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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

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.

Kai Thomenius

Kieran Wall

Kirk Wallace

Michelle Bezdecny

Tony Brewer

Mark Cheverton

Robert Pieciuk

Prabhjot Singh

Venkat Venkataramani

Rayette Fisher

Robert Wodnicki

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

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Ultrasound Systems

Broad range of applications and price points

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Transducer

Video Display

Beamformer

Scan Converter

Detector

System Controller

System Block Diagram

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

Element Isolation

Cuts

Signal Flex Ground Flex

Acoustic Absorber

Signal Electrode

Piezoceramic

Ground Electrode

Acoustic Matching

Layers

Acoustic Lens

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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

1.75D

Aperture

Focus

Discrete Dynamic

Static Dynamic, Symmetric

Dynamic, No Symmetry

Constraint

Dynamic, Steerable

Static

Dynamic Dynamic Fixed

1D 1.25D 1.5D 2D

Elevation

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Elevation Beamforming

Transducer

Element

Lens Lens

Focus

Image Slice Thickness

Depth

of Field

Depth of Field with Multi-Row Transducer

and Multiple Focal Zones

Multi-row array with multiple focal zones maintains uniform resolution over much greater range.

1D array relies on fixed lens for elevation focus. Good resolution at focus; poor in near & far field.

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1D

1.25D

1.5D

Elevation Beam Profiles

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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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Phantom with 2 mm Spherical Cysts

Single- vs. Multi-Row Arrays

Single Row

Multi- Row

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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

Preamps

Sum

Delays

To System

Channel

Digital or Analog?

Power &

Control

Transmit

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

To system

channel

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

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Probe Beamforming Leads to Handheld Systems

2D Transducer Array (vs. human hair)

Modular Beamformer in Probe Handle

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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

50 mm layers, 500 mm tall – Polymer (Photocurable Acrylate)

50 mm layers, sintered, Alumina

15 micron posts, polymer (Photocurable Acrylate)

Pt

PZT

Pt-PZT co-deposited & co-sintered

Periodic piezoceramic columnar array

~80 micron columns

Mag Z

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8

Freq (MHz)

DMP Piezo Blank

keff 0.53

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Handheld Devices – More Users, Smarter Products

Start

Document

Imaging

Management

End

Automatic image optimization

Automatic application recognition

Imaging guidance

Automatic measurements

Intuitive indicators

Automatic annotation

Report generation

Automation opportunities:

• Intuitive: minimal training for new users

• Quick exams: < 3 minutes

• Limited user interface: 2-3 buttons

• Standardized: operator/patient-independent

Automated Gain Adjustment now in Products

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Rural Healthcare: Obstetrical Measurements

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

Gestational age from 2D data sets

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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

B-Mode Image Blood Flow Power HR Demodulated

Artery

Vein

Edge Tracking

Vessel Detection

Ultrasound Waveforms

Flo

w

A

rea

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Ultrasound R&D

Applications Technology •Redefine clinical workflow

Beyond Diagnosis

•U/S-guided HIFU •U/S-activated drug delivery

Miniaturization •Reduce cost & size •Improve quality/price •Increase access

Ubiquitous Sensing

•Home healthcare •Telemedicine

Diagnosis/Therapy

New Users

New capabilities

Sustaining Innovations for Established Market Segments •Novel •Demonstrable •Clinically relevant

Rural healthcare

Primary care

Image Fusion

Integrated Systems

Emerging Applications

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