High Energy Digital Radiography & 3D-CT for Industrial Systems · 2007-10-09 · Conventional Film Radiograph CT Imaging. C o p y r i g h t Reference: NDE High Energy Radiography

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Reference: NDE High Energy Radiography 3D-CTDIR June 2007

Page 1 of 24© British Crown Copyright 2007/MOD

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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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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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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Reference: NDE High Energy Radiography 3D-CTDIR June 2007Page 10 of 24© British Crown Copyright 2007/MOD

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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Slice plane

CT data set created from FPD system taken with 10MeV Minac @ 8MeV

Slice view - Animation

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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

Documents

High Energy Digital Radiography & 3D-CT for Industrial Systems · 2007-10-09 · Conventional Film Radiograph CT Imaging. C o p y r i g h t Reference: NDE High Energy Radiography