1. Optimization of Phase Contrast Imaging
Luke Powers
Chris Weaver
Jonathan Fermo
Alfred Luk
BME 273, Group 22
03/14/2005

2. Phase-Contrast Radiography
Traditional radiography uses differences in absorption to develop images
Phase-contrast Radiography (PC-R) uses differences in refraction and diffraction of the x-ray beam as it passes through the object
Results in enhanced edge effects in image compared to those found in absorption images

3. Spatial Coherence Description of the divergence of a wave
Desire a very large spatial coherence (d):
decrease focal spot size (f)
increase source-object distance (R1)
Waves similar enough for interference patterns to form when passing through edges of object

4. Edge Effects Waves near edges are bent
Waves not touching or passing through are not affected
Edge enhancement seen on film
Angle shift insignificant at close distances

5. Producing Phase Contrast
Image has two components: absorption and phase
Goal is to divide out absorption
Absorption component  detector touching object

6. Magnification Effect Changing R1+R2 Size of two images are not equal
Scale images to account for magnification
Most likely shrink I to Iabs for division
Poor accuracy will result in production of false edges

7. Our Device
Main Uses:
Optimizing distances for PC imaging of specific objects/tissues
Produce reproducible images
Produce no false edge effects
Images using scattering, defines pixel resolution < 150 microns
Additional Uses:
Rotational movement for CT images

8. PC-R Potential Phase Contrast Radiography:
Has potential to detect objects that are invisible on conventional radiography
Edge enhancements and early detection of breast cancer
Monochromatic beam reduces excess radiation dosage to patient

9. Objectives Build a device that aids in testing PC-R parameters
Stage movement & control accurate enough to pick up edges
Computer controlled movement of the object and detector

10. Programming Inputs: Outputs: LabView GUI: positions, energy Time/Date
Image #
Angle and x, y, z positions
Energy Used

11. Advisors Advisors: Principal Investigator: Frank E. Carroll, M.D.
Gary Shearer
Robert Traeger
Principal Investigator:
Edwin Donnelly, M.D.,
Ph.D. from Vanderbilt in Biomedical Engineering

12. Facilities W.M. Keck Free Electron Laser Center at Vanderbilt
Vanderbilt BME Department

13. Resources Monochromatic X-ray source at FEL
LabVIEW and Virtual Instruments
Stages, controllers, etc… for design construction provided by FEL & outside contractors

14. Design Schematic -Detector has z-stage movement (1m)
-Object has x (6cm), y (5cm), rotational (360 degrees) movement

15. Machine Shop Work Stepper motor mounts for x and y stages
Mounting Rotational Stage on x-y stage

16. Components

17. Linear Translation Stage (z)
Selected Components
Microcontroller
Linear Translation Stage (z)

18. Questions?