Reconstruction artifacts connected to drifts in components and limited mechanical accuracies of...
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Reconstruction artifacts connected to drifts in components and limited mechanical accuracies of micro-CT and nano-CT systems A. Sasov
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Transcript of Reconstruction artifacts connected to drifts in components and limited mechanical accuracies of...
Reconstruction artifacts connected to drifts in components and limited mechanical accuracies
of micro-CT and nano-CT systems
A. Sasov
• Slow thermal drift with long decay
• Random object movement during rotation
• Slow thermal drift with long decay
• Random object movement during rotation
• Slow thermal drift with long decay:
How to measure?
RD
Micro- focus or submicro- focus x-ray source
Object manipulator:rotation, translation
X-ray detector
Sample
Electron beam
Metal targetElectron-inducedX-ray source
• Slow thermal drift with long decay:
How to measure?
• Slow thermal drift with long decay:
How to measure?
• Slow thermal drift with long decay
Type of X-ray source?
Sealed microfocusGrounded cathode
Open (pumped) micro/nanofocusGrounded anode
Sealed microfocusGrounded anode
POSITION INSTABILITY:Up to +/- 10-20 of spot size Up to +/- 5 of spot size Typically under 0.5 of spot size
• Slow thermal drift with long decay
Object:10µm glass fibers in epoxy;800nm isotropic voxel size
Ok
• Slow thermal drift with long decay
How to avoid ?
• Slow thermal drift with long decay
Object:Composite material with plastic spheres;600nm isotropic voxel size
• Slow thermal drift with long decaybefore
after
• Slow thermal drift with long decay
• Random object movement during rotation
• Random object movement during rotation
How to measure?
• Random object movement during rotation
How to measure?
• Random object movement during rotation
Where it’s coming from?
• Random object movement during rotation
Where it’s coming from?
• Random object movement during rotation
Where it’s coming from?
Micos UPR160 air bearing stage:Max. radial runout is 180nm (+/- 90nm)
LAB AirBearing:Max. radial runout is 39nm…with active compensation - <5nm
• Random object movement during rotation
What to do if air-bearings cannot be used?
• Random object movement during rotation
How results look like?
Object:filamentous cyano bacterium,100 nm pixel size, 50nm X-ray spot size
Scanning Set-Up:Stepping motor in vacuum(microstepping mode)
• Random object movement during rotation
What can be done?
1. Standard FBP reconstruction
=unsharp/proper position
2. Forward projection=unsharp simulated projections
3. Centering original projections=sharp prj. @ proper position
4. Repeat FBP with centered prj.=sharp reconstruction
• Random object movement during rotation
Object:filamentous cyano bacterium,100 nm pixel size, 50nm source spot size
350 nm cell wall
• Slow thermal drift with long decay
• Random object movement during rotation
www.bruker-microct.com/products/downloads.htm
Nrecon (CPU, GPU-accelerated, 32 / 64bit OS)
