Elias Vajda, Carleton University
"Test-Retest Reliability of Magnetic Resonance Spectroscopy in Quantifying Brain Metabolites"
Magnetic resonance spectroscopy (MRS) enables non-invasive quantification of brain metabolites. It is a useful tool for studying auditory processing regions like Heschl’s Gyrus (HG), which has been linked with auditory hallucinations in schizophrenia. Accurate and reproducible MRS measurements are crucial for reliable metabolite analysis. This study compares two MRS sequences; PRESS and Semi-LASER, to determine which provides higher spectral quality and better reproducibility in the HG. Metabolite concentrations were measured in vivo in healthy participants using a test-retest approach and quantified via LCModel with simulated basis sets.
As well, we are currently conducting a test-retest study using the PRESS sequence, with the aim of distinguishing glycine (Gly) from myo-inositol in the thalamus. Gly, a co-agonist of the NMDA receptor, is of particular interest due to its potential role in neuropsychiatric disorders such as schizophrenia. However, separating it from myo-inositol is challenging, as their spectral signatures overlap significantly. This study uses spectral averaging to minimize the signal from myo-inositol, while enhancing the signal from Gly. Reproducibility of these results in healthy participants is an important step toward applying this methodology in schizophrenia research.
Sam Flynn, National Physical Laboratory
“Novel calorimeters for Ultra High Dose Rate (UHDR) radiation therapy”
Calorimeters have historically been limited to national measurement institutes as primary standards due to their size and complexity. However, the emergence of ultra-high dose rate radiotherapy (UHDR-RT), characterised by dose rates exceeding 40 Gy/s, necessitates new dosimetry solutions for accurate and safe measurements. Traditional ionisation chambers face challenges like ion recombination with the potential for clinically unacceptable high uncertainties. This presentation discusses novel secondary standard calorimeters designed for UHDR-RT applications for real-time dose monitoring, and an experimental design for a new hybrid ionisation chamber/calorimeter instrument. The implications for clinical dosimetry and the future of radiation therapy will be highlighted, emphasising the need for innovative approaches in modern radiotherapy.