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336 results on '"Archambault, L."'

1. Ultra-Hypo Fractionated Prostate IGRT with HDR Brachytherapy Boost as Compared to a Moderate-Hypo Fractionated Approach: Patient Reported Outcomes (PRO's) of a Phase Two Study Interim Analysis

Author

Martin, A.G., primary, Carignan, D., additional, Beaudry, M.M., additional, Menard, E., additional, Foster, W., additional, Vigneault, E., additional, Magnan, S., additional, Lachance, B., additional, Poulin, E., additional, Archambault, L., additional, Lacroix, F., additional, Beaulieu, L., additional, and Després, P., additional

Published
2022
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6. FLASH Modalities Track (Oral Presentations) OVERVIEW AND CURRENT STATUS OF THE JOINT RESEARCH PROJECT UHDPULSE: “METROLOGY FOR ADVANCED RADIOTHERAPY USING PARTICLE BEAMS WITH ULTRA-HIGH PULSE DOSE RATES”

Author

Schüller, A., primary, Kapsch, R.-P., additional, Bourgouin, A., additional, Zboril, M., additional, Giesen, U., additional, Subiel, A., additional, Peier, P., additional, Šolc, J., additional, Knyziak, A., additional, Fouillade, C., additional, Heinrich, S., additional, De Marzi, L., additional, Bailat, C., additional, Caresana, M., additional, Olšovcová, V., additional, Cimmino, A., additional, Versaci, R., additional, Ambrožová, I., additional, Pivec, J., additional, Oancea, C., additional, Fleta, C., additional, Gomez, F., additional, Milluzzo, G., additional, Borghesi, M., additional, Pawelke, J., additional, Poppinga, D., additional, Kranzer, R., additional, Poppe, B., additional, Looe, H.K., additional, Schoenfeld, A., additional, Busold, S., additional, Salvador, S., additional, Lahaye, C., additional, Rossomme, S., additional, Schmitzer, C., additional, Renaud, J., additional, Mcewen, M., additional, Archambault, L., additional, Felici, G., additional, Fausti, F., additional, Pullia, M., additional, Stephan, F., additional, Bruza, P., additional, Ashraf, R., additional, Vanhavere, F., additional, Michel, T., additional, Gasparini, A., additional, and Vanreusel, V., additional

Published
2022
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10. Understanding Lactobacillus paracasei and Streptococcus oralis biofilm interactions through agent-based modeling

Author

Angela Thompson, Reinhard Laubenbacher, Archambault L, Pedro Mendes, Anna Dongari-Bagtzoglou, and Koshy-Chenthittayil S

Subjects
Probiotic, Streptococcus oralis, biology, Lactobacillus paracasei, law, Biofilm, Virulence, biology.organism_classification, Candida albicans, Pathogen, Organism, Microbiology, law.invention
Abstract

As common commensals residing on mucosal tissues, Lactobacillus species are known to encourage health, while recent findings highlight the pathogenic roles of Streptococcus species in these environments. In this study we used a combination of in vivo imaging experiments and computational modeling to explore biofilm interactions between Streptococcus oralis, an accessory pathogen in oral Candidiasis, and Lactobacillus paracasei, an organism with known probiotic properties. A computational agent-based model was created where the two species only interact by competing for space and nutrients. Quantification of bacterial growth in live biofilms indicated that S. oralis biomass and cell numbers were much lower than predicted by the model. Two subsequent models were then created to examine more complex interactions between these species, one where L. paracasei secretes a surfactant, and another where L. paracasei secretes an inhibitor of S. oralis growth. Further biofilm experiments support the hypothesis that L. paracasei may secrete an inhibitor of S. oralis growth, although they do not exclude that a surfactant could also be involved. This contribution shows how agent-based modeling and experiments can be used in synergy to address multiple species biofilm interactions, with important roles in mucosal health and disease.IMPORTANCEWe previously discovered a role of the oral commensal Streptococcus oralis as an accessory pathogen. S. oralis increases the virulence of Candida albicans infections in murine oral candidiasis and epithelial cell models through mechanisms which promote the formation of tissue-damaging biofilms. Lactobacillus species have known inhibitory effects on biofilm formation of many microbes, including Streptococcus species. Agent-based modeling has great advantages as a means of exploring multifaceted relationships between organisms in complex environments such as biofilms. Here we used an iterative collaborative process between experimentation and modeling to reveal aspects of the mostly unexplored relationship between S. oralis and L. paracasei in biofilm growth. The inhibitory nature of L. paracasei on S. oralis in biofilms may be exploited as a means of preventing or alleviating mucosal fungal infections.

Published
2021
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14. On the use of polychromatic cameras for high spatial resolution spectral dose measurements.

Author

Cloutier, E, Beaulieu, L, and Archambault, L

Subjects
SPATIAL resolution, INTERPOLATION algorithms, CAMERAS, SIGNAL-to-noise ratio, SCINTILLATION counters, STANDARD deviations, MEASUREMENT, SCINTILLATORS
Abstract

Objective. Despite the demonstrated benefits of hyperspectral formalism for stem effect corrections in the context of fiber dose measurements, this approach has not been yet translated into volumetric measurements where cameras are typically used for their distinguishing spatial resolution. This work investigates demosaicing algorithms for polychromatic cameras based spectral imaging. Approach. The scintillation and Cherenkov signals produced in a radioluminescent phantom are imaged by a polychromatic camera and isolated using the spectral formalism. To do so, five demosaicing algorithms are investigated from calibration to measurements: a clustering method and four interpolation algorithms. The resulting accuracy of scintillation and Cherenkov images is evaluated with measurements of the differences (mean ± standard deviation) between the obtained and expected signals from profiles drawn across a scintillation spot. Signal-to-noise ratio and signal-to-background ratio are further measured and compared in the resulting scintillation images. Finally, the resulting differences on the scintillation signal from a 0.2 × 0.2 cm2 region-of-interest (ROI) were reported. Main results. Clustering, OpenCV, bilinear, Malvar and Menon demosaicing algorithms respectively yielded differences of 3 ± 5%, 1 ± 3%, 1 ± 3%, 1 ± 2% and 2 ± 4% in the resulting scintillation images. For the Cherenkov images, all algorithms provided differences below 1%. All methods enabled measurements over the detectability (SBR > 2) and sensitivity (SNR > 5) thresholds with the bilinear algorithm providing the best SNR value. Clustering, OpenCV, bilinear, Malvar and Menon demosaicing algorithms respectively provided differences on the ROI analysis of 7 ± 5%, 3 ± 2%, 3 ± 2%, 4 ± 2%, 7 ± 3%. Significance. Radioluminescent signals can accurately be isolated using a single polychromatic camera. Moreover, demosaicing using a bilinear kernel provided the best results and enabled Cherenkov signal subtraction while preserving the full spatial resolution of the camera. [ABSTRACT FROM AUTHOR]

Published
2022
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18. O027 - FLASH Modalities Track (Oral Presentations) OVERVIEW AND CURRENT STATUS OF THE JOINT RESEARCH PROJECT UHDPULSE: “METROLOGY FOR ADVANCED RADIOTHERAPY USING PARTICLE BEAMS WITH ULTRA-HIGH PULSE DOSE RATES”

Author

Schüller, A., Kapsch, R.-P., Bourgouin, A., Zboril, M., Giesen, U., Subiel, A., Peier, P., Šolc, J., Knyziak, A., Fouillade, C., Heinrich, S., De Marzi, L., Bailat, C., Caresana, M., Olšovcová, V., Cimmino, A., Versaci, R., Ambrožová, I., Pivec, J., Oancea, C., Fleta, C., Gomez, F., Milluzzo, G., Borghesi, M., Pawelke, J., Poppinga, D., Kranzer, R., Poppe, B., Looe, H.K., Schoenfeld, A., Busold, S., Salvador, S., Lahaye, C., Rossomme, S., Schmitzer, C., Renaud, J., Mcewen, M., Archambault, L., Felici, G., Fausti, F., Pullia, M., Stephan, F., Bruza, P., Ashraf, R., Vanhavere, F., Michel, T., Gasparini, A., and Vanreusel, V.

Published
2022
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22. Radiotherapy-induced cardiac implantable electronic device disorders in cancer patients

Author

Bagur, R, Chamula, M, Brouillard, E, Lavi, S, Nombela-Franco, L, Julien, AS, Archambault, L, Varfalvy, N, Turcotte-Gosselin, F, Beaupré, F, Joncas, SX, Gaudreault, V, Parviz, Y, Teefy, PJ, Mamas, MA, and Lavoie, C

Subjects
RC0254
Abstract

Radiotherapy can affect the electronic components of a cardiac implantable electronic device (CIED) resulting in malfunction and/or damage. We sought to assess the incidence, predictors, and clinical impact of CIED dysfunction (CIED-D) after radiotherapy for cancer treatment. Clinical characteristics, cancer, different types of CIEDs, and radiation dose were evaluated. The investigation identified 230 patients, mean age 78 ± 8 years and 70% were men. A total of 199 patients had pacemakers (59% dual chamber), 21 (9%) cardioverter-defibrillators, and 10 (4%) resynchronizators or defibrillators. The left pectoral (n = 192, 83%) was the most common CIED location. Sixteen patients (7%) experienced 18 events of CIED-D after radiotherapy. Reset to backup pacing mode was the most common encountered dysfunction, and only 1 (6%) patient of those with CIED-D experienced symptoms of atrioventricular dyssynchrony. Those who had CIED-D tended to have a shorter device age at the time of radiotherapy compared to those who did not (2.5 ± 1.5 vs 3.8 ± 3.4 years, p = 0.09). The total dose prescribed to the tumor was significantly greater among those who had CIED-D (66 ± 30 vs 42 ± 23 Gy, p

Published
2017

30. Verification of proton range, position, and intensity in IMPT with a 3D liquid scintillator detector system

Author

Archambault, L., Poenisch, F., Sahoo, N., Robertson, D., Lee, A., Gillin, M. T., Mohan, R., and Beddar, S.

Subjects
Radiation Therapy Physics, Quality Control, Physics::Medical Physics, Calibration, Proton Therapy, Physics::Accelerator Physics, Reproducibility of Results, Scintillation Counting, Radiotherapy, Intensity-Modulated
Abstract

Intensity-modulated proton therapy (IMPT) using spot scanned proton beams relies on the delivery of a large number of beamlets to shape the dose distribution in a highly conformal manner. The authors have developed a 3D system based on liquid scintillator to measure the spatial location, intensity, and depth of penetration (energy) of the proton beamlets in near real-time.The detector system consists of a 20 × 20 × 20 cc liquid scintillator (LS) material in a light tight enclosure connected to a CCD camera. This camera has a field of view of 25.7 by 19.3 cm and a pixel size of 0.4 mm. While the LS is irradiated, the camera continuously acquires images of the light distribution produced inside the LS. Irradiations were made with proton pencil beams produced with a spot-scanning nozzle. Pencil beams with nominal ranges in water between 9.5 and 17.6 cm were scanned to irradiate an area of 10 × 10 cm square on the surface of the LS phantom. Image frames were acquired at 50 ms per frame.The signal to noise ratio of a typical Bragg peak was about 170. Proton range measured from the light distribution produced in the LS was accurate to within 0.3 mm on average. The largest deviation seen between the nominal and measured range was 0.6 mm. Lateral position of the measured pencil beam was accurate to within 0.4 mm on average. The largest deviation seen between the nominal and measured lateral position was 0.8 mm; however, the accuracy of this measurement could be improved by correcting light scattering artifacts. Intensity of single proton spots were measured with precision ranging from 3 % for the smallest spot intensity (0.005 MU) to 0.5 % for the largest spot (0.04 MU).Our LS detector system has been shown to be capable of fast, submillimeter spatial localization of proton spots delivered in a 3D volume. This system could be used for beam range, intensity and position verification in IMPT.

Published
2012

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