OMPI Seminar: Amir Pourmoghaddas and Ruth Wilkins

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Thursday, November 19, 2015

Time: 3:30-5:00 pm. Refreshments start at 3:15 pm.

Location: The Ottawa Hospital Auditorium, second floor, General Campus


Webstream has been arranged for this month's presentation. If you want to watch it from your computer, the webcast link is: 



1. Analytically-based photon scatter modeling for a dedicated cardiac SPECT camera

By Amir Pourmoghaddas, Carleton University and The University of Ottawa Heart Institute.

Abstract: Photon scatter is one of the main effects contributing to the degradation of image quality and to quantitative inaccuracy in Cardiac SPECT imaging. One possible way to calculate photon scatter is to model the photon propagation from emission until the photon is lost or detected by the camera, such as in Monte Carlo approaches. Monte Carlo calculations have the advantage of being capable of producing extremely accurate and precise results, but have a large computational burden. In this talk, I will present a technique based on the analytic photon distribution (APD) method for calculating the photon distribution in SPECT projections, as measured with our dedicated pinhole cardiac SPECT camera.  This technique uses an estimate of the source distribution and a map of the attenuating medium and is capable of producing scatter calculations in times that have the potential for integration in the clinic. Validation of the technique using phantom experiments will also be presented.


2. The Canadian Biodosimetry Network

By Ruth Wilkins, Health Canada

Abstract: Health Canada is the lead of the Canadian Biodosimetry Network which provides biologically based dose assessments for potentially exposed individuals during a large scale event involving radiological or nuclear material. During such an event, biodosimetry is essential for providing timely assessments of radiation exposure for the general population and to identify first responders who must be restricted from further exposure.

The dicentric chromosome assay (DCA) is currently the accepted biodosimetry method for radiation dose assessment; however in a mass casualty scenario this assay is not well suited for providing timely dose estimates due to its time- and expertise-intensive nature. Health Canada has been working to increase triage-quality biological dosimetry throughput by networking both within Canada and internationally.  For such networks to function, it is essential to perform proficiency testing to ensure each laboratorys ability to produce high quality dose assessments.

A series of these inter-comparisons will be described.  In addition, much effort has been devoted to developing novel, high throughput methods for biological dosimetry.  An overview of recent progress in these methods will be presented.