Author: "Jean Michel Létang" - Searchworks@Jio Institute Digital Library Search Results

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101. A track length estimator method for dose calculations in low-energy x-ray irradiations: implementation, properties and performance

Author: Claudio Ferrero, Alberto Mittone, Fabien Baldacci, Nicolas Freud, F. Delaire, Alberto Bravin, F. Smekens, Jean Michel Létang, Paola Coan, David Sarrut, S. Gasilov, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre Léon Bérard [Lyon], Faculty of Physics, Ludwig-Maximilians-Universität München (LMU), Faculty of Medicine, European Synchrotron Radiation Facility (ESRF), Imagerie Tomographique et Radiothérapie, Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Baldacci, F, Mittone, A, Bravin, A, Coan, P, Delaire, F, Ferrero, C, Gasilov, S, Letang, J, Sarrut, D, Smekens, F, and Freud, N
Subjects: Cone beam computed tomography, Monte Carlo method, Biophysics, Linear energy transfer, FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA), [SDV.CAN]Life Sciences [q-bio]/Cancer, Radiation Dosage, Sensitivity and Specificity, Kerma, Photon Beam Radiation Therapy, Optics, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Animals, Humans, Radiology, Nuclear Medicine and imaging, Computer Simulation, Linear Energy Transfer, Irradiation, Radiometry, Monte Carlo simulation, Physics, Models, Statistical, Radiological and Ultrasound Technology, Variance reduction, business.industry, X-Rays, Dose calculation, GATE, Reproducibility of Results, Track length estimator, Kerma approximation, [PHYS.PHYS.PHYS-MED-PH]Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], Body Burden, business, Monte Carlo Method, Beam (structure), Algorithms, Software
Abstract: International audience; The track length estimator (TLE) method, an "on-the-fly" fluence tally in Monte Carlo (MC) simulations, recently implemented in GATE 6.2, is known as a powerful tool to accelerate dose calculations in the domain of low-energy x-ray irradiations using the kerma approximation. Overall efficiency gains of the TLE with respect to analogous MC were reported in the literature for regions of interest in various applications (photon beam radiation therapy, x-ray imaging). The behaviour of the TLE method in terms of statistical properties, dose deposition patterns, and computational efficiency compared to analogous MC simulations was investigated. The statistical properties of the dose deposition were first assessed. Derivations of the variance reduction factor of TLE versus analogous MC were carried out, starting from the expression of the dose estimate variance in the TLE and analogous MC schemes. Two test cases were chosen to benchmark the TLE performance in comparison with analogous MC: (i) a small animal irradiation under stereotactic synchrotron radiation therapy conditions and (ii) the irradiation of a human pelvis during a cone beam computed tomography acquisition. Dose distribution patterns and efficiency gain maps were analysed. The efficiency gain exhibits strong variations within a given irradiation case, depending on the geometrical (voxel size, ballistics) and physical (material and beam properties) parameters on the voxel scale. Typical values lie between 10 and 103, with lower levels in dense regions (bone) outside the irradiated channels (scattered dose only), and higher levels in soft tissues directly exposed to the beams.
Published: 2015
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102. Geant4 simulation of the response of phosphor screens for X-ray imaging

Author: Daniel Babot, A.H. Walenta, A. Koch, Gerard Montarou, S.A. Pistrui-Maximean, Jean Michel Létang, Nicolas Freud, B. Munier, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Nuclear and High Energy Physics, Monte Carlo method, Geant4, Phosphor, Scintillator, Modulation Transfer Function, 01 natural sciences, 030218 nuclear medicine & medical imaging, 010309 optics, 03 medical and health sciences, 0302 clinical medicine, Optics, Nondestructive testing, Optical transfer function, 0103 physical sciences, Medical imaging, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation, Monte Carlo simulation, Physics, business.industry, phosphor screen, X-ray imaging, Detector, business, Voltage
Abstract: poster Pistrui-Maximean, submitted to NIM A; In order to predict and optimize the response of phosphor screens, it is important to understand the role played by the different physical processes inside the scintillator layer. Monte Carlo simulations were carried out to determine the Modulation Transfer Function (MTF) of phosphor screens for energies used in X-ray medical imaging and nondestructive testing applications. The visualization of the dose distribution inside the phosphor layer gives an insight into how the MTF is progressively degraded by X-ray and electron transport. The simulation model allows to study the inﬂuence of physical and technological parameters on the detector performances, as well as to design and optimize new detector conﬁgurations. Preliminary MTF measurements have been carried out and agreement with experimental data has been found in the case of a commercial screen (Kodak Lanex Fine), at an X-ray tube potential voltage of 100 kV. Further validation with other screens (transparent or granular) at different energies is under way.
Published: 2006
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103. Fast and robust ray casting algorithms for virtual X-ray imaging

Author: Daniel Babot, Nicolas Freud, Jean Michel Létang, Philippe Duvauchelle, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon, Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Nuclear and High Energy Physics, 010308 nuclear & particles physics, business.industry, Computer science, Astrophysics::High Energy Astrophysical Phenomena, Computation, Monte Carlo method, 01 natural sciences, 3D rendering, Computer graphics, Robustness (computer science), 0103 physical sciences, Deterministic simulation, Ray casting, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, 010306 general physics, business, Instrumentation, Algorithm, ComputingMilieux_MISCELLANEOUS, ComputingMethodologies_COMPUTERGRAPHICS, Digital radiography
Abstract: Deterministic calculations based on ray casting techniques are known as a powerful alternative to the Monte Carlo approach to simulate X- or γ-ray imaging modalities (e.g. digital radiography and computed tomography), whenever computation time is a critical issue. One of the key components, from the viewpoint of computing resource expense, is the algorithm which determines the path length travelled by each ray through complex 3D objects. This issue has given rise to intensive research in the field of 3D rendering (in the visible light domain) during the last decades. The present work proposes algorithmic solutions adapted from state-of-the-art computer graphics to carry out ray casting in X-ray imaging configurations. This work provides an algorithmic basis to simulate direct transmission of X-rays, as well as scattering and secondary emission of radiation. Emphasis is laid on the speed and robustness issues. Computation times are given in a typical case of radiography simulation.
Published: 2006
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104. Investigation of artefact sources in synchrotron microtomography via virtual X-ray imaging

Author: Peter Cloetens, Jean Michel Létang, Franck Vidal, and Gilles Peix
Subjects: Physics, Nuclear and High Energy Physics, business.industry, Detector, Streak, Experimental data, Synchrotron radiation, Context (language use), Field of view, 02 engineering and technology, 021001 nanoscience & nanotechnology, Synchrotron, 030218 nuclear medicine & medical imaging, law.invention, 03 medical and health sciences, 0302 clinical medicine, Optics, law, Optical transfer function, 0210 nano-technology, business, Instrumentation
Abstract: Qualitative and quantitative use of volumes reconstructed by computed tomography (CT) can be compromised due to artefacts which corrupt the data. This article illustrates a method based on virtual X-ray imaging to investigate sources of artefacts which occur in microtomography using synchrotron radiation. In this phenomenological study, different computer simulation methods based on physical X-ray properties, eventually coupled with experimental data, are used in order to compare artefacts obtained theoretically to those present in a volume acquired experimentally, or to predict them for a particular experimental setup. The article begins with the presentation of a synchrotron microtomographic slice of a reinforced fibre composite acquired at the European Synchrotron Radiation Facility (ESRF) containing streak artefacts. This experimental context is used as the motive throughout the paper to illustrate the investigation of some artefact sources. First, the contribution of direct radiation is compared to the contribution of secondary radiations. Then, the effect of some methodological aspects are detailed, including under-sampling, sample and camera misalignment, sample extending outside of the field of view and photonic noise. The effect of harmonic components present in the experimental spectrum are also simulated. Afterwards, detector properties, such as its impulse response or defective pixels, are taken into account. Finally, the importance of phase contrast effects is evaluated. In the last section, this investigation is discussed by putting emphasis on the experimental context which is used throughout this paper.
Published: 2005
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105. A hybrid approach to simulate multiple photon scattering in X-ray imaging

Author: Daniel Babot, Nicolas Freud, Jean Michel Létang, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nuclear and High Energy Physics, Scattering, Deterministic algorithm, Monte Carlo method, Compton scattering, Incoherent scatter, 01 natural sciences, 030218 nuclear medicine & medical imaging, Hybrid Monte Carlo, 03 medical and health sciences, symbols.namesake, 0302 clinical medicine, 0103 physical sciences, Deterministic simulation, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, symbols, Statistical physics, Rayleigh scattering, 010301 acoustics, Instrumentation, ComputingMilieux_MISCELLANEOUS
Abstract: A hybrid simulation approach is proposed to compute the contribution of scattered radiation in X- or γ-ray imaging. This approach takes advantage of the complementarity between the deterministic and probabilistic simulation methods. The proposed hybrid method consists of two stages. Firstly, a set of scattering events occurring in the inspected object is determined by means of classical Monte Carlo simulation. Secondly, this set of scattering events is used as a starting point to compute the energy imparted to the detector, with a deterministic algorithm based on a ‘forced detection’ scheme. For each scattering event, the probability for the scattered photon to reach each pixel of the detector is calculated using well-known physical models (form factor and incoherent scattering function approximations, in the case of Rayleigh and Compton scattering respectively). The results of the proposed hybrid approach are compared to those obtained with the Monte Carlo method alone (Geant4 code) and found to be in excellent agreement. The convergence of the results when the number of scattering events increases is studied. The proposed hybrid approach makes it possible to simulate the contribution of each type (Compton or Rayleigh) and order of scattering, separately or together, with a single PC, within reasonable computation times (from minutes to hours, depending on the number of pixels of the detector). This constitutes a substantial benefit, compared to classical simulation methods (Monte Carlo or deterministic approaches), which usually requires a parallel computing architecture to obtain comparable results.
Published: 2005
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106. Deterministic simulation of first-order scattering in virtual X-ray imaging

Author: S.A. Pistrui-Maximean, Nicolas Freud, Daniel Babot, Jean Michel Létang, Philippe Duvauchelle, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon, Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nuclear and High Energy Physics, Discretization, 010308 nuclear & particles physics, Deterministic algorithm, business.industry, Scattering, Computation, Monte Carlo method, Compton scattering, 01 natural sciences, Optics, 0103 physical sciences, Deterministic simulation, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Ray tracing (graphics), 010306 general physics, business, Instrumentation, Algorithm, ComputingMilieux_MISCELLANEOUS
Abstract: A deterministic algorithm is proposed to compute the contribution of first-order Compton- and Rayleigh-scattered radiation in X-ray imaging. This algorithm has been implemented in a simulation code named virtual X-ray imaging. The physical models chosen to account for photon scattering are the well-known form factor and incoherent scattering function approximations, which are recalled in this paper and whose limits of validity are briefly discussed. The proposed algorithm, based on a voxel discretization of the inspected object, is presented in detail, as well as its results in simple configurations, which are shown to converge when the sampling steps are chosen sufficiently small. Simple criteria for choosing correct sampling steps (voxel and pixel size) are established. The order of magnitude of the computation time necessary to simulate first-order scattering images amounts to hours with a PC architecture and can even be decreased down to minutes, if only a profile is computed (along a linear detector). Finally, the results obtained with the proposed algorithm are compared to the ones given by the Monte Carlo code Geant4 and found to be in excellent accordance, which constitutes a validation of our algorithm. The advantages and drawbacks of the proposed deterministic method versus the Monte Carlo method are briefly discussed.
Published: 2004
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107. Breast density and iodine quantification in spectral mammography

Author: Loick Verger, Véronique Rebuffel, Nicolas Freud, A. Brambilla, Y. Pavia, Jean Michel Létang, Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Imagerie Tomographique et Radiothérapie, Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon)
Subjects: Accuracy and precision, Materials science, medicine.diagnostic_test, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, Density estimation, medicine.disease, Grayscale, Imaging phantom, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Breast cancer, 030220 oncology & carcinogenesis, Absorbed dose, Contrast Enhanced Digital Mammography, medicine, Mammography, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, General Nursing, Biomedical engineering
Abstract: International audience; Breast density is known for being a parameter used in breast cancer risk models and might be measured during mammography exams. Automated methods based on grayscale values already exist, but they only allow a density estimation over the whole breast. Material decomposition approaches make it possible to define the breast density at each pixel based on a dual energy exposure. Furthermore, the use of contrast enhanced digital mammography exams is increasing and helps physicians to highlight blood vessels with higher permeability that may be related to malignant lesions. Nevertheless, this technique also requires two x-ray exposures. In this paper, we propose to take benefit of energy sensitive x-ray detectors that give access to several energy measurements in a single shot acquisition to both quantify breast density and iodine during a single mammography exam. To this purpose, a spectral mammography acquisition chain has been simulated and different material decomposition methods have been proposed and investigated using a simulated phantom under clinically achievable settings with an average absorbed dose by the mammary gland of 0.93 mGy (mimicking a 45 mm thick breast made of 50% fibroglandular tissue) using a 49 kVp with a tungsten anode, an inherent filtration of 0.8 mmBe and an additional filtration of 1.2 mmAl. Breast density is commonly defined as the ratio between glandular tissue and the sum of adipose and glandular tissues thicknesses. Standard polynomial material decomposition methods have been extended to make them compliant with 3-energy measurements in order to allow a three-material decomposition: adipose and glandular tissues as well as iodine concentration. Those methods allow to estimate iodine concentration with an average accuracy inferior to 0.15 mg ml−1 and breast density with a precision inferior to 8% (root-mean-square errors). Nevertheless, these methods are difficult to extend to more energy channels due to the least-square model inversion. To achieve better results, a maximum log-likelihood approach has been introduced to take into consideration more spectral information while improving accuracy and precision on measurements. Moreover, the use of the proposed method permits to accurately detect the absence of iodine and significantly improves the estimation of breast density compared to polynomial approaches. We also highlighted that there is a strong interest to increase the number of energy thresholds from 3 to 6, a less significant gain is still noticeable with more energy bins.
Published: 2017
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108. Influence of scattering on material quantification using multi-energy x-ray imaging

Author: Jean Michel Létang, Loick Verger, Joachim Tabary, Véronique Rebuffel, Nicolas Freud, and A. Sossin
Subjects: medicine.medical_specialty, Materials science, business.industry, Scattering, Radiography, Attenuation, X-ray, Radiation, Imaging phantom, medicine.anatomical_structure, Optics, medicine, Calibration, Cortical bone, Radiology, business
Abstract: New horizons in x-ray radiography and computed tomography (CT) have been opened up with the emergence of energy resolved x-ray imaging. This includes the ability to differentiate material components and estimate their equivalent thickness or relative ratio by processing a single shot acquisition image. However, such techniques require highly accurate images, especially for materials close in terms of attenuation. The presence of scattered radiation leads to a loss of contrast and, more importantly, a bias in radiographic material imaging and artefacts in CT. The aim of the present study was to evaluate the disturbance caused by scatter on multi-energy imaging, more precisely, on a material decomposition approach commonly used in radiography or CT. This evaluation was based on numerical simulations using Sindbad-SFFD. Results showed a significant impact of scattered radiation on quantification accuracy for a simplified thorax-sized numerical phantom with an average error of 157.1% and 74.1% for cortical bone and water thickness, respectively. When only 10% of scatter was considered the error still remained significant: 35.1% and 17.5% for cortical bone and water thickness, respectively. The study concludes that a scatter correction method should be performed prior to any material decomposition, if one aims to benefit from energy resolved data in an uncollimated geometry.
Published: 2014
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109. Online control of the beam range during Hadrontherapy: a review

Author: Jean Michel Létang, Dauvergne, D., Freud, N., Krimmer, J., Loïc Lestand, Voichita Maxim, Gerard Montarou, Simon Rit, Testa, E., Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre Léon Bérard [Lyon], Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)
Subjects: Quantitative Biology::Tissues and Organs, Physics::Medical Physics, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing
Abstract: National audience; One of the advantages of hadrontherapy with respect to conventional radiotherapy is the fact that the ions deposit a large quantity of their dose at the end of their path in the Bragg peak, which allows a maximization of the dose applied to the tumor and a minimization of the dose in healthy tissues. The lateral dose distribution is also quite narrow. Another advantage is the higher relative biological effectiveness. Due to the sharp falloff, one of the major issues for quality control during the treatment with ion beams is the control of the Bragg peak position and its conformation to the tumor volume. A mispositioning would either lead to an over-dosage of healthy tissue and/or an under-dosage in the target volume. Since no primary radiation is emerging from the patient during treatment, secondary radiation is used for in vivo monitoring purposes. The secondary radiation needs to have a weak interaction probability inside the patient to reach external detectors and it needs to be correlated to the primary beam dose distribution. This information on electromagnetic energy distribution (the LET) can be extracted from nuclear interactions. Several types of secondary radiations are being investigated in the LabEx PRIMES: (i) the detection of the two 511 keV gammas following a beta+ decay via a PET scanner, (ii) prompt secondary radiation following inelastic nuclear interactions, either prompt gamma rays via a collimated gamma or Compton camera, or light charged particles via second proton vertex imaging. Another quality assurance issue prior to the irradiation is under investigation in the LabEx: proton radiography and computed tomography (CT). This could improve proton therapy compared to current clinical practice since it could reduce the uncertainty of the proton therapy planning due to the lack of accuracy in the proton stopping power of tissues computed from photon CT images. We will review those different techniques under study in the frame of the WP1 of the LabEx PRIMES to setup a better online control of the beam range during therapy.
Published: 2014

110. Simulation of x-ray images from the planning CT for online correction of scatter in cone-beam CT

Author: Simon Rit, Romero, E., Vila Oliva, M., Brousmiche, S., Sarrut, D., Jean Michel Létang, Freud, N., Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Institute of Information and Communication Technologies, Electronics and Applied Mathematics (ICTEAM), Université Catholique de Louvain = Catholic University of Louvain (UCL), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL)
Subjects: [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing
Abstract: International audience; Purpose/Objective: To correct for scatter in cone-beam CT images and to calibrate the image intensities in Hounsfield units (HU) using fast and accurate simulation of x-ray images of the planning CT.
Published: 2014

111. Assessment and improvements of Geant4 hadronic models in the context of prompt-gamma hadrontherapy monitoring

Author: J. Krimmer, Marco Pinto, Denis Dauvergne, Jean Michel Létang, Etienne Testa, Nicolas Freud, Cédric Ray, George Dedes, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nuclear reaction, Range (particle radiation), Radiological and Ultrasound Technology, Proton, Radiotherapy, 010308 nuclear & particles physics, Monte Carlo method, Hadron, Nuclear Theory, Context (language use), 01 natural sciences, Charged particle, 030218 nuclear medicine & medical imaging, Nuclear physics, 03 medical and health sciences, 0302 clinical medicine, Gamma Rays, 0103 physical sciences, Humans, Radiology, Nuclear Medicine and imaging, Neutron, Nuclear Experiment, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Monte Carlo Method
Abstract: International audience; Monte Carlo simulations are nowadays essential tools for a wide range of research topics in the field of radiotherapy. They also play an important role in the effort to develop a real-time monitoring system for quality assurance in proton and carbon ion therapy, by means of prompt-gamma detection. The internal theoretical nuclear models of Monte Carlo simulation toolkits are of decisive importance for the accurate description of neutral or charged particle emission, produced by nuclear interactions between beam particles and target nuclei. We assess the performance of Geant4 nuclear models in the context of prompt-gamma emission, comparing them with experimental data from proton and carbon ion beams. As has been shown in the past and further indicated in our study, the prompt-gamma yields are consistently overestimated by Geant4 by a factor of about 100% to 200% over an energy range from 80 to 310 MeV/u for the case of 12C, and to a lesser extent for 160 MeV protons. Furthermore, we focus on the quantum molecular dynamics (QMD) modeling of ion-ion collisions, in order to optimize its description of light nuclei, which are abundant in the human body and mainly anticipated in hadrontherapy applications. The optimization has been performed by benchmarking QMD free parameters with well established nuclear properties. In addition, we study the effect of this optimization on charged particle emission. With the usage of the proposed parameter values, discrepancies reduce to less than 70%, with the highest values being attributed to the nucleon-ion induced prompt-gammas. This conclusion, also confirmed by the disagreement we observe in the case of proton beams, indicates the need for further investigation on nuclear models which describe proton and neutron induced nuclear reactions.
Published: 2014
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112. PO-0959: Optimal dose balance between energy levels for material decomposition with dual-energy X-ray CT

Author: S. Rit, Gloria Vilches-Freixas, Jean Michel Létang, K. Presich, and P. Steininger
Subjects: Electron density, Materials science, business.industry, Attenuation, X-ray, High voltage, Hematology, Computational physics, Balance (accounting), Oncology, Radiology Nuclear Medicine and imaging, Radiology, Nuclear Medicine and imaging, Material decomposition, Nuclear medicine, business, Energy (signal processing), Effective atomic number
Abstract: Dual-energy X-ray imaging is used to extract quantitative material information, e.g., electron density and effective atomic number Z, using the differencesof X-ray attenuation coefficients of materials at different energies. A detailed study of factors that could influence the precision of extracted data is of importance. The aim of this study was to determine the optimal dose balance between the low and the high voltage acquisitions for material decomposition with dual-energy X-ray CT.
Published: 2015
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113. Stereokinematic analysis of visual data in active convergent stereoscopy

Author: Jean Michel Létang, Amar Mitiche, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL)
Subjects: Basis (linear algebra), business.industry, Computer science, General Mathematics, Mode (statistics), Motion (geometry), 020207 software engineering, Stereoscopy, 02 engineering and technology, Computer Science Applications, law.invention, Interpretation (model theory), Stereopsis, Control and Systems Engineering, law, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, Computer vision, Artificial intelligence, business, ComputingMilieux_MISCELLANEOUS, Software
Abstract: The core contribution of this study is a mathematical model of combination of stereopsis and kineopsis under active viewing, a model to serve as a basis for algorithms implemental of active stereokinematic analysis of visual data. The model is specified by two main groups of equations: (A) The fundamental equations of interpretation: they relate the unknowns of perception (depth and motion in space) to image variables (image positions and optical velocities) and viewing system control variables (angles of stereoscopic convergence and angular velocities of viewing system movement), in a neck-eyes as well as a neck-less mode of active viewing, (B) The equations of control regimes: they specify trategies of control of stereoscopic viewing system movement (neck-eyes and neck-less modes) in the form of expressions integratable with the fundamental equations. The presentation of the model is prefaced by a motivational discussion, and the model's prerequisite background. It is postfaced by an account of some of its algorithmic implications.
Published: 1998
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114. Low Statistics Reconstruction of the Compton Camera Point Spread Function in 3D Prompt- \gamma Imaging of Ion Beam Therapy

Author: Nicolas Freud, Denis Dauvergne, M.-H. Richard, Jean Michel Létang, J.-L. Ley, X. Lojacono, Etienne Testa, Rémy Prost, Voichita Maxim, Cédric Ray, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Images et Modèles
Subjects: Point spread function, Physics, Nuclear and High Energy Physics, Photon, 010308 nuclear & particles physics, business.industry, Point source, Detector, Physics::Medical Physics, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Iterative reconstruction, 01 natural sciences, Photon counting, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Optics, Nuclear Energy and Engineering, Optical transfer function, 0103 physical sciences, Statistics, Electrical and Electronic Engineering, business, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Beam (structure)
Abstract: International audience; The Compton camera is a relevant imaging device for the detection of prompt photons produced by nuclear fragmentation in hadrontherapy. It may allow an improvement in detection efficiency compared to a standard gamma-camera but requires more sophisticated image reconstruction techniques. In this work, we simulate low statistics acquisitions from a point source having a broad energy spectrum compatible with hadrontherapy. We then reconstruct the image of the source with a recently developed filtered backprojection algorithm, a line-cone approach and an iterative List Mode Maximum Likelihood Expectation Maximization algorithm. Simulated data come from a Compton camera prototype designed for hadrontherapy online monitoring. Results indicate that the achievable resolution in directions parallel to the detector, that may include the beam direction, is compatible with the quality control requirements. With the prototype under study, the reconstructed image is elongated in the direction orthogonal to the detector. However this direction is of less interest in hadrontherapy where the first requirement is to determine the penetration depth of the beam in the patient. Additionally, the resolution may be recovered using a second camera.
Published: 2013
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115. Efficient simulated annealing for full inverse treatment planning

Author: Jean Michel Létang, Marc Robini, and Nicolas Freud
Subjects: Physics, Mathematical optimization, Speedup, Medical treatment, Annealing (metallurgy), Simulated annealing, Planning target volume, Inverse problem, Inverse treatment planning
Abstract: We consider the full inverse treatment planning (FITP) problem that arises in spot-scanning ion therapy. This inverse problem is to find optimal trajectories, energies and fluences of a fixed number of particle beams with the objective of delivering a prescribed dose to a target volume without irradiating nearby critical structures. Despite its potential spin-offs, FITP is rarely considered because it leads to a very challenging optimization task. Our contribution is twofold: (i) we show that FITP can be solved accurately using simulated annealing, and (ii) we construct efficient and theoretically sound candidate-solution generation mechanisms that speed up the annealing process by a factor of the order of 100.
Published: 2013
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116. Machine learning-based patient specific prompt-gamma dose monitoring in proton therapy

Author: Pierre Gueth, David Sarrut, Etienne Testa, Denis Dauvergne, Jean Michel Létang, Cédric Ray, Nicolas Freud, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)
Subjects: Male, Computer science, Machine learning, computer.software_genre, Sensitivity and Specificity, 030218 nuclear medicine & medical imaging, Radiotherapy, High-Energy, 03 medical and health sciences, 0302 clinical medicine, Gamma dose, Artificial Intelligence, Proton Therapy, Humans, Radiology, Nuclear Medicine and imaging, Radiometry, Proton therapy, Radiological and Ultrasound Technology, business.industry, Radiotherapy Planning, Computer-Assisted, Prostatic Neoplasms, Reproducibility of Results, Radiotherapy Dosage, Patient specific, Gamma Rays, 030220 oncology & carcinogenesis, Artificial intelligence, business, Tomography, X-Ray Computed, computer, Classifier (UML), [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Monte Carlo Method, Radiotherapy, Image-Guided
Abstract: International audience; Online dose monitoring in proton therapy is currently being investigated with prompt-gamma (PG) devices. PG emission was shown to be correlated with dose deposition. This relationship is mostly unknown under real conditions. We propose a machine learning approach based on simulations to create optimized treatment-specific classifiers that detect discrepancies between planned and delivered dose. Simulations were performed with the Monte-Carlo platform Gate/Geant4 for a spot-scanning proton therapy treatment and a PG camera prototype currently under investigation. The method first builds a learning set of perturbed situations corresponding to a range of patient translation. This set is then used to train a combined classifier using distal falloff and registered correlation measures. Classifier performances were evaluated using receiver operating characteristic curves and maximum associated specificity and sensitivity. A leave-one-out study showed that it is possible to detect discrepancies of 5 mm with specificity and sensitivity of 85% whereas using only distal falloff decreases the sensitivity down to 77% on the same data set. The proposed method could help to evaluate performance and to optimize the design of PG monitoring devices. It is generic: other learning sets of deviations, other measures and other types of classifiers could be studied to potentially reach better performance. At the moment, the main limitation lies in the computation time needed to perform the simulations.
Published: 2013
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117. Real-time online monitoring of the ion range by means of prompt secondary radiations

Author: J.-L. Ley, M. Chabot, Ilaria Rinaldi, M. Magne, Joel Herault, C. La Tessa, M. Dahoumane, Damien Prieels, H. Mathez, L. Lestand, M. De Rydt, Stephan Brons, V. Reithinger, L. Caponetto, C. Insa, L. Balleyguier, Voichita Maxim, D. Lambert, Baptiste Joly, Marco Pinto, J. Krimmer, R. Della Negra, R. Pleskac, Denis Dauvergne, George Dedes, Marc Winter, Jean Michel Létang, Gerard Montarou, Katia Parodi, Rémy Prost, P. Force, S. Deng, Julien Smeets, Nicolas Freud, J. Baudot, Y. Zoccarato, X. Lojacono, Etienne Testa, M. Vanstalle, M. H. Richard, Cédric Ray, F. Roellinghoff, X. Chen, Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Heidelberg Ion Beam Therapy Center - HIT, Heidelberg University Clinic, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Cyclotron Biomédical, Centre de Lutte contre le Cancer Antoine Lacassagne [Nice] (UNICANCER/CAL), UNICANCER-Université Côte d'Azur (UCA)-UNICANCER-Université Côte d'Azur (UCA), Biophysics Department [Darmstadt], Helmholtz Centre for Heavy Ion Research (GSI), Radiation Therapy and Radiation Oncology, University clinic Heidelberg, Ion Beam Applications SA, IBA, Images et Modèles, Rayet, Béatrice, Université de Strasbourg (UNISTRA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)
Subjects: Physics, Range (particle radiation), medicine.medical_specialty, [PHYS.PHYS.PHYS-MED-PH] Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Physics::Medical Physics, Detector, Gamma ray, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 3. Good health, 030218 nuclear medicine & medical imaging, Ion, Nuclear physics, 03 medical and health sciences, 0302 clinical medicine, 0103 physical sciences, [PHYS.PHYS.PHYS-MED-PH]Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], medicine, Dosimetry, Medical physics, Gamma ray detection
Abstract: International audience; Prompt secondary radiations such as gamma rays and protons can be used for ion-range monitoring during ion therapy either on an energy-slice basis or on a pencil-beam basis. We present a review of the ongoing activities in terms of detector developments, imaging, experimental and theoretical physics issues concerning the correlation between the physical dose and hadronic processes
Published: 2013
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118. Filtered backprojection proton CT reconstruction along most likely paths

Author: Simon, Rit, George, Dedes, Nicolas, Freud, David, Sarrut, and Jean Michel, Létang
Subjects: Image Processing, Computer-Assisted, Models, Theoretical, Protons, Tomography, X-Ray Computed, Algorithms
Abstract: Proton CT (pCT) has the potential to accurately measure the electron density map of tissues at low doses but the spatial resolution is prohibitive if the curved paths of protons in matter is not accounted for. The authors propose to account for an estimate of the most likely path of protons in a filtered backprojection (FBP) reconstruction algorithm.The energy loss of protons is first binned in several proton radiographs at different distances to the proton source to exploit the depth-dependency of the estimate of the most likely path. This process is named the distance-driven binning. A voxel-specific backprojection is then used to select the adequate radiograph in the distance-driven binning in order to propagate in the pCT image the best achievable spatial resolution in proton radiographs. The improvement in spatial resolution is demonstrated using Monte Carlo simulations of resolution phantoms.The spatial resolution in the distance-driven binning depended on the distance of the objects from the source and was optimal in the binned radiograph corresponding to that distance. The spatial resolution in the reconstructed pCT images decreased with the depth in the scanned object but it was always better than previous FBP algorithms assuming straight line paths. In a water cylinder with 20 cm diameter, the observed range of spatial resolutions was 0.7 - 1.6 mm compared to 1.0 - 2.4 mm at best with a straight line path assumption. The improvement was strongly enhanced in shorter 200° scans.Improved spatial resolution was obtained in pCT images with filtered backprojection reconstruction using most likely path estimates of protons. The improvement in spatial resolution combined with the practicality of FBP algorithms compared to iterative reconstruction algorithms makes this new algorithm a candidate of choice for clinical pCT.
Published: 2013

119. EP-1847: Comparison of stopping power estimators from dual-energy computed tomography for protontherapy

Author: Gloria Vilches-Freixas, S. Rit, and Jean Michel Létang
Subjects: Physics, 03 medical and health sciences, 0302 clinical medicine, Oncology, Radiology Nuclear Medicine and imaging, 030220 oncology & carcinogenesis, Stopping power (particle radiation), Estimator, Radiology, Nuclear Medicine and imaging, Dual-Energy Computed Tomography, Hematology, 030218 nuclear medicine & medical imaging, Computational physics
Published: 2016
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120. Monte Carlo simulation of prompt-γ emission in proton therapy using a track length estimator

Author: Nicolas Freud, David Sarrut, E. Testa, Marco Pinto, Denis Dauvergne, Jean Michel Létang, W. El Kanawati, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Ludwig Maximilians University, Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)
Subjects: Proton, variance reduction, Monte Carlo method, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Calibration, Radiology, Nuclear Medicine and imaging, Emission spectrum, Proton therapy, Monte Carlo simulation, prompt-γ imaging, Physics, Range (particle radiation), business.industry, Estimator, Hematology, Computational physics, Oncology, Radiology Nuclear Medicine and imaging, 030220 oncology & carcinogenesis, [PHYS.PHYS.PHYS-MED-PH]Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], Variance reduction, Nuclear medicine, business
Abstract: International audience; Purpose: Online in vivo control of the ion range in a patient during proton therapy is a major challenge for quality assurance of treatments. After measurements showed that prompt-γ emission is correlated to the ion range (Min et al 2006, Testa et al 2008), prompt-γ imaging emerged as apromising method (Verburg et al 2013). Fast methods are required to compute accurate prompt-γ emission maps to design and predict the camera response from treatment plans. An analytic computation method based on the structure of the dose calculation engines in treatment planning system has recently been proposed (Sterpin et al 2015). An alternative technique based on variance reduction in Monte Carlo (MC) calculations is developed here for computing prompt-γ emission maps in proton therapy.Materials/Methods: The track length estimator (TLE) method is a standard variance reduction technique in voxel-based dose computation in the kerma approximation (Williamson 1987), and similar approaches have also been developed for positron emitter distributions in proton therapy (Parodi et al 2007). A specific track length estimator has been developed here to design a continuous process along the proton track that locally deposits the expected value of the prompt-γ emission (induced by proton inelastic scattering) that would have occurred if a large number of protons with the same incident energy had followed the same step (i.e. track element). First an elemental database of prompt-γ emission spectra is established in the clinical energy range of incident protons for all elements in the composition of human tissues. This database of the prompt-γ spectra is built offline with high statistics. Regarding the implementation of the prompt-γ TLE MC tally, each proton deposits along its track the expectation of the prompt-γ spectra from the database according to the proton kinetic energy and the local material density and composition. All software developments have been carried out with the Gate/Geant4 toolkit.Results: A detailed statistical analysis is reported to characterize the dependency of the variance reduction on the geometrical (track length distribution) and physical (linear prompt-γ spectrum database) parameters. Benchmarking of the proposed technique with respect to an analogous MC technique is carried out. A large relative efficiency gain is reported, ca. 105. Such an efficiency gain could reduce the MC computing time of a full treatment from some weeks to less than one hour. Implementation issues are also addressed.Conclusions: This MC-based technique makes it possible to deal with complex situations such as heterogeneities for which proton straggling and secondary protons may have a decisive contribution. When considering translation to clinic, measurements for the prompt-γ s pectrum d atabase, or at least a sound calibration protocol of the simulated prompt-γ spectra, will have to be carried out.
Published: 2016
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121. Monte Carlo Nuclear Models Evaluation and Improvements for Real-Time Prompt Gamma-Ray Monitoring in Proton and Carbon Therapy

Author: Cédric Ray, Nicolas Freud, J. Krimmer, George Dedes, Denis Dauvergne, Marco Pinto, Jean Michel Létang, Marieke De Rydt, Etienne Testa, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Imagerie Tomographique et Radiothérapie, Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), CAS-PHABIO, and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL)
Subjects: Physics, Range (particle radiation), Proton, Ion beam, 010308 nuclear & particles physics, Nuclear Theory, Monte Carlo method, Gamma ray, chemistry.chemical_element, 01 natural sciences, 7. Clean energy, 030218 nuclear medicine & medical imaging, Nuclear physics, 03 medical and health sciences, 0302 clinical medicine, chemistry, Cascade, 0103 physical sciences, [PHYS.PHYS.PHYS-MED-PH]Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], Physics::Accelerator Physics, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Nuclear Experiment, Carbon, Free parameter
Abstract: Accurate Monte Carlo simulations are essential both for the development of an optimized detection array that will be used in clinical practice for precise ion beam range monitoring. Within GEANT4, both the Quantum Molecular Dynamics (QMD) and the Binary Cascade (BIC) models overestimate the overall prompt-gamma depth profile yields measured with carbon ion and proton beams. By optimizing the selection of free parameters of the models, better agreement with the data is obtained for low energy carbon beams (main gamma component by ion-ion collisions) as well as for proton beams and high energy carbon beams (main gamma component by nucleon-nucleus collisions).
Published: 2012

122. Electron density resolution determination and systematic uncertainties in proton computed tomography (pCT)

Author: J. Krimmer, Simon Rit, Etienne Testa, Nicolas Freud, Marieke De Rydt, Denis Dauvergne, Jean Michel Létang, Cédric Ray, George Dedes, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Instituut voor Kern- en Stralingsfysica, and Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven)
Subjects: Physics, Scanner, medicine.medical_specialty, Range (particle radiation), Electron density, Proton, Quantitative Biology::Tissues and Organs, Physics::Medical Physics, Resolution (electron density), Monte Carlo method, 030218 nuclear medicine & medical imaging, 3. Good health, Computational physics, 03 medical and health sciences, 0302 clinical medicine, 030220 oncology & carcinogenesis, medicine, Physics::Accelerator Physics, Medical physics, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Nuclear Experiment, Proton therapy, Beam (structure)
Abstract: International audience; The use of protons in radiotherapy offers a very precise and effective tool for malignant tumor treatment. In order to fully exploit the benefits of proton therapy, a precise determination of the proton range inside the patient is needed. Currently, this information is provided by conventional X-ray CT. In our work, we explore the theoretical limits of proton CT by means of Monte Carlo simulations. We focus on the accuracy in determining the electron density of different clinical relevant materials and the systematic uncertainties that influence the measurement with an ideal cone beam proton CT scanner.
Published: 2012
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123. Secondary radiations in cone-beam computed tomography: simulation study

Author: Jean Pierre Bruandet, Jean Michel Létang, Patricia Wils, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Imagerie Tomographique et Radiothérapie, Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Digisens, and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL)
Subjects: Physics, Image formation, Cone beam computed tomography, Photon, 010308 nuclear & particles physics, business.industry, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, Monte Carlo method, Detector, Bremsstrahlung, 01 natural sciences, Atomic and Molecular Physics, and Optics, 030218 nuclear medicine & medical imaging, Computer Science Applications, Convolution, 03 medical and health sciences, 0302 clinical medicine, Optics, 0103 physical sciences, Electrical and Electronic Engineering, business, Energy (signal processing)
Abstract: International audience; Accurate quantitative reconstruction in kV cone-beam computed tomography (CBCT) is challenged by the presence of secondary radiations (scattering, fluorescence, and bremsstrahlung photons) coming from the object and from the detector itself. The authors present a simulation study of the CBCT imaging chain and its integration into a comprehensive correction algorithm. A layer model of the flat-panel detector is built in a Monte Carlo environment in order to help in localizing and analyzing the secondary radiations. The contribution of these events to the final image is estimated with a convolution model to account for detector secondary radiations combined with a forced-detection scheme to speed-up the Monte Carlo simulation without loss of accuracy. We more specifically assess to what extent a 2D description of the flat-panel detector would be sufficient for the forward model (i.e., the image formation process) of an iterative correction algorithm, both in terms of energy and incidence angle of incoming photons. Results show that both object and detector secondary radiations have to be considered in CBCT. The correction algorithm iteratively compensates for the secondary radiations and the beam hardening in object space. Preliminary results on tomographic acquisitions demonstrate a quantitative improvement on the first iteration
Published: 2012
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124. 235 REAL-TIME PROTON BEAM RANGE MONITORING BY MEANS OF PROMPT-GAMMA DETECTION WITH A COLLIMATED CAMERA

Author: Nicolas Freud, Cédric Ray, E. Testa, F. Roellinghoff, J. Krimmer, A. Benilov, Frédéric Stichelbaut, Julien Smeets, Denis Dauvergne, Jean Michel Létang, Georgios Dedes, M.-H. Richard, D. Prieels, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Ion Beam Applications SA, IBA, Imagerie Tomographique et Radiothérapie, and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon)
Subjects: Range (particle radiation), Materials science, Proton, business.industry, Hematology, Collimated light, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Optics, Oncology, 030220 oncology & carcinogenesis, [PHYS.PHYS.PHYS-MED-PH]Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], Radiology, Nuclear Medicine and imaging, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], business, Gamma detection, Beam (structure), ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2012
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125. Image reconstruction for Compton camera applied to 3D prompt γ imaging during ion beam therapy

Author: Nicolas Freud, X. Lojacono, Etienne Testa, Rémy Prost, Denis Dauvergne, Voichita Maxim, Jean Michel Létang, M.-H. Richard, and Cédric Ray
Subjects: Physics, 010308 nuclear & particles physics, business.industry, Detector, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Compton scattering, Iterative reconstruction, 01 natural sciences, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Camera auto-calibration, Computer Science::Computer Vision and Pattern Recognition, 0103 physical sciences, Medical imaging, Pinhole camera model, Computer vision, Artificial intelligence, business, Image resolution, Camera resectioning
Abstract: The Compton camera is an imaging device relevant for the detection of prompt photons produced during nuclear fragmentation in hadrontherapy. It allows a considerable improvement in detection compared to a standard gamma-camera but also requires more sophisticated image reconstruction techniques. In this work we apply a recently developed filtered backprojection algorithm to data simulated from a realistic Compton camera prototype designed for hadrontherapy on-line monitoring. We reconstruct images of a point source having a broad energy spectrum compatible with the up-mentioned application. Preliminary results indicate that the achievable resolution in directions parallel to the camera, thus including the beam direction, are compatible with the quality control requirements. With the prototype under study, the reconstructed image is elongated in the direction orthogonal to the camera. However this direction is of less interest and the resolution may be easily recovered using a second camera.
Published: 2011
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126. Design of a Compton camera for 3D prompt-γ imaging during ion beam therapy

Author: A.H. Walenta, Marius Chevallier, M. Testa, Nicolas Freud, F. Roellinghoff, Gerard Montarou, M.-H. Richard, F. Le Foulher, Etienne Testa, Denis Dauvergne, Jean Michel Létang, Julie Constanzo, Cédric Ray, P. Henriquet, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), CAS-PHABIO, Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), GEANT4, Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Nuclear and High Energy Physics, Photon, Ion beam, Point source, Physics::Instrumentation and Detectors, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Geant4, Bragg peak, 01 natural sciences, Lyso, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Optics, Hodoscope, hadrontherapy, 0103 physical sciences, prompt gamma, Instrumentation, Image resolution, Compton camera, Physics, 010308 nuclear & particles physics, business.industry, Detector, [PHYS.PHYS.PHYS-MED-PH]Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], ion beam therapy, business
Abstract: We investigate, by means of Geant4 simulations, a real-time method to control the position of the Bragg peak during ion therapy, based on a Compton camera in combination with a beam tagging device (hodoscope) in order to detect the prompt gamma emitted during nuclear fragmentation. The proposed set-up consists of a stack of 2 mm thick silicon strip detectors and a LYSO absorber detector. The γ emission points are reconstructed analytically by intersecting the ion trajectories given by the beam hodoscope and the Compton cones given by the camera. The camera response to a polychromatic point source in air is analyzed with regard to both spatial resolution and detection efficiency. Various geometrical configurations of the camera have been tested. In the proposed configuration, for a typical polychromatic photon point source, the spatial resolution of the camera is about 8.3 mm FWHM and the detection efficiency 2.5×10−4 (reconstructable photons/emitted photons in 4 π ). Finally, the clinical applicability of our system is considered and possible starting points for further developments of a prototype are discussed.
Published: 2010
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127. Design Guidelines for a Double Scattering Compton Camera for Prompt-gamma Imaging During Ion Beam Therapy: A Monte Carlo Simulation Study

Author: A.H. Walenta, M.-H. Richard, M. Chevallier, F. Le Foulher, Denis Dauvergne, Jean Michel Létang, F. Roellinghoff, Nicolas Freud, Etienne Testa, Gerard Montarou, P. Henriquet, Cédric Ray, M. Testa, Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), CAS-PHABIO, Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)
Subjects: Point spread function, Nuclear and High Energy Physics, Photon, [SDV.IB.IMA]Life Sciences [q-bio]/Bioengineering/Imaging, Astrophysics::High Energy Astrophysical Phenomena, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Geant4, Bragg peak, Photon energy, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Optics, Hodoscope, hadrontherapy, Electrical and Electronic Engineering, prompt gamma, Image resolution, Physics, business.industry, compton camera, Detector, Compton scattering, Nuclear Energy and Engineering, 030220 oncology & carcinogenesis, [PHYS.PHYS.PHYS-MED-PH]Physics [physics]/Physics [physics]/Medical Physics [physics.med-ph], ion beam therapy, business
Abstract: In hadrontherapy in order to fully take advantage of the assets of the ion irradiation, the position of the Bragg peak has to be monitored accurately. Here, we investigate a monitoring method relying on the detection in real time of the prompt gamma emitted quasi instantaneously during the nuclear fragmentation processes. Our detection system combines a beam hodoscope and a double scattering Compton camera. The prompt-gamma emission points are reconstructed by intersecting the ion trajectories given by the hodoscope and the Compton cones reconstructed with the camera. We propose here to study in terms of point spread function and efficiency the theoretical feasibility of the emission points reconstruction with our set-up in the case of a photon point source in air. First we analyze the nature of all the interactions which are likely to produce an energy deposit in the three detectors of the camera. It is underlined that upper energy thresholds in both scatter detectors are required in order to select mainly Compton events (one Compton interaction in each scatter detector and one interaction in the absorber detector). Then, we study the influence of various parameters such as the photon energy and the inter-detector distances on the Compton camera response. These studies are carried out by means of Geant4 simulations. We use a source with a spectrum corresponding to the prompt-gamma spectrum emitted during the carbon ion irradiation of a water phantom. In the current configuration, the spatial resolution of the Compton camera is about 6 mm (Full Width at Half Maximum) and the detection efficiency 10^{-5}. Finally, provided the detection efficiency is increased, the clinical applicability of our system is considered.
Published: 2010
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128. Design study of a Compton camera for prompt γ imaging during ion beam therapy

Author: Denis Dauvergne, Jean Michel Létang, A.H. Walenta, F. Roellinghoff, M. Chevallier, Gerard Montarou, Etienne Testa, M.-H. Richard, Nicolas Freud, M. Testa, F. Le Foulher, P. Henriquet, and Cédric Ray
Subjects: Physics, Photon, Optics, Hodoscope, Ion beam, business.industry, Point source, Astrophysics::High Energy Astrophysical Phenomena, Bragg peak, Photon energy, business, Image resolution, Ion
Abstract: In hadrontherapy in order to fully take advantage of the assets of the ion irradiation, the position of the Bragg peak has to be monitored accurately. Here, we propose a monitoring method relying on the detection in real time of the prompt γ emitted quasi instantaneously during the nuclear fragmentation processes. Our detection system combines a beam hodoscope and a double scattering Compton camera. The prompt γ emission points are reconstructed by intersecting the ion trajectories given by the hodoscope and the Compton cones reconstructed with the camera. We studied the influence of various parameters such as the photon energy and the inter-detector distances on the Compton camera response to a photon point source. This study was carried out by means of Geant4 simulations. In the current configuration, for a photon source with a typical prompt γ spectrum, the spatial resolution of the Compton camera is about 5.6 mm and the detection efficiency 10−5.
Published: 2009
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129. Simulation of dose deposition in stereotactic synchrotron radiation therapy: a fast approach combining Monte Carlo and deterministic algorithms

Author: Jean-François Adam, Hélène Elleaume, Claudio Ferrero, F. Smekens, Daniel Babot, Alberto Bravin, Jean Michel Létang, Nicolas Freud, François Estève, Smekens, F, Freud, N, Létang, J, Adam, J, Ferrero, C, Elleaume, H, Bravin, A, Estève, F, Babot, D, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon, Grenoble Institut des Neurosciences (GIN), Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Santé et de la Recherche Médicale (INSERM), European Synchrotron Radiation Facility (ESRF), Unité IRM, CHU Grenoble, Serduc, Raphael, and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)
Subjects: Photon, Time Factors, Monte Carlo method, Synchrotron radiation, FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA), Radiation Dosage, Radiosurgery, 01 natural sciences, Models, Biological, 030218 nuclear medicine & medical imaging, Hybrid Monte Carlo, 03 medical and health sciences, symbols.namesake, 0302 clinical medicine, 0103 physical sciences, Animals, Humans, Radiology, Nuclear Medicine and imaging, [SDV.NEU] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], Rayleigh scattering, Physics, Radiological and Ultrasound Technology, 010308 nuclear & particles physics, Scattering, Compton scattering, Radiotherapy Dosage, Rats, Monte Carlo simulation, dosimetry, Benchmarking, Ray casting, symbols, [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], Algorithm, Head, Monte Carlo Method, Algorithms, Synchrotrons
Abstract: A hybrid approach, combining deterministic and Monte Carlo (MC) calculations, is proposed to compute the distribution of dose deposited during stereotactic synchrotron radiation therapy treatment. The proposed approach divides the computation into two parts: (i) the dose deposited by primary radiation (coming directly from the incident x-ray beam) is calculated in a deterministic way using ray casting techniques and energy-absorption coefficient tables and (ii) the dose deposited by secondary radiation (Rayleigh and Compton scattering, fluorescence) is computed using a hybrid algorithm combining MC and deterministic calculations. In the MC part, a small number of particle histories are simulated. Every time a scattering or fluorescence event takes place, a splitting mechanism is applied, so that multiple secondary photons are generated with a reduced weight. The secondary events are further processed in a deterministic way, using ray casting techniques. The whole simulation, carried out within the framework of the Monte Carlo code Geant4, is shown to converge towards the same results as the full MC simulation. The speed of convergence is found to depend notably on the splitting multiplicity, which can easily be optimized. To assess the performance of the proposed algorithm, we compare it to state-of-the-art MC simulations, accelerated by the track length estimator technique (TLE), considering a clinically realistic test case. It is found that the hybrid approach is significantly faster than the MC/TLE method. The gain in speed in a test case was about 25 for a constant precision. Therefore, this method appears to be suitable for treatment planning applications. © 2009 Institute of Physics and Engineering in Medicine.
Published: 2009
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130. A beam stop based correction procedure for high spatial frequency scatter in industrial cone-beam X-ray CT

Author: Daniel Babot, A. Peterzol, Jean Michel Létang, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nuclear and High Energy Physics, business.industry, Detector, X-ray, Digital imaging, 01 natural sciences, Flat panel detector, 030218 nuclear medicine & medical imaging, 010309 optics, 03 medical and health sciences, 0302 clinical medicine, Optics, Sampling (signal processing), Nondestructive testing, 0103 physical sciences, categₛt2i, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Imagerie tomographique et thérapie par rayonnement, business, Instrumentation, Energy (signal processing), Beam (structure), ComputingMilieux_MISCELLANEOUS
Abstract: In the energy range of industrial cone-beam CT (a 450 kV X-ray tube is used), the detector scatter (veiling glare) turned out to be the most important source of secondary radiation for a digital imaging system working in the indirect conversion mode. It has been shown that the detector scatter drives the shape of the total image scatter. As a consequence, the latter may be characterized by an important high spatial frequency content questioning the hypothesis, frequently invoked in the scatter correction techniques, of a slowly varying scatter. We propose a beam stop array (BSA) based method for the evaluation/subtraction of the image scatter. The technique has the potential of simultaneously manage all sources of scattering radiation. It can be used in the high spatial frequency scatter case at the condition of opportunely selecting the BSA effective sampling step. It has been shown that the BSA approach can be also successfully combined with a beam hardening correction scheme based on the linearisation method. The work we present is supported by experimental measurements performed with two test objects at two different beam qualities: (i) 200 kV + 2.5 mm of Cu and (ii) 400 kV + 4 mm of Pb and 1 mm of Cd. The detector scatter represents about 36% and 65% of the total white field image for the two investigated beam qualities, respectively.
Published: 2008

131. Monitoring the Bragg peak location of 73 MeV/u carbon ions by means of prompt $\gamma$-ray measurements

Author: M. Testa, J.-C. Poizat, Michel Chevallier, F. Le Foulher, Nicolas Freud, Etienne Testa, Cédric Ray, Denis Dauvergne, Jean Michel Létang, M. Bajard, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), CAS-PHABIO, Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon
Subjects: Materials science, Physics and Astronomy (miscellaneous), [PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], business.industry, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Dose profile, Bragg peak, Physics - Atomic Physics, 030218 nuclear medicine & medical imaging, Ion, 03 medical and health sciences, Transverse plane, 0302 clinical medicine, Optics, 030220 oncology & carcinogenesis, Electromagnetic shielding, Neutron, Irradiation, business
Abstract: By means of a time-of-flight technique, we measured the longitudinal profile of prompt $\gamma$-rays emitted by 73 MeV/u $^{13}$C ions irradiating a PMMA target. This technique allowed us to minimize the shielding against neutrons and scattered $\gamma$-rays, and to correlate prompt gamma emission to the ion path. This correlation, together with a high counting rate, paves the way toward real-time monitoring of the longitudinal dose profile during ion therapy treatments. Moreover, the time correlation between the prompt gamma detection and the transverse position of the incident ions measured by a beam monitor can provide real-time 3D control of the irradiation., Comment: to be published in Applied Physics Letters
Published: 2008
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132. A hybrid approach for fast simulation of dose deposition in stereotactic synchrotron radiotherapy

Author: Claudio Ferrero, Alberto Bravin, Daniel Babot, H. Elleaume, Nicolas Freud, Jean Michel Létang, C. Boudou, C. Mary, François Estève, Freud, N, Letang Jean, M, Mary, C, Boudou, C, Ferrero, C, Elleaume, H, Bravin, A, Esteve, F, Babot, D, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), CCIN2P3, and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon
Subjects: Nuclear and High Energy Physics, Hybrid simulation, Deterministic algorithm, Quantitative Biology::Tissues and Organs, Physics::Medical Physics, Monte Carlo method, Synchrotron radiation, FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA), Statistical fluctuations, Fluorescence, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, symbols.namesake, 0302 clinical medicine, Optics, Deterministic simulation, Dosimetry, Electrical and Electronic Engineering, Rayleigh scattering, Physics, business.industry, Dose calculation, Compton scattering, Ray casting, 3. Good health, Nuclear Energy and Engineering, 030220 oncology & carcinogenesis, symbols, [SDV.IB]Life Sciences [q-bio]/Bioengineering, business, Stereotactic synchrotron radiation therapy, Treatment planning, Rayleigh and Compton scattering
Abstract: International audience; A hybrid approach was developed to compute the dose deposited in cancerous and healthy tissues during stereotactic synchrotron radiation therapy treatment. The proposed approach divides the computation into two parts: (1) the dose deposited by primary radiation (coming directly from the incident X-ray beam) is calculated using a deterministic algorithm based on ray casting, optimized for transport in voxelized geometries; (2) the dose deposited by secondary radiation (Rayleigh and Compton scattering, fluorescence) is computed using a hybrid algorithm combining Monte Carlo and deterministic calculations. In the Monte Carlo part, a set of scattering and fluorescence events occurring in the patient is determined. These events are further processed in a deterministic way, which considerably improves the statistics of the final dose map. The results obtained in test cases are compared to those obtained with the Monte Carlo method alone (Geant4 and MCNPX codes) and found to be in excellent agreement. The proposed simulation scheme makes it possible to simulate dose maps with a single PC, featuring computation time and statistical fluctuations substantially reduced in comparison with full Monte Carlo simulations.
Published: 2008
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133. Dose profile monitoring with carbon ions by means of prompt-gamma measurements

Author: Cédric Ray, J.-C. Poizat, F. Le Foulher, M. Testa, Etienne Testa, M. Chevallier, Nicolas Freud, M. Bajard, Denis Dauvergne, Jean Michel Létang, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), CAS-PHABIO, Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon, and Girod, Dominique
Subjects: Nuclear and High Energy Physics, prompt gamma-rays, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Astrophysics::High Energy Astrophysical Phenomena, Cyclotron, Analytical chemistry, Dose profile, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, 030218 nuclear medicine & medical imaging, law.invention, Ion, 03 medical and health sciences, Key point, 0302 clinical medicine, Optics, law, hadrontherapy, 0103 physical sciences, Dosimetry, Neutron, Instrumentation, Physics, dosimetry, 010308 nuclear & particles physics, business.industry, Gamma ray, monitoring, Electromagnetic shielding, business
Abstract: International audience; A key point in the quality control of ion therapy is real-time monitoring and imaging of the dose delivered to the patient. Among the possible signals that can be used to make such a monitoring, prompt gamma-rays issued from nuclear fragmentation are possible candidates, provided the correlation between the emission profile and the primary beam range can be established. By means of simultaneous energy and time of flight discrimination, we could measure the longitudinal profile of the prompt gamma-rays emitted by 73 MeV/u carbon ions stopping inside a PMMA target. This technique allowed us to minimize the shielding against neutrons and scattered gamma rays, and to find a good correlation between the prompt gamma profile and the ion range. This profile was studied as a function of the observation angle. By extrapolating our results to higher energies and realistic detection efficiencies, we showed that prompt gamma-ray measurements make it feasible to control in real time the longitudinal dose during ion therapy treatments.
Published: 2008
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134. Fast Dose Calculation for Stereotactic Synchrotron Radiotherapy

Author: Daniel Babot, Claudio Ferrero, Jean Michel Létang, Caroline Boudou, Nicolas Freud, C. Mary, Hélène Elleaume, François Estève, Alberto Bravin, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Hospices Civils de Lyon (HCL)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre Léon Bérard [Lyon], INSERM U836, équipe 6, Rayonnement synchrotron et recherche médicale, Grenoble Institut des Neurosciences (GIN), Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Santé et de la Recherche Médicale (INSERM), European Synchrotron Radiation Facility (ESRF), Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Grenoble, Université Joseph Fourier - Grenoble 1 (UJF)-CHU Grenoble-CHU Grenoble-Biomedical Beamline (ID17), European Synchrotron Radiation Facility (ESRF)-European Synchrotron Radiation Facility (ESRF), Freud, N, Letang, J, Mary, C, Boudou, C, Ferrero, C, Elleaume, H, Bravin, A, Esteve, F, and Babot, D
Subjects: Deterministic algorithm, Quantitative Biology::Tissues and Organs, Computation, Physics::Medical Physics, Monte Carlo method, FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA), Statistical fluctuations, 01 natural sciences, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, 0103 physical sciences, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Humans, Dosimetry, radiotherapy, fast dose calculation, ray tracing, ComputingMilieux_MISCELLANEOUS, Simulation, Physics, 010308 nuclear & particles physics, Radiotherapy Dosage, Models, Theoretical, Hybrid algorithm, 3. Good health, Computational physics, Personal computer, Ray casting, Monte Carlo Method, Algorithms, Synchrotrons
Abstract: A hybrid approach is proposed to compute the dose deposited in cancerous and healthy tissues during stereotactic synchrotron radiotherapy treatment. In this approach the computation is divided into two parts: (1) the primary dose is calculated using a deterministic algorithm based on ray casting; (2) the secondary dose (due to scattering and fluorescence) is computed using a hybrid algorithm combining Monte Carlo and a deterministic method. The results obtained for test cases are compared to those obtained with the Monte Carlo method alone (Geant4 code) and found to be in excellent agreement. The proposed simulation scheme makes it possible to simulate dose maps with a single personal computer, with computation time and statistical fluctuations substantially reduced in comparison with conventional Monte Carlo simulations. © 2007 IEEE.
Published: 2007
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135. Simulation study of the role played by intensifying or support layers in scintillation screens

Author: A. Koch, Jean Michel Létang, Nicolas Freud, S.A. Pistrui-Maximean, A.H. Walenta, Gerard Montarou, Daniel Babot, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nuclear and High Energy Physics, Scintillation, 010308 nuclear & particles physics, business.industry, Phosphor, Substrate (printing), Radiation, 01 natural sciences, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, Nuclear Energy and Engineering, chemistry, Optical transfer function, 0103 physical sciences, Polyethylene terephthalate, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Optoelectronics, Electrical and Electronic Engineering, Optical filter, business, Layer (electronics), ComputingMilieux_MISCELLANEOUS
Abstract: The advantage of using reinforcing substrate layers with phosphor screens is that they increase the phosphor sensitivity and filter the scattered radiation, while providing a mechanical support for the phosphor layer. A simulation model based on the Monte Carlo code Geant4 was developed to study the influence of the substrate properties (material, thickness) on the phosphor screen spatial response. The optimal substrate/phosphor combinations have been determined at given sensitivity of the screen. Of all studied cases at medium energy (300 keV), a configuration with slight improvement in the screen spatial response has been found. Moreover, the results show that, without degrading the performances of the screen, the phosphor thickness may be significantly reduced (by 35% in the case of a 0.05 mm Pb substrate). Besides, PolyEthylene Terephthalate (PET) makes a good mechanical support (of up to minimum 4 mm in thickness) for the phosphor layer. The simulation methodology permitted to study the role played by the X-ray and electron processes inside the substrate layer.
Published: 2007

136. Quality Control of High Temperature Reactors (HTR) compacts via X-Ray Tomography

Author: Tisseur, D., Banchet, J., Duny, P. -G, Vitali, M. -P, Peix, G., Jean Michel Létang, Département Imagerie et Simulation pour le Contrôle (DISC), Laboratoire d'Intégration des Systèmes et des Technologies (LIST (CEA)), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Centre Léon Bérard [Lyon], Laboratoire d'Intégration des Systèmes et des Technologies (LIST), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)
Subjects: [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2007

137. Measurement and Monte Carlo modeling of the spatial response of scintillation screens

Author: Nicolas Freud, Daniel Babot, Jean Michel Létang, A. Koch, A.H. Walenta, S.A. Pistrui-Maximean, Gerard Montarou, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nuclear and High Energy Physics, Scintillation, business.industry, Monte Carlo method, Scintillator, 01 natural sciences, Light scattering, 030218 nuclear medicine & medical imaging, 010309 optics, 03 medical and health sciences, Random search, 0302 clinical medicine, Optics, 0103 physical sciences, Convergence (routing), [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Stochastic optimization, business, Instrumentation, Algorithm, ComputingMilieux_MISCELLANEOUS, Voltage
Abstract: In this article, we propose a detailed protocol to carry out measurements of the spatial response of scintillation screens and to assess the agreement with simulated results. The experimental measurements have been carried out using a practical implementation of the slit method. A Monte Carlo simulation model of scintillator screens, implemented with the toolkit Geant4, has been used to study the influence of the acquisition setup parameters and to compare with the experimental results. An algorithm of global stochastic optimization based on a localized random search method has been implemented to adjust the optical parameters (optical scattering and absorption coefficients). The algorithm has been tested for different X-ray tube voltages (40, 70 and 100 kV). A satisfactory convergence between the results simulated with the optimized model and the experimental measurements is obtained.
Published: 2007

138. SU-E-J-147: Monte Carlo Study of the Precision and Accuracy of Proton CT Reconstructed Relative Stopping Power Maps

Author: N Arbor, Etienne Testa, Katia Parodi, Georgios Dedes, Simon Rit, Denis Dauvergne, Jean Michel Létang, and Yuki M. Asano
Subjects: Physics, Accuracy and precision, Scanner, business.industry, Monte Carlo method, Detector, General Medicine, Iterative reconstruction, Imaging phantom, Optics, Calibration, business, Nuclear medicine, Proton therapy
Abstract: Purpose: The quantification of the intrinsic performances of proton computed tomography (pCT) as a modality for treatment planning in proton therapy. The performance of an ideal pCT scanner is studied as a function of various parameters. Methods: Using GATE/Geant4, we simulated an ideal pCT scanner and scans of several cylindrical phantoms with various tissue equivalent inserts of different sizes. Insert materials were selected in order to be of clinical relevance. Tomographic images were reconstructed using a filtered backprojection algorithm taking into account the scattering of protons into the phantom. To quantify the performance of the ideal pCT scanner, we study the precision and the accuracy with respect to the theoretical relative stopping power ratios (RSP) values for different beam energies, imaging doses, insert sizes and detector positions. The planning range uncertainty resulting from the reconstructed RSP is also assessed by comparison with the range of the protons in the analytically simulated phantoms. Results: The results indicate that pCT can intrinsically achieve RSP resolution below 1%, for most examined tissues at beam energies below 300 MeV and for imaging doses around 1 mGy. RSP maps accuracy of less than 0.5 % is observed for most tissue types within the studied dosemore » range (0.2–1.5 mGy). Finally, the uncertainty in the proton range due to the accuracy of the reconstructed RSP map is well below 1%. Conclusion: This work explores the intrinsic performance of pCT as an imaging modality for proton treatment planning. The obtained results show that under ideal conditions, 3D RSP maps can be reconstructed with an accuracy better than 1%. Hence, pCT is a promising candidate for reducing the range uncertainties introduced by the use of X-ray CT alongside with a semiempirical calibration to RSP.Supported by the DFG Cluster of Excellence Munich-Centre for Advanced Photonics (MAP)« less
Published: 2015
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139. PD-0139: Monte Carlo evaluation of X-ray and proton CT for the prediction of the range of proton therapy beams

Author: N Arbor, Katia Parodi, E. Testa, S. Rit, Denis Dauvergne, Georgios Dedes, Jean Michel Létang, and C.T. Quinones
Subjects: Physics, Range (particle radiation), Proton, business.industry, Detector, X-ray, Hematology, Stopping power, Computational physics, Oncology, Radiology Nuclear Medicine and imaging, Radiology, Nuclear Medicine and imaging, Monte carlo evaluation, Nuclear Experiment, Nuclear medicine, business, Proton therapy, Energy (signal processing)
Abstract: Proton computed tomography (CT) has been described as a solution to image the proton relative stopping power (RSP) of patient tissues and could therefore reduce the uncertainty and associated margins of the conversion of X-ray CT images to RSP maps. Several studies have already demonstrated the capability of proton imaging to reconstruct tissue RSP but the quantification of the improvement with respect to X-ray CT is still missing. This study aimed at quantifying the accuracy of RSP maps reconstructed from X-ray and proton CT and their impact on the prediction of proton ranges under idealized conditions, i.e., perfect detectors for the position and the energy of protons and realistic but perfectly known X-ray source and flat panel.
Published: 2015
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140. A hybrid approach to simulate X-ray imaging techniques, combining Monte Carlo and deterministic algorithms

Author: Daniel Babot, Nicolas Freud, Jean Michel Létang, Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Centre de Recherche et d'Application en Traitement de l'Image et du Signal (CREATIS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-École Supérieure Chimie Physique Électronique de Lyon-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Deterministic algorithm, Monte Carlo method, Monte Carlo method for photon transport, 01 natural sciences, 030218 nuclear medicine & medical imaging, Hybrid Monte Carlo, 03 medical and health sciences, 0302 clinical medicine, Nuclear Energy and Engineering, Deterministic simulation, 0103 physical sciences, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Dynamic Monte Carlo method, Monte Carlo integration, Kinetic Monte Carlo, Electrical and Electronic Engineering, Algorithm, ComputingMilieux_MISCELLANEOUS, Monte Carlo molecular modeling
Abstract: In this paper, we propose a hybrid approach to simulate multiple scattering of photons in objects under X-ray inspection, without recourse to parallel computing and without any approximation sacrificing accuracy. Photon scattering is considered from two points of view: it contributes to X-ray imaging and to the dose absorbed by the patient. The proposed hybrid approach consists of a Monte Carlo stage followed by a deterministic phase, thus taking advantage of the complementarity between these two methods. In the first stage, a set of scattering events occurring in the inspected object is determined by means of classical Monte Carlo simulation. Then this set of scattering events is used to compute the energy imparted to the detector, with a deterministic algorithm based on a "forced detection" scheme. Regarding dose evaluation, we propose to assess separately the energy deposited by direct radiation (using a deterministic algorithm) and by scattered radiation (using our hybrid approach). The results obtained in a test case are compared to those obtained with the Monte Carlo method alone (Geant4 code) and found to be in excellent agreement. The proposed hybrid approach makes it possible to simulate the contribution of each type (Compton or Rayleigh) and order of scattering, separately or together, with a single PC, within reasonable computation times (from minutes to hours, depending on the required detector resolution and statistics). It is possible to simulate radiographic images virtually free from photon noise. In the case of dose evaluation, the hybrid approach appears particularly suitable to calculate the dose absorbed by regions of interest (rather than the entire irradiated organ) with computation time and statistical fluctuations considerably reduced in comparison with conventional Monte Carlo simulation.
Published: 2005
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141. Signal-to-noise ratio criterion for the optimization of dual-energy acquisition using virtual X-ray imaging: application to glass wool

Author: Gilles Peix, Jean Michel Létang, Nicolas Freud, Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), Centre Léon Bérard [Lyon], Controle Non Destructif par Rayonnements Ionisants (CNDRI), Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), and Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon
Subjects: Physics, X-ray, Glass wool, Inversion (meteorology), System of linear equations, 01 natural sciences, Atomic and Molecular Physics, and Optics, Spectral line, 030218 nuclear medicine & medical imaging, Computer Science Applications, Data modeling, 010309 optics, 03 medical and health sciences, 0302 clinical medicine, 0103 physical sciences, Deterministic simulation, Calibration, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Electrical and Electronic Engineering, Algorithm, ComputingMilieux_MISCELLANEOUS
Abstract: Dual-energy techniques are used to carry out selective and quantitative imaging of materials consisting of two components. We present a technique that takes advantage of a deterministic simulation tool to find the optimal x-ray spectra used in a dual-energy system and to calibrate the measurement protocol. To optimize the choice of energy spectra, a signal-to-noise ratio (SNR) criterion on the estimated thickness of the materials is established. To further study the reliability of the SNR criterion, it is first compared to the measurement quality, expressed by a contrast-to-noise ratio, which characterizes the input images. Then, the numerical conditioning of the linear dual-energy system of equations is investigated to probe the stability of the inversion. Once the choice of energy spectra is settled, the reconstructed values of the thickness are modeled as third-order polynomials expressed in terms of dual-energy measurements. An application to glass-wool materials is presented.
Published: 2004

142. X-ray Tomography applied to the characterization of cellular materials. Related Finite Element modeling problems

Author: Souhail Youssef, Rémy Dendievel, Eric Maire, Jean Michel Létang, Arnaud Fazekas, Peter Cloetens, Luc Salvo, Matériaux, ingénierie et science [Villeurbanne] (MATEIS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Science et Ingénierie des Matériaux et Procédés (SIMaP), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Génie physique et mécanique des matériaux (GPM2), Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique de Grenoble (INPG), European Synchrotron Radiation Facility (ESRF), Imagerie Tomographique et Radiothérapie, Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS), Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Jean Monnet [Saint-Étienne] (UJM)-Hospices Civils de Lyon (HCL)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Centre Léon Bérard [Lyon]
Subjects: Materials science, Similarity (geometry), Scale (ratio), General Engineering, Metal foam, Finite element method, Characterization (materials science), Visualization, [SPI.MAT]Engineering Sciences [physics]/Materials, Ceramics and Composites, Forensic engineering, [INFO.INFO-IM]Computer Science [cs]/Medical Imaging, Polygon mesh, Tomography, Composite material, Biological system, ComputingMilieux_MISCELLANEOUS
Abstract: The analyses of several materials exhibiting a cellular structure have been carried out using X-ray tomography. This new technique allows the three dimensional and non destructive visualisation of the studied materials at the scale of their cellular microstructure. Qualitative examples are given for metal foams, bread and cellular concrete. The similarity between these materials is striking. It has been measured by quantitative 3D image processing. The different Finite Element Methods available today to produce meshes from these images are presented and discussed in the final part of this paper.
Published: 2003

143. 148 REAL-TIME PROMPT GAMMA RAY MONITORING FOR PROTON AND CARBON THERAPY: MONTE CARLO NUCLEAR MODELS EVALUATION AND IMPROVEMENTS

Author: Cédric Ray, Marco Pinto, Marius Chevallier, J. Krimmer, Denis Dauvergne, E. Testa, V. Reithinger, Jean Michel Létang, M. De Rydt, Georgios Dedes, M.-H. Richard, Nicolas Freud, and F. Roellinghoff
Subjects: Carbon therapy, Materials science, Proton, business.industry, Monte Carlo method, Gamma ray, Hematology, 030218 nuclear medicine & medical imaging, Nuclear physics, 03 medical and health sciences, 0302 clinical medicine, Oncology, 030220 oncology & carcinogenesis, Radiology, Nuclear Medicine and imaging, Nuclear medicine, business
Published: 2012
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144. 240 SPATIAL CORRELATIONS BETWEEN IMAGES DERIVED FROM DYNAMIC FDG-PET

Author: Nicolas Freud, Denis Dauvergne, Jean Michel Létang, Cédric Ray, J. Krimmer, P. Henriquet, Georgios Dedes, M.-H. Richard, E. Testa, M. De Rydt, V. Reithinger, and Michel Chevallier
Subjects: 03 medical and health sciences, 0302 clinical medicine, Oncology, business.industry, 030220 oncology & carcinogenesis, Radiology, Nuclear Medicine and imaging, Hematology, Nuclear medicine, business, 030218 nuclear medicine & medical imaging
Published: 2012
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145. 136 REAL-TIME MONITORING OF THE BRAGG PEAK DURING ION THERAPY: RECENT DEVELOPMENTS OF THE BEAM DETECTION SYSTEM

Author: Denis Dauvergne, Jean Michel Létang, Etienne Testa, M. De Rydt, Y. Zoccaratto, V. Reithinger, S. Deng, F. Roellinghoff, Georgios Dedes, M.-H. Richard, Marco Pinto, M. Chevallier, J. Krimmer, H. Mattez, Nicolas Freud, and Cédric Ray
Subjects: Materials science, business.industry, Bragg peak, Hematology, 030218 nuclear medicine & medical imaging, Ion, 03 medical and health sciences, 0302 clinical medicine, Optics, Oncology, 030220 oncology & carcinogenesis, Radiology, Nuclear Medicine and imaging, business, Beam (structure)
Published: 2012
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146. A review of the use and potential of the GATE Monte Carlo simulation code for radiation therapy and dosimetry applications

Author: Sara Marcatili, Lydia Maigne, Jean Michel Létang, Yann Perrot, Thibault Mauxion, Dennis R. Schaart, Nicolas Freud, Charlotte Robert, Dimitris Visvikis, Uwe Pietrzyk, David Sarrut, George Loudos, Irène Buvat, Panagiotis Papadimitroulas, Manuel Bardiès, Sébastien Jan, and Nicolas Boussion
Subjects: medicine.medical_specialty, medicine.diagnostic_test, Proton, Computer science, medicine.medical_treatment, Monte Carlo method, Brachytherapy, Computed tomography, General Medicine, Scintigraphy, Radiation therapy, medicine, Medical imaging, Code (cryptography), Dosimetry, Medical physics, External beam radiotherapy, Intraoperative radiotherapy, Simulation
Abstract: In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same frameworkis emphasized. The computational times associated with several applications are provided to illustrate the practical feasibility of the simulations using current computing facilities.
Published: 2014
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147. 156: Research and development of a TOF-based multi-slit collimated camera for online hadrontherapy monitoring

Author: Marco Pinto, F. Roellinghoff, J. Krimmer, Nicolas Freud, Denis Dauvergne, Jean Michel Létang, Cédric Ray, and E. Testa
Subjects: medicine.medical_specialty, Dose delivery, Range (particle radiation), Modality (human–computer interaction), medicine.diagnostic_test, Computer science, business.industry, Bragg peak, Hematology, Slit, Collimated light, Optics, Oncology, Positron emission tomography, medicine, Radiology, Nuclear Medicine and imaging, Medical physics, business, Beam (structure)
Abstract: Purpose: Hadrontherapy is an innovative radiotherapy modality that allows for high tumour conformality due to the characteristic Bragg peak in the dose-depth profile. However, the high precision involved also makes the monitoring of dose delivery more critical. Currently, only positron emission tomography is clinically implemented but other techniques may also provide clinically-relevant information, namely the ones relying on prompt-radiation emission. This work addresses the research and development (R&D) of a TOFbased multi-slit collimated camera, one of the possible devices that use prompt-radiation information to monitor dose delivery in particular for proton and carbon ion treatments. This camera involves the detection of prompt gammas emitted during the treatment along the beam axis, for which the correlation with the range of particles in matter has been extensively demonstrated.
Published: 2014
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148. 122: Development of a Time-Of-Flight Compton Camera for Online Control of Ion Therapy

Author: J.-L. Ley, H. Mathez, Denis Dauvergne, Jean Michel Létang, Nicolas Freud, L. Lestand, E. Testa, Cédric Ray, M.-H. Richard, B. Joly, Y. Zoccarato, M. Dahoumane, J. Krimmer, and Gerard Montarou
Subjects: medicine.medical_specialty, Computer science, business.industry, Monte Carlo method, Hematology, Compton camera, Coincidence, Ion, Time of flight, Optics, Oncology, medicine, Radiology, Nuclear Medicine and imaging, Medical physics, business
Abstract: The aim of irradiation monitoring during a treatment in ion therapy is to control in real time the agreement between the delivered dose and the planned treatment. In fact, the discrepancies might come from uncertainties such as the positioning or the anatomical changes of the patient can lead to ion-range variations of a few millimeters. Several devices are under development over the world to detect secondary radiations, which are correlated to the dose deposited by incident ions. Compton cameras are in particular investigated for their potential high efficiency. The present work aims at discussing the clinical applicability of a Compton camera design by means of Monte Carlo simulations validated against measurements of single and coincidence rates.
Published: 2014
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149. PO-0921: Simulation of x-ray images from the planning CT for online correction of scatter in cone-beam CT

Author: S. Rit, David Sarrut, Nicolas Freud, M. Vila Oliva, Sébastien Brousmiche, Jean Michel Létang, and E. Romero
Subjects: Physics, medicine.medical_specialty, business.industry, Hematology, Optics, Oncology, Computer Science::Computer Vision and Pattern Recognition, Rotational angiography, Hounsfield scale, X ray image, medicine, Radiology, Nuclear Medicine and imaging, Radiology, business, Cone beam ct
Abstract: Purpose/Objective: To correct for scatter in cone-beam CT images and to calibrate the image intensities in Hounsfield units (HU) using fast and accurate simulation of x-ray images of the planning CT.
Published: 2014
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150. 241 REAL-TIME MONITORING OF THE BRAGG PEAK DURING ION THERAPY: A FEASIBILITY STUDY OF INTERACTION VERTEX IMAGING

Author: V. Reithinger, E. Testa, Michel Chevallier, Nicolas Freud, J. Krimmer, Denis Dauvergne, Jean Michel Létang, P. Henriquet, M.-H. Richard, Georgios Dedes, Cédric Ray, and M. De Rydt
Subjects: Vertex (graph theory), Physics, medicine.medical_specialty, Particle physics, Oncology, medicine, Radiology, Nuclear Medicine and imaging, Medical physics, Bragg peak, Hematology, Ion
Published: 2012
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