October 30, 2023   
1-2pm ET   

Tim Szczykutowicz, UWisconsin
Topic: Photon Counting CT: Latest Results from Deep Silicon Based systems

At the moment, photon counting CT is the latest greatest thing in CT. Currently, there are three regulatory approved photon counting scanners in the world, all utilizing cadmium based detection systems. This lecture will review some of the basics of photon counting CT and then go on to discuss results from a prototype Deep Silicon based system. The speaker has first hand experience with the system, being currently in the middle of a human subject research trial at the University of Wisconsin Madison. This lecture will specifically focus on some spatial resolution comparisons to energy integrating CT as well as characterizations of the Deep Silicon scanner’s ability to provide accurate CT numbers, effective atomic numbers, and iodine quantification. Some human subject cases will also be presented.  


November 20, 2023
1-2pm ET

Sarah Aubert, UHN Toronto
Topic: Feasibility of Photon-Counting Angiography

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.

January 29, 2024
1-2pm ET

Atiyah Yahya, UAlberta
Topic: Aspects of In-Vivo Fat Quantification with Magnetic Resonance Spectroscopy

Proton (1H) Magnetic Resonance Spectroscopy (MRS) can enable fat composition assessment in vivoThe presentation will first provide an overview of MRS including concepts such as chemical shift, J-coupling and in-vivo MRS pulse sequencesFollowing 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 contentChallenges in quantification due to overlap of peaks will be discussedExamples of how spectral editing, where J-coupling evolution can be exploited to resolve target fat spins of interest, will be presentedIt 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. 

February 26, 2024
1-2pm ET

Thor Bjarnason, Interior Health, Kelowna
Topic: CAR CT Accreditation

The Canadian Association of Radiologists has long run a Mammography Accreditation Program. CAR is designing accreditation programs for other modalities, including Computed Tomography (CT). This lecture will first give a broad overview of the accreditation programs in development. A deeper dive into the CT Accreditation Program (CTAP) will follow that includes items of interest to Medical Physicists, such as: qualification requirements (Radiologists, Technologists, Medical Physicists), quality control (Radiologist, Technologist, Medical Physicist), protocol review requirements, display requirements and QC, and radiation scatter measurements. 

March 25, 2024
1-2pm ET

Bassem Elshahat, Corewell Health William Beaumont University Hospital
Topic: A Review of the Occupational Exposure to the Lens of the Eye for Medical Radiation Workers

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