PRESENTATIONS (2)
Student presentation:
“A Novel Calorimeter for Synchrotron Produced Monochromatic X-ray Beams”
Synchrotrons are a source of naturally collimated and high flux X-ray
photons with dose rates several orders of magnitude greater than
conventional X-ray tubes. The potential to produce micro-meter sized
pencil beams with the appropriate collimation makes them a valuable
research tool. Synchrotron sources have been used to develop novel
treatment modalities such as Microbeam Radiotherapy, to investigate the
radiation response of subcellular targets and to quantify dose response in
the X-ray range. To realize the full potential of synchrotron radiation
sources as a dosimetric research tool a traceable metrology standard is
being developed.
A novel design for a calorimeter prototype to address the unique
measurement challenges will be discussed. Preliminary measurement results,
using the calorimeter prototype, will also be presented.
By Islam El Gamal, Carleton University
Supervisor: Dr. Malcolm McEwen, National Research Council Canada
Member presentation:
“Improved functional MRI acquisition and modelling for imaging brain
function and physiology”
Functional magnetic resonance imaging (fMRI) based on the Blood
Oxygenation Level-Dependent (BOLD) signal has revolutionized human
neurosciences by providing a non-invasive tool for dynamically mapping
brain activity without the use of ionizing radiation or exogenous contrast
agents. BOLD fMRI, whereby the oxygen saturation of hemoglobin in blood
modulates the MRI signal level, is influenced by a wide range of
biophysical and physiological factors. This makes BOLD fMRI challenging to
relate to both the underlying neuronal activity and brain physiology. In
this talk, I will overview my efforts to make calibrated fMRI – a
quantitative technique that can tease apart the metabolic and hemodynamic
contributions to the BOLD signal – more widely accessible through improved
biophysical signal modelling and image acquisition. I will then describe
my contributions to pulse sequence development for performing high spatial
resolution fMRI at 7 tesla, where I demonstrated functional activation at
0.6-mm isotropic voxel size – the highest published spatial resolution for
human fMRI using a whole-head receiver coil.
By Dr. Avery Berman
Department of Physics, Carleton University