Yohan Bélanger Abstract

Le calcul exact de la dose en radiothérapie repose sur la connaissance du milieu d\’interaction et du modèle utilisé pour le représenter. Plus le modèle s\’approche des caractéristiques fondamentales du milieu et des interactions, plus le résultat du calcul de dose est exact. À l\’heure actuelle, les simulations Monte Carlo sont considérées comme étalon d\’exactitude car elles reposent sur les processus fondamentaux d\’interactions. Cependant, ces techniques de calcul de dose sont relativement lentes et mal adaptées à une utilisation clinique. Ce projet vise à developer un calcul de dose s\’appuyant sur plusieurs éléments physiques fondamentaux sans passer par les méthodes Monte Carlo. Ainsi, l\’objectif est d\’obtenir un calcul analytique qui s\’approchera des résultats Monte Carlo mais beaucoup plus rapidement. Des processeurs graphiques seront utilisés à cet effet.

Tanner Connell Abstract

The potential benefit of using scattering foil free beams for delivery of modulated electron radiotherapy is investigated in this work. Removal of the scattering foil from the beamline showed a measured bremsstrahlung tail dose reduction just beyond Rp by a factor of 12.2, 6.9, 7.4, 7.4 and 8.3 for 6, 9, 12, 16 and 20 MeV beams respectively for 2×2 cm2 defined on-axis fields when compared to the clinical beamline. Monte Carlo simulations were matched to measured data through careful tuning of source parameters and the modification of certain accelerator components beyond the manufacturer’s specifications.

An accelerator model based on the clinical beamline and one with the scattering foil removed were imported into a Monte Carlo based treatment planning system (McGill Monte Carlo Treatment Planning). A treatment planning study was conducted on a test phantom consisting of a PTV and two distal organs at risk (OAR) by comparing a plan using the clinical beamline to a plan using a scattering foil free beamline. A DVH comparison revealed that for quasi-identical target coverage, the volume of each OAR receiving a given dose was reduced, thus reducing the dose deposited in healthy tissue.

Sébastien Laberge Abstract

The project consists in developing a new simulation platform to study the effect of different PET/MR imaging acquisition parameters on the textural features of simulated images. This software will facilitate the use on a cluster of MRI simulators JEMRIS and SIMRI and PET simulator Gate using input digital tumor models obtained from clinical data. It will also allow the fusion of PET and MRI images and the computation of a wide variety of textual features on both clinical and simulated images. The platform’s first anticipated use is to enhance the textural properties of FDGGPET and MRI images that have been identified to be strong prognostic factors in soft-tissue sarcoma cancer. MRI and PET tumor models will have to be created from clinical images to be used in the simulators A variety of MRI sequences will have to be implemented and the parameters that have an impact on computed textures will have to be isolated. Likewise, a variety of PET reconstruction algorithms will have to be implemented for both 2D and 3D acquisitions, while considering attenuation correction algorithms. Following this step, the effects of PET acquisition and reconstruction parameters on computed textures will have to be determined. Finally, to study the full potential of FDGGPET and MR textural features, the platform will have to allow convenient fusion and textural analysis of PET and MRI images. Prediction models will eventually have to be implemented, and the data formats must facilitate the use of the platform on a large number of study cases.

Huaping Lin Abstract

In this project organic electronics (with a particular focus on organic field effect transistors (OFETs)) will be designed, fabricated and tested in ionizing radiation fields to explore their properties as radiation detectors and dosimeters. Organic materials have excellent potential as radiation dosimeters due to their near water-equivalence across a wide range of energies (kilovoltage to megavoltage). Detector designs will be investigated to minimize dependencies on: direction, temperature, dose rate, energy, radiation type etc.

The potential for cheap, flexible fabrication techniques will also permit the exploration of two dimensional arrays of OFETs for planar dose measurements in a radiotherapy setting.

Ola Maria Abstract

Group of Canadians experience radiation pneumonitis (RP) following lung cancer radiotherapy and their lung tissue becomes destroyed further. Among cancer victims, lung cancer accounts for the highest death rate in Canada and worldwide, with a 5-year survival rate of only 15% and no significant improvement over the past 3 decades. The Canadian Cancer Society expects that 24,100 new lung cancer cases will be diagnosed in 2013 with an estimated 20,600 deaths. This accounts for 27% of all cancer deaths with 87% of these cases classified in clinic as Non-Small Cell Lung Cancer (NSCLC). About 60-70% of NSCLC patients receive radiotherapy and it is the main option for inoperable locally advanced cancer patients. However, RP is a potentially fatal lung inflammation that develops in about 30% of thoracic irradiations and damages normal lung tissues within 3-6 months. Patients with RP suffer considerable morbidity and severe reduction in their quality of life. At present, there is no adequate treatment for RP, therefore, developing alternative strategies to restore lung function would ultimately enrich the Canadian capacity and expertise in the area of Medical Oncology. The objective of this proposed research is to use Mesenchymal stem cells (MSCs) from bone marrow to repair lung tissue following induction of lung cancer and RP in rats. We hypothesize that transplanted MSCs could be used to restore radiation-induced lung damage and mitigate effects of pneumonitis and its lethal fibrotic sequelae using lung cancer-induced model. As a preclinical necessary step, we will use 3 approaches to protect lung tissue; administration of Amifostine (cell protector) versus alpha-2- macroglobulin (α2M, inflammation modulator) or administration of MSCs. To ensure safe beneficial delivery and to avoid risk of interference of administered MSCs with cancer treatment or contribution to tumorigenesis, we will run our experiment on rat model that have developed lung cancer. The clinical potential impact of successful restoration of radiation-damaged lungs in vivo in lung cancer model without need for whole organ transplantation would be a key breakthrough for a new direction in treatment of millions of lung cancer patients worldwide. In addition, this study would provide new insights into lung stem cell response to irradiation, corresponding circulating biomarkers and potentially uncover new molecular mechanisms and targets for mitigating toxicity risk in radiotherapy in NSCLC.

Ola Maria Publications

1. Ola M Maria, Ahmed M Maria, Norma Ybarra, Krishinima Jeyaseelan, Sangkyu Lee, Jessica Perez, Mostafa Y Shalaby, Shirley Lehnert, Sergio Faria, Monica Serban, Jan Seuntjens, Issam El Naqa (2016) Mesenchymal Stem Cells Adopt Lung Cell Phenotype in Normal and Radiation-induced Lung Injury Conditions, Applied immunohistochemistry & molecular morphology: 2016 Apr; 24(4):283-95. doi: 10.1097/PAI.0000000000000180.

Chrystian Quintero Matteus Abstract

The project objective is the implementation of radiochromic film dosimetry protocol for CTDI measurements as a part of annual QA on CT simulators and kV CBCT systems attached on linear accelerators. The first part of the project is development of the MatLab application for film measurements analysis. The second part of the project is the investigation of the influence of different scanning parameters on CTDI measurements and comparison of the measured and tabulated data for different CT scanners.

Jose Rubio Sanchez Abstract

This project involves the design, fabrication and evaluation of various organic electronic devices for the measurement of radiation fields. Our previous work in this area has demonstrated that existing organic field effect transistors (OFETs) can be employed as radiation detectors and they demonstrate excellent linearity with accumulated dose. This project will carry out a systematic evaluation of existing and novel OFET devices with the objective of maximizing the water equivalence of the devices across as wide an energy range as possible. Variables in the design include: the shape of the active area of the device, the thickness of various device components (i.e. gate, dielectric, semiconductor) as well as the composition of the components. Different designs will be studied and the response of certain characteristics (i.e. threshold voltage and charge mobility) will be investigated as a function of accumulated radiation dose.

Laurel Stothers Abstract

This summer project will involve Monte Carlo simulations of radiation transport sarcoma cancer. MRI and PET tumor models will have to be created from clinical images to be used in the simulators A variety of MRI sequences will have to be implemented and the parameters that have an impact on computed textures will have to be isolated. Likewise, a variety of PET reconstruction algorithms will have to be implemented for both 2D and 3D acquisitions, while considering attenuation correction algorithms. Following this step, the effects of PET acquisition and reconstruction parameters on computed textures will have to be determined. Finally, to study the full potential of FDG-­‐PET and MR textural features, the platform will have to allow convenient fusion and textural analysis of PET and MRI images. Prediction models will eventually have to be implemented, and the data formats must facilitate the use of the platform on a large number of study cases. through proposed organic field effect transistor designs. The simulations will be designed to investigate the perturbation of the radiation field introduced by the presence of the detectors and to evaluate the water equivalence of the detector materials across a wide energy range. Device composition will be a primary focus of the work, investigating the effects of different components (i.e. gate material, insulator and semiconductor) on the perturbation as well as the physical dimensions of the detector.

Julien Refour Tannenbaum Abstract

Measurement of CT Dose Using AAPM Task Group Report No. 111 Dose in CT is universally measured by the computed tomography dose index (CTDI),a concept introduced nearly thirty years ago. The key reason this concept has been so widely adopted, is the simplicity of its implementation. The measurement of CTDI, involves only a 10 cm long ion chamber, dedicated CTDI phantoms, and an electrometer. Despite its wide use, most experts feel that it is time to retire the CTDI concept. CTDI systematically underestimates the dose in multi slice scanners and the concept fails to apply to cone beam scanners. These limitations of the CTDI, have been the driving force behind the formation of AAPM Task Group no. 111. This group looks into finding better metrics for evaluating CT dose, which would apply to all CT scanning modes for now and into the foreseeable future.
The report of Task group No. 111 came out in Feb. 2010. It proposes a new measurement modality using a small volume ionization chamber placed in a phantom long enough to establish dose equilibrium at the position of the chamber.
To date, the body of literature on the implementation of TG 111 is sparse and there exists an opportunity to make a substantial contribution to the field of CT dosimetry.
The goal of this project is to implement the suggestions of TG 111 in our clinic and to compare the TG 111 dose to CTDI. We will explore all areas of application, including axial, helical and cone beam CT dose and we will identify conditions in which the new proposed protocol fails.

Dominique Guillet Abstract

Current techniques to acquire patient surface data are often very expensive and lack flexibility. In this study, the use of the Microsoft Kinect to reliably acquire 3D scans of patient surface is investigated. A design is presented to make the system easily applicable to the clinic. Potential applications of the device to radiotherapy are also presented. Scan reproducibility was tested by repeatedly scanning an anthropomorphic phantom. Scan accuracy was tested by comparing Kinect scans to the surface extracted from a CT dataset of a Rando® anthropomorphic phantom, which was considered as the true reference surface. Average signed distances of 0.12 ± 2.34 mm and 0.13 ± 2.04 were obtained between the compared surfaces for reproducibility and accuracy respectively. This is conclusive, since it indicates that the variations observed come largely from noise distributed around an average distance close to 0 mm. Moreover, the range of the noise is small enough for the system to reliably capture a patient’s surface. A system was also designed using two Kinects used together to acquire 3D surfaces in a quick and stable was that is applicable to the clinic. Finally, applications of the device to radiotherapy are demonstrated. Its use to detect local positioning errors is presented, where small local variations difficult to see what the naked eye are clearly visible. The system was also used to predict collisions using gantry and patient scans and thus ensure the safety of unconventional trajectories.

Joannie Desroches Abstract

Cancer is often difficult to distinguish from normal tissue. This is particularly important during brain tumor resection, since patient survival and prognosis is greatly influenced by the extent of resection. The goal of the project is to assess the molecular differences between cancer and normal brain using Raman spectroscopy. This is an optical technique to observe low-frequency rotational and vibrational modes in a system.

The system is consisted of a fiber-optic probe, a laser emitting at 785 nm and a grating-based spectrometer coupled to a CCD detector. The technique has been used by the research group in vivo to discriminate cancer and normal brain, and has shown good results for classification. The next step of this project is a chemometrics analysis to determine the relative concentration of molecular components in brain tumors versus normal brain tissue.

Joseph Carr Abstract

Intraoperative radiotherapy (IORT) with the INTRABEAM ® system is used in the treatment of breast cancer and several other malignancies. During treatment, the x-ray source is housed inside a spherical applicator of diameter appropriate for the size of the surgical cavity. Currently, the treatment time is a function of prescribed dose and applicator size. The radiation dose follows a spherical distribution and falls off sharply at distance. Current prescribed dose for all breast patients is 20Gy at the applicator surface. The properties of the radiation source are taken into account when calculating the treatment time. However, inter-patient variations related to shape, size and composition of near-by tissues and organs are not taken into account. The true delivered dose therefore will differ from the estimated.
With this project, we aim to implement the use of Monte Carlo simulations for INTRABEAM® IORT. The initial work consists of selecting a Monte Carlo code that is most appropriate for modeling IORT. The following tasks will involve the definition of all source and patient parameters that are required for accurate dose calculation. The patient’s tomographic images acquired pre-surgery will be used to recognize tissue composition heterogeneities. The size of the INTRABEAM applicator will be inferred from the tumor size, while its location is related to the location of the tumor mass. The simulated doses will be evaluated extensively through measurement in humanoid phantom and water.

Jessie To Abstract

Mesenchymal stem cells (MSCs) have yielded promising results in regenerative therapy and have been suggested to treat radiation-damaged tissue in cancer patients. However, this remains controversial because MSC-cancer cell interactions are still unclear. Previous studies show that karyotypically normal, tumour-associated MSCs have up-regulated proto-oncogenes compared to MSCs found elsewhere. Given this, we hypothesized that bone-marrow-derived MSCs may also up-regulate proto-oncogenes if exposed to a cancerous environment.
To test our hypothesis, we extracted bone-marrow-derived MSCs from Sprague Dawley rats and co-cultured them with A549 lung cancer cells to simulate a cancerous microenvironment. This was done for 48, 72, and 120 hours in both MSCGM and F12K cancer media. Following, we reverse-transcribed the extracted RNA and monitored the expression of two proto-oncogenes, carcinoembryonic antigen (CEA) and epithelial cell-adhesion molecule (EpCAM).
There was no significant increase in EpCAM expression after 48-h and 120-h co-cultures. However, after 72-h, there was a significant increase of 1.51x in MSCGM and 5.24x in F12K medium. In contrast, CEA expression was elevated at a relatively constant level (1.46x-1.84x) after co-culture in MSCGM (48-h, 72-h, 120-h) and F12K media (48-h, 120-h). However, similar to EpCAM, CEA expression spiked to 3.39x after the 72-h co-culture in F12K.
Our results demonstrate that A549 cancer cells have a profound impact on MSC expression phenotype. Clinically, this pertains to tissue repair in cancerous environments – therapeutically injected MSCs may behave similarly to MSCs co-cultured with cancer cells. If our results hold true in vivo, MSC transplantation may pose unwarranted risk for lung cancer patients.

Robert Maglieri Abstract

Compared to photons, electrons and protons, studies of atomic bomb survivors and animals have shown that neutrons can be up to 20 times more effective at inducing cancer. This radiation weighting factor is dependant on neutron energy and varies from 5 at low (< 10 keV) and high (> 2 MeV) energies to its peak of 20 at medium (~1 MeV) energies. To reduce the rate of neutron-induced second cancers, the physical mechanisms that relate the effective dose of different energies to cancer induction at the microdosimetric level must be understood.
The goal of this project is to investigate the microdosimetric differences between high and low energy neutrons in their relation to cancer risk. The objectives are to: 1) develop low-energy neutron transport for GEANT4-DNA, 2) simulate and quantify neutron interactions with DNA, and, 3) evaluate radiation weighting factors in terms of neutron energy.
1) Recently, a Monte Carlo (MC) package, GEANT4-DNA, has been developed for the transport of electrons, protons and photons at the DNA level. In this project, neutron transport will be integrated into GEANT4-DNA code leading to a complete simulation of neutrons and their secondary particles.
2) In this work, neutron production during photon and proton therapy will be simulated using GEANT4-DNA. MC neutron spectra will be compared with measurements around a linac accelerator and cyclotron using the Nested Neutron Spectrometer. Upon validation of the spectrum, it will be possible to tally the energy deposition and track-averaged linear energy transfer of neutrons and their secondary particles in the DNA molecule.
3) Our neutron-DNA model will be used to provide Monte Carlo data to correlate specific endpoints from DNA damage, such as single and double strand breaks, with neutron energies for comparison with existing neutron weighting factors. Furthermore, a biological laboratory study examining the differences of in vitro cell damage as a function of neutron energy will be undertaken in our wet lab for experimental validation.

Jessica Perez Abstract

Background and rationale
Among cancer patients undergoing radiation therapy, some will develop side effects. Radiation-induced lung disease (RILD) manifests in up to 30% of thoracic irradiations.
Stem cell therapy is currently under preclinical investigation for the treatment of RILD. Mesenchymal stem cells (MSC) have demonstrated great promise in regenerative medicine for multiple organs including the lungs.MSC have been shown to differentiate and exhibit an epithelial phenotype but more research is needed to understand and assess mechanisms of MSC differentiation. Molecular imaging has the potential to evaluate the ability of MSC for tissue repair function in vivo and non-invasively. In this work we will design and optimize imaging probes to track and monitor MSC differentiation in the context of lung regeneration after radiation-induced injury.
Objectives and research plan:
The lack of a reliable imaging tool to assess the behaviour of stem cells in the context of lung injury prompted us to design imaging probes capable of monitoring the dynamics of lung repair and differentiation.

1. Track stem cells in vivo with molecular imaging
Our lab is currently developing a rat model for RILD and cell therapy. We will use optical imaging methods to visualize and track MSC in vivo.

2. Develop a reporter gene construct to assess lung marker expression in differentiating cells
A reporter gene construct will be used to assess the expression of lung markers after differentiation induction. Promoters specific to lung epithelial cells will be used to drive the expression of a fluorescent reporter.

3. Design a biosensor to assess functional activity of differentiated cells
We will use the metabolic activity known to occur within the lung as a functional assessment of cell differentiation. The approach is to investigate cytochrome activity as basis of the design of a biosensor constructed with quantum dots nanoparticles.

4. Assess lung regeneration with microendoscopy.
With microendoscopy we are capable of non-invasively image lung status at the cellular level, in real time and this technique is also amenable to fluorescence endomicroscopy. We will therefore investigate the possibilities of using such a technique together with our imaging probes to assess MSC behaviour.

Jessica Perez Publications

1. Gabriel Paré, Réjean Lebel, Jessica Perez, Frédéric Chagnon, Marc-André Bonin, Catherine Bibeau, Issam El Naqa, Eric Marsault, Martin Lepage and Olivier Lesur (2017) “Emerging applications of intra-vital smart micro-imaging: from bench-to-bedside “In: Microscopy and imaging science: practical approaches to applied research and education; pp:120-133. Published in February 2017.
2. Perez JR, Ybarra N, Chagnon F, Serban M, Pare G, Lesur O, Seuntjens J & El Naqa I (2017) Image-Guided Fluorescence Endomicroscopy: From Macro- to Micro-Imaging of Radiation Induced Pulmonary Fibrosis, Scientific Reports 7:17829. doi:10.1038/s41598-017-18070-x.
3. Jessica R. Perez, Sangkyu Lee, Norma Ybarra, Ola Maria, Monica Serban, Krishinima Jeyaseelan, Li Ming Wang, Jan Seuntjens & Issam El Naqa (2017) A comparative analysis of longitudinal computed tomography and histopathology for evaluating the potential of mesenchymal stem cells in mitigating radiation-induced pulmonary fibrosis, Sci Rep. 2017 August 22; 7(1) 9056. DOI:10.1038/s41598-017-09021-7.
4. Perez JR†,, Ybarra N, Chagnon F, Serban M, Lee S, Seuntjens J, Lesur O, El Naqa I. (2017) Tracking of Mesenchymal Stem Cells with Fluorescnce Endomicroscopy Imaging in Radiotherapy-Induced Lung Injury, Sci Rep. 2017 Jan 19;7:40748. doi: 10.1038/srep40748.

Éric Poulin Abstract

La curiethérapie interstititelle à haut debit de dose (HDR) est une technique de choix pour le traitement du cancer du seinet de la prostate. Il nèexiste présentement aucun système dèéchographie 3D (3DUS) suffisamment évolué pour faire la planification et le guidage en temps reel du traitment de curiethérapie HDR du sein. De plus, le nombre et la position des catheters sont choisis manuellement ce qui peut avoir comme consequence de dinimuer lèefficacité des traitements. Le but de mon projet est de déveloper et intégrer de nouvelles technologies afin de les introduire dans le protocole Clinique de curiethérapie HDR. Mon hypothèse est que ces nouvelles technologies vont permettre d’améliorer la qualité et render plus rapide les traitements de curiethérapie HDR. Mes premières investigations seront de concevoir et valider un algorithme d’optimisation de la position et du nombre de cathéterm lié à l’algorithme de planification inverse IPSA. Ensuite, une nouvelle approche sera d/velopp/e, utilisant l’échographie 3D, afin de planifier et guider en tempsGréel les traitements de curiethèrapie HDR du sein. La precision et la robustesse dèun systèeme de guidage par radiofréquence, pour les catheters, sera par la suite évaluer. Finalement, un nouveau prototype 3DUS sera développé et validé. Les nouvelles approches proposes dnas ce projet pourraient avoir un impact majeur sur les procedures cliniques en curiethérapie interstitielle HDR.

David Goncalves Abstract

The project involves creation of biocompatible rare earth-based nanoparticles and testing them for activity against cancer in vitro and in vivo, with or without radiation therapy.
We will develop a new kind of particle for radiosensitization of tumours by direct intratumoral or possibly intravenous injection and test them in vitro and in vivo. The particles, cerium-doped lanthanum fluoride (LaF3:Ce), are made of low-toxicity constituents and have many desirable photophysical properties compared to currently existing radiosensitizers in the field. They can radiosensitize tumours on their own via the photoelectric effect, or they may be conjugated to a photosensitizer for X-ray based singlet oxygen generation.
Until the LaF3:Ce NPs are ready for experimentation, we will be doing similar work with gold nanoparticles conjugated to doxorubicin (Au-Dox). Au-Dox is effective against Melanoma xenografts as previously shown in our lab. It suppresses the growth of B16 xenografts in immunocompetent mice by 80% vs control groups.

Eric Christiansen Abstract

A proposed dosimetry formalism for small and non-standard fields involves the determination of ionization chamber correction factors to convert the dose measured in a clinical plan to the dose associated with either a static machine-specific reference (MSR) field, and/or a plan-class specific reference (PCSR) composite field being as close as possible to a class of clinical plans of interest. The aim of this work is to determine, with experiments and Monte Carlo simulations, ion chamber correction factors for a large number of representative Cyberknife treatments. The experimental portion of the project will use a commercial plastic scintillation detector (PSD) as the reference dosimeter. The EGSnrc Monte Carlo package will be used to develop a model of the Cyberknife accelerator, and apply the model to calculate the ion chamber correction factors.
Investigation will begin with simple isocentric plans with a single collimator at a fixed depth in a circular phantom and will continue by systematically increasing plan complexity in order to explore the suitability of the PCSR- based correction over the MSR-based correction. The selection of an appropriate measurement location for individual patient plans and within the PCSR and clinical field is also non-trivial and will be investigated using the predicted dose gradients and verified using radiochromic film.

Jeremy Ahearn Abstract

Specific DVH’s were converted into a new format and placed in a database to be used at the Glen Site.

Aidan Marchildon Abstract

Development of Monte Carlo Simulation Code for INTRABEAM® Radiation Therapy and Dosimetry Applications
Abstract:
Intraoperative radiotherapy (IORT) with the INTRABEAM ® system is used in the treatment of breast cancer and several other malignancies. During treatment, the x-ray source is housed inside a spherical applicator of diameter appropriate for the size of the surgical cavity. Currently, the treatment time is a function of prescribed dose and applicator size. The radiation dose follows a spherical distribution and falls off sharply at distance. Current prescribed dose for all breast patients is 20Gy at the applicator surface. The properties of the radiation source are taken into account when calculating the treatment time. However, inter-patient variations related to shape, size and composition of near-by tissues and organs are not taken into account. The true delivered dose therefore will differ from the estimated.
The general aim of this project is to develop a treatment planning system that will allow for treatment simulations with INTRABEAM device on patients’ CT images. Earlier work consisted of developing a Monte Carlo-based TPS; the proposed project will build on earlier results. Simulations will be performed in the CT scan of human considering tissue heterogeneities.
In addition, a clinical protocol for in-vivo dose measurement using Gafchromic film will be developed. Following the film dose calibrations, measurements will be perfomed in water and humanoid phantoms to validate the results of treatment planning simulations.

David Herreira Abstract

Radiation oncology patients are seldom provided with personalized treatment information. As a consequence, they are unable to fully plan their lives during radiotherapy.
In an attempt to address this issue, we have developed a novel application that is both secure and confidential and allows real-time encrypted communication via a cloud-based bridge database.

Yunzhi Ma Publications

1. F. Ballester, Å. Carlsson Tedgren, D. Granero, A. Haworth, F. Mourtada, G. Paiva Fonseca, K. Zourari, P. Papagiannis, M.J. Rivard, F-A. Siebert, R.S. Sloboda, R.L. Smith, R.M. Thomson, F. Verhaegen, J. Vijande, Y. Ma and L. Beaulieu (2015) A Systematic Characterization of the Low Energy Response of Plastic Scintillation Detectors, Med. Phys. 42(6):3048.

Pavlos Papaconstadopoulos Abstract

In recent year the medical physics community has shown an increased interest in the physics and dosimetry of small MV photon beams such as those used for the purposes of stereotactic radiosurgery (SRS) and Intensity Modulated Radiation Therapy (IMRT). The delivery of small photon beams can be performed by specialized units (Cyberknife, GammaKnife, TomoTherapy) or by conventional linear accelerators equipped with highGdefinition multi-leaf collimators, such as the BrainLab MLC on the Varian Novalis Tx. Even though the above technological improvements offer highly accurate delivery of small radiation beams, several investigators have questioned if the technology has moved ahead of our understanding of basic physics principles. The purpose of this study is to study the relationship between the detectorGspecific readings and variations of the source size. As a first step, MCGcalculated correction factors will be derived for a set of small field detectors on central and offGaxis positions. The calculated correction factors could then be applied to correct each dose profile. During this process, componentGspecific perturbation factors can also be derived. The ‘true’ dose profiles can be assumed to be affected only by variations of the source size. A series of dose profile characteristics can be derived and related to variations of the source size. This process would improve our understanding of the source occlusion effect and potentially help us investigate the most sensitive parameters related to the source size. Furthermore, very small field profiles (less than 5 mm) can be studied at this step. Even though these fields are not used in radiotherapy, they can potentially be more sensitive indicators of the source occlusion effect.
On the relationship between stereotactic dose profiles and source size.
*Derive correction factors for small field dosimeters.
*Sensitivity analysis between x-ray source and detector-specific response.

Pavlos Papaconstadopoulos Publications

1. Papaconstadopoulos P, Tessier F and Seuntjens J, (2014) On the correction, perturbation andmodification of small field detectors in relative dosimetry. Phys Med Biol. 59(19):5937-5952.October 2014.
2. Papaconstadopoulos P, Hegyi G., Seuntjens J, and Devic S., (2014) A protocol for EBT3 radiochromic film dosimetry using reflection scanning, Med. Phys. 41(12): 122101.
3. P Papaconstadopoulos, I R Levesque, R Maglieri, and J Seuntjens (2016) Direct reconstruction of the source intensity distribution of a clinical linear accelerator using a maximum likelihood expectation maximization algorithm, Physics in medicine and biology 61(3): 1078-1094; January 2016.

Gloria Bäckström Abstract

Proton and other light ions have a physical distribution of energy deposited that allows to better concentrate the dose to the tumor than for conventional radiotherapy. The biological response is quantified in terms of the relative biological effectiveness (RBE) for a given biological endpoint. RBE depends on the reference radiation, cell line, particle type and linear energy transfer of the irradiating particle. However, in a tumor, RBE can vary. This variation might be caused by different complexity of the DNA damage occurring in the cell nucleus due to the proximity between energy deposit sites. The relative distances between energy deposit sites change with radiation quality, and lead to different pattern formation of groups or clusters. Monte Carlo (MC) codes can be used for particle transport in matter. Track structure codes are a class of MC codes that generate in detail the spatial pattern of energy deposit sites due to the event-by-event simulation of particle interactions. Our aim is to develop and use track structure codes to search for a relationship between frequency distribution of order of clusters of energy deposit sites, as a descriptor of radiation impact, and RBE for cell survival for various radiation qualities. A method for predicting RBE values for protons on the basis of dose-response data obtained from photons will be developed and can be included in treatment plans. In addition, differences in dose distribution for proton dose plans with a fixed and modeled RBE will be compared for treatment of brain tumors in children.

Mehryar Keschavarz Abstract

Q+ – Addressing the pain of waiting.

Mehryar Keschavarz Publications

To Be Added.

Kyle O’Grady Abstract

The McGill Monte Carlo Treatment Planning System (MMCTP) has been used for several research studies at McGill University and is used for some clinical applications at the McGill University Health Centre (MUHC). MMCTP calculations for 6 MV and 18 MV photon beams for the Varian Clinac 21EX linear accelerator have been tuned and validated against measured 3D water phantom data obtained using a liquid ionization chamber and an air-filled ionization chamber. The measured data were compared to EGSnrc Monte Carlo calculations using the egs chamber user code, which allows for the inclusion of detector effects in the simulation. Effects such as volume averaging and the non-water equivalence of the detector components we quantified in detailed detector models of the PTW microLion, Exradin A1SL and Exradin A12. This allowed for more accurate tuning of the beam model free parameters, such as electron energy, spot size, and angular divergence. After validation, the tuned accelerator model was implemented into the MMCTP workstation for clinical applications. The current project goal has been to investigate methods for modelling the Varian TrueBeam linear accelerator for use in future Monte Carlo simulations, beginning with the 6 MV flattened and flattening-filter-free (FFF) photon beams. Varian does not provide the proprietary information required to construct accurate models of the TrueBeam, so alternate modelling options have been explored. The first method investigated was to use the Varian VirtualLinac, a cloud-based phase space solution. The second method was to create an EGSnrc implementation of a published PENELOPE model known as FakeBeam. The third method currently being investigated is to modify the existing model of the Clinac 21EX to match Varian.

Sangkyu Lee Abstract

The mortality of lung cancer is amongst the highest of all cancer types and radiotherapy (RT) is used for more than 50% of lung cancer treatments. A concern for radiation pneumonitis (RP) is a major obstacle to increasing radiation prescription for better chance of tumor killing. Indeed patients show large variability in RP under similar RT plans. There are studies that patient-specific levels of particular biomarkers (proteins and genes) are responsible for such variability, which might explain inadequate accuracy of pre-existing prediction models that are solely based on dosimetry (amount of radiation deposited in body). Therefore, it is important to model RP as a system where interactions among biological and physical stimuli (radiation) take place. We will apply and further develop a statistical technique called machine learning to capture the complex relationships among biological and dosimetric variables in our prospective lung cancer patient database. The proposed project can potentially deliver a large impact on radiation oncology and radiobiology. If we can identify patient’s low RP risk by using our biophysical prediction model, they might be eligible for a more aggressive RT plan leading to a better chance of cancer cure without significantly affecting iatrogenic morbidity. Our machine-learning based approach might provide a new way to analyze and understand radiation induced normal tissue toxicities, which can be used to design better therapeutic intervention.

Sangkyu Lee Publications

1. Lee S, Ybarra N, Jeyaseelan K, Faria S, Kopek N, Brisebois P, Bradley JD, Robinson C, Seuntjens J, El Naqa I. (2015) Bayesian network ensemble as a multivariate strategy to predict radiation pneumonitis risk, Med. Phys. 42(5): 2421.
2. Lee S, El Naqa I. (2015) Machine Learning Methodology. In El Naqa I, Li R, Murphy MJ, Machine Learning in Radiation Oncology, (pp. 21-39), Springer International Publishing.
3. O.M Maria, AM Maria, N Ybarra, K Jeyaseelan, S Lee, J Perez, MY Shalaby, S Lehnert, S Faria, M Serban, J Seuntjens, I El Naqa (2015) Mesenchymal Stem Cells Adopt Lung Cell Phenotype in Normal and Radiation-induced Lung Injury Conditions. Applied immunohistochemistry & molecular morphology: (July 2015, pub, ahead of print).
4. S Lee*, N. Ybarra, K. Jeyaseelan, S Faria, N Kopek, I El Naqa (2015) Bayesian Network Representation of Radiation Pneumonitis Onset After Hypofractionated Stereotactic Body Radiation Therapy (SBRT) for Lung Cancer, ASTRO’s 57th Annual Meeting, San Antonio, TX, October 18-21, 2015. International Journal of radiation oncology, biology, physics 11/2015 93(3):S54-S55.

Jonathan Boivin Abstract

La dose de radiation impliquée au cours de procédures de radiologie interventionnelles guides par fluoroscopie (IGF) soulève certaines inquietudes en raison d’un niveau avoisinant ou surpassant le seuil d’appaarition des effets determinists, En effet, il n’est pas rare que la peau absorbe une dose de plusieurs grays au cours de la procedure, un niveau comparable à une séance de radiothérapie. Curieusement, la donse n’est pas mesurée durant l’intervention. Seule une evaluation de certains parameters dosimétrique est disponible, mais ceuxGci ne fournissent aucun renseignement sur la dose absorbée à la peau ou à quelque organe que se soit. En consequence, la dose peut dépasser le seuil d’occurrence des effets determinists sans être détectée. Le but du projet consiste à metre au point un prototype de dosimèetre permettant de mesurer la dose à la peau un temps reel au cours d’une procedure IGF. Ce système utilise une fibre scintillante émettant de la lumière lorsq’elle est exposée aux radiations, ainsi que d’un tube photomultiplicateur collectant le signal produit. Le projet comporte quatre phases principales. La calibration du détecteur a d’abord permis d’ observer sa réponse en fonction de la dose recue. Des mesures aréalisées sur un fantôme humanoide ont ensuite servi à valider le fonctionnement du prototype dans des conditions cliniques d’intervention. La troisième phase vise essentiellement à relever des mesures auprès des patients, quoique ces demarches n’aient pas été engages jusqu’à present. Parallèlement à ces experiences, un modèle informatique de la sale de radiologie interventionnelle a été construit en vue de simuler par calcul Monte Carlo la distribution de dose en surface et à l’intérieur d’un patient, puis auprès du personnel exposé.

Fernando Parois Japiassu Abstract

The risk of developing a solid tumor after exposure to ionizing radiation is well established via a linear dose effects x, for the range of radiation dose from 0.2 to 2 Sv. However, the epidemiology does not provide information and responses to the emergence of secondary tumors induced by ionizing radiation in patients undergoing radiotherapy treatments, where a small volume of the patient is irradiated with high doses of radiation (treatment dose) and the remainder of the body is subjected to low and medium doses due to the inevitable unwanted radiation that reaches areas outside the treatment area.
The objective of this research is to quantify, through experimental measurements and computer simulations using the Monte Carlo method, the unwanted dose outside the treatment area, that patients undergoing radiotherapy sessions are exposed to and that, according to the most current literature, has enormous potential to produce secondary tumors in parts of the body distant from the region primarily treated. This study is important in particular in the case of pediatric cancers, where the life expectancy of patients, and therefore the likelihood of developing secondary tumors, is higher.
To accomplish this objective, it is intended to simulate values of doses deposited in various organs in the body of patients undergoing radiotherapy sessions, especially for regions where experimental measurements would be difficult. This can be done using phantoms based on volume element, known as voxel phantom. It is also intended to perform several experimental measurements using dosimeters such as thermoluminescent, diodes or MOSFET in phantoms that simulate the human body.

Simon Dobri Abstract

The goal of the project is to develop a novel radiation detector for dosimetric purposes. The detector will be based on the principle of interferometry. An electro-optic crystal placed in the probing arm of the interferometer will change its refractive index when exposed to ionizing radiation, making possible a measurement of the dose to the crystal. This can be used to calibrate the radiation source for use on patients in the clinic.

Simon Vallières Abstract

The main objectives in cancer treatment by radiotherapy is to deliver a high dose of radiation to the tumor while sparing as much as possible healthy tissues. During the past decades, gold nanoparticles have shown interesting properties to enhance energy deposition in tissues. Either by specific targeting or by the enhanced permeability and retention (EPR) effect, nanoparticles can accumulate preferentially in tumors, thereby delimiting a local increase in dose deposition and thus permiting to reduce the dose given to healthy tissues. In our work, we conjugate gold nanoparticles with doxorubicin, a chemotherapeutic agent. We therefore act on two simulatenous fronts, namely with chemotherapy and nanoparticle-enhanced radiotherapy treatments. We use a murine model in which B16 melanoma cells are grafted subcutaneously on the flank of the mice. Intratumoral injections of gold-doxorubicin conjugates are then given, followed by a single dose of irradiation. The effectiveness of the treatment can then be compared to the control groups and the dose enhancement be quantified. In order to understand the mechanism of dose deposition through the use of nanoparticles, Monte Carlo simulation are also developed using Geant4. This helps us to find the optimal enhancement parameters in terms of photon energy, nanoparticle size, nanoparticle concentration, spatial distribution, etc. The aim of this project is to test different experimental conditions in order to determine the best combination that will allow us to cure the mice by a complete eradication of the tumors.

Mikaël Simard Abstract

Magnetic resonance imaging (MRI) can visualize musculoskeletal (MSK) tissue and also obtain quantitative information about structure, content and mechanical behavior. We are seeking non-­‐invasive biomarkers of early disease related to the mechanical properties of the tissue, as any successful treatment of joint disease must restore joint mechanical function. This project will develop and validate a potential biomarker for tissue degeneration processes in MSK tissue based on a non-­‐ invasive MRI exam, from which we can infer mechanical function of these tissues. This marker will allow us to better track disease progression and evaluate treatment effectiveness. As an integral part of a large collaborative project with scientists and clinicians at Stanford University, we will use an approach called magnetization transfer (MT) MRI, known in neurology for brain white matter diseases, to quantify non-­‐aqueous macromolecular components of tissue (proteins and lipids). MSK tissues also show MT effects linked to matrix proteins. This project will consist largely of analyzing data already collected in pilot scans in six cadaver knee specimens, and using the results of this analysis to plan future methods development. These methods will subsequently be used in a cohort of patients with osteoarthritis, a disease that affects MSK tissues. The method of MT MRI has broader applications, notably in brain imaging, and has been proposed for characterization of cancer tumor cellularity and muscular pathology.

Ibtissam Benzyane Abstract

Dans ce projet, le stagiaire de recherche sera appele a étudier la complementarite de l’imagerie TEP et IRM pour l’etude de la reponse aux traitements de radiotherapie des sarcomes des tissus mous. Les sarcomes constituent un groupe relativement rare de neoplasmes se developpant principalement dans les muscles des extremites du corps, et possedant un risque metastatique eleve. Une plus grande comprehension de leur biologie fonctionnelle est requise afin d’envisager des traitements mieux adaptes a chaque patient dans le but d’ameliorer le taux de survie. Pour ce faire, le stagiaire de recherche analysera les images de 15 patients ayant reçu 4 differents types de scans TEP et IRM a 3 moments differents durant la gestion du traitement de radiotherapie (avant, pendant, et apres le traitement), pour un total de 180 scans. Les 4 types de scans TEP et IRM sont les suivants : 1) [18F] fluorodeoxyglucose -TEP, un type de scan permettant d’etudier le metabolisme des tumeurs, une caracteristique reliee à l’agressivite tumorale; 2) [18F] fluoromisonidazole -TEP, un type de scan permettant d’etudier les divers degres d’oxygenation à l’interieur des tumeurs, une caracteristique reliee à la résistance tumorale à la radotherapie; 3) Diffusion-weighted MRI (DW-MRI), un type de scan permettant d’etudier les divers degres de diffusion de l’eau a travers les tumeurs, une caracteristique reliee à la densite cellulaire tumorale ; et 4) Dynamic contrast-enhanced MRI (DCE-MRI), un type de scan permettant d’etudier les divers degres de perfusion des tumeurs, une caracteristique reliee à la vascularisation tumorale. Ce groupe d’images d’images rassemblees par le Centre Universitaire de Santé McGill (CUSM) lors des trois dernieres annees est unique au monde.

Ibtissam Benzyane Publications

To Be Added

Daniel Markel Abstract

The incorporation of multimodality treatment planning into radiation therapy has seen increased clinical usage over the past decade. Adaptive radiotherapy is the process of incorporating inter-treatment anatomical information into the treatment planning process. This necessitates adapting three objectives; target definition, patient volume registration and beam parameters to the daily context which is often determined using on-board imagers such as cone-beam CT (CBCT) and mega-voltage CT (MVCT).
This project aims to address outstanding problems associated with the practical application of online adaptive radiotherapy such as the use of imaging modalities with poor contrast-to-noise ratios and the time required for treatment re-planning. This is done by investigating the use of the Jensen Rényi divergence metric to re-optimize segmentation, registration and beam parameters. This general divergence metric has been shown to provide improved noise tolerance making it ideal for use with modalities such as CBCT and MVCT. Improved efficiency is accomplished by coupling
the energy functions of each of the objectives and performing them simultaneously, leading to iterative improvement of each process by the other two. By using an adaptive mesh that conforms to the volume geometry, leveraging the GPU and prioritizing which control points to evaluate during optimization, further reductions in processing time can be realized. The goal of this project is the development of algorithms to realize the clinical practicality of online adaptive radiotherapy planning.

Daniel Markel Publications

1. D. Markel, H. Zaidi, I. El Naqa (2013) Novel Multimodality Segmentation using Level Sets and Jensen-Renyi Divergence, Med. Phys. 40(12), 121908, December 2013.
2. James C. L. Chow, Runqing Jiang, Alexander Kiciak and Daniel Markel (2016) Dosimetric comparison between the prostate intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans using the planning target volume (PTV) dose–volume factor, Journal of Radiotherapy in Practice 15(02), 6 pages. Published online April 21, 2016.
3. D. Markel, I. Levesque, J. Larkin, P. Leger, I. El Naqa (2016) A 4D biomechanical lung phantom for joint segmentation/ registration evaluation, Phys Med Biol. 2016 Oct 7;61(19):7012-7030. Epub 2016 Sep 20.

Olivier Fillion Abstract

The goal of this project is to use a deformable image registration algorithm to deform a CT scan acquired for treatment planning onto one or more daily CBCT acquired prior or after the delivery of a treatment fraction in order to generate a new dataset for plan evaluation. The parameters of the deformation algorithm will be adjusted so that the registered image will possess the accurate CT numbers of the planning CT and the correct ‘anatomy-of-the-day’ from the CBCT. Thus, we hypothesized that the registered image could be used in a treatment planning system to compute the dose actually received by the patient for a given treatment fraction and assess whether this plan still meets its clinical objectives.

Patricia Duguay-Drouin Abstract

Les scintillateurs plastiques ont fait leur preuve dans le domaine de la dosimétrie et leurs avantages sont bien connus. Leur application permet entre autres de calculer des doses in vivo et en temps réel. Par contre, les détecteurs a scintillateurs plastiques (PSD) actuels ne permettent qu’un seul point de mesure par fibre collectrice, ce qui est un désavantage lors de certaines applications clinique. Une alternative a ce problème est le détecteur a scintillateurs plastiques multi-points (mPSD), car il ne requiert qu’une seule insertion de détecteur et permet le calcul de dose a plusieurs points simultanément. Le but de ce projet est de caractériser la chaine optique d’un mPSD a 2 points dans le but d’optimiser la sélection de ses composantes. Plusieurs détecteurs sont construits a partir de quatre scintillateurs plastiques et de points quantiques. Les scintillateurs sont couples a une fibre optique collectrice et ensuite connectes a un spectromètre. La partie scintillante est irradiée a une énergie de 125kVp pour éviter la contamination Cerenkov. Les spectres individuels pour chacun des scintillateurs sont mesures en irradiant un seul point a la fois et en blindant le deuxième point. Aussi, les spectres combines de toutes les combinaisons de scintillateurs sont mesures en irradiant les deux composantes en même temps. La forme et I’ intensité de ces spectres sont ensuite étudiées.

Patricia St-Amant Abstract

Évaluation de l’échographie Clarity 3D comme modalité d’imagerie en curiethérapie. Le système de la sonde échographique Clarity 3D permet la fusion entre les images ultrasons (3DUS) et les images CT. Le but du projet est de déterminer si la planification de traitement est améliorée, dans les cas de cancer du col de l’utérus, en utilisant ces images fusionnées au lieu de celles du CT uniquement. Une meilleure image est définie, dans le cadre de ce projet, comme une image se rapprochant des images par RM. Dans un premier temps, les contours faits par trois médecins
sont évalués pour vérifier la variation de délimitation des différentes structures d’intérêt (utérus, col, HR-CTV et rectum/sigmoïde) pour les 4 modalités d’imagerie étudiées (IRM, CT, 3DUS, 3DUS-CT). L’analyse de comparaison des contours est effectuée de plusieurs façons : 1 ) comparaison des volumes absolus, 2) comparaison de dimensions absolues et 3) comparaison des coefficients de Dice. A la fin de cette étape, il sera possible de conclure sur la qualité
des contours obtenus grâce à la fusion des images 3DUS et CT. La deuxième étape du projet est la planification de traitement sur les images fusionnées et la comparaison de ces plans avec ceux des autres modalités d’imagerie pour vérifier s’il y a une amélioration de la qualité du plan de traitement obtenu avec les images 3DUS-CT. À la fin de ce projet, il sera alors possible de conclure si le système permet une amélioration de la qualité du traitement, et si les images peuvent remplacer les IRM

Susannah Hickling Abstract

Radiation therapy is an important tool used in cancer treatment, with the goal being to deliver a sufficient amount of ionizing radiation dose to eradicate the tumor while minimizing the dose imparted to healthy tissue. Due to changes in tumor characteristics over the course of treatment, it is important to monitor tumor shape and properties to ensure optimal treatment effectiveness and safety. The use of image guided technology would be invaluable in providing real time information regarding the dose distribution and corresponding anatomy, however such a system is not presently available. The goal of this project is to investigate the use of x-ray acoustic computed tomography (XACT) for this purpose. XACT images the dose distribution following a pulse of irradiation by detecting radiation-induced acoustic waves. The first goal of the present work is to build upon the existing XACT simulation workflow developed at McGill to improve its accuracy, and properly validate it with experimental measurements. The second objective is to develop an experimental XACT-ultrasound system capable of concurrently imaging both the dose distribution and anatomy. Thirdly, phantoms representing different cancer sites, such as the prostate and breast, will be used to test the experimental system. Comparisons to simulations will be made. Finally, this system will be tested on animals.

Susannah Hickling Publications

1. Susannah Hickling†,, Hao Lei, Maritza Hobson, Pierre Leger, Xueding Wang, Issam El Naqa (2017) Experimental evaluation of x-ray acoustic computed tomography for radiotherapy dosimetry applications, Med Phys.;44(2):608-617. doi: 10.1002/mp.12039. Epub 2017 Feb.
2. Hickling S, Leger P, El Naqa I (2016) On the Detectability of Acoustic Waves Induced Following Irradiation by a Radiotherapy Linear Accelerator, IEEE Trans Ultrason Ferroelectr Freq Control. 63 (5): 683 – 691.

Vincent Turgeon Abstract

Positron emission tomography (PET) is a diagnostic functional imaging technique in which beta particle-emitting radioactive tracers, that are injected into the patient, are monitored to quantify physiological, biochemical, and pharmacological functions at cellular and molecular levels. PET is ideally suited to monitor cell and molecular events early in a disease such as cancer and during pharmacological or radiation therapy. The measurement of radioactive tracer concentration in blood plasma, known as the input function (IF), is required to accurately model kinetic parameters for PET. However, the IF is usually derived from multiple blood samples drawn from an arterial cannula. The IF is therefore acquired by invasively withdrawing arterial blood, which can cause significant discomfort to the patient and complications.
Furthermore, present methods are resource demanding because specialized equipment and trained staff are needed to properly perform arterial cannulation (e.g., for anaesthetics) to withdraw and assay the plasma samples. This project aims at developing a technology that acquires the IF non-invasively in real time during PET. The system will be user friendly and cost effective, and will therefore be practical to incorporate in the clinical workflow. The non-invasive system will eliminate the patient discomfort and potential hazards that are associated with present methods to acquire the IF. Several applications are underused because arterial cannulation is required. Some examples include cerebral blood flow assessment, tumor perfusion studies and absolute glucose metabolism quantification.

Vincent Turgeon Publications

1. To Be Added

Michael Caouette-Mansour Abstract

Preparation of a study for Germany: 65 patients was prepared for a study on head and neck tutor: CT\’s, PET and personal informations were gathered for each patient which had a modified plan and GTV for a radiotherapy treatment. An anonymization program was created on the base of a pre existing script applied to the Dicom file of the patients .

Michael Caouette-Mansour Publications

To Be Added

Dylan Mann-Krzisnik Abstract

The more recent TG-186 model-based formalism has been suggested on many occasions as an important improvement from the water-based TG-43 formalism for low-energy brachytherapy. To reproduce patient-specific geometries, tissue elemental compositions are taken into account. The current project will serve to investigate the effect of uncertainty in elemental composition on low-energy brachytherapy when applying the TG-186 approach. These uncertainties will be assessed through tongue cancer patient studies.

Dylan Mann-Krzisnik Publications

1. Dylan Mann-Krzisnik†, Frank Verhaegen, Shirin A. Enger (2018) The influence of tissue composition uncertainty on dose distributions in brachytherapy, Journal of the European Society of Radiotherapy and Oncology 126(3):394-410. Published online February 7, 2018, DOI: https://doi.org/10.1016/j.radonc.2018.01.007 . pii: S0167-8140(18)30024-0.

Julia Albers Abstract

Radiation threapy requires balancing tumour control and normal tissue toxicity, in order to ensure optimal outcomes. This, however, can be a challenging task when assessing a plan during the treatment planning process. Plan evaluation metrics and dose constraints are established by various protocols, but their implementation in the clinical routine can be overwhelming and time-consuming. In addition, with the advent of novel, more complex treatment techniques for external beam radiotherapy that offer more conformal dose distributions and sharp dose gradients, it is even more so important to have a high level of confidence in the plan accuracy. With these techniques being increasingly used in the clinic, there is a need for treatment planning assessment tools to alleviate the workload of physicists and dosimetrists. In addition, retrospectively evaluating different plan parameters is also important in analyzing treatment outcomes, which facilitate studies that often become the basis of treatment planning constraints and guidelines. The purpose of this project can be stated in two different but complementary parts. Firstly, the goal is to develop a user-friendly software tool for dosimetrists that aims to facilitate plan evaluation during the treatment planning process, and the second is to create a framework for retrospective batch analysis of treatment plans that can quickly provide plan parameters of past plans. The Eclipse Scripting API (ESAPI) a scipting tool designed specifically for it’s use, will be used for convenient integration into the treatment planning workflow .

Julia Albers Publications

To Be Added

Charles-Antoine Collins Fekete Publications

1. Collins-Fekete C-A, Plamondon M, Martin A-G, Vigneault É, Verhaegen F, Beaulieu L. (2014) Quantifying the effect of seed orientation in postplanning dosimetry of low-dose-rate prostate brachytherapy, Med. Phys. 41, 101704.
2. Collins-Fekete C-A, Plamondon M, Martin A-G, Vigneault É, Verhaegen F, Beaulieu L. (2015) Calcifications in low-dose rate prostate seed brachytherapy treatment: post-planning dosimetry and predictive factors, Radiotherapy Oncology. 114(3):339-44.
3. Collins-Fekete C-A, Dias M.F., Doolan P., Beaulieu L., Seco J. (2015) Developing a phenomenological model of the proton trajectory within a heterogeneous medium required for proton imaging, Physics in Medicine and Biology 60(13): 5071-5082.
4. Charles-Antoine Collins-Fekete, Sébastien Brousmiche, Stephen K N Portillo, Luc Beaulieu and Joao Seco (2016) A maximum likelihood method for high resolution proton radiography/proton CT, Physics in Medicine and Biology 61(23) November 3, 2016.

Marie-Annie Saucier Abstract

La reconstruction itérative en tomodensitométrie pose des défis importants tant en ce qui a trait à la modélisation physique du système à l’étude qu’à l’implémentation algorithmique. Ce projet d’intéresse aux deux aspects (modélisation et implémentation) dans le cadre de l’imagerie tomodensitométrique en faisceau conique. L’objectif est d’obtenir des images plus justes en considérant l’effet du rayonnement diffusé. La plateforme OpenRTK sera utilisée pour le développement et un engin Monte Carlo pourra aussi être greffé au modèle pour tenir compte du rayonnement diffusé. Cet engin sera basé sur GPUMCD, un code développé au labo.
À terme, ce projet permettra d’obtenir des valeurs plus justes en tomodensitométrie en faisceau conique.

Yonas Mekuria Abstract

In brachytherapy, the dose gradients are much more significant than in external beam in general and the competition between Compton scattering and the photoelectric effect, in particular for low energy brachytherapy, adds to the complexity of performing experimental measurements. In fact, the accuracy of source strength measurements by standard laboratories is less than for EBRT and the establishment of a primary standard of dose to water, while in the works, has proven a difficult task to accomplish. It is therefore quite a daunting task to ask every clinical physicist, especially in small centers, to perform experimental validation of new algorithms.

The project aims to develop numerical phantoms and build physical phantoms from the most interesting numerical ones to enable advanced quality control and quality assurance of new algorithms and delivery techniques for brachytherapy users.

This project is performed within the framework of Prof. Beaulieu industrial research chair .

Yonas Mekuria Publications

1) To Be Added .

Hui Wang Abstract

To be added.

Hui Wang Publications

1. To Be Added.

Nathan Drezner Abstract

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Nathan Drezner Publications

1. To Be Added.

Tongyou Yang Abstract

To be added.

Tongyou Yang Publications

1. To Be Added.

Thomas Tendron Abstract

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Thomas Tendron Publications

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Youngsun Jin Abstract

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Youngsun Jin Publications

1. To Be Added.

Yuan Chen Abstract

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Yuan Chen Publications

1. To Be Added.