high energy digital radiography & 3d-ct for industrial systems · 2007-10-09 · conventional...
TRANSCRIPT
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Reference: NDE High Energy Radiography 3D-CTDIR June 2007
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Non-Destructive Evaluation (N.D.E.)
at
A.W.E. Aldermaston
UK
Richard Watson
Senior Engineer NDE
High Energy Digital Radiography & 3D-CT for Industrial Systems
DIR 2007 - International Symposium on Digital industrial Radiology and Computed Tomography, June 25-27, 2007, Lyon, France
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Reference: NDE High Energy Radiography 3D-CTDIR June 2007
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High Energy Digital Radiography
Introduction – CT imaging
High Energy definition / Facilities
Digital Detectors
Test objects, alignment, shielding
Position and motion control
Experiments, collimation, filters
Data handling
Results
Summary
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Reference: NDE High Energy Radiography 3D-CTDIR June 2007
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An enormous amount of useful data is lost in the process of projecting 3D Data onto a 2D image plane.
Additionally, overlaying parts within complex assemblies can make radiographic film interpretation difficult, a CT slice enables a different view of the data for analysis
CT slice ImageConventional Film
Radiograph
CT Imaging
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CT Imaging
Fan Beam System
2D array CT Systems
X-ray Computed Tomography (CT) provides the 3rd
dimensional view. AWE currently has a number of CT
systems.
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In the medical imaging sector, next generation scintillator materials, Am-Si flat panel imaging sensors together with major advances in CCD
technology promise high fidelity, high resolution digital images at lower X-ray dose to patients.
The same technology is being developed for industrial applications.
Most industrial systems are designed to work at significantly lower energies – typically 100 – 200 KeV with a maximum up to 300KeV
Our systems use much higher energies typically 4 – 10 MeV
High Energy Digital Radiography
• High Energy Definition: > 1MeV
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High Energy Digital RadiographyFacilities at AWE
2 Facilities have been used during development.
4.2 MeV Linac - NDE Development use
2 – 10 MeV Minac – NDE Development use
Some limited work has been done with Computed Radiography systems at high energy
Detector
Collection of image data
Object
X-Ray set 4MeV to 10MeV
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We are currently developing DRTR & CT systems
for the radiographic imaging of components & assemblies.
Systems include a lens coupled, glass scintillator,
X-ray energies typically 4MeV - 10 MeV.
Digital Radiography Detectors
Hammamatsu ORCA
1280 x 1024 pixels
14 bit detector
Image size 2.5MB
45° turning mirror
Pb Shielding
Scintillator
Camera
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Amorphous silicon AmSi flat panel detector
X-ray energies typically 4MeV - 10 MeV.
Digital Radiography Detectors
Based on Varian Paxscan 4030
High Energy coating, X-Tek
3200 x 2304 pixels
12 bit detector
Image size 14.7MB
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Digital Radiography DetectorsComputed Radiography
An example CR film scanner using Phosphor plates instead of film for
high energy Radiography
• Problems with noise on image
System used :-
High Resolution screens (50µm),4175 x 5084 pixels
12 bit detectorImage size 60.7 MB
This system was lent to us by another section at AWE
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High Energy Test ObjectsDesign of the Radiographic Test Pieces
High Z section (4.2 MeV)
Interlocking cylinders
Low Z section (420KeV)
125mm Al block
Tungsten
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High Energy Test ObjectsCopper Vessel with Steel insert
Side view
Top view
Base view
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High Energy Radiography Alignment, Shielding, Motion control
Shielding100mm Pb Camera system 1.1 tonne housing
150mm Pb AmSi FPD 1.5 tonne housing
AlignmentBeam
Detector
Turntable
Object
Motion ControlPrecision Turntables, with rotation and one translation axis.
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High Energy RadiographyCollimation, Filters, scatter
Collimation
Tungsten collimator at source
Filters
1 – 5 mm at source; 3mm in normal conditions
0.5 – 2mm Cu at detector
Scatter
Back scatter
Component internal scatter
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Data Handling / Image ProcessingDigital Camera & Flat Panel Detector (FPD)
Frame acquisition time and read out
Black & White References
1Deg Steps : 360 images
Frame averaging
Typical data set sizes
Camera 0.9 GB
FPD 5.2 GB
Now tending to use smaller rotational steps, typically 0.4° (900images), thus larger data requirements;
Camera 2.25GB
FPD 13.23GB
Utilising methods to reduce data handling
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Data Sets – Typical sizes
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Pixels (x) (Mb)dataset
1024s, 8b 1024s,16b
1281922563845127681024153620483072
Slices
Dat
aset
siz
e in
MB
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ResultsImages from some experiments:-
Digital Radiograph from FPD taken with 6Mev Minac
Rotational Sequence
Example graphs from FPD system taken with
4.2MeV Linac
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Results
Example graph from CR system taken with
6MeV Betatron
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Results
Example graph from CR system taken with
4.2MeV Linac
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ResultsImages from some experiments:-
Slice plane
CT data set created from FPD system taken with 10MeV Minac @ 8MeV
Slice view - Animation
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ResultsImages from some experiments:-
3D CT view - Animation
CT data set created from 2D array system taken with 10MeV Minac @ 8MeV
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Further Data Set - AMBER
Amber 8bit animation.avi
Amber 8bit slice through Z axis.avi
Amber 8bit with slice plane.avi
Amber vgs.aviCT data set created from
Camera system taken with 10MeV Minac @ 6MeV
Steel vessel, created as part of a Model Based Engineering
project – (aMBEr)
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Image Processing & CT AcquisitionPC advances in recent times have enables much larger data sets to be processed within a reasonable time.
We currently use a 64bit PC with 16GB RAM, 2 x dual core CPUs, which can reconstruct a 1k cube in < 10 minute
Multi-rotation enables objects to be scanned which are larger than the detector width.
Image stitching when scanning large objects
Measurements with 3D volumetric data – VGS & Haptics
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Future WorkWe are doing further experiments to help characterise our systems and to further improve the resolution.
We are investigating Neural networking as a means of helping to identify features within a radiograph
Explore the use of Monte Carlo N Particle (MCNP) methods to improve the results
Extend the range of test components and materials used to validate the systems
Looking at other acquisition systems, interested in CR (computed radiography) & LDA (Linear Diode Array) for high energy work.
Haptics – Tactile tool to interact with and analyse & use as a measurement tool.
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• 2 Main High energy sources used, 3rd used only for CR
• 4.2MeV Linac
• 6 – 10 MeV Minac
• 6 MeV Betatron
• 2 Detectors (DR & CT), 3rd Images only
• 14bit CCD Camera & Scintillator
• 12bit Flat Panel AmSi Detector
• High Res CR Plates
•2 Acquisition systems (commercial)
High Energy Radiography & 3D-CT for Industrial Systems -Summary
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High Energy Digital Radiography & 3D-CT for Industrial Systems
Thank you for your time
Any further questions?
Richard Watson
Senior Engineer NDE
AWE Aldermaston UK