development of x-ray computed tomography image quality
TRANSCRIPT
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s
NASA Goddard Space Flight CenterMaterials Engineering BranchOSMA NDE Program
P.I. Justin S. Jones, Ph.D.
Collaborators: Antonio Moreno, Olivia Landgrover, Grace Fischetti
LaRC Additive Manufacturing Mini-TIM
November 9, 2018
From left: Convergent line pair gauge, duplex line pair gauge, step block, plaque penetrameter [ndtsupply.com]
2D DR Image
X-Ray Image Quality IndicatorsMotivation
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
2OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
3D CT Image
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
3OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
• Develop methodology and tools to assess Computed Tomography (CT) system performance.
– Fabricate Image Quality Indicators (IQIs) using materials and internal features useful for assessing inspection capabilities.
– Analyze IQI volume data to assess CT detectability limits, contrast sensitivity, resolution, etc.
– IQIs conducive to CT should be of more uniform cross-sectional aspect ratio
Program Goals/Initiatives
4
Original Concept: Cylindrical IQI
4
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
5
Cylindrical IQI
5
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
Various design features ranging in size to assess both manufacturability (per AM method) and CT inspectability.
Flat bottom holes(4 - 0.5 mm OD)
Row of cylinders (0.5 mm OD)
Cone(4 – 0.05 mm OD)
Rectangular prisms (1 - 0.05 mm width)
Cylinders (4 - 1 mm OD) Cylinders
(0.5 – 0.05 mm OD)
6
Cylindrical IQI
6
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
7
Cylindrical IQI: Intended Performance Verification Elements
7
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
Diameter = 25.4 mm
• Resolution • Contrast Sensitivity• CT Dimensional Measurement Accuracy (CT
metrology relative to conventional measurements)
Contrast to Noise Ratio as function of:• Geometric shape• Size• Location• Density (using filled powder)
Edge sharpness/resolution:• Modulated transfer function (MTF)• Convergent features
8
Cylindrical IQI: as Assessment Tool for AM Process Control
8
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
1 mm1 mm 1 mm1 mm
7 mm6.5 mm5.5 mm 6 mm
1 mm
Print defects
Incomplete Features
Inconsistencies
9
Hybrid Insert IQI
9
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
10
• Redesign to incorporate some existing features, but leave room for other additions:
• Rod or powder inserts to assess contrast sensitivity to various materials
• Flexible, rolled up test patterns to assess resolution
• Flexible IQI inserts tested on 100 or 125 micron Kapton substrates using either sputtered or photolithographic deposited gold.
Existing IQI features
Interchangeable, flexible, patterned inserts
Roll up
Not to scale. Features sizes exaggerated.
Hybrid IQI with Flexible Lithographic Patterned Inserts
10OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
20x25 mm Kapton film, typical of that used for the deposition substrate
11
Pre-existing photolithography patterns. ~2 mm total pattern length.
• Patterns came out well on first attempt. Good adhesion of Au to Kapton, though need protective coating for durability (e.g. parylene, polyurethane)
• Some “bubbling” observed on Kaptonsurface. May be residual from etch process.
• Challenges in dealing with microfabrication facility, high costs, schedules, etc.
11
Hybrid IQI with Flexible Lithographic Patterned Inserts
Gold pattern thickness measured via laser confocal microscope: 536 nm
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
12
Hybrid IQI with Flexible Lithographic Patterned Inserts
12
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
Lithographic pattern inserted into plastic SLA printed IQI
13
Some other CT IQI concepts
13
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
14
Hybrid IQI with Flexible Wire Grid Inserts
14
• Other insert materials being explored to avoid costly lithography• Wire meshes of varying, defined density, formed into screen
tubes and placed in concentric pattern IQI
Roll up and insert
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
Proof-of-Concept Trial
15
Taper IQI
Proof-of-Concept Trial
15
• Matching shell and insert, with slightly different taper angles.
• Idea is to create very small features within CT where tapers converge using simple design features.
• The above is a first cut proof of concept for more complex varying taper designs.
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
16
Most Recent Efforts: Pyramid IQI
16
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
17
Pyramid IQI
17
- Original design…
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
18
Pyramid IQI
18
• Pyramid 3D converging line pair gauge consists of a different sized pair of channels on each side
• As you approach top of pyramid, all features scale smaller
• Upon cross-section at any height, 2D slice provides a set of different sized line pairs
- Original design…
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
19
19
Pyramid IQI with sputtered gold inlays
Gold sputter deposition (~2 microns nominal) to aid in contrast of line pair tracks for higher kV scan applications.
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
Credit: Stephen Lebair/GSFC/ATA for Au sputter
20
20
Pyramid IQI with sputtered gold inlays
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
21
21
Pyramid IQI: SLA plastic with electroless nickel coating
UV projection 3D printed version
3D printed version with electroless Ni deposition to
aid contrast
Mini version with the electroless Ni
deposition
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
22
22
Pyramid IQI: SLA plastic with electroless nickel coating
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
23
23
Pyramid IQI: Ni-coated and use of external fiducials for alignment, elevation gauge, and external verification.
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
24
24
Pyramid IQI: Penetrameter Insert Concept (laser micro-machined discs)
Inner hole sizes not to scale. Actual holes will
be much smaller.
Conventional “2D” radiographic hole penetrameters
CT of xCT “Pyramid IQI”
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
25
25
Pyramid IQI: Penetrameter Insert Concept (laser micro-machined discs)
Inner hole sizes not to scale. Actual holes will
be much smaller.
Initial concept
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
26
Pyramid IQI, Next Steps
26
• Pursuing full metal version (~2-3x smaller) printed using micro laser sintering (possibly working with Precipart or 3D MicroPrint GmbH)
• Currently incorporating other “internal features” such as disc penetrameters
• Print IQI set to cover range of sizes and run CT system assessments
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
27
A few other activities in the lab…
27
• Round Robin testing of the ASTM E07/F42 Inserts and Prisms
• 9 scans; various combinations of inserts and both the small stepped pyramid and small cone
• Interested in line defects and contrast sensitivity of defect with increasing wall thickness
• New start proposal (OSMA NDE program) on AM Flaws
• Assess the key NDE signal-related differences between flaws in AM parts versus conventional parts
• Looking at 2 key variables: Surface roughness and grain structure
• NESC support for micrometeorite impact assessment for COPVs
• Cryogenic CT scan Capability• Contrast enhancements for CT and for PT of
AM parts• Various ongoing GSFC Program-related work• Lunar sample research• Efforts to push awareness for CT for In-Space
Use!
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)
1st cryoCT scan Lunar meteorite
28
Thanks for your time!
28
OSMA NDE ProgramLaRC AM Technical Interchange Meeting – November 9, 2018
Development of x-Ray Computed Tomography Image Quality Indicators, “IQI”s (GSFC-Jones)