South Eastern Applied Materials Research Centre Principles and Applications of X-ray Micro Tomography Presented by Dr. Ramesh Raghavendra SEAM Centre Director & Technology Gateway Manager Presented to: MSI 2015 Symposium University of Limerick, 27 th August 2015
Presentation Outline • SEAM Introduction & activities • X-ray tomography origin • X-ray tomography- Principles and Method • X-ray micro-tomography applications – Case Studies
SEAM – Who We Are….. • SEAM is a Materials Science and Engineering Research Centre working both in industrial and academic spheres, with the aim of bridging the gap between academia and industry. • SEAM is based within Waterford Institute of Technology, Waterford. • SEAM Launched in 2009 • Member of EI Technology Gateway Network, a nationwide resource for industry delivering solutions on near to market problems for industrial partners 3
What does SEAM do? SEAM, regarded as one of Ireland’s leading Technology Gateways offer Engineering Materials Technology supports to industries Provide unique world class professional services to industries and undertake materials research based projects 4
SEAM Core Capabilities CT scan (X-ray tomography): Non • destructive 3D analysis of materials and components Product design optimisation through • overlaying of scanned CT data over original CAD data 3D Metrology solutions • Finite Element Modelling (FEM) of • components & systems Failure analysis of product components • Provider of bespoke solutions for customer • specific issues 3D Metal Additive Manufacturing •
Two walk – in CT Systems at SEAM (Probably the only place in the world to have 2-walk in systems in an academic institute)
Nanotom (180 kV) at SEAM • Samples up to 60mm Φ • Plastics and small metal samples
V|TOME|X L 300 (dual tube) at SEAM • Samples up to 600mm Φ • Large heavy metal samples (up to 90mm solid Ni based super-alloys
SEAM’S OTHER KEY CAPABILITIES • Finite Element Analysis Ansys work bench (Commercial License) Two high performance work stations • Synthesis and characterisation of: - Polymeric materials - Adhesives - Glass and glass-ceramics • Failure Analysis of : - Medical devices and bio-material components -Structural and electronic components • Act as one stop shop for getting job done through external sources for any materials related investigations which are beyond SEAM resource capabilities
SEAM’s Impeccable Industry Collaborative Record • Established collaborations with over 100 Irish Based Industries • 75% of SEAM clients are Multinationals (MNCs) and 25% are Indigenous clients • Executed over 800 direct funded Industrial projects since 2009
SEAM Client Companies SEAM currently assists over 100 companies in Ireland
Recognition Won Knowledge Transfer Ireland (KTI) Award 2015 under Industrial Consultancy Impact category
SEAM’s current Applied Research/Academic Activities • Developing an arthoscopically accessible cartilage defect measuring device (EI Commercialisation program). • Collaborating with PMBRC to produce a prolonged release Injectable Delivery system for a certain medical condition (Com fund programme) • Development of a novel sensor system for real time in-situ monitoring of Tool wear in Precision Engineering Applications (EU: FP7-SME Program; Project Co-ordinator Dr. Ramesh Raghavendra) • Supervising Two Ph.Ds & 2 WIT Mech Engg student projects • Providing placement training for WIT Engg graduates 13
X-ray Micro Computed Tomography (XMT) Theory and Applications 14
Tomography : ‘ Tomos ’ = slice or section + ‘ graphy ’ = field of study Alessandro Vallebona. Invented the principle of tomography in 1930
Sir Godfrey Hounsfield developed first medical CT scanner in 1969 His work was funded by EMI mainly due to the the success of The Beatles in the 1960’s.
What is X-Ray Microtomography (XMT)? • X-ray microtomography is a non-destructive analysis technique used to visualise and characterise objects in three dimensions. • It is the process of imaging an object from many directions using penetrating radiation X-ray projection image (e.g. X-rays) and using a computer to determine the interior structure of that object from these projected images • XMT can be considered as a miniaturised version of medical CT or CAT scanning 3D Reconstructed model
X-Ray Computed Tomography -Components of a µCT system Detector Manipulator X-Ray Gun 180 kV Tungsten Target 2 MP CMOS Detector ~1080 projections acquired
The Method • The method involves the acquisition of a series of x-ray projection images (similar to those used by a medical doctor to diagnose a broken bone) at a known number of angular positions through 360 degrees. • Variation in the contrast of each projection image relates to how the x-rays are attenuated as they penetrate the sample. • X-ray attenuation increases proportionally to both the electron density and thickness of the sample material thus resulting in a darker project image. • X-ray must penetrate sample at all angles through 360° • Specialised mathematical calculations known as 'reconstruction algorithms' are used to create a 3D image from the x-ray projections.
X-Ray Microtomography basics – contd.. • X-ray attenuation increases proportionally to both the electron density and thickness of the sample material thus resulting in a darker project image. • X-ray must penetrate sample at all angles through 360° • Specialised mathematical calculations known as 'reconstruction algorithms' are used to create a 3D image from the x-ray projections.
X-ray Microtomography: Data Reconstruction • Axial slice views are computed from the x-ray projections using back projection reconstruction algorithms • 3D rendering of the all axial slice views allows visualisation of the 3D model X-ray projections 3D rendered model Computed axial slice
X-ray Microtomography: Data Analysis 0.3 mm Visualisation software permits numerous analysis options from creating sections through the 3D model to quantification of size, internal porosity, surface area or segmentation based on differences in density . 0.2 mm
XMT components: X-ray Tube (source) • Positively charged anode • Negatively charged cathode – Heated filament releases electrons (e - ) – e - are accelerated towards positively charged anode – Kinetic energy related to the voltage potential – e - strike anode target generating • Heat (up to 99%) • X-rays 23
XMT components: X-ray Tube (source) contd.. Sources available in various powers and focal spot abilities. Seam utilise high performance variable focus tubes • Nanofocus (0.8µm) 180kV • Microfocus (3µm) 300kV 24
XMT components: Detector panel Scintillator Material 25
XMT components: Detector Panel 26
XMT components- Scintillator Typically one of two materials: • CsI – Cesium Iodide • Gadox – Gadolinium oxysulfide CsI is more sensitive but prone to higher levels of ghosting. Gadox is less susceptible to ghosting but less sensitive. CsI is used in VTOMEX L 300 Gadox is used in Nanotom system Fabrication and imaging characterization of high sensitive CsI(Tl) and Gd2O2S(Tb) scintillator screens for X-ray imaging 27 detectors: Bo Kyung Cha, Jong Yul Kim, Cheulmuu Sim, Gyuseong Cho
X-ray Computed Tomography Achieving Magnification Sample diameters from sub-mm to 500mm. Detail detectability to below 1µm Height ranges up to 600mm. Weight capacity up to 50kg. Rule of thumb for calculating spatial resolution (µm): Largest dimension (mm) divided by 2000. 28
Case Studies • Dental frameworks • Tablet discolouration • Powder Application Demonstration 29
Dental Frameworks The problem: • Many different systems exist to create cast CoCr denture frameworks using impressions taken from a patient’s mouth • Which, if any, sprueing system produces the most geometrical accurate casting? Data used with permission of Michael McDowell, School of Dentistry, Royal 30 Victoria Hospital, Belfast
Overview of the Components Framework 1 Framework 2 Framework 3 Data used with permission of Michael McDowell, School of Dentistry, Royal 31 Victoria Hospital, Belfast
Overview of the Components – contd … Model Framework Data used with permission of Michael McDowell, School of Dentistry, Royal 32 Victoria Hospital, Belfast
Overview of the Components- contd.. Framework 1 Framework 2 Framework 3 Data used with permission of Michael McDowell, School of Dentistry, Royal 33 Victoria Hospital, Belfast
Frameworks Aligned to Model Framework 1 Framework 2 Framework 3 Data used with permission of Michael McDowell, School of Dentistry, Royal 34 Victoria Hospital, Belfast
Nominal Comparison Framework 1 Framework 2 Framework 3 Data used with permission of Michael McDowell, School of Dentistry, Royal 35 Victoria Hospital, Belfast
Deviation Comparison Data used with permission of Michael McDowell, School of Dentistry, Royal 36 Victoria Hospital, Belfast
Conclusion • Sample 1 is the best overall match to the model . Data used with permission of Michael McDowell, School of Dentistry, Royal 37 Victoria Hospital, Belfast
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