1. Interaction of X-rays with Matter and Imaging
Gocha Khelashvili
Assistant Research Professor of Physics
Illinois Institute of Technology
Research Medical Physicist
EXELAR Medical Corporation

2. The Plan X-ray Interactions with Matter Used at Imaging Energies
Photoelectric Effect
Coherent Scattering
Incoherent Scattering
Pair and Triplet Production
Refraction
Small- and Ultra-small Angle Scattering
Radiography
How does it work?
Imaging Parameters and Sources of X-ray contrast
Drawbacks of Radiography
Diffraction Enhanced Imaging (DEI)
Drawbacks of DEI
Multiple Image Radiography (MIR-Planar Mode)
Sources of X-ray contrast
MIR parameters and images
MIR Model Based on Discrete Scatterers
Multiple scattering series approach and MIR transport equation
Solution of MIR transport equation
Imaging Parameters
Summary

3. Photoelectric Effect

4. Thompson (Classical) Scattering

5. Thompson (Classical) Scattering

6. Rayleigh Scattering (Coherent Scattering)

7. Rayleigh Scattering (Coherent Scattering)

8. Compton Scattering (Incoherent Scattering)

9. Compton Scattering (Incoherent Scattering)

10. Effects of Binding Energy in Compton (Incoherent) Scattering

11. Effects of Binding Energy in Compton (Incoherent) Scattering

12. Pair Production

13. Pair Production in Nuclear Coulomb Force Field

14. Pair Production in Nuclear Coulomb Force Field

15. Pair Production in the Electric Field (Triplet Production)

17. Radiography Setup

19. Radiography Setup and Imaging Principles
Radiology Setup
Object
Double Crystal Monochromator Si(333)
Incident X-ray beam
Area Detector
Attenuation Law
Image
Image Contrast

20. Drawbacks of Radiography
Incoherently Scattered Beam
Detector Pixel
Object Pixel
Attenuated Beam
(by absorption)
Image Contrast

21. DEI Setup and Imaging Principles
Area Detector
Object
Double Crystal Monochromator Si(333)
Analyzer Crystal
Si(333)
Incident X-ray beam

22. Formation of DE Images
Incoherently Scattered Beam is Blocked by Crystal
Detector Pixel
Object Pixel
Enhanced Attenuated Beam

23. Physics of DEI Data from NSLS X27 Relative Intensity I/Io
Pisano, Johnston(UNC); Sayers(NCSU); Zhong (BNL); Thomlinson (ESRF); Chapman(IIT)
Low Angle
Side
High Angle
Side
1.00
0.80
0.60
Relative Intensity I/Io
0.40
0.20
0.00
-10 -5 5 10
Analyzer Angle (mradians)
Data from NSLS X27

24. Calculation of DEI Images
Low Angle
Side
High Angle
Side
1.00
0.80
0.60
Relative Intensity I/Io
0.40
0.20
0.00
-10 -5 5 10
Analyzer Angle (mrad)

25. Comparison - Conventional and DEI ACR - Phantom
DEI
Map
Conventional
On the left is a road map to the test object or phantom
This object is imaged with a conventional x-ray machine and the image is graded by how many of the features can be seen in the images. This number determines if a machine can be used to image women.
The middle image is a conventional image or radiograph of this phantom; approximately 70% of the features are visible.
The right image is our “DEI” image. This image was taken at the same dose at the middle image and shows all of the intentional features along with some things which are “impossible” with conventional radiography…
tape, scratches, air bubbles...

26. DEI image of ACR phantom - smallest calcifications
Data from NSLS X27

27. Cancer in Breast Tissue
Pisano, Johnston(UNC); Sayers(NCSU); Zhong (BNL); Thomlinson (ESRF); Chapman(IIT)
This is a sample of excised breast tissue in which there is a type of cancer called infiltrating ductal carcinoma. This is the most common type of breast cancer. This sample shows this cancer in a conventional radiograph as the lighter or white region.
Our DEI images show this region in a clearer crisper way in the absorption image in the middle
And shows features which are not seen in radiography at all in the refraction image.
Note the three dimensional character of the refraction image…this is an intrinsically edge enhanced image which finds boundaries of materials very well.
The refraction image shows the fibrosis associated with cancer much farther away than either the conventional radiography or even our DEI absorption image.
This image and sample has been investigated in detail by a pathologist and our MD and shows features never before seen in radiography.
Conventional
DEI - Absorption
DEI - Refraction
BNL Sept 1997

28. Drawbacks of DEI
Detector Pixel
Object Pixel

29. Experimental Evidence of Problems in DEI

30. Experimental Results Rod, off-center Background Thick Paper-1
-0.6
-0.2
0.2
0.6 1
x 10 -5
Rod, off-center
Thick Paper
200
400
600
Background
Rod and Paper

31. Refraction images Profiles MIR DEI Position (pixels) no paper
thick paper
thin paper
no paper 50
100
150
200
0.2
0.4
0.6
0.8 1
Position (pixels)
MIR
DEI

34. Generalization to CT Reconstruction

35. A Physical Model of MIR Object Voxel
Khelashvili, Brankov (IIT), Chapman (U.Sask), Anastasio, Yang (IIT), Zang (BNL), Wernick (IIT)
Phys. Med. Biol. 51 (2006)
Object Voxel

36. Multiple Ultra-Small Angle Scattering
Radiation Transport Theory Approach

37. MIR Radiation Transfer Equation

38. Ultra-Small Angle Approximation

39. General Solution

40. Phase Function

41. Phase Function

42. Plane Wave Solution

43. Plane Wave Solution

44. Imaging Parameters

45. Experimental Conformation
Lucite container – wedge shaped.
Polymethylmethacrylate (PMMA) microspheres in glycerin.

46. Experimental Conformation

47. labDEI System X-ray Source Detector Analyzer Pre-mono & Mono
Morrison, Nesch, Torres, Khelashvili (IIT), Hasnah (U. Qatar) Chapman (U.Sask)
Detector
Analyzer
Pre-mono & Mono
X-ray Source

48. Lab DEI System tissue images
Morrison, Nesch, Torres, Khelashvili, Chapman (IIT)
Muehleman (Rush Medical College)
1cm
cartilage
bone

49. Summary
First reliable Theoretical Model of DEI – MIR has been developed that Model can be used to simulate experiments starting from source, through crystals (this was known), through object (was unknown), through analyzer crystal (partially known – dynamical theory of diffraction – but crystal and beam specific calculations need to be done).
Monte – Carlo simulation of DEI/MIR imaging system (G.Khelashvili – U. Saskatchewan / Nesch LLC)
CT reconstructions – some steps are already taken in this direction – J. Brankov at all “A computed tomography implementation of multiple-image radiography” Med. Phys. 33 (2006)
CSRRI (IIT) / Nesch LLC – are developing in-lab research DEI instrument

50. Acknowledgements
L.D. Chapman (Anatomy and Cell Biology, University of Saskatchewan, Canada)
J. Brankov, M. Wernick, Y. Yang, M. Anastasio (Biomed. Engineering, IIT)
T. Morrison (CSRRI, IIT) and I. Nesch (Nesch LLC)
C. Muehleman (Department of Anatomy and Cell Biology, Rush Medical College)