Hong Shen, Gerd Melkus

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Thursday, March 20, 2014
3:30 - 5:00 pm
West Foustanellas Auditorium (H-2366) - 2-nd floor - The University of Ottawa Heart Institute, 40 Ruskin Street

1. "The NRC Wide-Angle Free-Air Chamber"
Hong Shen - Carleton University/NRC

Abstract: NRC is setting up a national primary standard to calibrate radioactive seeds for low dose-rate brachytherapy. A commercial wide-angle free air chamber (WAFAC), based on the design pioneered by NIST, was introduced recently for measurement of air kerma strength of the seeds.  In order to test the performance of the chamber, it was set up in a low-energy X-ray beam (effective energy of 31 keV) where the air kerma rate has been established using the existing NRC air kerma standard. Excellent agreement of the air kerma rate obtained with the WAFAC using the same aperture opening  as the primary standard free-air chamber (FAC) validates the proper functioning of this new instrument. Measurements were also carried out for a range of WAFAC apertures, including the 80 mm aperture used for seed measurements. The results show the importance of including air scatter corrections for large aperture openings. Preliminary measurements with 125I seeds give results that are consistent with the stated seed activity. Work is ongoing to establish the correction factors and uncertainty estimates.

2. "Development and application of biochemical MRI methods for Musculoskeletal Research"
Gerd Melkus - The Ottawa Hospital

Abstract: Osteoarthritis and lower back pain are two major diseases which are linked to the degeneration of cartilage and adjacent tissues such as subchondral bone. Non-invasive imaging techniques can help understand articular cartilage and cartilage repair tissue. Recent developments in the field of Magnetic Resonance Imaging (MRI) can be used to characterize these tissues not only morphologically, but also biochemically. In this presentation, the concepts of quantitative MRI methods (gagCEST, T1rho and Diffusion Tensor Imaging) will be discussed.  Moreover, pre-clinical and clinical applications will be shown where biochemical MRI can be used to visualize non-invasively the composition of cartilage and adjacent tissues.