CREOL Room 103
Friday, January 16, 2015
Seminar: Gamma-Ray Computed Radiography using a Fluorochlorozirconate Glass-Ceramic Storage Phosphor Plate by Dr. Jacqueline A. Johnson 1.30.15/ 9:30-10:30am/ CREOL Rm 103
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
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.
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