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Claims  |
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What is claimed is:
1. An ultrasound signal processing apparatus, comprising:
an image processing apparatus receiving real-time data frames of either one
of ultrasound vector data or ultrasound raster data corresponding to a
current ultrasound scan of a patient, the image processing apparatus for
performing an image enhancement process on said received data frames to
generate real-time or near real-time ultrasound images, said image
processing apparatus programmable to receive object code embodying the
image enhancement process, the image processing apparatus comprising:
a pair of frame buffers for receiving said data frames;
a first processor for accessing a first ultrasound data frame from either
one or both of said pair of frame buffers, (ii) for executing first
processing tasks upon the first ultrasound data frame to generate a
processed data frame, and (iii) for generating a first processor
completion signal upon completing said first processing tasks; and
all output buffer for receiving the processed data frame.
2. The ultrasound signal processing apparatus of claim 1, further
comprising:
a vector processing apparatus receiving real-time data frames of ultrasound
vector data corresponding to a current ultrasound scan of a patient, the
vector processing apparatus for performing any one or more of: (i)
improving signal to noise ratio of an ultrasound echo signal, (ii)
identifying flow within a scanned area of a patient by analyzing flow
parameters in an ultrasound flow signal, and (iii) identifying and
removing doppler shift from an ultrasound doppler signal; and said vector
processing apparatus programmable to receive object code embodying a
vector processing task.
3. An ultrasound signal processing apparatus comprising;
an image processing apparatus receiving real-time data frames of either one
of ultrasound vector data or ultrasound raster data corresponding to a
current ultrasound scan of a patient, the image processing apparatus for
performing an image enhancement process on said received data frames to
generate real-time or near real-time ultrasound images, said image
processing apparatus programmable to receive object code embodying the
image enhancement process, the image processing apparatus comprising:
a pair of frame buffers for receiving said data frames;
a first multi-processor (i) for accessing a first ultrasound data frame
from either one or both of said pair of frame buffers, (ii) for executing
first processing tasks upon the first ultrasound data frame to generate a
first-processed data frame, and (iii) for generating a first processor
completion signal upon completing said first processing tasks;
memory for storing the first-processed data frame;
a second integrated multi-processor (i) for receiving the first processor
completion signal and in response executing second processing tasks upon
the first-processed data frame to generate a second-processed data frame,
and (ii) for moving the second-processed data frame;
a crossbar switch for coupling said memory to each of said first and second
integrated multi-processors, said first-processed data frame accessible by
said second integrated multi-processor through said memory and crossbar
switch; and
an output buffer for receiving the second-processed data frame; and
wherein the first processing tasks and second-processing tasks comprise
ultrasound image processing tasks.
4. The apparatus of claim 3, in which said image processing apparatus
further comprises:
a frame controller for determining which one of the pair of frame buffers
receives incoming data of the first ultrasound data frame at a given time;
and
an output buffer controller for outputting the second-processed data frame
in response to a control signal from the second multi-processor.
5. The apparatus of claim 3, in which intermittent frames in a sequence of
ultrasound data frames are dropped when a frame buffer is unavailable for
loading resulting in a sequence of near real-time first ultrasound data
frames being loaded into the pair of frame buffers, said first integrated
multi-processor processing sequentially-loaded first ultrasound data
frames and said second integrated multi-processor further processing the
sequentially-loaded first data frames to generate near real-time image
data for visual display.
6. An ultrasound signal processing apparatus, comprising:
an image processing apparatus receiving real-time data frames of either one
of ultrasound vector data or ultrasound raster data corresponding to a
current ultrasound scan of a patient, the image processing apparatus for
performing an image enhancement process on said received data frames to
generate real-time or near real-time ultrasound images, said image
processing apparatus programmable to receive object code embodying the
image enhancement process, the image processing apparatus comprising:
a pair of frame buffers for receiving said data frames;
a first multi-processor (i) for accessing a first ultrasound data frame
from either one or both of said pair of frame buffers, (ii) for executing
first processing tasks upon the first ultrasound data frame to generate a
first-processed data frame, and (iii) for generating a first processor
completion signal upon completing said first processing tasks;
memory for storing the first-processed data frame;
a second integrated multi-processor (i) for receiving the first processor
completion signal and in response executing second processing tasks upon
the first-processed data frame to generate a second-processed data frame,
and (ii) for moving the second,processed data frame;
a crossbar switch for coupling said memory to each of said first and second
integrated multi-processors, said first-processed data frame accessible by
said second integrated multi-processor through said memory and crossbar
switch; and
an output buffer for receiving the second-processed data frame; and
wherein the first processing tasks and second-processing tasks comprise
ultrasound image processing tasks; and
in which the pair of frame buffers comprise:
a first register for receiving ultrasound raster data;
a second register for receiving ultrasound vector data;
a first frame buffer for storing one ultrasound data frame comprising
either one or both of said-vector data and raster data;
a second frame buffer for storing another ultrasound data frame comprising
either one or both of said vector data and raster data;
a first demultiplexer for selecting a data path between said first frame
buffer and either one of said first register, second register and first
multi-processor;
a second demultiplexer for selecting a data path between said second frame
buffer and either one of said first register, second register and first
multi-processor;
and wherein said frame controller configures said first and second
demultiplexers and determines whether said first ultrasound data frame is
stored in said first frame buffer as said one ultrasound data frame or in
said second frame buffer as said another ultrasound data frame.
7. The apparatus of claim 6, in which said pair of frame buffers further
comprise:
a first multiplexer for selecting an output data path from said first frame
buffer coupling at a given time said first frame buffer to one of said
second register and said first multi-processor;
a second multiplexer for selecting an output data path from said second
frame buffer coupling at a given time said second frame buffer to one of
said second register and said first multi-processor; and
and wherein said frame controller configures said first and second
multiplexers and determines from which frame buffer data is output.
8. An ultrasound signal processing apparatus, comprising:
an image processing apparatus receiving real-time data frames of either one
of ultrasound vector data or ultrasound raster data corresponding to a
current ultrasound scan of a patient, the apparatus for performing an
image enhancement process on said received data frames to generate
real-time or near real-time ultrasound images, said image processing
apparatus programmable to receive object code embodying the image
enhancement process;
a scan conversion processing apparatus receiving real-time data frames of
ultrasound vector data corresponding to a current ultrasound scan of a
patient, the scan conversion processing apparatus for adjusting the
content of a data frame into cartesian-coordinate raster data, said scan
conversion processing apparatus programmable to receive object code
embodying a scan conversion process; and
a vector processing apparatus receiving real-time data frames of ultrasound
vector data corresponding to a current ultrasound scan of a patient, the
vector processing apparatus for performing any one or more of: (i)
improving signal to noise ratio of an ultrasound echo signal, (ii)
identifying flow within a scanned area of a patient by analyzing flow
parameters in an ultrasound flow signal, and (iii) identifying and
removing doppler shift from an ultrasound doppler signal; and said vector
processing apparatus programmable to receive object code embodying a
vector processing task; and
wherein at least one of said image processing apparatus, scan conversion
processing apparatus and vector processing apparatus comprise:
a pair of frame buffers for receiving said data frames;
a first processor for accessing a first ultrasound data frame from either
one or both of said pair of frame buffers, (ii) for executing first
processing tasks upon the first ultrasound data frame to generate a
processed data frame, and (iii) for generating a first processor
completion signal upon completing said first processing tasks; and
an output buffer for receiving the processed data frame.
9. The ultrasound signal processing apparatus of claim 8, in which said
image processing apparatus, scan conversion processing apparatus and
vector processing apparatus together comprise the pair of frame buffers,
the first processor, and the output buffer.
10. The ultrasound signal processing apparatus of claim 8, in which the
first processor is a first multi-processor and the processed data frame is
a first-processed data frame, and in which said at least, one of said
image processing apparatus, scan conversion processing apparatus and
vector processing apparatus, further comprises:
memory for storing the first-processed data frame;
a second integrated multi-processor (i) for receiving the first processor
completion signal and in response executing second processing tasks upon
the first-processed data frame to generate a second-processed data frame,
and (ii) for moving the second-processed data frame;
a crossbar switch for coupling said memory to each of said first and second
integrated multi-processors, said first-processed data frame accessible by
said second integrated multi-processor through said memory and crossbar
switch; and
an output buffer for receiving the second-processed data frame; and
wherein the first processing tasks and second-processing tasks comprise
ultrasound image processing tasks.
11. A programmable ultrasound signal processing apparatus receiving
ultrasound data, comprising:
a pair of frame buffers receiving real-time data frames of either one or
both of ultrasound vector data or ultrasound raster data corresponding to
a current ultrasound scan of a patient;
a first integrated multi-processor (i) for accessing a first ultrasound
data frame from either one or both of said pair of frame buffers, (ii) for
executing first processing tasks upon the first ultrasound data frame to
generate a first-processed data frame, and (iii) for generating a first
processor completion signal upon completing said first processing tasks,
said first multi-processor programmable for receiving object code
corresponding to alternative first processing tasks;
memory for storing the first-processed data frame;
a second integrated multi-processor (i) for receiving the first processor
completion signal and in response executing second processing tasks upon
the first-processed data frame to generate a second-processed data frame,
and (ii) for moving the second-processed data frame, said second
multi-processor programmable for receiving object code corresponding to
alternative second processing tasks;
a crossbar switch for coupling said memory to each of said first and second
integrated multi-processors, said first-processed data frame accessible by
said second integrated multi-processor through said memory and crossbar
switch; and
an output buffer for receiving the second-processed data frame.
12. The apparatus of claim 11, wherein either one or both of the first
processing tasks and second-processing tasks comprise ultrasound image
processing tasks for generating real-time or near real-time ultrasound
images,
13. The apparatus of claim 11, wherein either one or both of the first
processing tasks and second processing tasks comprise scan conversion
tasks.
14. The apparatus of claim 11, further comprising:
a frame controller for determining which one of the pair of frame buffers
receives incoming data of the first ultrasound data frame at a given time;
and
an output buffer controller for outputting the second-processed data frame
in response to a control signal from the second multi-processor.
15. The apparatus of claim 11, in which intermittent frames in a sequence
of ultrasound data frames are dropped when a frame buffer is unavailable
for loading resulting in a sequence of near real-time first ultrasound
data frames being loaded into the pair of frame buffers, said first
integrated multi-processor processing sequentially-loaded first ultrasound
data frames and said second integrated multi-processor further processing
the sequentially-loaded first data frames to generate near real-time data
for output.
16. A programmable ultrasound signal processing apparatus receiving
ultrasound data, comprising:
a pair of frame buffers for receiving frames of either one or both of
ultrasound vector data or ultrasound raster data corresponding to a
current ultrasound scan of a patient;
a first integrated multi-processor (i) for accessing a first ultrasound
data frame from either one or both of said pair of frame buffers, (ii) for
executing first processing tasks upon the first ultrasound data frame to
generate a first-processed data frame, and (iii) for generating a first
processor completion signal upon completing said first processing tasks,
said first multi-processor programmable for receiving object code
corresponding to alternative first processing tasks;
memory for storing the first-processed data frame;.
a second integrated multi-processor (i) for receiving the first processor
completion signal and in response executing second processing tasks upon
the first-processed data frame to generate a second-processed data frame,
and (ii) for moving the second-processed data frame, said second
multi-processor programmable for receiving object code corresponding to
alternative second processing tasks;
a crossbar switch for coupling said memory to each of said first and second
integrated multi-processors, said first-processed data frame accessible by
said second integrated multi-processor through said memory and crossbar
switch; and
an output buffer for receiving the second-processed data frame; and
wherein either one or both of the first processing tasks and second
processing tasks comprise vector processing tasks.
17. A programmable ultrasound signal processing apparatus receiving
ultrasound data, comprising:
a pair of frame buffers for receiving frames of either one or both of
ultrasound vector data or ultrasound raster data corresponding to a
current ultrasound scan of a patient;
a first integrated multi-processor (i) for accessing a first ultrasound
data frame from either one or both of said pair of frame buffers, (ii) for
executing first processing tasks upon the first ultrasound data frame to
generate a first-processed data frame, and (iii) for generating a first
processor completion signal upon completing said first processing tasks,
said first multi-processor programmable for receiving object code
corresponding to alternative first processing tasks;
memory for storing the first-processed data frame;
a second integrated multi-processor (i) for receiving the first processor
completion signal and in response executing second processing tasks upon
the first-processed data frame to generate a second-processed data frame,
and (ii) for moving the second-processed data frame, said second
multi-processor programmable for receiving object code corresponding to
alternative second processing tasks;
a crossbar switch for coupling said memory to each of said first and second
integrated multi-processors, said first-processed data frame accessible by
said second integrated multi-processor through said memory and crossbar
switch; and
an output buffer for receiving the second-processed data frame; and
wherein either one or both of the first processing tasks and second
processing tasks comprise deriving vector processing parameters for output
to a vector processing subsystem.
18. A programmable ultrasound signal processing apparatus receiving
ultrasound data, comprising:
a pair of frame buffers for receiving frames of either one or both of
ultrasound vector data or ultrasound raster data corresponding to a
current ultrasound scan of a patient;
a first integrated multi-processor (i) for accessing a first ultrasound
data frame from either one or both of said pair of frame buffers, (ii) for
executing first processing tasks upon the first ultrasound data frame to
generate a first-processed data frame, and (iii) for generating a first
processor completion signal upon completing said first processing tasks,
said first multi-processor programmable for receiving object code
corresponding to alternative first processing tasks;
memory for storing the first-processed data frame;
a second integrated multi-processor (i) for receiving the first processor
completion signal and in response executing second processing tasks upon
the first-processed data frame to generate a second-processed data frame,
and (ii) for moving the second-processed data frame, said second
multi-processor programmable for receiving object code corresponding to
alternative second processing tasks;
a crossbar switch for coupling said memory to each of said first and second
integrated multi-processors, said first-processed data frame accessible by
said second integrated multi-processor through said memory and crossbar
switch; and
an output buffer for receiving the second-processed data frame; and
in which the pair of frame buffers comprise:
a first register for receiving ultrasound raster data;
a second register for receiving ultrasound vector data;
a first frame buffer for storing one ultrasound data frame comprising
either one or both of said vector data and raster data;
a second frame buffer for storing another ultrasound data frame comprising
either one or both of said vector data and raster data;
a first demultiplexer for selecting a data path between said first frame
buffer and either one of said first register, second register and first
multi-processor;
a second demultiplexer for selecting a data path between said second frame
buffer and either one of said first register, second register and first
multi-processor;
and wherein said frame controller configures said first and second
demultiplexers and determines whether said first ultrasound data frame is
stored in said first frame buffer as said one ultrasound data frame or in
said second frame buffer as said another ultrasound data frame.
19. The apparatus of claim 18, in which said pair of frame buffers further
comprise:
a first multiplexer for selecting an output data path from said first frame
buffer coupling at a given time said first frame buffer to one of said
second register and said first multi-processor;
a second multiplexer for selecting an output data path from said second
frame buffer coupling at a given time said second frame buffer to one of
said second register and said first multi-processor; and
and wherein said frame controller configures said first and second
multiplexers and determines from which frame buffer data is output. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention relates to ultrasound medical diagnostic imaging systems,
and more particularly to a programmable ultrasound signal processing
apparatus for varying clinical applications.
Medical imaging systems are used as diagnostic tools for viewing internal
areas of a patient's body. Imaging systems based on ultrasound technology
are desirable because such systems are non-invasive, portable and
generally easy to use. To produce enough images per second to support real
time imaging of a patient, ultrasound systems conventionally require
separate processing boards for each processing task. A given processing
board is designed to do specific tasks and typically is redesigned if
processing requirements or processing algorithms change. Thus, an
ultrasound system, although, generally easy to use, conventionally is
constructed using dedicated hardware subsystems.
The medical and ultrasound research community continue to explore new
clinical applications for ultrasound technology. New clinical applications
require many man-years of design engineering and clinical testing.
Feedback during testing leads to changes in ultrasound system design and
clinical application procedure. The development process typically is an
iterative design process. Because different ultrasound processing boards
are needed for changing requirements, the development time of a clinical
application and ultrasound system design can be slow. Further, as state of
the art circuit speeds increase, new board designs and architectures have
been needed to incorporate such circuitry into an ultrasound system. In
brief, conventional ultrasound system architectures have been
characterized by a lack of versatility and lack of programmability. This
has been a problem slowing the development of new clinical applications.
Accordingly, there is a need for a versatile, programmable ultrasound
system adaptable to new and varying clinical application requirements.
FIG. 1 shows a block diagram of a conventional ultrasound medical
diagnostic imaging system 10. A system controller 12 receives and displays
user control information via a user interface 14. During operation, system
control signals are output to an ultrasound front end (i.e., transducer
18, transmitter 16, beam-former 20 and related circuitry) and to various
subsystems. A transmitter 16 generates output signals to a transducer 18
to define aperture, apodization, focus and steering of ultrasound signals.
The transducer 18 is an array of transducer elements. The elements define
multiple channels, each channel for transmitting and/or receiving
ultrasound signals.. Transmitted ultrasound signals are in part absorbed,
dispersed, refracted and reflected when travelling through a patient.
Reflected signals are sensed by the transducer 18 and captured as a
patterned beam by beam-former 20. The captured signals are sent to an echo
signal processing subsystem 22, color flow processing subsystem 24 and/or
doppler processing subsystem 26 according to the mode of operation.
The echo processing subsystem 22 performs echo signal processing to improve
the echo signal's signal to noise ratio. In one implementation signal
enhancement, energy detection and image enhancement filtering occurs. The
color flow processing subsystem 24 estimates flow parameters using
correlation, flow averaging and/or other processes. The doppler processing
subsystem 26 determines doppler shift and performs frequency filtering to
remove the doppler shift and improve spectral frequency response. In one
doppler implementation signal enhancement, spectral estimation, energy
detection and derived waveform filtering occurs.
Outputs of subsystems 22 and 24 are sent to a scan converter 28 which
converts polar vector data or scales linear vector data into
cartesian-coordinate raster data. The echo, flow and doppler data streams
then are input to the video processing subsystem 30 which synchronizes
data and generates image position, gray scale and color characteristics
for visual and audio output devices 32. Output is displayed in real-time
and/or stored via video cassette recorder for later playback. Typically a
strip chart device also is included for showing a patient's physiological
status. The echo processing subsystem 22, color flow processing subsystem
24 and doppler processing subsystem 26 designs vary according to the
clinical application. Accordingly, there is a need for a more flexible
architecture able to accommodate various ultrasound clinical applications.
SUMMARY OF THE INVENTION
According to the invention, an ultrasound signal processing apparatus
provides a programmable data processing platform for various clinical
ultrasound applications. The signal processing apparatus is a portion of
an ultrasound medical diagnostic imaging system. Alternative data
transformation processes are hosted by the apparatus according to the
desired clinical application.
According to one aspect of the invention, the apparatus embodies a
programmable image processing subsystem for adding image processing
capability to an ultrasound system. Various image processing and image
enhancement processes can be loaded in and executed, (e.g., histogram
equalization, contrast limited adaptive histogram equalization, edge
detection, boundary enhancement, 2-D graphics, 3-D volume visualization,
tissue characterization, perfusion measurements, image segmentation,
speckle reduction).
According to another aspect of the invention, the programmable ultrasound
signal processing apparatus also hosts one or more vector processing
(e.g., echo processing, flow processing, doppler processing) and/or scan
conversion processes. Echo signal processing functions, such as signal
enhancement filtering, energy detection and image enhancement filtering
are hosted. Flow processing functions, such as correlation, flow averaging
or another flow indicator derivation are hosted. Doppler signal processing
functions, such as signal enhancement filtering, spectral estimation,
energy detection, and derived waveform filtering are hosted. Thus, one or
more vector processing functions previously implemented using dedicated
hardware, alternatively, is hosted on the programmable apparatus. Further,
scan conversion processes previously implemented in dedicated hardware,
alternatively, are hosted on the programmable apparatus. Also, more
effective solutions can be implemented by downloading differing computer
processes.
According to another aspect of the invention, vector signal processing,
scan conversion and image processing functions are performed in real-time
or near real-time during ultrasound scanning of a patient. Alternatively,
the functions are performed off-line in a delayed playback or "cine"
playback mode.
According to another aspect of the invention, the programmable ultrasound
signal processing apparatus includes one or more processors for executing
various vector signal processing, scan conversion and/or image processing
functions. According to one inventive embodiment, the ultrasound signal
processing apparatus includes a pair of multi-processors, (e.g., a pair of
multimedia video processor chips, each chip embodying a plurality of
digital signal processors). The multi-processors are coupled to shared
memory via a 2.times.2 crossbar switch. System data and control signals
are input to the apparatus via a modified-VME interface. Vector data
and/or scan-converted data is input to the apparatus via a pair of frame
buffers. The frame buffers receive respective frames in an alternating
buffer fashion. In one implementation the frame buffers also serve as an
output path for processed vector data to be routed to vector processing
subsystem(s) or to a scan converter. For other outputs a multi-processor
routes processed raster data to an output buffer for forwarding to an
output device or video processing subsystem.
The multi-processors perform vector processing tasks, image processing
tasks and/or scan conversion. The specific processes executed vary
according to the clinical application. Object code for one or more
processes is loaded via the modified-VME interface and stored in a
respective multi-processor's local memory.
According to another aspect of this invention, the first multi-processor
manages system communications and data acquisition, while the second
multi-processor manages video (e.g., raster) data output. The first
multi-processor retrieves a first frame of data, processes the data
in-part, then signals the second multi-processor to take control of the
data frame. The second multi-processor then accesses the first frame
through shared memory to finish processing the data. The processed data
frame then is moved to an output buffer. The data then is output from the
output buffer to an output device or video processing subsystem. While the
second multi-processor is processing the first frame, the first
multi-processor retrieves a second frame of data. In this manner, data
frames cascade through the ultrasound signal processing apparatus.
According to alternative embodiments the programmable ultrasound signal
processing apparatus includes multiple programmable processor boards
configured for executing respective vector processing, image processing
and scan conversion functions.
According to one alternative embodiment, the apparatus combines a
programmable platform with conventional vector processing boards able to
receive filter parameter inputs. As a result, the ultrasound signal
processing apparatus is able to look ahead during real-time and near
real-time operation to redefine and load vector processing subsystem
filter parameters.
The problem addressed by this invention is the lack of flexibility in
conventional ultrasound medical diagnostic system architectures. Such
architectures are not readily adapted to new or evolving clinical
applications, nor to advances in technology. The solution described here
is to implement a versatile, powerful (e.g., fast, high throughput)
ultrasound signal-processing architecture effectively programmed for a
desired clinical application. Different computer programs embodying a
vector processing, image processing, scan conversion and/or video
processing function are loaded into the processors for a given clinical
application. Instead of redesigning subsystems to adapt to a new clinical
application, new software is loaded into the programmable, hardware
configuration. A meritorious effect is that shorter time-to-market system
configurations are achievable for new clinical applications. An advantage
is that sophisticated data transformation processes are executed in
real-time or near real-time to satisfy clinical diagnostic imaging
requirements without "tailoring" (i.e., redesigning) dedicated application
circuit boards. For various multi-processor embodiments, allocation of
data management among multi-processors allows sophisticated ultrasound
processing to be performed in real-time and near real-time.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a conventional ultrasound medical diagnostic
imaging system;
FIG. 2 is a block diagram of an ultrasound medical diagnostic imaging
system with back-end processing according to an embodiment of this
invention;
FIG. 3 is a functional block diagram of back-end processing in the system
of FIG. 2 according to an embodiment of this invention;
FIG. 4 is a block diagram of the programmable ultrasound signal processing
apparatus according to an embodiment of this invention;
FIG. 5 is a block diagram for one embodiment of a multi-processor of FIG.
4;
FIG. 6 is a diagram of the input frame buffers of FIG. 4 according to one
embodiment;
FIG. 7 is a diagram of the output buffer of FIG. 4 according to one
embodiment;
FIGS. 8-10 are flow charts of data movement through the programmable
ultrasound signal processing apparatus of FIG. 4 according to one
embodiment of the invention;
FIG. 11 is a block diagram of a back-end processing subsystem configuration
according to an embodiment of this invention;
FIG. 12 is a block diagram of a back-end processing subsystem configuration
according to another embodiment of this invention; and
FIG. 13 is a block diagram of a back-end processing subsystem configuration
according to another embodiment of this invention.
DESCRIPTION OF SPECIFIC EMBODIMENTS
Overview
FIG. 2 shows a block diagram of an ultrasound medical diagnostic imaging
system 40 having a back-end signal processing subsystem 50. Like portions
of system 40 relative to system 10 (see FIG. 1) are shown with like
numbers (i.e., system controller 12, user interface 14, transmitter 16,
transducer 18, beam-former 20 and data output devices 32). The function of
the system 40 is to perform diagnostic imaging of a patient using
ultrasound data. Ultrasound signals are transmitted via transducer 18 into
a patient. Reflected signals are detected and used to derive internal
images of the patient for a scanned area/volume. The function of back-end
processing subsystem(s) 50 is to process the raw beam data and generate
image data for output devices 32.
FIG. 3 is a block diagram of back-end processing functions. Digital echo
signals, flow signals and/or doppler signals are received at the back-end
processing subsystem(s) 50 according to various modes of operation. Such
input signals are referred to herein as vector signals. For a transducer
18 performing sector scanning, the vector signals are digital
polar-coordinate data samples of echo, flow and/or doppler signals. For a
transducer 18 performing linear scanning, the vector signals are digital
cartesian-coordinate data samples of echo, flow and/or doppler signals.
Back-end processing includes echo signal processing 52, flow signal
processing 54, doppler signal processing 56, scan conversion 58, image
processing 60 and video processing 62. Echo signal processing 52 typically
encompasses signal enhancement filtering, energy detection and image
enhancement filtering. Various filtering and convolution techniques are
employed. The purpose of echo signal processing 52 is to enhance the
signal to noise ratio of the echo signal. Flow signal processing 54
analyzes signals for flow parameters. Typical parameter .derivations
include sample correlation and flow averaging. The purpose of flow signal
processing 54 is to identify flow and turbulence within a scanned area.
Doppler signal processing 56 typically encompasses signal enhancement
filtering, spectral estimation processing, energy detection, and derived
waveform filtering. The purpose of doppler signal processing 56 is to
identify and filter out doppler shift, to improve spectral frequency
response and to coordinate spectral mapping.
A scan conversion process 58 converts the processed vector data streams
from echo signal processing 52 and flow signal processing 54. For
polar-coordinate vector data the data is converted into
cartesian-coordinate raster data. For cartesian-coordinate vector data the
data is scaled into cartesian-coordinate raster data.
Image processing 60 includes image enhancement processes executed on the
raster data or vector data. In an off-line delayed payback (e.g., cine
playback) mode of operation image data, vector data and/or raster data is
received from image memory 64 and processed. Image processing tasks for
varying applications includes histogram equalization, contrast limited
adaptive histogram equalization, edge enhancement, boundary enhancement,
2-D graphics, 3-D volume visualization, tissue characterization, perfusion
measurements, image segmentation, edge detection and speckle reduction.
Video processing 62 executes on the image processed data to generate video
signals, audio signals, and graphing signals for output to a display
device, audio device, storage device (e.g., VCR) and/or charting device.
Video processing 62 in some applications also executes on doppler
processed vector data to generate similar video signals, audio signals,
and graphing signals for output to the display device, audio device,
storage device and/or charting device.
According to the invention, image processing 60, echo signal processing 52,
flow signal processing 54, doppler signal processing 56, scan conversion
58 and/or video processing 62 are hosted on a programmable ultrasound
signal processing apparatus 70. According to various configurations, the
processing tasks 52-62 are hosted on one or more of such apparatus 70.
Programmable Ultrasound Signal Processing Apparatus
FIG. 4 shows a block diagram of the programmable ultrasound signal
processing apparatus 70. Apparatus 70 includes multiple processors for
performing the various vector processing, image processing, scan
conversion and/or video processing tasks. In a specific embodiment a pair
of processors 102, 104 are included. Data management is divided among the
multiple processors 102, 104 so that a first processor 102 manages system
and front end data communication, while a second processor 104 manages
raster data output communication. The apparatus 70 also includes local
memory 106, 108, crossbar switch 110, shared memory 112, modified-VME
interface 114, frame buffer/controller 116 and output buffer/controller
118.
Processors:
In one embodiment each processor 102, 104 includes one or more digital
signal processors. In a specific embodiment each processor 102, 104 is a
multi-processor, such as a Texas Instruments multimedia video processor
("MVP") (part no. TMS320C80). FIG. 5 shows a block diagram of an MVP
multi-processor. The MVP combines on a single semiconductor chip, four
fully programmable digital signal processors 124, 126, 128, 130 and a
master processor 132 for handling multiple data streams via a transfer
controller 134. Several on-chip random access memory (RAM) devices 136,
138, 140, 142, 144 serve as resident memory accessible to the digital
signal processors (DSPs) 124-130 via a crossbar network 146. The MVP has a
throughput rating of approximately 2 billion operations per second. The
master processor 132 is a RISC processor with an integral floating point
unit. According to this embodiment the master processor 132 coordinates
and distributes processing tasks among the DSPs 124-130 and manages
external off-chip communications. A JTAG/emulation port 148 is included
for aid in testing, development and diagnostics.
Each DSP 124-130 includes two address generators, three input 32-bit ALUs,
a 16.times.16 multiplier, three zero-overhead loop controllers, and a
32-bit barrel shifter. Each RAM 136-144 has a 10 kB capacity providing 50
kB of single-cycle SRAM. Memory 136-144 is partitioned in blocks with each
block serving as either data RAM, parameter RAM, data cache or instruction
cache. The data caches and instruction caches serve as a primary cache.
The transfer controller 134 services the on-chip caches and interfaces to
external memory (e.g., local memory 106 or 108, and shared memory 112).
The MVP also includes a pair of video controllers 150. Controllers 150
generate video synchronization signals or synchronize data transfer rates
with external video signals.
Local Memory, Shared Memory, Crossbar:
Referring again to FIG. 4 each multi-processor 102, 104 has a respective
dedicated local memory 106, 108, serving as a secondary cache. Each local
memory 102, 104 has capacity for storing a frame of ultrasound data. In
one embodiment a 2 MB capacity is provided at each local memory 102, 104.
In addition shared memory 112 is included. In one embodiment shared memory
112 is implemented as two separate 64 MB memory banks 120, 122 for a total
of 128 MB shared memory. The storage capacity of local memory 102, 104 and
shared memory 112 varies for alternative embodiments. The multi-processors
102, 104 access shared memory through crossbar switch 110. For a two
multi-processor embodiment, a 2.times.2 crossbar switch is implemented.
The purpose of the crossbar switch 110 is to allow the multiple processors
102, 104 simultaneous access to the shared memory banks. The crossbar
switch 110 includes a pair of transceivers for each input channel, along
with a crossbar controller.
The function of the crossbar controller is (i) to manage requests for
access and (ii) to refresh shared memory 112. If a multi-processor 102
requests access to a shared memory bank 120, 122 not currently being
accessed by the other multi-processor 104, then the access is granted. If
the multi-processor 102 requests access to a shared memory bank 120, 122
currently being accessed, then the multi-processor 102 waits until the
memory bank is available. Simultaneous access to a shared memory bank 120,
122 thus is available when the accesses are to separate memory banks. For
reconciling simultaneous requests for access, one multi-processor 102 is
prescribed to have priority for a specific one shared memory bank 120,
while the other multi-processor 104 is prescribed priority for the other
shared memory bank 122. If both multi-processors 102, 104 request access
to a common bank, then the processor with the prescribed priority for that
bank is granted access. However, to avoid lengthy delays, the other
multi-processor is granted access after the current access, even if the
higher priority multi-processor comes right back with a second request.
For example, consider the case in which multi-processor 102 has the
prescribed priority to the first memory bank 120. The first
multi-processor 102 makes two sequential requests for access to bank 120,
while multi-processor 104 also makes a request to bank 120. Because of the
prescribed priority, the first multi-processor 102 is granted access for
its first request. Next, however, the second multi-processor 104 is
granted access. Then, the first multi-processor 102 is granted access for
its second request.
Modified-VME Interface:
System control signals are received by apparatus 70 from the system
controller 12 via a modified-VME interface 114. The modified-VME interface
114 is similar to a standard VME interface, but with a different connector
size so as to fit into an ultrasound system 40 back-plane. The
communication protocol is VME standard with unnecessary signals not being
supported. In an alternative embodiment a standard VME interface is used.
The modified-VME interface includes a back-plane interface, an external
address decoder/controller, an interrupt requester, an internal address
decoder/controller and dual port memory. The back-plane interface couples
the apparatus 70 to a system 40 bus enabling communication with the system
controller 12. System data and control signals are received via the
back-plane interface and stored in the dual-port memory based upon address
decoding and interrupt-based handshaking. Dual port memory has a receive
buffer and a transmit buffer. In a specific embodiment the dual port
memory is a 2K.times.16 dual port RAM. Processor bus transceivers isolate
the multi-processor 102, 104 address and data busses from the system bus.
For data flow from the system controller 12 into the apparatus 70, the
system controller 12 writes data into the transmit buffer. The system
controller 12 then signals the VME interrupt requester, which in turn
generates an interrupt to the first multi-processor 102. Multi-processor
102 reads the transmit buffer, then signals the VME interface to generate
an interrupt to the system controller 12 signifying that the transmit
buffer is available for loading.
Data flow from the apparatus 70 to the system controller 12 is similarly
controlled. Multi-processor 102 writes data into the receive buffer, then
signals the VME interrupt requester to generate an interrupt to the system
controller 12. The system controller 12 reads from the receive buffer,
then signals the VME interrupt requester to interrupt multi-processor 102
to signify that the receive buffer is available for loading.
Frame Buffer/Controller:
The frame buffer/controller 116 serves as a data interface with an
ultrasound front end, another programmable ultrasound signal processing
apparatus 70, another back-end processing subsystem and/or image memory
64. FIG. 6 shows a block diagram of the frame b | | |
