Electrical Impedance Tomography for Deformable Media Camille - - PowerPoint PPT Presentation

▶
electrical impedance tomography for deformable media
SMART_READER_LITE
LIVE PREVIEW

Electrical Impedance Tomography for Deformable Media Camille - - PowerPoint PPT Presentation

Oct 29, 2022 248 likes •463 views

Electrical Impedance Tomography for Deformable Media Camille Gmez-Laberge, M.A.Sc. Andy Adler, Ph.D. Dept. of Systems and Computer Engineering Carleton University, Ottawa, Canada ICEBI 2007 Outline Lung ventilation EIT Image

slide-1
SLIDE 1

Electrical Impedance Tomography for Deformable Media

Camille Gómez-Laberge, M.A.Sc. Andy Adler, Ph.D.

  • Dept. of Systems and Computer Engineering

Carleton University, Ottawa, Canada ICEBI 2007

slide-2
SLIDE 2

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Outline

  • Lung ventilation EIT
  • Image variability from boundary

deformation

  • Electrode displacement regularization
  • Imaging of deformable media
  • 3D EIT Jacobian calculations
slide-3
SLIDE 3

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Lung ventilation EIT

boundary voltage v v v internal conductivity applied current

slide-4
SLIDE 4

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Lung ventilation EIT

internal conductivity inverse solution 1.discretize 2.linearize 3.regularize boundary voltage

=

X

slide-5
SLIDE 5

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Boundary deformation

  • Lung ventilation imaging is prone to
  • throacic deformation
  • posture change
  • Thorax expansion per manoeuvre
  • tidal breathing: circumference increases 1%
  • total lung capacity: circumference increases 5%
  • These deformations cause significant

artefacts

slide-6
SLIDE 6

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Boundary deformation

correct incorrect A R

slide-7
SLIDE 7

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Electrode displacement regularization

boundary voltage internal conductivity electrode displacement image

slide-8
SLIDE 8

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Electrode displacement regularization

slide-9
SLIDE 9

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • Building R: a priori claims
  • conductivity distribution is smooth
  • adjacent electrode displacements are

correlated

Electrode displacement regularization

slide-10
SLIDE 10

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Electrode displacement regularization

  • 1
  • 1

3

  • 1
  • 1
  • 1
  • 1

elements elements 4

2 5 8

4 electrodes electrodes

  • 1
  • 1

2

  • 1
  • 1
slide-11
SLIDE 11

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • Electrode displacement

regularization

slide-12
SLIDE 12

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • Building J: sensitivity to deformation
  • conductivity change will affect boundary

voltage

  • displacements will affect boundary voltage

Electrode displacement Jacobian

slide-13
SLIDE 13

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

electrodes elements voltage voltage

Electrode displacement Jacobian

slide-14
SLIDE 14

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • Electrode displacement

Jacobian

Calculating the Jacobian becomes time consuming for large FEM > 30,000 elements

slide-15
SLIDE 15

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Imaging deformable media

1% 5% true standard proposed simulation phantom

slide-16
SLIDE 16

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

Imaging deformable media

Human TLC-RC breathing: 1.2 sec. increments Human “paradoxical” breathing: 1.2 sec. increments

slide-17
SLIDE 17

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • Jacobian calculation time increases

exponentially for large 3-D FEM

3D EIT Jacobian

Model pair Elements

forward

inverse

A

7,680 1,536

B

15,360 3,072

slide-18
SLIDE 18

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • Save time by calculating J directly from

the FEM system matrix

3D EIT Jacobian

slide-19
SLIDE 19

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • Derived J using rank-one asymmetric

matrix perturbations

3D EIT Jacobian

slide-20
SLIDE 20

cgomez@sce.carleton.ca EIT for deformable media ICEBI 2007

  • ICEBI Graz Committee
  • My supervisor: Dr. Andy Adler
  • Bio-impedance scientific community

Thank you: