1. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 0 X-ray Phase Contrast Imaging Vincent Revol Zürich, 04.06.2009

2. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 1 X-ray Imaging : The story Discovered in 1895 by W. Roentgen (Nobel Price) Found widespread applications in imaging and structural analysis Phase contrast imaging found interest in the 80’s (3 rd generation synchrotrons) Project Motivation: Democratize the method for real applications Develop the technology toward higher energies

3. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 2 Outline of the talk Physical Principle What is phase contrast imaging? Operating Principle How can we measure the phase with X-rays? Set Up Presentation How is it implemented? Results How does it looks like? Outline What are the challenges?

4. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 3 X-ray Imaging Terminology Object Interaction between object and x-rays = „contrast“ X-ray sourceDetector

5. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 4 Conventional Radiography ObjectX-ray sourceDetector Absorption Image Photoelectric effect Compton Scattering Object

6. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 5 Differential Phase Contrast Image Object X-ray source Detector Refraction Differential Phase Contrast Image Object

7. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 6 Why is Phase Contrast Imaging better? E (eV) δ,β 100 μm Mylar behind 100 μm Copper  Absorption Contrast = 0.2% Phase Contrast = 17.6% n = 1-  + i  δ δ δ β β β

8. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 7 Decoherence Image Object X-ray source Detector Small Angle X-ray Scattering Decoherence Image objekt

9. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 8 Outline of the talk Physical Principle What is phase contrast imaging? Operating Principle How can we measure the phase with X-rays? Set Up Presentation How is it implemented? Results How does it looks like? Outline What are the challenges?

10. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 9 Talbot-Lau grating interferometer set-up X-ray source Beam splitter grating „Phase Grating“ G1G1 Detector Method invented at Paul Scherrer Institut PSI

11. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 10 Beam Splitter Grating: “Talbot Effect” d ~ cm Operating Principle X-rays p ~ μm Can not be resolved by standard X-ray detectors!!

12. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 11 Talbot-Lau grating interferometer set-up X-ray source G 1 : Beam splitter grating G2G2 Detector Analyzer grating G1G1

13. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 12 Phase Stepping: X-ray Pixel = 48 μm Average over many periods Operating Principle

14. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 13 X-ray Pixel = 48 μm Average over many periods Phase Stepping: Operating Principle

15. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 14 X-ray Pixel = 48 μm Average over many periods Phase Stepping: Operating Principle

16. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 15 X-ray Pixel = 48 μm Average over many periods Phase Stepping: Operating Principle

17. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 16 Phase Stepping Curve X-ray Phase Stepping Phase Stepping: Operating Principle

18. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 17 Talbot-Lau grating interferometer set-up X-ray source G0G0 G 0 : Source grating G 1 : Beam splitter grating G 2 : Analyzer grating Sample G2G2 G1G1 Detector Interferometer

19. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 18 X-ray Phase Stepping Image Extraction A ΔAΔA φ

20. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 19 Image Extraction X-ray Phase Stepping A ΔAΔA φ without object with object AAbsorption Image φDifferential Phase Contrast ΔA / ADecoherence Image

21. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 20 Outline of the talk Physical Principle What is phase contrast imaging? Operating Principle How can we measure the phase with X-rays? Set Up Presentation How is it implemented? Results How does it looks like? Outline What are the challenges?

22. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 21 System Construction Mechanical Assembly - Design done by CAD (Solidworks) - Fabrication at the Physics Institute Workshop Measurement Automation - Control of the motors, detector… - Programmed in the Labview environment

23. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 22 Gratings Fabrication Fabricated at the CSEM Neuchâtel Grating set for 25keV - Fabrication at the CSEM Neuchâtel

24. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 23 Outline of the talk Physical Principle What is phase contrast imaging? Operating Principle How can we measure the phase with X-rays? Set Up Presentation How is it implemented? Results How does it looks like? Outline What are the challenges?

25. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 24 Results : Single Projection Images of an apricot V tube = 40kV Absorption Decoherence Differential Phase Image

26. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 25 Results : Single Projection and Tomography Images of a polymer fiber in a syringe V tube = 40kV Absorption Decoherence Differential Phase Image 1 mm Tomography 1 mm Single Projection

27. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 26 Outline of the talk Physical Principle What is phase contrast imaging? Operating Principle How can we measure the phase with X-rays? Set Up Presentation How is it implemented? Results How does it looks like? Outline What are the challenges?

28. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 27 Objectives - Achieve Phase Contrast Imaging at 60-80 keV  Build gratings with higher aspect ratio - Increase the field of view  Compensate the non-spherical profile of the gratings - Optimize the set up for real applications  Reconstruction, tomography and features extraction algorithms - Develop some new ideas… δ,β E (eV) t ( μ m) E (eV)

29. Copyright 2009 CSEM | PhD Seminar, 4 th June 2009| V. Revol | Page 28 Thank you for your attention!