dimensional visualizer receiving an
`output from the image organizer and providing a human
`Sensible three dimensional image.
`Still further in accordance with a preferred embodiment of
`the present invention the electronic circuitry includes video
`capture circuitry for capturing a time Series of two
`dimensional Video images of a Video stream, an image
`organizer, combining the individual two-dimensional video
`images into a three-dimensional image based on information
`from the at least one inertial Sensor, and a three-dimensional
`Visualizer receiving an output from Said image organizer and
`providing a human Sensible three dimensional image.
`Additionally in accordance with a preferred embodiment
`of the present invention the electronic circuitry includes
`circuitry for receiving information representing individual
`two-dimensional ultraSonic images and combining the indi
`vidual two-dimensional ultraSonic images into a three
`dimensional image based on information from the at least
`one inertial Sensor.
`Preferably the electronic circuitry creates the three
`dimensional image by interpolating image values from the
`individual two-dimensional ultraSonic images.
`Additionally in accordance with a preferred embodiment
`of the present invention, the ultrasonic imaging System also
`
`FIELD OF THE INVENTION
`The present invention relates to ultraSonic imaging gen
`erally and more particularly to three-dimensional ultrasonic
`imaging using conventional two-dimensional ultraSonic
`imaging apparatus.
`BACKGROUND OF THE INVENTION
`There exists a variety of two-dimensional ultraSonic
`imaging apparatus. Such apparatus is used in various medi
`cal disciplines, Such as cardiology, radiology and obstetrics.
`In the field of obstetrics, apparatus having a very large
`installed base in the U.S.A. is the General Electric Model
`GE-3200. Other two-dimensional ultraSonic imaging appa
`ratus is commercially available inter alia from ATL, a
`subsidiary of Phillips, Acuson, Toshiba Ultrasound, Siemens
`Ultrasound and Hewlett-Packard Ultrasound.
`Three-dimensional ultraSonic imaging apparatus is also
`known and commercially available from 3-D Ultrasound
`Inc. of North Carolina, U.S.A.
`Various mechanisms have been employed in an attempt to
`retrofit conventional two-dimensional ultrasonic imaging
`apparatus for use in providing three-dimensional ultraSonic
`images. These include, for example:
`mechanical assemblies which constrain the motion of the
`ultraSonic probe and measure its position using rotary
`position encoders,
`electromagnetic position Sensors which require an exter
`nal field generator in the vicinity of the patient;
`optical position Sensors which require mounting of cam
`eras in the vicinity of the patient;
`acoustic position Sensors which require transducers to be
`mounted onto the patient; and
`motor assemblies which move at least part of the probe at
`a constant rate which allows image position and ori
`entation to have a fixed relationship to timing.
`The following U.S. Patents are believed to be relevant to
`the general field of the present invention: U.S. Pat. Nos.
`5,817,022; 5,398,691; and 4,932,414.
`SUMMARY OF THE INVENTION
`The present invention Seeks to provide an ultrasonic
`imaging probe and an ultrasonic imaging System which
`provides three-dimensional imaging and which is character
`ized by Simplicity of construction and operation and rela
`tively low cost. The System may be implemented in original
`equipment or as a retrofit to existing equipment having only
`two-dimensional imaging capabilities.
`There is thus provided in accordance with a preferred
`embodiment of the present invention a retrofit ultrasonic
`imaging System including an ultraSonic imaging System
`comprising a probe including at least one ultraSonic
`transducer, and at least one inertial Sensor, and electronic
`circuitry connected to the probe for causing the at least one
`ultraSonic transducer to transmit ultrasonic energy into a
`region and to receive reflected ultrasonic energy therefrom,
`creating a plurality of generally two-dimensional images
`whose geometrical relationship is indicated by outputs from
`the at least one inertial Sensor.
`Further in accordance with a preferred embodiment of the
`present invention the inertial Sensor includes a gyroscope.
`Still further in accordance with a preferred embodiment of
`the present invention the gyroscope is capable of Sensing
`motion having one degree of freedom.
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`

`3
`includes an operator actuated Switch for Selectably operating
`Said at least one inertial Sensor. Preferably the imaging
`System also includes an operator Sensible indicator indicat
`ing operation of the at least one inertial Sensor.
`There is also provided in accordance with another pre
`ferred embodiment of the present invention an ultrasonic
`imaging System including a probe comprising at least one
`ultraSonic transducer, and at least one Sensor which does not
`require provision of a reference external thereto, and elec
`tronic circuitry connected to the probe for causing the at
`least one ultraSonic transducer to transmit ultraSonic energy
`into a region and to receive reflected ultrasonic energy
`therefrom, creating a plurality of generally two-dimensional
`images whose geometrical relationship is indicated by out
`puts from the at least one Sensor.
`There is further provided in accordance with yet another
`preferred embodiment of the present invention a probe
`assembly for use in an ultraSonic imaging System and
`including at least one ultraSonic transducer, and at least one
`inertial Sensor.
`Further in accordance with a preferred embodiment of the
`present invention the at least one inertial Sensor comprises a
`gyroscope capable of Sensing motion having one degree of
`freedom.
`Still further in accordance with a preferred embodiment of
`the present invention the gyroscope is capable of Sensing
`motion having more than one degree of freedom.
`Additionally in accordance with a preferred embodiment
`of the present invention the probe also includes electronic
`circuitry creating a plurality of generally two-dimensional
`images whose geometrical relationship is indicated by out
`puts from the at least one inertial Sensor.
`Preferably the electronic circuitry includes video capture
`circuitry for capturing individual two-dimensional video
`images, an image organizer, combining the individual two
`dimensional Video images into a three-dimensional image
`based on information from Said at least one inertial Sensor,
`and a three-dimensional visualizer receiving an output from
`Said image organizer and providing a human Sensible three
`dimensional image.
`Further in accordance with a preferred embodiment of the
`present invention the electronic circuitry includes circuitry
`for receiving information representing individual two
`dimensional ultraSonic images and combining the individual
`two-dimensional ultraSonic images into a three-dimensional
`image based on information from the at least one inertial
`SCSO.
`Still further in accordance with a preferred embodiment of
`the present invention the a probe assembly also includes an
`operator actuated Switch for Selectably operating the at least
`one inertial sensor. Preferably the operator sensible indicator
`indicating operation of Said at least one inertial Sensor.
`There is also provided in accordance with yet another
`preferred embodiment of the present invention a method for
`providing ultraSonic imaging including the Steps of provid
`ing a probe including an ultraSonic transducer and at least
`one inertial Sensor, causing the ultraSonic transducer to
`transmit ultraSonic energy into a region and to receive
`reflected ultraSonic energy therefrom, creating a plurality of
`generally two-dimensional images, and determining a Spa
`tial relationship between the plurality of two-dimensional
`images using outputs from the at least one inertial Sensor.
`Further in accordance with a preferred embodiment of the
`present invention the Step of causing includes the Step of
`rotating the probe about a generally fixed axis at a location
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`US 6,315,724 B1
`
`4
`of interest, thereby producing a plurality of generally two
`dimensional images lying in planes which interSect at the
`axis and whose relative orientations are known from outputs
`of the at least one inertial Sensor.
`Still further in accordance with a preferred embodiment of
`the present invention the method also includes the Steps of
`capturing individual two-dimensional Video images and
`combining the individual two-dimensional Video images
`into a three-dimensional image based on information from
`the at least one inertial Sensor.
`Additionally in accordance with a preferred embodiment
`of the present invention the method also includes the Steps
`of receiving information representing individual two
`dimensional ultraSonic images and combining the individual
`two-dimensional ultraSonic images into a three-dimensional
`image based on information from the at least one inertial
`SCSO.
`Further in accordance with a preferred embodiment of the
`present invention the method also includes operator actua
`tion of a Switch for Selectably operating the at least one
`inertial sensor. Preferably the method also includes provid
`ing a visual indication of operation of Said at least one
`inertial Sensor.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`The present invention will be understood and appreciated
`more fully from the following detailed description taken in
`conjunction with the drawings in which:
`FIG. 1 is a simplified block diagram illustration of a
`retrofit ultraSonic imaging System constructed and operative
`in accordance with one preferred embodiment of the present
`invention;
`FIG. 2 is a simplified block diagram illustration of a probe
`assembly forming part of the embodiment of FIG. 1;
`FIG. 3 is a simplified pictorial illustration of the probe
`assembly of FIG. 2;
`FIG. 4 is a Sectional illustration of a coaxial cable forming
`part of the probe assembly of FIG. 3, taken along lines
`IV -IV in FIG. 3;
`FIG. 5 is a simplified flow chart illustration of three
`dimensional data acquisition in the embodiment of FIGS.
`1-4;
`FIG. 6 is a simplified flow chart illustration of a two
`dimensional image acquisition Step shown in the flow chart
`of FIG. 5;
`FIG. 7 is a simplified flow chart illustration of an embed
`ding step shown in the flow chart of FIG. 5;
`FIG. 8 is a simplified block diagram illustration of a probe
`assembly forming part of the System of FIG. 1 in accordance
`with an alternative embodiment of the present invention;
`FIG. 9 is a simplified pictorial illustration of the probe
`assembly of FIG. 8;
`FIG. 10 is a sectional illustration of a coaxial cable
`forming part of the probe assembly of FIG. 8, taken along
`lines X-X in FIG.8;
`FIG. 11 is a simplified flow chart illustration of three
`dimensional data acquisition in the embodiment of FIGS.
`8–10; and
`FIG. 12 is a simplified flow chart illustration of an
`embedding step shown in the flow chart of FIG. 11.
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`Reference is now made to FIG. 1, which is a simplified
`block diagram illustration of an ultrasonic imaging System
`
`

`

`S
`constructed and operative in accordance with a preferred
`embodiment of the present invention. The system may be
`implemented in original equipment or as a retrofit to existing
`equipment having only two-dimensional imaging capabili
`ties. An example of a retrofit existing System is described
`hereinbelow with the understanding that the present inven
`tion applies equally to a non-retrofit implementation.
`AS Seen in FIG. 1, an existing System, typically a Model
`GE 3200 manufactured by General Electric Company of the
`U.S.A. or an UltraMark 4+ or HDI Series, both manufac
`tured by ATL Inc. of Seattle, Wash., U.S.A., is provided and
`includes conventional System electronics 100, comprising a
`transducer interface port 102 and an image output port 104.
`A video monitor 106, a VCR 108 and a page printer 110 are
`typically coupled to the image output port 104.
`In accordance with a preferred embodiment of the present
`invention, in place of a conventional ultraSonic probe
`assembly, there is provided and coupled to port 102 an
`inertial probe assembly 112, constructed and operative in
`accordance with a preferred embodiment of the present
`invention. As will be described in greater detail hereinbelow,
`the inertial probe assembly 112 includes an inertial Sensor
`114 which is actuated by an operator-controlled Switch 116
`and typically provides at least an angular velocity output.
`The Switch 116 may be located on the probe, as illustrated.
`Alternatively it may be located elsewhere in the System.
`Additionally in accordance with a preferred embodiment
`of the present invention there is provided three-dimensional
`imaging circuitry 120, constructed and operative in accor
`dance with a preferred embodiment of the present invention.
`Circuitry 120, which is preferably embodied in a combina
`tion of hardware and Software, typically comprises an inte
`grator 122, which receives the output of inertial sensor 114.
`Video capture circuitry 124, receives a video image output
`from image output port 104 of system electronics 100 and an
`inertial Sensor operation indication output from Switch 116.
`Outputs from integrator 122 and from Video capture
`circuitry 124 are Supplied to a 3D image generator 126. In
`the embodiment of FIGS. 2-7, wherein the inertial sensor
`114 is typically a tracker operative to Sense motion having
`one degree of freedom, the 3D image generator 126 is
`operative to Synchronize various two-dimensional images
`captured by circuitry 124 during a rotational Sweep carried
`out by the probe assembly 112 about a fixed axis.
`The output of 3D image generator 126 is supplied to a 3D
`volume visualizer 130, which may receive an optional input
`from a track ball controller 132 or other suitable input device
`and provides an output to video switching circuitry 134. The
`output of 3D image generator 126 may also be employed to
`carry out various measurements. Video Switching circuitry
`134 also receives a Video image output from System elec
`tronics 100 via image output port 104 and provides outputs
`to the video monitor 106, VCR 108 and page printer 110.
`Video switching circuitry 134 may also provide Switching of
`outputs of the VCR 108 to the video monitor 106.
`Reference is now made to FIG. 2, which is a simplified
`block diagram illustration of a preferred Structure of a probe
`assembly 112 forming part of the system of FIG. 1 in
`accordance with one embodiment of the present invention.
`The probe assembly of FIG. 2 preferably includes a trans
`ducer housing 200 within which is located a conventional
`ultraSonic transducer array 202, Such as a 128 element array
`which is commercially available from Sonora Medical
`Systems, Inc. of Longmont, Colo.
`In accordance with a preferred embodiment of the present
`invention, there is also provided within the transducer hous
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`ing 200 an angle tracker 204, Such as a Two-Axis Angular
`Rate Gyro (TAARG) commercially available from Rafael of
`Israel and described in U.S. Pat. No. 4,930,365, the disclo
`Sure of which is hereby incorporated by reference. Angle
`tracker 204 corresponds to inertial sensor 114 (FIG. 1).
`Additionally located within the transducer housing 200 there
`may be provided a manually operable ON-OFF switch 206,
`which corresponds to Switch 116 (FIG. 1). Preferably, a LED
`208 is associated with Switch 206, to indicate when the
`System is ready for data acquisition and thus that informa
`tion provided by the angle tracker 204 is being acquired.
`Alternatively, the LED 208 may be located elsewhere in the
`System or any other Suitable type of indicator may be
`provided.
`The transducer housing 200 and its internal components
`are coupled via a connector cable 210 to a multifunctional
`connector 212. The multifunctional connector 212 is illus
`trated in FIG.3 and the cable 210 is illustrated in section in
`FIG. 4.
`As seen in FIGS. 2-4, the connector cable 210 preferably
`includes at the interior thereof angle tracker actuation and
`output cables 214 and 216 as well as a switch status cable
`218 and a LED actuation cable 220. These cables are
`surrounded by a shield 222 and outwardly thereof by a
`collection of typically 128 transducer output cables 224 and
`by an outer cable shield 226. Where the Switch 116 and LED
`208 are not part of the probe assembly 112, cables 218 and
`220 may be obviated in the connector cable 210.
`Multifunctional connector 212 typically includes a 156
`pin array 230, as seen in FIG. 3, which is preferably plug
`compatible with conventional transducer interface ports 102
`of conventional system electronics 100 of conventional
`ultrasonic imaging systems such as Model GE 3200 manu
`factured by General Electric Company of the U.S.A. or an
`UltraMark 4+, manufactured by ATL Inc. of Seattle, Wash.,
`U.S.A.
`AS Seen in FIG. 2, multifunctional connector 212 may
`include multiplexing electronicS 232 which is usually
`employed in connectors which are conventionally connected
`to conventional transducer interface ports 102 of conven
`tional system electronics 100 of some conventional ultra
`Sonic imaging Systems. Such as Model GE 3200 manufac
`tured by General Electric company of the U.S.A.
`Multifunctional connector 212 preferably also includes
`tracker electronicS 234 including actuation generation and
`Sensor processing. Tracker electronicS 234 Suitable for use
`with angle tracker 204 is commercially available from
`Rafael of Israel, as part of the Two-Axis Angular-Rate Gyro
`(TAARG), described in U.S. Pat. No. 4,930,365. The output
`of tracker electronicS 234 is preferably the angular Velocity
`output which is Supplied to integrator 122.
`Reference is now made to FIG. 5, which is a simplified
`flow chart illustration of three-dimensional data acquisition
`in the embodiment of FIGS. 1-4. Initially, the inertial probe
`assembly 112 (FIG. 1) including angle tracker 204 (FIG. 2)
`is positioned by an operator relative to a patient for 3
`dimensional image acquisition.
`The operator then actuates switch 206 (FIG. 2) and waits
`for the LED 208 (FIG. 2) to light, indicating that the 3D
`imaging circuitry 120 (FIG. 1) is ready for 3D imaging
`input. The operator then rotates the probe assembly 112
`about a fixed axis through a desired angular range.
`As the probe assembly 112 is rotated about the fixed axis
`through the desired angular range, the Video capture cir
`cuitry 124 (FIG. 1) captures 2D images and the integrator
`122 (FIG. 1) integrates angular velocities derived from the
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`angle tracker 204 to obtain the relative angular position of
`each acquired 2D image.
`Each 2D image is thus tagged with a relative angular
`position and Saved in a buffer.
`When the operator has finished a desired angular Sweep
`about a fixed axis, he may operate Switch 206 to terminate
`2D image acquisition.
`The acquired and duly tagged 2D images are then embed
`ded in a 3D volume. The operator may then Select regions of
`interest within the 3D volume, preferably in accordance with
`the teachings of U.S. patent applications Ser. Nos. 09/351,
`252 and 09/352,002, both filed Jul 12, 1999, the disclosure
`of which is hereby incorporated by reference. A 3D video
`image of the Selected region of interest from a Selected
`Viewpoint may then be generated by conventional technique,
`for example as discussed in “Efficient Ray Tracing of
`Volume Data”, by M. Levoy, ACM Transactions on
`Graphics, Vol. 9, No. 3, pp. 245-261, 1990, the disclosure of
`which is hereby incorporated by reference.
`Reference is now made to FIG. 6, which is a simplified
`flow chart illustration of a typical two-dimensional image
`acquisition step shown in the flow chart of FIG. 5. As seen
`in FIG. 6, the 2D image acquisition Step may be entirely
`conventional, as known in the prior art. Multiplexing elec
`tronicS is preferably employed for Selecting an appropriate
`Subset of transducer elements. The Selected transducer ele
`ments are pulsed with appropriate relative delays to form a
`focused acoustic beam.
`The received echoes from a transmitted acoustic beam are
`amplified , delayed and Summed to provide a spatially
`focused receive beam. Consecutive time Samples of the
`receive acoustic beam form a line of image information
`which is stored.
`The foregoing procedure is repeated for multiple different
`Selected Subsets of transducer elements until a 2D video
`image is built up. Appropriate 2D Video images are captured,
`typically by circuitry 124 (FIG. 1).
`Reference is now made to FIG. 7, which is a simplified
`flow chart illustration of an embedding Step shown in the
`flow chart of FIG. 5. The input to the functionality of FIG.
`7 is a Series of Stored 2D imageS which are tagged with
`relative angular position information. The desired output
`from the functionality of FIG. 7 is a 3D volumetric image
`preferably defined in Cartesian coordinates which includes
`the Volume within the patient Scanned by the operator
`rotating the inertial probe assembly about the fixed axis
`through a given range of angles.
`For each voxel in the 3D volumetric image, the following
`StepS are preferably carried out:
`Determination of the cylindrical coordinates for each
`voxel.
`Identification of two stored 2D imageS whose planes are
`closest to the voxel on each of two sides thereof.
`Interpolating image values for the VOXel from the Stored
`2D images whose planes are closest to the Voxel on each of
`two sides thereof.
`Once all of the relevant voxels have been dealt with a
`Volumetric image in Cartesian coordinates is provided and
`preferably stored.
`Reference is now made to FIG. 8, which is a simplified
`block diagram illustration of a preferred Structure of a probe
`assembly 112 forming part of the system of FIG. 1 in
`accordance with another embodiment of the present inven
`tion. The probe assembly of FIG. 8 preferably includes a
`transducer housing 300 within which is located a conven
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`tional ultrasonic