OMPI Seminar: Eric Christiansen and Trevor Stocki and Year End BBQ

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Thursday, May 23, 2019

Time: 3:30 - 5:00 pm, Refreshments start at 3:15 pm. BBQ to follow (see below).

Location: National Research Council, 1200 Montreal Road (at Blair Road), Kelvin Room (M36)


1) 4D-VMAT plan optimization: Robustness against variations in breathing pattern

Eric Christiansen, Carleton University, Department of Physics

Supervisors: Emily Heath & Tong Xu

Abstract:  Volumetric modulated arc therapy (VMAT) is a radiation therapy technique that can deliver dose distributions which conform tightly around the tumour, and as such have become a standard radiotherapy treatment for many cancer sites. To accomplish this high degree of conformity, a multi-leaf collimator (MLC) inside the treatment machine is used to modulate the intensity of the radiation beam while it is rotated around the patient. Internal organ motion during radiotherapy, such as the movement of the lungs due to breathing, can distort these highly conformal treatments, leading to a blurred dose distribution. This deviation from the planned dose may result in an increased dose to healthy tissues and/or a decreased dose to the tumour, thereby compromising treatment outcomes. A variety of approaches have been developed to address tumour motion during radiation therapy, but the ideal solution would be to adapt the radiation beam delivery in real-time to follow the tumour motion.  PeTrack is a tracking system developed at Carleton University that can accurately measure tumour motion using positron-emitting markers implanted directly into the tumour. A 4D-VMAT treatment optimization algorithm will be presented, which coupled with PeTrack or other real-time tracking system, could be used to deliver a conformal therapy to mobile tumours. In contrast to some 4D-VMAT approaches, dose is computed along all specific tumour trajectories. Further, the algorithm uses a patient-specific probabilistic model of the breathing pattern to compute the expectation value and variance of the dose integrated over all possible trajectories. The optimization is based on a combination of a quadratic objective function and a variance term, which is included so that the final plan is robust to changes in the expected patient breathing pattern.


2) “Radioecology of Small Modular Reactors (SMRs): Can sunken subs help us?”

Trevor Stocki, Health Canada

Abstract: A number of countries are doing research into developing Small Modular nuclear Reactors (SMR) for electrical power generation. These types of reactors could be used to power remote locations, heavy industry applications, and on-grid applications.  This nothing new, from 1968 to 1975, the Americans used a “SMR” in the Panama Canal Zone for electricity.  This was a floating nuclear power station, named the MH-1A. More recently the Russians have put two nuclear reactors on a barge and plan to send it to a remote Arctic community to replace diesel power generation.  Canada also has a road map for SMRs.  Health Canada is required to review environmental assessments, so Health Canada is interested in the radio-ecological consequences of SMRs in terms of radiation dose received by humans.  A possible first step in understanding SMRs is to understand the radioecology of the nuclear submarines that have been sunk in the Kara Sea and surrounding area. The question posed is can this help shine any light on the issue for SMRs? The submarine, K-27 will be discussed.



If you haven’t already done so, please RSVP to OMPI year-end BBQ using the following link:

The team at NRC will be shopping to order based on RSVPs, so please confirm your attendance and meal preference as soon as possible to avoid missing out on the fun!