first experiments in surface-based mechanical property reconstruction of gelatine phantoms a....
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![Page 1: First experiments in surface-based mechanical property reconstruction of gelatine phantoms A. Peters, S. Wortmann, R. Elliott, M. Staiger, J.G. Chase,](https://reader030.vdocuments.mx/reader030/viewer/2022032805/56649efa5503460f94c0befb/html5/thumbnails/1.jpg)
First experiments in surface-based mechanical property reconstruction of gelatine phantoms
A. Peters, S. Wortmann, R. Elliott, M. Staiger,J.G. Chase, E.E.W. Van Houten
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Digital Image-based Elasto-Tomography (DIET) aims to be a low-cost alternative to current breast cancer screening modalities
Based on elastographic principles and low-cost digital imaging techniques
Introduction
The DIET System
[1] Peters et. al, JSME Int. Journal, (2004)
Four major steps in the DIET system
Actuate Capture Process Reconstruct
Simulation studies undertaken have proven the concept of surface-based mechanical property reconstruction[1]
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Cylindrical tissue-approximating gelatine phantoms
Actuation achieved using dSPACETM, laser interferometer, linear voice-coil actuator with amplifier
Methods
Phantom Studies
Motion captured using two consumer-level digital cameras
Manually-applied dots on tracked on phantom surface
Real motion approximated with a least-squares fitted ellipsoid
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Finite Element (FE) model of cylinder created and meshed
Actuated with same constraints as real gelatine phantom
Sparse parallel direct matrix inversion and solution performed with MUMPS[2] and Goto BLAS[3]
Methods
FE Simulation
Projecting a measured motion point back to the surface of a 3D mesh to allow motion comparison
[2] Amestoy et. al, Parallel Computing, (2005) [3] http://www.tacc.utexas.edu/resources/software/
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Forward FE simulation performed at small intervals over a range of homogeneous stiffness values
Results
Simulated Motion
Sample displacement solutions at a range of
stiffness values
Testing showed 22k node mesh solutions were converged at 10kPa and above
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Results
Motion Error Sweep
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Qualitative comparison made between actual motion and simulated phantom motion at 27kPa
Results
Direct Comparison
Homogeneous gelatine phantom stiffness successfully identified using steady-state
motion measurements and a FE model
MEASURED SIMULATED27kPa
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Damping and phase
Material non-linearity
More advanced reconstruction Multiple parameters Gradient-descent Genetic algorithm/simulated annealing
Tighter integration of motion capture and processing
Acknowledgements PhD supervisors
Data collection Jérôme Rouzé & Arnaud Milsant Edouard Ravini & Fabrice Jandet
Conclusions
Current Challenges