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Medical image processing Medical image processing and finite element analysisand finite element analysis
András HajduAndrás Hajdu
UNIVERSITY OF UNIVERSITY OF DEBRECENDEBRECENHUNGARYHUNGARY
SSIP 2003July 3-12, 2003
Timişoara, Romania
MEDIPMEDIPPlatformPlatform independent software system independent software system for medical imagefor medical image processingprocessing
The aim of the project is to develop an informatical background
to theoretical and applied studies in the field of multi-modal medical image processing,
which results may lead tomarketable products.
MEDIPMEDIPPlatformPlatform independent software system independent software system for medical imagefor medical image processingprocessing
Department of Information Technology,University of Debrecen
PET Center, University of Debrecen
Mediso Medical Imaging System Ltd.
Developers
Department of Orthopedic Surgery,University of Debrecen
Faculty of Health Sciences, Chair of Radiotherapy,Semmelweis University
Faculty of Medicine Dept. of Radiology and Oncotherapy,Semmelweis University
Test partners
MEDIPMEDIPPlatformPlatform independent software system independent software system for medical imagefor medical image processingprocessing
01.200401.200301.2002
finished sessions
current session
future sessions
1. Survey, problem specification
2. Modelling, system plans
3. Implementation
4. Implementation,optimisation
5. Fine tuning,testing, presentation
SesSes11 Ses2Ses2 Ses3Ses3 SesSes44 SesSes55
Dependence
Feedback
Pert diagram
MEDIPMEDIP – Demostration programs – Demostration programsPlatformPlatform independent software system independent software system for medical imagefor medical image processingprocessing
Finite element modellingfor virtual surgery
Selection of volume of interest based on image fusion
4D visualization of gated heart and lung inspections
Dept. of Information Tech., UD
Dept. of Orthopaedy, UD
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Demonstration program
Finite element modeling for virtual surgery
Connecting to theConnecting to the b base librariesase libraries FFileile I/O I/O (DICOM) (DICOM) Segmentation techniquesSegmentation techniques Contour tracking, ROI selectionContour tracking, ROI selection Morphological operationsMorphological operations Complex GUIComplex GUI ROI and VOI ROI and VOI 2D/3D 2D/3D visualizationvisualization 3D geometric navigation3D geometric navigation PrintingPrinting
Demonstration program
Finite element modeling for virtual surgery
Demonstration program
FEM surgery planning frame program
Login (database opening)
Launching (opening new/existing profile)
DICOM file importImage manipulation (morphological filtering)
Creating geometric model
Segmentation (automatic/manual)
FEM contact
Adjusting parameters
Demonstration program
Surgery planning (virtual osteotomy)
3D visualization, selecting VOI
Surgery planning (virtual osteotomy)Surgery planning (virtual osteotomy)
Case studyCase study
Zoltán CsernátonyZoltán Csernátony, Department of Orthopaedics, UD, Department of Orthopaedics, UDSzabolcs Molnár, Department of Orthopaedics, UDSzabolcs Molnár, Department of Orthopaedics, UDSándor ManóSándor Manó, College Faculty of Engineering, UD, College Faculty of Engineering, UDAndrásAndrás HajduHajdu, Institute of Informatics, UD, Institute of Informatics, UDZoltánZoltán ZörgőZörgő, Institute of Informatics, UD, Institute of Informatics, UD
ANALYZIS OF A NEW FEMUR ANALYZIS OF A NEW FEMUR LEGTHENING SURGERYLEGTHENING SURGERY
LowerLower extremityextremity inequalityinequality
Shorter femur Shorter tibia
Handling the problem (I.)Handling the problem (I.)
Orthopaedic shoes
Handling the problem (II.)Handling the problem (II.)
Surgical intervention(after Wagner and Ilizarov)
cutting distancing ossification
!
A new lengthening methodA new lengthening method
Torsion and angulation could also be correnced
Potencial instrumentationPotencial instrumentation
In the past there existed no way of In the past there existed no way of testing new interventions but to try it out testing new interventions but to try it out in vivoin vivo
This days technology makes is possible This days technology makes is possible to test and adjust new operative to test and adjust new operative interventions before even one cut is interventions before even one cut is mademade
Past and presentPast and present
Validating new ideasValidating new ideas
Laboratory tests Finite element analysis
How can we use FEM/FEA?How can we use FEM/FEA?
CT slicesimage
processinggeometrical
reconstruction
Building up a basic modelBuilding up a basic model
Importing images in Importing images in CT CT firmware format firmware format (DICOM)(DICOM)
Image enhancement (sharpening, filtering)Image enhancement (sharpening, filtering) Extracting ROIsExtracting ROIs
Building up a basic modelBuilding up a basic model Applying contour splines (Euclidean geometry)Applying contour splines (Euclidean geometry)
Reconstructing solid model (Coons patches)Reconstructing solid model (Coons patches)
Modeling intervention Modeling intervention geometry (I.)geometry (I.)
Based on the path of the cutting toolBased on the path of the cutting tool
We need to determine:We need to determine: Cutting thicknessCutting thickness PitchPitch Ending hole parametersEnding hole parameters
Modeling interventionModeling interventiongeometry (II.)geometry (II.)
We subtract the object representing We subtract the object representing the the „„removed tissueremoved tissue” ” from the femur modelfrom the femur model
Modeling intervention Modeling intervention physicsphysics The bone tissue should be The bone tissue should be
modeled as a very complicated modeled as a very complicated nonlinear anisotropic materialnonlinear anisotropic material
We are using linearWe are using linear elasticelastic izotropicizotropic andand orthotropicorthotropicmaterial models insteadmaterial models instead
We mesh the modelWe mesh the model One end is fixed, on the other end One end is fixed, on the other end
a traction force is applieda traction force is applied How big is the evolved stress? How big is the evolved stress?
How much elongation can it How much elongation can it support?support?
Some resultsSome results
There exists an optimal combination of parameter values
2 3
6,00 249 730 000 223 490 000
7,00 222 730 000 231 270 000
8,00 263 800 000 247 180 000
2 36,00 499 460 000 446 990 0007,00 445 460 000 462 530 0008,00 527 600 000 494 370 000
2 36,00 749 190 000 670 480 0007,00 668 190 000 693 800 0008,00 791 400 000 741 550 000
2 36,00 998 910 000 893 970 0007,00 890 920 000 925 060 0008,00 1 055 200 000 1 995 000 000
2 36,00 1 248 600 000 1 117 500 0007,00 1 113 700 000 1 156 300 0008,00 1 319 000 000 1 570 000 000
Min (Best)Max (Worst)
rem
ain
ing
tissu
e
(mm
)
cutting thickness (mm)Equivalent stress (von Misses)Pa
1 mm elongation case
2 mm elongation case
3 mm elongation case
4 mm elongation case
5 mm elongation case
The greatest stress values evolve near the The greatest stress values evolve near the ending holes. ending holes.
The inward oriented conical bore appears to be The inward oriented conical bore appears to be the most suitablethe most suitable
Additional adjustmentsAdditional adjustments
We have built a schematic modelWe have built a schematic model It is a cylindrical pipe with inner and It is a cylindrical pipe with inner and
outer diameters equaling the outer diameters equaling the femur’s average diametersfemur’s average diameters
The same analysis were performedThe same analysis were performed
• The stress values measured on the pipe-model were 1.61 (D=0.27) times lower under same conditions• There was a 91% correlation between the two datasets
Checking the resultsChecking the results
Future plansFuture plans
More precise material modeling by using More precise material modeling by using cylindrical layers, and other element typescylindrical layers, and other element types
In-vitro lab tests based on the resultsIn-vitro lab tests based on the results
Thank you for your attention.Thank you for your attention.