U.S. patent application number 13/951805 was filed with the patent office on 2014-01-30 for portable ultrasonic imaging probe including transducer array.
This patent application is currently assigned to Interson Corporation. Invention is credited to Roman Solek.
Application Number | 20140031693 13/951805 |
Document ID | / |
Family ID | 49995522 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140031693 |
Kind Code |
A1 |
Solek; Roman |
January 30, 2014 |
PORTABLE ULTRASONIC IMAGING PROBE INCLUDING TRANSDUCER ARRAY
Abstract
The invention provides a portable ultrasonic imaging probe
directly connectable to an off-the-shelf laptop computer. The probe
produces raw digitized data comprising envelope detected ultrasound
echo data from an array of ultrasound transducers, and transmits
the data to the host computer thereby enabling the host computer to
form real-time ultrasonic images of human tissue without the need
for any additional electronics. In particular embodiments, the
probe includes a plurality of transmit switches configured to
connect a transmitting group of the ultrasound transducers to a
pulser; a plurality of receive switches configured to connect a
receiving group of the ultrasound transducers to analog summing,
amplification and signal processing circuitry; and a
transmit/receive controller which selects which of said ultrasound
transducers are in the transmitting group and which of said
ultrasound transducers are in the receiving group. The ultrasound
transducers may be conventional or micromachined ultrasound
transducers.
Inventors: |
Solek; Roman; (Pleasanton,
CA) |
Assignee: |
Interson Corporation
Pleasanton
CA
|
Family ID: |
49995522 |
Appl. No.: |
13/951805 |
Filed: |
July 26, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61676193 |
Jul 26, 2012 |
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Current U.S.
Class: |
600/447 |
Current CPC
Class: |
B06B 1/0215 20130101;
G01S 15/8915 20130101; A61B 8/4444 20130101; A61B 8/4427 20130101;
A61B 8/4494 20130101; A61B 8/52 20130101; B06B 1/0622 20130101;
A61B 8/145 20130101; B06B 2201/76 20130101; B06B 2201/55 20130101;
G01S 7/52079 20130101; A61B 8/54 20130101; A61B 8/56 20130101; A61B
8/461 20130101; G01S 7/5208 20130101; G01S 15/8927 20130101; B06B
2201/51 20130101 |
Class at
Publication: |
600/447 |
International
Class: |
A61B 8/00 20060101
A61B008/00; A61B 8/08 20060101 A61B008/08; A61B 8/14 20060101
A61B008/14 |
Claims
1. A portable ultrasonic imaging probe that is adapted to connect
to a host computer via a passive interface cable, the portable
ultrasound imaging probe comprising: a probe head including an
array of ultrasound transducers; a high voltage (HV) pulser adapted
to energize two or more transducers to emit ultrasound; analog
summing, amplification and signal processing circuitry configured
to combine echoes detected by two or more ultrasound transducers
into a single analog echo signal; a single analog-to-digital
converter (ADC) that converts the analog echo signal, output by the
analog summing, amplification and signal processing circuitry, to a
digital echo signal; and interface circuitry adapted to transfer
the digital echo signal across a passive interface cable to a host
computer that can perform digital processing of the digital echo
signal in order to display an ultrasound image; a plurality of
transmit (Tx) switches configured to connect a transmitting group
of the ultrasound transducers to the (HV) pulser; a plurality of
receive (Rx) switches configured to connect a receiving group of
the ultrasound transducers to the analog summing, amplification and
signal processing circuitry; a transmit/receive controller
connected to the plurality of transmit (Tx) switches and the
plurality of receive (Rx) switches wherein the transmit/receive
controller selects which of said ultrasound transducers are in the
transmitting group and which of said ultrasound transducers are in
the receiving group.
2. The portable ultrasonic imaging probe of claim 1, wherein said
transmitting group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
ultrasound imaging probe emits a focused ultrasound beam.
3. The portable ultrasonic imaging probe of claim 1, wherein said
transmitting group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
transmitting group of transducers forms an ultrasound transmitter
which changes in position within the array of transducers between
the first time, the second time and the third time.
4. The portable ultrasonic imaging probe of claim 1, wherein said
transmitting group of ultrasound transducers comprises: a first
plurality of transducers at a first time, wherein the first
plurality of transducers form a first annular cluster in said array
of transducers; a second plurality of transducers different than
the first plurality at a second time, wherein the second plurality
of transducers form a second annular cluster in said array of
transducers; and a third plurality of transducers different than
the first plurality and the second plurality a third time, wherein
the third plurality of transducers form a third annular cluster in
said array of transducers; wherein the first annular cluster has a
larger aperture diameter than the second annular cluster, and the
second annular cluster has a larger aperture than the third annular
cluster such that the transmitting group of transducers forms a
variable aperture ultrasound transmitter.
5. The portable ultrasonic imaging probe of claim 1, wherein said
receiving group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
receiving group of transducers forms an ultrasound receiver which
changes in size between the first time, the second time and the
third time.
6. The portable ultrasonic imaging probe of claim 1, wherein said
receiving group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
receiving group of transducers forms an ultrasound receiver which
changes in position between the first time, the second time and the
third time.
7. The portable ultrasonic imaging probe of claim 1, wherein: said
transmitting group of ultrasound transducers comprises a first
plurality of transducers at a first time, a second plurality of
transducers different than the first plurality at a second time,
and a third plurality of transducers different than the first
plurality and the second plurality a third time; and said receiving
group of ultrasound transducers comprises a fourth plurality of
transducers at a fourth time; a fifth plurality of transducers
different than the fourth plurality at a fourth time; and a sixth
plurality of transducers different than the fourth plurality and
the fifth plurality at a sixth time.
8. The portable ultrasonic imaging probe of claim 1, wherein said
array of transducers comprises a plurality of ultrasound
transducers arranged in a row.
9. The portable ultrasonic imaging probe of claim 1, wherein said
array of transducers comprises a plurality of ultrasound
transducers arranged in plurality of parallel rows.
10. The portable ultrasonic imaging probe of claim 1, wherein said
transducers are micromachined ultrasound transducers (MUTs).
11. A portable ultrasonic imaging probe that is adapted to connect
via a passive interface cable to a host computer that can perform
digital processing in order to display an ultrasound image, the
portable ultrasound imaging probe comprising: a probe head
including an array of ultrasound transducers; a power circuit
adapted to energize two or more transducers to emit ultrasound;
analog processing circuitry configured to combine echoes detected
by two or more ultrasound transducers into an analog echo signal;
an analog-to-digital converter (ADC) that converts the analog echo
signal, output by the analog signal processing circuitry, into a
single channel digital echo signal; and interface circuitry adapted
to transfer the digital echo signal across a passive interface
cable to the host computer for digital processing in order to
display an ultrasound image; a plurality of switches configured to
connect a transmitting group of the ultrasound transducers to the
power circuit and configured to connect a receiving group of the
ultrasound transducers to the analog processing circuitry; a
transmit/receive controller connected to the plurality of switches,
wherein the transmit/receive controller selects which of said
ultrasound transducers are in the transmitting group and which of
said ultrasound transducers are in the receiving group.
12. The portable ultrasonic imaging probe of claim 11, wherein said
transmitting group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
ultrasound imaging probe emits a focused ultrasound beam.
13. The portable ultrasonic imaging probe of claim 11, wherein said
transmitting group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
transmitting group of transducers forms an ultrasound transmitter
which changes in position within the array of transducers between
the first time, the second time and the third time.
14. The portable ultrasonic imaging probe of claim 11, wherein said
transmitting group of ultrasound transducers comprises: a first
plurality of transducers at a first time, wherein the first
plurality of transducers form a first annular cluster in said array
of transducers; a second plurality of transducers different than
the first plurality at a second time, wherein the second plurality
of transducers form a second annular cluster in said array of
transducers; and a third plurality of transducers different than
the first plurality and the second plurality a third time, wherein
the third plurality of transducers form a third annular cluster in
said array of transducers; wherein the first annular cluster has a
larger aperture diameter than the second annular cluster, and the
second annular cluster has a larger aperture than the third annular
cluster such that the transmitting group of transducers forms a
variable aperture ultrasound transmitter.
15. The portable ultrasonic imaging probe of claim 11, wherein said
receiving group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
receiving group of transducers forms an ultrasound receiver which
changes in size between the first time, the second time and the
third time.
16. The portable ultrasonic imaging probe of claim 11, wherein said
receiving group of ultrasound transducers comprises: a first
plurality of transducers at a first time; a second plurality of
transducers different than the first plurality at a second time;
and a third plurality of transducers different than the first
plurality and the second plurality a third time; whereby the
receiving group of transducers forms an ultrasound receiver which
changes in position between the first time, the second time and the
third time.
17. The portable ultrasonic imaging probe of claim 11, wherein:
said transmitting group of ultrasound transducers comprises a first
plurality of transducers at a first time, a second plurality of
transducers different than the first plurality at a second time,
and a third plurality of transducers different than the first
plurality and the second plurality a third time; and said receiving
group of ultrasound transducers comprises a fourth plurality of
transducers at a fourth time; a fifth plurality of transducers
different than the fourth plurality at a fourth time; and a sixth
plurality of transducers different than the fourth plurality and
the fifth plurality at a sixth time.
18. The portable ultrasonic imaging probe of claim 11, wherein said
array of transducers comprises a plurality of ultrasound
transducers arranged in a row.
19. The portable ultrasonic imaging probe of claim 1, wherein said
array of transducers comprises a plurality of ultrasound
transducers arranged in plurality of parallel rows.
20. The portable ultrasonic imaging probe of claim 1, wherein said
transducers are micromachined ultrasound transducers (MUTs).
21. A portable ultrasonic imaging probe that is adapted to connect
via a USB cable to a host computer that can perform digital
processing in order to display an ultrasound image, the portable
ultrasound imaging probe comprising: a probe head including an
array of ultrasound transducers; a power circuit adapted to
energize two or more transducers to emit ultrasound; analog
processing circuitry configured to combine echoes detected by two
or more ultrasound transducers into an analog echo signal; an
analog-to-digital converter (ADC) that converts the analog echo
signal, output by the analog signal processing circuitry, into a
single digital echo signal; and interface circuitry adapted to
transfer the digital echo signal across said USB cable to the host
computer for digital processing in order to display an ultrasound
image; a plurality of switches configured to connect a transmitting
group of the ultrasound transducers to the power circuit and
configured to connect a receiving group of the ultrasound
transducers to the analog processing circuitry; wherein said
transmitting group of ultrasound transducers comprises: a first
plurality of transducers at a first time, a second plurality of
transducers different than the first plurality at a second time,
and a third plurality of transducers different than the first
plurality and the second plurality a third time.
22. The portable ultrasonic imaging probe of claim 21 wherein said
transmitting group of transducers forms an ultrasound transmitter
which changes in position within the array of transducers between
the first time, the second time and the third time.
23. The portable ultrasonic imaging probe of claim 21, wherein: the
first plurality of transducers forms a first annular cluster in
said array of transducers; the second plurality of transducers form
a second annular cluster in said array of transducers; and the
third plurality of transducers forms a third annular cluster in
said array of transducers; wherein the first annular cluster has a
larger aperture diameter than the second annular cluster, and the
second annular cluster has a larger aperture than the third annular
cluster such that the transmitting group of transducers forms a
variable aperture ultrasound transmitter.
24. The portable ultrasonic imaging probe of claim 21, wherein said
receiving group of ultrasound transducers comprises: a fourth
plurality of transducers at a fourth time; a fifth plurality of
transducers different than the fourth plurality at a fifth time;
and a sixth plurality of transducers different than the fourth
plurality and the fifth plurality at a sixth time; whereby the
receiving group of transducers forms an ultrasound receiver which
changes in size between the fourth time, the fifth time and the
sixth time.
26. The portable ultrasonic imaging probe of claim 21, wherein said
receiving group of ultrasound transducers comprises: a fourth
plurality of transducers at a fourth time; a fifth plurality of
transducers different than the fourth plurality at a fifth time;
and a sixth plurality of transducers, different than the fourth
plurality and the fifth plurality, at a sixth time; whereby the
receiving group of transducers forms an ultrasound receiver which
changes in position between the fourth time, the fifth time and the
sixth time.
27. The portable ultrasonic imaging probe of claim 21, wherein said
array of transducers comprises a plurality of ultrasound
transducers arranged in a row.
28. The portable ultrasonic imaging probe of claim 21, wherein said
array of transducers comprises a plurality of ultrasound
transducers arranged in plurality of parallel rows.
29. The portable ultrasonic imaging probe of claim 21, wherein said
transducers are micromachined ultrasound transducers (MUTs).
30. The portable ultrasonic imaging probe of claim 21, in
combination with said host computer and a USB cable connecting said
interface circuitry to said host computer.
Description
PRIORITY CLAIM
[0001] This application claims the benefit of priority to U.S.
Provisional Patent Application No. 61/676,193 filed Jul. 26, 2012
entitled "PORTABLE ULTRASOUND IMAGING PROBE INCLUDING MEMS BASED
TRANSDUCER ARRAY" which application is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to portable ultrasonic imaging
probes, and more specifically, to such probes including a
transducer array, wherein such probes can be directly connected to
a host computer, such as an off-the-shelf laptop computer, or the
like.
BACKGROUND
[0003] Typically, ultrasound imaging systems include a hand-held
probe that is connected by a cable to a relatively large and
expensive piece of hardware that is dedicated to performing
ultrasound signal processing and displaying ultrasound images. Such
systems, because of their high cost, are typically only available
in hospitals or in the offices of specialists, such as
radiologists. Recently, there has been an interest in developing
more portable ultrasound imaging systems that can be used with
personal computers. Preferably, such a portable ultrasound probe
can be used with an off-the-shelf host computer, such as a personal
computer, and is inexpensive enough to provide ultrasound imaging
capabilities to general practitioners and health clinics having
limited financial resources.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1A is a high level diagram showing elements of the
present invention.
[0005] FIG. 1B illustrates an ultrasonic imaging probe according to
an embodiment of the present invention originally described with
reference to FIG. 1A.
[0006] FIG. 2A is a block diagram that shows additional details of
an ultrasonic imaging probe according to an embodiment of the
present invention.
[0007] FIG. 2B illustrates some further details of some of the
blocks introduced in FIG. 2A, according to an embodiment of the
present invention.
[0008] FIG. 2C illustrates a perspective view of a probe head
assembly, according to an embodiment of the present invention.
[0009] FIG. 2D illustrates how odd and even rows of transducers can
be staggered relative to one another according to an embodiment of
the present invention.
[0010] FIG. 2E illustrates an alternative array of ultrasound
transducers according to an embodiment of the present
invention.
[0011] FIG. 2F is a block diagram that shows details of an
alternative ultrasonic imaging probe according to an embodiment of
the present invention.
[0012] FIG. 3A shows how sets of micromachined ultrasound
transducers can be used to form a moving quasi-annular array
transducer according to an embodiment of the present invention.
[0013] FIG. 3B is a blown-up view of two of the vectors shown in
FIG. 3A.
[0014] FIGS. 3C-3F show how sets of ultrasound transducers can be
used to form a moving square array transducer according to an
embodiment of the present invention.
[0015] FIGS. 4A-4D illustrate a transmit sequence, according to an
embodiment of the present invention.
[0016] FIGS. 5A-5D illustrate a receive sequence, according to an
embodiment of the present invention.
[0017] FIGS. 6A-6D illustrate a receive sequence, according to an
embodiment of the present invention.
DETAILED DESCRIPTION
[0018] In the following detailed description, reference is made to
the accompanying drawings that form a part hereof, and in which is
shown by way of illustration specific illustrative embodiments. It
is to be understood that other embodiments may be utilized and that
mechanical and electrical changes may be made. The following
detailed description is, therefore, not to be taken in a limiting
sense. In the description that follows, like numerals or reference
designators will be used to refer to like parts or elements
throughout. In addition, the first digit of a reference number
identifies the drawing in which the reference number first
appears.
[0019] FIG. 1A shows an ultrasonic imaging probe 102, according to
an embodiment of the present invention, which is connected by a
passive interface cable 106 to a host computer 112. Ultrasonic
imaging probe 102 includes an array of ultrasound transducers for
transmitting and receiving ultrasound pulses as will be described
below. The host computer 112 can be a desktop personal computer
(PC), a laptop PC, a pocket PC, a tablet PC, a mobile phone capable
or running software programs (often referred to as a "smart
phone"), a personal digital assistant, or the like. The passive
interface cable 106, which includes connectors and passive wires,
can be a Universal Serial Bus (USB) cable (e.g., a USB 2.0 cable),
a FireWire (also known as IEEE 1394) cable, or the like. Preferably
the probe 102 is not connected to any other device or power supply.
Thus, in a preferred embodiment the probe 102 receives all its
necessary power from the host computer 112 via the passive
interface cable 106. In alternative embodiments, probe 102 can
include a battery and a wireless transceiver, in which case the
probe can wireless communicate with the host computer, and the
probe can generate all its necessary power from the battery.
[0020] As will be described in more detail below, in accordance
with embodiments of the present invention, the probe 102 enables
the host computer 112, via software running on the host computer
112, to form real-time ultrasonic images of a target 100 (e.g.,
human tissue or other materials) without the need for any
additional internal or external electronics, power supply, or
support devices. In certain embodiments, the probe 102 produces raw
digitized data that is envelope detected ultrasound echo data from
an array of ultrasound transducers in the probe 102, and transmits
such raw data to the host computer 112. The raw digitized data can
optionally also be logarithmically compressed, depending upon
implementation.
[0021] In an embodiment, when the host computer 112 receives raw
data via the passive interface cable 106 from the probe 102, the
host computer 112 performs time gain compensation (TGC), gray-scale
mapping, and scan conversion of the raw data using software that
runs on the host computer 112, and displays the resultant video
images. The probe does not include any moving mechanical parts,
thereby reducing the complexity and cost of the probe 102 and
increasing its reliability. The term "raw data", as used herein,
refers to ultrasound imaging data that has not yet been time gain
compensated, gray-scale mapped and scan converted. As described
below, such raw data is included in the digital signal that is
transferred from the probe 102 to the host computer 112.
[0022] As shown in FIG. 1A, the host computer 112 will likely
include a communications port 108, a communications chip-set 122, a
central processing unit (CPU) 124, memory 126, a display 128, and
an input device 130, such as a keyboard, mouse, touch screen, track
ball, or the like. Additionally, the host computer 112 runs
software that enables the host to control specific aspects of the
probe 102. Such software also enables the host computer 112 to
perform time gain compensation (also known as time gain
correction), gray-scale mapping, and scan conversion of the raw
data received from the probe 112 over the passive interface cable
106. The host computer 112 can then display the resulting
ultrasound video on the display 128, as well as store such video in
its memory 126, or another data storage device (not shown).
[0023] The article "A New Time-Gain Correction Method for Standard
B-Mode Ultrasound Imaging", by William D. Richard, IEEE
Transactions of Medical Imaging, Vol. 8, No. 3, pp. 283-285,
September 1989, which is incorporated herein by reference,
describes an exemplary time gain correction technique that can be
performed by the host computer 112. The article "Real-Time
Ultrasonic Scan Conversation via Linear Interpolation of
Oversampled Vectors," Ultrasonic Imaging, Vol. 16, pp. 109-123,
April 1994, which is incorporated herein by reference, describes an
exemplary scan conversion technique that can be performed by the
host computer 112. These are just exemplary details of the host
computer 112, which are not meant to be limiting.
[0024] The passive interface cable 106 includes at least one data
line over which data is carried, and at least one power line to
provide power to a peripheral device, which in this case is the
ultrasonic imaging probe 102. For example, where the passive
interface cable 106 is a USB 2.0 cable, one wire of the cable
provides about 5V at about 1/2 Amp. In alternative embodiments, the
passive interface cable 106 is a Firewire cable, which also
includes a power wire. Other types of passive interface cable can
be used if desired. However, as mentioned above, it is preferred
that the passive interface cable 106 is a standard off-the-shelf
cable that can interface with an off-the-shelf interface IC. The
term passive as used herein refers to a cable that does not
regenerate signals or process them in any way. In an alternative
embodiment, the probe 102 and the host computer 112 communicate
wirelessly, and the probe 102 includes a battery that is used to
power the components within the probe.
[0025] FIG. 1B illustrates an example where the host computer 112
is a laptop. FIG. 1B also shows an exemplary ergonomic design of a
housing 103 for the ultrasonic imaging probe 102 of the present
invention. Other ergonomic designs are of course possible, and
within the scope of the present invention. Also, as explained
above, other types of host computer 112 can also be used. FIG. 1B
also shows that the ultrasonic imaging probe 102 includes a probe
head assembly 105.
[0026] In accordance with certain embodiments, the data samples
produced by the ultrasound imaging probe 102 of the present
invention are transmitted by the probe 102 across the interface
cable 106 to the host computer 112. In a specific embodiment, this
is accomplished when the host computer 112 reads the data
temporarily stored in the buffers of the interface IC 204. The host
computer 112 runs software that enables the host to perform time
gain compensation (TGC), gray-scale mapping, and scan conversion of
the data received from the probe 102. The host computer generates
and displays the resultant ultrasound video images. Advantageously,
the host computer 112 does not need to perform electronic
beamforming or other equivalent image processing, thereby
simplifying the software that the host computer 112 runs.
[0027] The host computer 112 can use the digital data received from
the ultrasound device 102 to provide any available type of
ultrasound imaging mode can be used by the host computer 112 to
display the ultrasound images, including, but not limited to
A-mode, B-mode, M-mode, etc. For example, in B-mode, the host
computer 112 performs know scan conversion such that the brightness
of a pixel is based on the intensity of the echo return.
[0028] A benefit of specific embodiments of the present invention
is that only digital signals are transmitted from the probe 102 to
the host computer 112, thereby providing for better signal-to-noise
ratio than if analog signals were transmitted from the probe 102 to
the host computer 112, or to some intermediate apparatus between
the host computer and the probe. Another benefit of specific
embodiments of the present invention is that the probe 102 can be
used with a standard off-the-shelf passive interface cable.
[0029] A further benefit of specific embodiments of the present
invention is that the probe 102 does not perform any time gain
compensation, gray-scale mapping and scan conversion, thereby
significantly decreasing the complexity, power requirements and
cost of the probe 102. Conventionally, functions such as scan
conversion, time gain correction (also known as time gain
compensation) and gray-scale mapping are performed by a machine
that is dedicated to obtaining ultrasound images, or by an
intermediate device that is located between the probe and host
computer. In contrast, in embodiments of the present invention,
software running on the host computer 112 is used to perform these
functions, thereby reducing the complexity and cost of the portable
ultrasonic imaging probe 102.
[0030] FIG. 2A is a block diagram that shows additional details of
an ultrasonic imaging probe according to an embodiment of the
present invention. Additional details of the ultrasonic imaging
probe 102, according to specific embodiments of the present
invention, shall now be described with reference FIG. 2A. As shown
in FIG. 2A, in accordance with an embodiment of the present
invention, the probe 102 includes a peripheral connector 104 and an
interface IC 204 that enables the probe 102 to interface with the
host computer 112 via the interface cable 106. The connector 104
and the interface IC 204 are preferably off-the-shelf devices, but
can be custom devices.
[0031] In accordance with an embodiment illustrated in FIG. 2A,
specific certain components (shown within a large dash-lined
rectangle) are located within the probe head assembly 105, with the
remaining components being within the housing 103 of the ultrasonic
imaging probe 102. An interface cable 209 connects the components
within the housing 103 to the components within the probe head
assembly 105.
[0032] The probe 102 is also shown as including a digital control
and processing block 206, an analog to digital converter (ADC) 208
and a high voltage power supply (HVPS) 250. The HVPS 250 provides
power to a high voltage (HV) pulser 224. Additionally, the probe
102 is shown as including a micromachined ultrasound transducer
(MUT) array 220, which includes individually controllable MUT
elements 221, which are discussed in additional detail below. A
transmit and receive (Tx/Rx) controller 240 accesses vector
configuration and timing data stored within a memory 230 in order
to controls transmit (Tx) switches 222 and receive (Rx) switches
216, to thereby control the operation of the MUT elements 221 of
the MUT array 220, as described in additional detail below. In
certain embodiments, such vector configuration and timing data is
stored within a look-up table (LUT) within the memory 230.
[0033] The probe 102 also includes analog summing, amplification
and processing circuitry 215. In accordance with an embodiment, the
analog summing, amplification and processing circuitry 215 includes
summing resistors 214 and a summing amplifier 212, which are
discussed in more detail with reference to FIG. 2B, and an analog
signal processing block 210. The analog signal processing block 210
can include, e.g., a pre-amplifier, a filter (e.g., a low pass or
bandpass filter) and an envelope detector, and optionally a
logarithmic amplifier. Such a pre-amplifier can be, e.g., a very
low noise amplifier that provides about 20 dB of gain. The filter
can filter out frequencies that are not of interest. The summing
resistors 214 and the summing amplifier 212 combine numerous echo
signals (received using numerous MUT elements) into a single echo
signal. In accordance with an embodiment, this single echo signal
is pre-amplified, filtered (e.g., low pass filtered) and envelope
detected to produce a radio frequency (RF) signal. Logarithmic
compression can be performed within the analog signal processing
block 210, or within the digital control and processing block 210,
or alternatively, within the host computer 112.
[0034] The RF signal output by the analog signal processing block
210 is digitized by the ADC 208. The ADC 208 samples the RF signal
(e.g., at 30 or 48 MHz), to thereby digitize the signal, and
provides the digitized signal to the digital control and processing
block 210. The digital control and processing block 206 could be
implemented, e.g., using a complex programmable logic device
(CPLD), a field-programmable gate array (FPGA), an application
specific integrated circuit (ASIC) or some other circuitry. The
digital control and processing clock 206 control functions and
timing of the hardware in the probe, and depending upon
implementation, can also perform digital signal processing of the
digital signal output by the ADC 208. For example, the digital
control and processing block 206 can perform logarithmic
compression, as was mentioned above. The digital control and
processing clock 206 also controls the Tx/Rx controller 240.
[0035] The Tx/Rx controller 240, which can be implemented using an
FPGA, an ASIC or some other circuitry, controls the Tx switches 222
so that a selected set of the MUTs transmit ultrasonic pulses
generated by a high voltage (HV) pulser 224. The host computer 112,
through the passive interface cable 106, and the interface IC 204
can control the amplitude, frequency and duration of the pulses
output by the HV pulser 224. For example, the host computer 112 can
write vector configuration and timing data to the memory 230.
Additionally, the host computer 112 can send instructions to the
probe 102 that cause the probe 102 to select, from the memory 230,
specific transmit and receive vector control and timing data used
to control transmission and reception of ultrasonic pulses.
[0036] The HV pulser 224 is powered by the HVPS 250, which
generates the high voltage potential(s) required by the HV pulser
224 from a lower voltage (e.g., 5V) received via the passive
interface cable 106. Depending upon implementation, the HV pulser
224 can produce unipolar pulses, or bipolar pulses. Unipolar pulses
can be, e.g., high voltage pulses that are as large as 100V. Where
the HV pulser 224 produces bipolar pulses, the HV pulser 224 may
produce, e.g., both positive and negative high voltage pulses that
can be as large as +/-100V. In such embodiments, the HVPS 250 can
provide up to +/-100V supply rails to the HV pulser 224. Exemplary
details of an HVPS, which can be used to implement the HVPS 250,
are shown in and described with reference to FIG. 4 of U.S. Patent
Publication No. 2007/0239019, which U.S. Patent Publication is
incorporated herein by reference in its entirety. Alternative high
voltage power supplies known in the art may also used as HVPS
250.
[0037] The probe 102 can also include a linear regulator IC (now
shown) with integrated power switches and low quiescent current
requirements designed for USB applications. For example, such a
linear regular IC can produce a 3.3V digital supply and a 3.3V
analog voltage supply, which are used to provide power to the
various circuits/blocks within the probe 102. For example, a 3.3V
digital supply can power the interface IC 204 and the digital
control and processing block 206; and a 3.3V analog supply can
power the summing amplifier 212 and the analog signal processing
circuitry 210. An exemplary IC that can be used for the linear
regulator IC is the TPS2148 3.3-V LDO and Dual Switch for USB
Peripheral Power Management IC, available from Texas Instruments of
Dallas, Tx.
[0038] Preferably, the probe 102 is configured as a single channel
architecture, which means that only a single ADC 208 is required,
and only a single data signal is transmitted from the probe 102 to
the host 112 at any given time. However, in alternative
embodiments, a multiple channel architecture that includes multiple
ADCs can be implemented. Unless stated otherwise, the embodiments
described herein include a single channel architecture. Another
benefit of specific embodiments of the present invention is that
the MUT array 220 is in close proximity to (i.e., within the same
housing as) the analog summing, amplifying and processing circuitry
215 and the ADC 208 (see FIG. 2A). This provides for good
signal-to-noise (S/N) ratio, as compared to systems where the
analog signals output by the transducers must travel across a
relatively long distance before they are amplified and/or
digitized.
[0039] As mentioned above, the portable ultrasound imaging probe
102 includes an array of ultrasound transducers, which includes
numerous transducers. In a preferred embodiment, the portable
ultrasound imaging probe 102 includes a micromachined ultrasound
transducer (MUT) array 220, which includes numerous MUTs 221, each
of which can be referred to as an MUT element (or simply as an
MUT). Each MUT element can include a single MUT cell, or multiple
MUT cells hardwired together. Such a MUT array 220, which can also
be referred to as an array of MUTs, is an example of a MEMS based
transducer, since the MUTs are examples of micro-electro-mechanical
systems (MEMS). A MUT is one example of an ultrasound transducer.
However, the principles of the present invention are also
applicable to arrays of ultrasound transducers and ultrasound
transducers other than MUTs. Thus, although the following
description refers to MUTs, alternative ultrasound transducers and
transducer arrays can be used in place of the MUTs and MUT arrays
described below.
[0040] Each MUT cell can be a capacitive MUT (cMUT) cell or a
piezoelectric MUT (pMUT) cell, but is not limited thereto. Such
cells typically include a membrane (often referred to as a
diaphragm) and two or more electrodes. For transmission, the
electrodes and membrane are used to modulate a capacitive charge
that vibrates the membrane and thereby transmits a sound wave. For
reception, the electrodes and membrane are used to convert the
sound vibration of a received ultrasound signal into a modulated
capacitance. More specifically, when an AC signal is applied across
the electrodes, the MUT generates ultrasonic waves in the medium of
interest to thereby function as a transmitter. When ultrasonic
waves are applied to the membrane of a MUT, the MUT generates an
alternating signal as the capacitance of the MUT is varied to
thereby function as a receiver of ultrasonic waves.
[0041] Each MUT element can simply be referred to as an MUT, and a
plurality of MUT elements can simply be referred to as MUTs.
Preferably, the MUT array 220 is encased in material that has the
proper acoustic impedance to be matched with acoustic impedance of
human tissue.
[0042] Advantageously, MUTs can be made using semiconductor
fabrication processes, such as microfabrication processes generally
referred to as "micromachining" Micromachining is the formation of
microscopic structures using patterning, deposition and/or etching.
Patterning generally includes lithography, which can be performed
using projection-aligners or wafer-steppers, but is not limited
thereto. Deposition can be physical vapor deposition (PVD),
chemical vapor deposition (CVD), low-pressure chemical vapor
deposition (LPCVD), or plasma chemical vapor deposition (PECVD),
but is not limited thereto. Etching can include wet-chemical
etching, plasma-etching, ion-milling, sputter-etching or
laser-etching, but is not limited thereto.
[0043] Micromachining is typically performed on substrates or
wafers made of silicon, glass, sapphire or ceramic. Such substrates
or wafers are generally very flat and smooth and have lateral
dimensions in inches. They are usually processed as groups in
cassettes as they travel from process tool to process tool. Each
substrate can advantageously (but not necessarily) incorporate
numerous copies of a product. Micromachining can include the use of
conventional or known micromachinable materials including silicon,
sapphire, glass materials of all types, polymers (such as
polyimide), polysilicon, silicon nitride, silicon oxynitride, thin
film metals such as aluminum alloys, copper alloys and tungsten,
spin-on-glasses (SOGs), implantable or diffused dopants and grown
films such as silicon oxides and nitrides, but is not limited
thereto.
[0044] In accordance with an embodiment, the MUT array 220 includes
M rows.times.N columns of transducer elements, with the MUTs 221
being illustrated as small circles in FIG. 2A. For example, if M=20
and N=100, then the MUT array would include 2000 MUTs. In
accordance with an embodiment, half of the MUTs 221 can be
selectively used for transmitting ultrasonic pulses, and the other
half of the MUTs 221 can be selectively used for receiving "echo
pulses". Continuing with the example where the MUT array 220
includes 2000 MUTs, then 1000 of the MUTs 221 can be can be
selectively used for transmitting ultrasonic pulses, and 1000 of
the MUTs 221 can be selectively used for receiving "echo pulses".
More generally, P1 percent of the MUTs can be selectively used for
transmitting ultrasonic pulses, and P2 percent (where P2=100%-P1)
of the MUTs can be selectively used for receiving "echo pulses".
Unless specified otherwise, it will be assumed that P1=P2=50%, such
that half of the MUTs can be selectively used for transmitting
ultrasonic pulses, and half of the MUTs can be selectively used for
receiving "echo pulses". For illustrative purposes, the MUTs that
can be used for transmitting ultrasonic pulses, which can be
referred to as Tx MUTs, are illustrated in FIG. 2A as small filled
circles 223; and the MUTs that can be used for receiving ultrasonic
pulses, which can be referred to as Rx MUTs, are illustrated in
FIG. 2A as small unfilled circles 225.
[0045] Each of the MUTs 221 can have a circumferential shape that
is circular, as shown. Each MUT 221 can be, e.g., about 50
micrometers in diameter, but is not limited thereto. The distance
from the edge of one MUT 221 to its closest adjacent MUT 221 can
be, e.g., about 70 micrometers, but is not limited thereto.
Alternatively, each of the MUTs can have another circumferential
shape, including, but not limited to, square or hexagonal. In
accordance with certain embodiments, the Tx MUTs 223 and the Rx
MUTs 225 are structurally the same. In such embodiments, the only
difference between a Tx MUT 223 and an Rx MUT 225 is how the MUT is
connected to other circuitry and used. In other embodiments, the Tx
MUTs 223 can be structurally different from the Rx MUTs 225. In
alternative embodiments, each of MUTs 221 may be replaced with
conventional ultrasound transducers which may be square or circular
in shape (see, e.g. FIGS. 2E and 2F).
[0046] All of the rows and columns can be inline with one another,
as shown in FIG. 2A. Alternatively, odd rows can be staggered
relative even rows, as shown in FIG. 2D. It is also possible that
odd columns be staggered relative to even columns. Other variations
are also possible, and within the scope of an embodiment of the
present invention. In the embodiment shown in FIG. 2A, the Tx MUTs
223 and the Rx MUTs 225 alternate in a way that creates minimum
pitch in linear array configuration, thereby enabling better
lateral resolution.
[0047] As will be described in further detail below, at any given
time, a set of the Tx MUTs 223 can be selected for transmitting
ultrasonic pulses, and a set of the Rx MUTs 225 can be selected for
receiving echo pulses. For example, sets of Tx MUTs 223 that
collectively make up rings can be used to form a quasi-annular
array transducer, as will be described below with reference to
FIGS. 3-5. Switches 222, which can be referred to as Tx switches
222, can be used to select which Tx MUTs 223 are active at a time.
Similarly, switches 216, which can be referred to as Rx switches,
can be used to select which Rx MUTs 225 are active at a time. In
accordance with an embodiment, each of the Tx MUTs 223 is connected
to a corresponding Tx switch. When the Tx switch is turned on
(which can also be referred to as closed), the Tx MUT 223 is
connected by its corresponding Tx switch to the HV pulser 224,
thereby causing the Tx MUT 223 to output an ultrasonic pulse. When
multiple MUTs 223 are triggered simultaneously (i.e.,
simultaneously connected by switches to the HV pulser 224), the
multiple MUTs collectively produce an ultrasonic pulse or
wave-front.
[0048] Selected Tx MUTs 223 transmit ultrasonic pulses into the
target region being examined, and selected Rx MUTs 225 receive
reflected ultrasonic pulses (i.e., "echo pulses") returning from
the region. When transmitting, the selected Tx MUTs 223 are excited
to high-frequency oscillation by the pulses emitted by the HV
pulser 224, thereby generating ultrasound pulses that can be
directed at a target region/object to be imaged.
[0049] These ultrasound pulses (also referred to as ultrasonic
pulses) produced by the selected Tx MUTs 223 are echoed back
towards the selected Rx MUTs 225 from some point within the target
region/object, e.g., at boundary layers between two media with
differing acoustic impedances. The echo pulses received by the
selected Rx MUTs 225 are converted into corresponding low-level
electrical input signals (i.e., the "echo signals") that are
provided to the analog summing, amplification and processing
circuitry 215. In specific embodiments, to receive echo pulses, the
Rx switches 216 selectively connect a set of the Rx MUTs 225 to
summing resistors 214, which are used to sum the echo pulses at the
input of a summing amplifier 212.
[0050] Advantageously, in certain embodiments, the vectors may be
uploaded to memory (look-up-table) 230 from Host Computer 112 in
order to upgrade probe 102 or provide a set of vectors suitable for
a particular imaging application. For example different vectors can
be provided for imaging different portions of the human body,
different tissues, or different depths depending on the
application. A user can select the appropriate application (imaging
purpose) in the host computer 112 which can then transfer an
appropriate vector set to memory 230 over passive interface cable
106 prior to imaging. Alternatively memory 230 can include a
plurality of vector sets suitable for different applications and
the user can select which of those vector sets is used by Tx/Rx
Controller 215 in a particular imaging session by input to host
computer 112 or using an interface/switch/multiposition switch on
probe housing 103. After download or selection of a pre-existing
vector set in memory 230, the vector set can be used by Tx/Rx
Controller 215 to configure Tx switches 222 and Rx switches 216 to
cause Tx MUTS 223 and Rx MUTS 225 to transmit and receive
ultrasound pulses in accordance with the downloaded vectors
suitable for the intended application.
[0051] FIG. 2B illustrates some further details of some of the
blocks introduced in FIG. 2A, according to an embodiment of the
present invention. In specific embodiments, to receive echo pulses,
the Rx switches 216 selectively connect a set of the Rx MUTs 225 to
summing resistors 214, which are used to sum the echo pulses at the
input of a summing amplifier 212. In accordance with an embodiment,
the analog summing, amplification and processing circuitry 215
includes summing resistors 214 and a summing amplifier 212.
Exemplary details of the Rx switches 216, the summing resistors 214
and the summing amplifier 212 are shown in FIG. 2B.
[0052] Note that, as previously discussed, single channel
architecture is used. Accordingly, the Rx switches 216 (or Tx/Rx)
switches connect a plurality of selected MUTS 225 to analog
summing, amplification and signal processing circuitry 215. Note
that there are a plurality of summing resistors 214 in order that
they may be connected to a selected plurality of Rx MUTS 225.
Analog summing, amplification and signal processing circuitry 215
is configured to combine the plurality of echo signals produced by
the plurality of the ultrasound transducers 225 into a single
analog echo signal. This can be achieved using summing amplifier
212. A single analog-to-digital converter 208 (ADC) then converts
the analog echo signal into a single digital echo signal for
transmission to a host computer that can perform digital processing
of the digital echo signal in order to display an ultrasound
image.
[0053] FIG. 2C illustrates a perspective view of a probe head
assembly, according to an embodiment of the present invention. A
shown in FIG. 2C, MUT array 220 is positioned at the end of head
assembly 105. FIG. 2C also shows a portion of the interface cable
209, which is used to connect the components within the probe head
assembly 105 to components within the probe housing 103.
[0054] FIG. 2D illustrates how odd and even rows of MUTS 221 can be
staggered relative to one another. All of the rows and columns can
be inline with one another, as shown in FIG. 2A. Alternatively, odd
rows can be staggered relative even rows, as shown in FIG. 2D. It
is also possible that odd columns be staggered relative to even
columns. Other variations are also possible, and within the scope
of an embodiment of the present invention. In the embodiment shown
in FIG. 2D, the Tx MUTs 223 and the Rx MUTs 225 alternate in a way
that creates minimum pitch in linear array configuration, thereby
enabling better lateral resolution. As mentioned above, sets of Tx
MUTs 223 that collectively makes up rings/circles that can be used
to form a quasi-annular array transducer, as described below with
reference to FIGS. 3A-5D.
[0055] FIG. 2E illustrates an alternative array of ultrasound
transducers according to an embodiment of the present invention. As
shown in FIG. 2E, an alternative ultrasound transducer array 260
includes a regular distribution of 128 rectangular ultrasound
transducers 262 arranged in a linear array (single row). In
alternative embodiments transducer array 260 may be square,
rectangular, linear or another shape and may comprise one, or a
plurality of, rows and/or columns of transducers. Transducer array
260 may comprise a different number of transducers depending on the
application. For example, transducer array 260 may comprise 8, 16,
32, 64, 128, 256 or more transducers 262. Transducers 262 may be
any suitable shape for assembly into an array including for
example, square, rectangular, or circular. Alternative transducer
array 260 may be used in place of MUT array 220 in all embodiments
described herein.
[0056] Transducer array 260 is preferably planar in shape i.e. all
of transducers 262 lay in a single flat plane (not curved).
Moreover, in preferred embodiments no lens or other beam forming
device is placed over transducer array 260. Accordingly, similar or
identical ultrasound beams can be produced by similar groups of
transducers 262 at different locations in transducer array 260.
[0057] Transducers 262 can be made using conventional technology
known in the art and may be, for example, piezo-electric
transducers or capacitive transducers. In an embodiment ultrasound
transducers 262 are substantially rectangular piezoelectric
transducers approximately 5 mm by 0.3 mm in size. A set of 16
adjacent transducers acting together form a substantially square
ultrasound source.
[0058] As shown in FIG. 2F, Transducers 262 are selectively
connected by Tx/Rx switches 266 to HV pulser 224 and analog
processing circuitry 215. Each of ultrasound transducers 262 may be
used for transmitting ultrasound pulses or receiving ultrasound
echoes depending on the configuration of the Tx/Rx switches 266 as
controlled by Tx/Rx Controller 240. Alternatively, certain
transducers 262 may be used only for transmitting ultrasound pulses
and other may be used only for detecting ultrasound echoes. In this
alternative embodiment, switches Tx switches 222 and Rx switches
216 are used in place of Tx/Rx switches 266.
[0059] Note that, as previously discussed, single channel
architecture is used in combination with transducer array 260.
Accordingly, the Tx/Rx switches 266 (or Rx switches 216 in an
alternative embodiment) connect the plurality of selected
transducers 262 to analog summing, amplification and signal
processing circuitry 215 which is configured to combine echo
signals produced by a plurality of the ultrasound transducers 262
into a single analog echo signal. A single analog-to-digital
converter (ADC) then converts the analog echo signal into a digital
echo signal for transmission to a host computer that can perform
digital processing of the digital echo signal in order to display
an ultrasound image.
[0060] FIG. 2F is a block diagram that shows details of an
alternative ultrasonic imaging probe according to an embodiment of
the present invention. FIG. 2F has almost all the elements of FIG.
2A as previously described. However MUT Array 220 has been replaced
transducer array 260. Additionally, Tx/Rx switches 266 are used in
place of the Tx switches 222 and Rx switches 216 of FIG. 2A such
that each of the ultrasound transducers 262 may be used for
transmitting or receiving ultrasound depending on the configuration
of the Tx/Rx switches 266 at a particular point in time.
[0061] The Tx/Rx switches 266 can be used to connect a selected set
of the transducers 262 to either the HV pulser 224, or the analog
summing, amplification and processing circuitry 215, depending on
whether the transducers 262 are to be used for transmitting or
receiving ultrasound pulses at a particular time. When a high
voltage pulse is produced by the HV pulser 224, the Tx/Rx switches
automatically block the high voltage from damaging the analog
summing, amplification and processing circuitry 215. When the HV
pulser 224 is not producing a pulse, the Tx/Rx switches disconnect
a selected set of transducers 262 from the pulser 224, and instead
connect a selected set of transducers 262 to the analog summing,
amplification and processing circuitry 215. Note that Tx/Rx
switches 266 may also be used in combination with MUT array 220
(see, e.g. FIGS. 2A and 2D).
[0062] FIG. 3A illustrates how sets of micromachined ultrasound
transducers (MUTs) that collectively make up rings can be used to
form a quasi-annular array transducer, and that such rings can be
moved to emulate the mechanical movement of an annular array
transducer, without requiring any moving parts. Referring to FIG.
3A, illustrated therein are a plurality of possible MUT vectors,
each of which is made up of a plurality of annular rings/circles of
MUTs 221. Each such vector can be made up of a plurality of
different sets of MUTs 221, wherein each set of MUTs defines a
different annular ring/circle of MUTs 221, as can be appreciated
from the discussion of FIGS. 4A-4D below. Still referring to FIG.
3A, illustrated therein are four different MUT vectors, the first
one of which is labeled Vector 1, and the last one of which is
labeled Vector X. If, e.g., X=128, that would mean that 128 of the
annular array MUT vectors can be produced using the MUT array 220.
More specifically, by controlling the Tx and Rx switches 222 and
216 (in FIG. 2A), the various MUT Vectors (1 through 128) can be
selected, one after the other, to emulate an annular array (annular
shaped ultrasound transmitter) that is mechanically moved through
128 different physical positions (as shown by arrow 300). However,
here there is no mechanical movement; but rather, different MUTs
221 are selected at sequential points in time in order to emulate
the movement. Thus, by controlling the Tx switches 222 to select
different groups of Tx MUTS 223 at different times, the
transmitting group of transducers forms an ultrasound transmitter
which effectively changes position within the array of transducers
over time. Similarly by controlling the Rx switches 216 to select
different groups of Rx MUTS 225 at different times, the receiving
group of transducers forms an ultrasound receiver which effectively
changes position within the array of transducers over time.
[0063] FIG. 3B is a blown-up view of two of the closely spaced
adjacent vectors, X/2 and X/2+1, shown in FIG. 3A. FIG. 3B shows a
MUT array 220 which includes a plurality of MUTs 221, some or all
of which may function as Tx MUTs 223 and some or all of which may
function a Rx MUTs 225. The adjacent vectors X/2 and X/2+1 show how
different groups of Tx MUTS 223 and Rx MUTS 225 are selected (by Tx
switches 222 and Rx switches 216 configured by Tx/Rx controller
240) for transmitting and receiving ultrasound pulses at different
sequential periods in time. As, shown, in the embodiments shown in
FIGS. 3A and 3B, the Tx MUTs 223 and the Rx MUTs 225 alternate in a
way that creates minimum pitch in linear array configuration,
thereby enabling better lateral resolution.
[0064] FIGS. 3C-3F show how sets of ultrasound transducers 262 of
ultrasound transducer array 260 of FIGS. 2E and 2F can be used to
form a moving square array transducer according to an embodiment of
the present invention. In each of FIGS. 3C-3F the set 350, 360,
370, 380 of transducers 262 connected by Tx/Rx switches to HV
pulser 224 as indicated by shading of transducers 262. Each set
350, 360, 370, 380 of sixteen adjacent transducers operates as a
single square ultrasound transmitter. Alternative shapes of
transmitter may be configured from different sets of transducers
262. As shown by FIGS. 3C-3F the active set of transducers can be
moved without mechanical movement merely by selecting different
transducers 262 for inclusion in the active set at a particular
time. Thus the portion or subarray of transducer array 260 that is
emitting ultrasound can "walk" around transducer array 260 under
the control of Tx/Rx switches 266 as configured by Tx/Rx Controller
240. Likewise the size, shape, and/or position of the set of
transducers 262 connected to analog processing circuitry 215 can
also be changed from one period of time to the next.
[0065] FIGS. 4A-4D illustrate how a transmit MUT vector can be used
to transmit focused ultrasound beams. FIGS. 4A-4D illustrates
different sized groups of Tx MUTs 223 rings/circle of Tx MUTs 223,
which can collectively be used to generate one focused ultrasound
beam. The different groups of Tx MUTS 223 and Rx MUTS 225 are
selected (by Tx switches 222 and Rx switches 216 configured by
Tx/Rx controller 240) for transmitting and receiving ultrasound
pulses at different sequential periods in time. More specifically,
the ring 410 of Tx MUTs 223 shown in FIG. 4A can be used to
collectively transmit a first ultrasound pulse. A short programmed
delay thereafter the ring 420 of Tx MUTs 223 shown in FIG. 4B can
be used to collectively transmit a second ultrasound pulse. A short
programmed delay thereafter the ring 430 of Tx MUTs 223 shown in
FIG. 4C can be used to collectively transmit a third ultrasound
pulse. And, a short programmed delay thereafter the circle 440 of
Tx MUTs 223 shown in FIG. 4D can be used to collectively transmit a
fourth ultrasound pulse. These four ultrasound pulses, sequentially
generated as mentioned above, collectively make up a focused
ultrasound beam.
[0066] By controlling the Tx switches 222 to select different
groups of Tx MUTS 223 at different times, the transmitting group of
transducers forms an ultrasound transmitter which effectively
changes shape and/or size and/or position over time. As shown in
FIGS. 4A-4D, the ring 410 in FIG. 4A has the largest aperture, and
the circle 440 in FIG. 4D has the smallest/no aperture. In FIGS.
4A-4D, the four different rings/circle 410, 420, 430, 440, do not
overlap one another. However, in alternative embodiments, there can
be overlap between the different rings/circle. In other words, a Tx
MUT 223 can be included in more than one annular ring/circle.
[0067] FIGS. 5A-5D illustrate how a receive MUT vector can be used
to receive echo pulses generated in response to the focused
ultrasound beam described with reference to FIGS. 4A-4D. FIGS.
5A-5D illustrates different sized circles of Rx MUTs 225, which can
collectively be used to receive echo pulses and produce an echo
signal. More specifically, the circle 510 of Rx MUTs 225 shown in
FIG. 5A can be used to collectively receive a first echo pulse; a
short programmed delay thereafter the circle 520 of Rx MUTs 225
shown in FIG. 5B can be used to collectively receive a second echo
pulse; a short programmed delay thereafter the circle 530 of Rx
MUTs 225 shown in FIG. 5C can be used to collectively receive a
third echo pulse; and a short programmed delay thereafter the
circle 540 of Rx MUTs 225 shown in FIG. 5D can be used to
collectively receive a fourth echo pulse. These four echo pulses
collectively make up a received ultrasound echo.
[0068] By controlling the Rx switches 216 to select different
groups of Rx MUTS 225 at different times, the receiving group of
transducers forms an ultrasound receiver which effectively changes
shape, size, or position within the array of transducers over time.
As shown in FIGS. 5A-5D, the circle 510 of Rx MUTs 225 in FIG. 5A,
which has the smallest diameter, will receive near field echoes. By
contrast, the circle 540 of Rx MUTs 225 in FIG. 5D, which has the
largest diameter, will receive the deepest field echoes. In FIGS.
5A-5D, the four different circles 510, 520, 530, 540, overlap one
another. However, in alternative embodiments, there can be no
overlap between the different circles. In other words, an Rx MUT
225 may or may not be included in more than one circle. Further, it
is noted that sets of the Rx MUTs 225 can be selected in such a way
that the active area of circular arrays can continuously increase
with a controlled number of sampling cycles in order to optimize
the resolution of the received signal from different depths.
[0069] Tx/Rx Controller 240 controls Tx switches 222 and Rx
switches 216 to select different groups of Tx MUTs 223 and Rx MUTS
225 at different times for sending and receiving ultrasound
transducers thereby allowing the MUT Array 220 to emulate an
ultrasound receiver and ultrasound transmitter which effectively
changes in shape, size, or position within the array of transducers
over time. While the Tx MUT and Rx MUT vectors shown in FIGS. 4A-4D
and 5A-5D include substantially circular and/or annular arrays,
because of the flexibility provided by the MUT array 220, the
vectors can have alternative shapes, such as, but not limited to
elliptical shapes. In alternative embodiments, the Tx MUTs 223 and
Rx MUTs 225 can be selectively connected to produce other types of
arrays, besides circular and/or annular arrays. In embodiments, the
vectors are stored in memory (look-up-table) 230.
[0070] Advantageously, the MUT array 220 and the circuitry used to
select sets of the MUTs can provide a continuously variable
aperture annular array. More specifically, such circuitry can be
used to activate sets of MUTs in such a way that the active area of
annular arrays will continuously shift in order to form ultrasound
beams with variable focal points. In other words, the MUT array 220
can be used to perform beam forming and aperture control for each
of a plurality of different MUT vectors. Advantageously, beam
shapes and aperture shapes and sizes can be optimized for both
transmit and receive signals.
[0071] In accordance with certain embodiments of the present
invention, preprogrammed vector configuration and timing data that
enables the various annular rings of Tx MUTs 223 shown in FIGS.
4A-4D to be fired in sequence is stored in the memory 230, e.g., in
a LUT. Similar data used to controls selection/activation of Rx
MUTs, as was described with reference to FIGS. 5A-5D, is also
stored in the memory 230 (see FIG. 2A).
[0072] FIGS. 6A-6D illustrate how a vectors can be used to receive
echo pulses generated in response to an ultrasound beam using
transducer array 260 of FIGS. 2E and 2F. FIGS. 6A-6D illustrates
different sized groups/subarrays 660, 670, 680, 690 of ultrasound
transducers 262 (shaded), which can collectively be used to receive
echo pulses and produce an echo signal. More specifically, the
subarray 660 of ultrasound transducers 262 shown in FIG. 6A can be
used to collectively receive a first echo pulse; a short programmed
delay thereafter the subarray 670 of ultrasound transducers 262
shown in FIG. 6B can be used to collectively receive a second echo
pulse; a short programmed delay thereafter the subarray 680 of
ultrasound transducers 262 shown in FIG. 6C can be used to
collectively receive a third echo pulse; and a short programmed
delay thereafter the subarray 690 of ultrasound transducers 262
shown in FIG. 6D can be used to collectively receive a fourth echo
pulse. These four echo pulses collectively make up a received
ultrasound echo.
[0073] By controlling the Tx/Rx switches 266 to select different
groups of ultrasound transducers 262 (shaded) at different times,
the receiving group of transducers forms an ultrasound receiver
which effectively changes shape, size, or position within the array
of transducers 260 over time. As shown in FIGS. 6A-6D, the subarray
660 of ultrasound transducers 262 shown in FIG. 6A, which has the
smallest size, will receive near field echoes. By contrast, the
subarray 690 of ultrasound transducers 262 shown in FIG. 6dD which
has the largest size will receive the deepest field echoes. The
increasing subarray size effectively provides a variable aperture
for receiving ultrasound echoes in order to enhance the resolution
of the received signal from different depths. The variable aperture
for receiving may be utilized with fixed or variable sizes of
transmitting subarrays of ultrasound transducers.
[0074] In FIGS. 6A-6D, the four different subarrays 660, 670, 680,
690, overlap one another. However, in alternative embodiments,
there can be no overlap between the different subarrays. In other
words, a transducer 262 may or may not be included in more than one
subarray. Further, it is noted that subarrays of the transducers
262 can be selected in such a way that the active area of the
subarray can continuously increase with a controlled number of
sampling cycles in order to optimize the resolution of the received
signal from different depths.
[0075] Tx/Rx Controller 240 controls Tx/Rx switches 266 (see FIG.
2F) to select different groups of transducers 262 at different
times for sending and receiving ultrasound transducers thereby
allowing the ultrasound array 260 to emulate an ultrasound receiver
and ultrasound transmitter which effectively changes in shape,
size, or position within the array of transducers over time.
Because of the flexibility provided by the transducer array 260,
the vectors can have alternative shapes. In embodiments, the
vectors are stored in memory (look-up-table) 230. Subarrays may
comprise non-adjacent transducers 262, i.e. within a region of
transducer array 260 certain transducers may be active for
receiving (or transmitting) ultrasound while other are inactive
depending on the desired vectors.
[0076] As described above with respect to the figures, in an
embodiment, the present invention provides a portable ultrasonic
imaging probe 102 that is adapted to connect to a host computer 112
via a passive interface cable 106. The portable ultrasound imaging
probe 106 includes a probe head 105 including an array of
ultrasound transducers, for example MUT Array 220. The array may
comprise one or more parallel rows of ultrasound transducers, or a
different shaped distribution of a plurality of ultrasound
transducers. The ultrasound transducers may be, for example,
micromachined ultrasound transducers MUTS 221 or other ultrasound
transducers known in the art.
[0077] The portable ultrasonic imaging probe 102 also includes a
pulse circuit, for example, a high voltage (HV) pulser 224 adapted
to energize two or more transducers to emit ultrasound. The
portable ultrasonic imaging probe 102 also includes analog
processing circuitry 215, including for example summing amplifier
212, and summing resistors 214, configured to process electrical
signals caused by ultrasound pulses received by two or more
ultrasound transducers into an analog echo signal. One or more
analog-to-digital converters (e.g. ADC 208) converts the analog
echo signal, output by the analog summing, amplification and signal
processing circuitry, to a digital echo signal, and an interface
circuit 204 transfers the digital echo signal across a passive
interface cable to a host computer that can perform digital
processing of the digital echo signal in order to display an
ultrasound image.
[0078] The portable ultrasonic imaging probe 102 also includes a
transmit/receive controller 215 connected to a plurality of
transmit (Tx) switches 222 and a plurality of receive (Rx) switches
216 wherein the transmit/receive controller 215 selects which of
said ultrasound transducers are in transmitting group and which of
said ultrasound transducers are in the receiving group at any point
in time. The transmit/receive controller 215 configures the
plurality of transmit (Tx) switches 222 to connect a transmitting
group of the ultrasound transducers to the (HV) pulser 224. The
transmit/receive controller 215 also configures a plurality of
receive (Rx) switches 2'6 to connect a receiving group of the
ultrasound transducers to the analog summing, amplification and
signal processing circuitry 215.
[0079] The portable ultrasonic imaging probe 102 operates such that
which ultrasound transducers of the ultrasound transducer array are
part of the receiving group and which are part of the receiving
group is configurable and can be changed over time under the
control of transmit/receive controller 215 in response. Transmit
and receive (Tx/Rx) controller 240 accesses vector configuration
and timing data stored within a memory 230 to identify which
transducers should be activated for transmitting (transmitting
group) or receiving ultrasound pulses (receiving group) and at what
time.
[0080] In accordance with the vector configuration and timing data
the transmitting group includes a first plurality of transducers at
a first time, a second plurality of transducers different than the
first plurality at a second time, and a third plurality of
transducers different than the first plurality and the second
plurality a third time. The configurable transmitting group
functions as a configurable ultrasound transmitter which can change
in shape, size or position within the transducer array over time.
This allows, for example the ultrasound imaging probe 102 to: emit
a focused ultrasound beam; change the depth or focus or position of
focus of the ultrasound beam; perform ultrasound beam forming; scan
the ultrasound beam without moving the head 105; and/or form a
variable aperture ultrasound transmitter; and use configurable
aperture control.
[0081] In accordance with the vector configuration and timing data
the receiving group includes a first plurality of transducers at a
first time, a second plurality of transducers different than the
first plurality at a second time, and a third plurality of
transducers different than the first plurality and the second
plurality a third time. The configurable receiving group functions
as a configurable ultrasound receiver which can change in shape,
size or position within the transducer array over time. This
allows, for example the ultrasound imaging probe 102 to: change the
size, shape, or position of the configurable ultrasound receiver
over time (in relation, for example, to the timing of the emission
of ultrasound pulses). The receiving group can be selected in such
a way that the active area of receiving transducers can be
configured and changed over a number of sampling cycles in order to
optimize the resolution of the received signal from different
depths, different tissues, and in different applications.
[0082] In alternative embodiments, rather than having half the MUTs
221 dedicated to functioning as Tx MUTs 223, and half the MUTs 221
dedicating to functioning as Rx MUTs 225, each of the MUTs 221 of
the MUT array 220 can be capable of being used as either an Rx MUT
223 or a Tx MUT 225. In such alternative embodiments,
transmit/receive (Tx/Rx) switches (not shown) can be used in place
of the Tx switches 222 and the Rx switches 216. The Tx/Rx switches
can be used to connect a selected set of the MUTs 221 to either the
HV pulser 224 or the analog summing, amplification and processing
circuitry 215 depending on whether the MUTs 221 are to be used for
transmitting or receiving ultrasound pulses at a particular time.
When a high voltage pulse is produced by the HV pulser 224, the
Tx/Rx switches would automatically block the high voltage from
damaging the analog summing, amplification and processing circuitry
215. When the HV pulser 224 is not producing a pulse, the Tx/Rx
switches disconnect a selected set of MUTs 221 from the HV pulser
224, and instead connect a selected set of MUTs to the analog
summing, amplification and processing circuitry 215. However, Tx/Rx
switches are relatively expensive compared to switches required to
perform only one of the Tx switching and Rx switching functions.
Accordingly, the aforementioned embodiments where certain MUTs 221
are dedicated to transmission, and other MUTs 221 are dedicated to
reception, such a configuration may be preferable where it is
desirable to eliminate the need for expensive Tx/Rx switches.
[0083] The foregoing description of preferred embodiments of the
present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed. Many
modifications and variations will be apparent to one of ordinary
skill in the relevant arts. The above mentioned part numbers are
exemplary, and are not meant to be limiting. Accordingly, other
parts can be substituted for those mentioned above.
[0084] The embodiments were chosen and described in order to best
explain the principles of the invention and its practical
application, thereby enabling others skilled in the art to
understand the invention for various embodiments and with various
modifications that are suited to the particular use contemplated.
It is intended that the scope of the invention be defined by the
claims and their equivalents.
* * * * *