Seminar: Gamma-Ray Computed Radiography using a
Fluorochlorozirconate Glass-Ceramic Storage Phosphor Plate by Dr. Jacqueline A.
Johnson
Friday, January 30, 2015 9:30 AM to 10:30 AM
CREOL Room 103
CREOL Room 103
Jacqueline A. Johnson
Department of Mechanical, Aerospace, and Biomedical
Engineering
University of Tennessee Space Institute
Celebrating the International Year of Light 2015
Abstract:
A fluorochlorozirconate (FCZ) glass-ceramic containing
orthorhombic barium chloride crystals doped with divalent europium was
evaluated for use as a storage phosphor in gamma-ray imaging. X-ray diffraction
and phosphorimetry of the glass-ceramic sample showed the presence of a
significant amount of orthorhombic barium chloride crystals in the glass
matrix. Transmission electron microscopy and scanning electron microscopy were
used to identify crystal size, structure, and morphology. The size of the
orthorhombic barium chloride crystals in the FCZ glass matrix was very large,
~0.5-0.7 μm, which can limit image resolution. The FCZ glass-ceramic sample was
exposed to 1 MeV gamma rays to determine its photostimulated emission
characteristics at high energies, which were found to be suitable for imaging
applications. Test images were made at 2 MeV energies using gap and step
wedge phantoms. Gaps as small as 101.6 µm in a 440 stainless steel phantom were
imaged using the sample imaging plate. Analysis of an image created using a
depleted uranium step wedge phantom showed that emission is proportional to
incident energy at the sample. The results showed that the sample imaging plate
has potential for gamma-ray computed radiography and dosimetry applications.
Keywords: functional composites; glasses; ceramics;
non-destructive testing.
Biography:
Dr. Johnson completed her doctorate in solid state physicsin
the research area of magnetic phase transitions at the University of Liverpool
in 1985. She transitioned to working on glass materials after being approached
by Pilkington Glass to solve technical problems. She was a Professor in
Liverpool until 1995 when she joined Argonne National Laboratory in the United
States, where she was introduced to solving the structure of amorphous
materials using neutron scattering. After a 2-year period in administration she
returned to research to develop a new mammography system using a glass-ceramic
plate. In 2007, Dr. Johnson returned to academia at the University of Tennessee
Space Institute and continues to synthesize and characterize glasses, glass
ceramics and nanomaterials pertaining to medical devices, non-destructive
evaluation and image enhancement.
For additional information:
Dr. Kathleen Richardson
Professor of Optics
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