Ultrasound Miniaturization
Scott Smith
Ultrasound Probes Lab
Clinical Systems and Devices
GE Global Research
2011 Joint AAPM / COMP Meeting July 31-August 4 Vancouver
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Acknowledgements
Charles Baumgartner
Tim Fiorillo
Warren Lee
Robert Lewandowski
David Mills
Chet Saj
George Sogoian
Doug Wildes\
Chris Yetter
Carl Chalek
Scott Cogan
Scott Dianis
Congjian Xia
Aaron Dentinger
Bruno Haider
Chris Hazard
Ralph Hoctor
Srinivasan Jagannathan
Jing Jin
Larry Mo
Suhyun Park
Wayne Rigby
Kai Thomenius
Kieran Wall
Kirk Wallace
Michelle Bezdecny
Tony Brewer
Mark Cheverton
Robert Pieciuk
Prabhjot Singh
Venkat Venkataramani
Rayette Fisher
Robert Wodnicki
This project have been supported in part by Award Number 1RC2EB011439 from the National
Institute of Biomedical Imaging and Bioengineering (NIBIB), and 1R01CA1152677 from the
National Cancer Institute (NCI). The content is solely the responsibility of the authors and does
not necessarily represent the official views of NCI, NIBIB or the NIH.
Unless otherwise noted, all photography and drawings are the property of General Electric.
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Ultrasound Systems
Broad range of applications
and price points
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System Block Diagram
Scan
Converter
Detector
Video Display
Transducer Beamformer
System Controller
User Interface
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How did the imager get so small?
Electronics & ASICs miniaturization
CPUs & Software evolution
Sensors with embedded beamforming
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Ultrasound
Probes
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Transducer Array Structure
Acoustic Lens
Element
Isolation
Cuts
Acoustic
Matching
Layers
Ground Electrode
Piezoceramic
Signal Electrode
Acoustic Absorber
Ground Flex
Signal Flex
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How can you make a better image?
Goals:
Achieve uniform elevation resolution
(slice thickness) over an extended range.
Preserve lateral & axial image quality
Constraints:
Limited number of system channels
Patient access (probe footprint)
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Transducer Array Taxonomy
Elevation
1D
1.25D
1.5D
1.75D
2D
Fixed
Discrete
Dynamic
Dynamic
Dynamic
Static
Static
Dynamic,
Symmetric
Dynamic,
No Symmetry
Constraint
Dynamic,
Steerable
Aperture
Focus
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Elevation Beamforming
1D array relies on fixed
lens for elevation
focus. Good resolution
at focus; poor in near &
far field.
Transducer
Element
Image Slice Thickness
Lens
Lens
Focus
Depth
of Field
Multi-row array with
multiple focal zones
maintains uniform
resolution over much
greater range.
Depth of Field with Multi-Row Transducer
and Multiple Focal Zones
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Elevation Beam Profiles
1D
1.25D
1.5D
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Aperture Design: Compromises
Performance vs. Probe + System Cost
1D vs. 1.25D vs. 1.5D vs. 1.75D vs. 2D
Application => Footprint, Frame rate, ...
Number & size of rows, elements
Beam quality vs. intercostal or endo access
Lens (single vs. multi-focus), Apodization
Time delays for elevation beamforming
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Single- vs. Multi-Row Arrays
Single
Row
MultiRow
Phantom with 2 mm Spherical Cysts
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2D Array Strategies
Sparse arrays: use 10% - 25% of elements
Active elements in probe = channels in system (256 – 512)
+ Established probe technology
– Poor image quality (grating lobes, weak penetration)
Dense arrays: use all elements
Active elements in probe (2K – 3K) >> channels in system
+ Good image quality
– Beamforming electronics in probe
High voltage Transmit vs. low voltage Receive
High density, low power: packaging, interconnect, cooling
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Sub-Array Beamformer in Probe
Power &
Control
Preamps
To System
Channel
Sum
Delays
Transmit
Digital or Analog?
Connects a group of transducer elements to each system channel
Low-power analog beamformer: Phase rotation or Delay lines
Small delays only: static steering of small sub-aperture
Dynamic focusing & full-aperture delays by system beamformer
B. Savord & R. Solomon, Philips
2003 IEEE Ultrasonics Symposium
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2D Array Strategies II
Matrix arrays:
Switches connect elements into linear or annular groups
Reconfigure switches to change steering direction
or change focus (esp. transmit focus)
+ System sees probe as 1D or annular array
– Need many small, high-voltage, low-loss switches
tightly integrated with transducer elements
To system
channel
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Probe Beamforming
Leads to Handheld Systems
Modular Beamformer
in Probe Handle
2D Transducer Array
(vs. human hair)
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The Other Miniaturizaton:
Intracardiac Arrays
Lee et.al. IEEE Trans. UFFC 58, 1478, (2011)
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DMP: Materials & Structures
High aspect ratio structures, shapes on demand
Materials demonstrated: Alumina, Polymers, PZT, Platinum, Phosphors
Pt
PZT
50 mm layers, 500 mm tall – Polymer
(Photocurable Acrylate)
50 mm layers, sintered, Alumina
Pt-PZT co-deposited &
co-sintered
Mag Z
25
20
15
10
5
0
0
1
2
3
4
5
6
7
8
Freq (MHz)
15 micron posts, polymer
(Photocurable Acrylate)
Periodic piezoceramic columnar array
~80 micron columns
DMP Piezo Blank
keff 0.53
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Handheld Devices – More Users, Smarter Products
• Intuitive: minimal training for new users
• Quick exams: < 3 minutes
• Limited user interface: 2-3 buttons
• Standardized: operator/patient-independent
Automation opportunities:
Start
Imaging
Management
Document
Automatic image optimization
Automatic application recognition
Imaging guidance
Automatic measurements
Intuitive indicators
Automatic annotation
Report generation
End
Automated Gain Adjustment now in Products
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Rural Healthcare:
Obstetrical Measurements
Gestational age from 2D data sets
Motivators:
 Pregnancy dating
 Placenta previa
 Multiple gestations, breech
Performance
 Currently automated
algorithm within +/- 5 days
of manual estimates.
BPD = 59.1
mm GA =
23 wk
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Automated Fetal Measurements:
Working with 3D data sets
Auto facial Recognition
Coming over several years.
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Automatic Blood Vessel Measurements
Edge Tracking
Vessel Detection
B-Mode Image
Ultrasound Waveforms
Area
Artery
Blood Flow Power
HR Demodulated
Flow
Vein
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Ultrasound R&D
Diagnosis/Therapy
Beyond Diagnosis
•U/S-guided HIFU
•U/S-activated
drug delivery
New
capabilities
Applications Technology
•Redefine clinical workflow
Sustaining Innovations
for Established Market
Segments
•Novel
•Demonstrable
•Clinically relevant
Ubiquitous Sensing
•Home healthcare
•Telemedicine
Integrated
Systems
Image
Fusion
Primary
care
Rural
healthcare
Emerging
Applications
Miniaturization
•Reduce cost & size
•Improve quality/price
•Increase access
New Users
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