Sessions

Abstract:

Cardiovascular disease is the leading cause of death globally, with coronary heart disease being one of the most common types of cardiovascular disease. Two-dimensional x-ray based imaging of the coronary arteries is used to verify and guide interventions. To obtain a good quality image of the vasculature, a contrast agent is administered. Currently, patients who are suspected of having coronary heart disease will receive a coronary angiogram. There is potential to improve the visualization of coronary heart disease by subtracting anatomic noise, such as bone or soft tissue, that surrounds the contrast-enhanced vasculature in angiographic images. There are two subtraction-based methods that can be used to remove anatomic noise from an x-ray image: digital subtraction angiography and dual-energy angiography with kV-switching. However, these techniques are not used to image the coronary arteries due to their susceptibility to motion artifacts and high tube load demands. Technological advancements have led to the development of photon-counting x-ray detectors that can estimate the energy distribution of photons at rates adequate for x-ray imaging applications. As such, the use of photon counting x-ray detectors would allow for dual-energy imaging with a single-exposure, allowing for the removal of anatomic noise without motion artifacts. The use of this technique could potentially lead to better visualization and diagnosis of heart disease. This research focuses on examining the feasibility of dual-energy imaging using a photon-counting x-ray detector for improved imaging of coronary heart disease. We have explored theoretical models to quantify image quality of subtraction-based and energy-resolved angiography methods. In addition, we have experimentally optimized single-exposure dual-energy angiography implemented with a benchtop two-bin photon-counting x-ray detector and compared optimized image quality of the proposed single-exposure approach to optimized image quality for digital subtraction angiography and kV-switching dual-energy angiography techniques. Optimization was performed for various phantom thicknesses under different scatter conditions and images were compared in terms of the signal-difference-to-noise ratio per root entrance air kerma. In addition, image quality was examined when anti-correlated noise reduction (ACNR) was applied.  

Abstract:

Proton (1H) Magnetic Resonance Spectroscopy (MRS) can enable fat composition assessment in vivo.  The presentation will first provide an overview of MRS including concepts such as chemical shift, J-coupling and in-vivo MRS pulse sequences.  Following that the fatty acid spectrum will be discussed and distinct resonances from different fat proton groups will be highlighted.  The presentation will describe how the different fat peaks enable certain aspects of fat quantification to be determined such as fat unsaturation, di-glyceride and omega-3 content.  Challenges in quantification due to overlap of peaks will be discussed.  Examples of how spectral editing, where J-coupling evolution can be exploited to resolve target fat spins of interest, will be presented.  It will be demonstrated how sequence timings of an MRS pulse sequence can be optimized for signal from protons of interest while suppressing that from contaminating spins.  Examples from research work conducted at 3 T and at 9.4 T will be provided. 

Abstract:  

In its publication 113, ICRP noted there was evidence of a risk to Lens among those working in Cath Lab where radiation protection had not been optimized. In this lecture we will review the following: 

1. Method of monitoring of doses to the lens of the eye in workplace 
2. Current Occupational lens dose limit: Canada, USA and other countries 
3. ICRP Dose limits to the lens 
4. Cataract 
5. Workplace assessment for exposure: who needs lens dosimeter- IAEA guidance. 
6. Optimization of protection