Denis Dauvergne | Université Claude Bernard Lyon 1 (original) (raw)

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Papers by Denis Dauvergne

In order to take advantage of the assets of ion irradiation, the position of the Bragg peak has t... more In order to take advantage of the assets of ion irradiation, the position of the Bragg peak has to be monitored accurately. Here we propose a technique relying on the detection of the prompt with a Compton camera. We reconstruct analytically the prompt- emission points by intersecting the ion trajectories given by a beam hodoscope and the Compton cones reconstructed with the camera. For the Compton camera, we investigate the use of a stack of 2 mm thick silicon strip detectors as a scatterer and one scintillator as an absorber. The answer of the Compton camera to a photon point source with a realistic spectrum (corresponding to the prompt- spectrum emitted during the carbon irradiation of a water phantom) is studied. The goal of this study is to tune the design of the absorber detector. First the absorber detector dimensions are optimized. Then we compare the performances of three scintillators : LYSO, NaI and LaBr3. Finally, we study the influence of the spatial and energy resoluti...

Hadrontherapy treatments require a very high precision on the dose deposition ( 2.5% and 1-2mm) i... more Hadrontherapy treatments require a very high precision on the dose deposition ( 2.5% and 1-2mm) in order to keep the benefits of the precise ions' ballistic. The largest uncertainty on the physical dose deposition is due to ion fragmentation. Up to now, the simulation codes are not able to reproduce the fragmentation process with the required precision. To constraint the nuclear models and complete fragmentation cross sections databases; our collaboration has performed an experiment on May 2008 at GANIL with a 95 MeV/u 12C beam. We have measured the fluence, energy and angular distributions of charged fragments and neutrons coming from nuclear reactions of incident 12C on thick water-like PMMA targets. Preliminary comparisons between GEANT4 (G4BinaryLightIonReaction) simulations and experimental data show huge discrepancies.

We will present the first results obtained on the Radiograaff platform after irradiating two cell... more We will present the first results obtained on the Radiograaff platform after irradiating two cell lines of HNSCC (Head and Neck Squamous Carcinoma Cells). The Radiograaff platform which has been setup at the 4MV Van de Graaff accelerator of the Institut de Physique Nucléaire de Lyon, is a horizontal beam facility dedicated for radiobiological experiments with medium-energy protons. Previous experiments have shown that exposure to radiation with high linear energy transfer (LET) induced clonogenic cell death for SCC61 (radiosensitive) and SQ20B (radioresistant) cells (HNSCC cells), the latter systematically showing less sensitivity (Maalouf et al. 2009). At 3 MeV, the Relative Biological Effectiveness of protons at 10% of cell inactivation was reported for V79 cell line to range between 1 and 1. 6 (Paganetti et al. 2002). Thus, this platform constitutes a tool to study the specific effects of high Linear Energy Transfert (LET) radiations to cells.

Radiation Effects and Defects in Solids, 1993

Radiation Effects and Defects in Solids, 1993

The 132 pb 1 of data collected by ALEPH from 1991 to 1994 have been used to analyze and ! product... more The 132 pb 1 of data collected by ALEPH from 1991 to 1994 have been used to analyze and ! production in decays. The following branching fractions have been measured: B( ! !h ) = (1:91 0:07 0:06) 10 2 ; B( ! !h 0 ) = (4:3 0:6 0:5) 10 3 ; B( ! K ) = (2:9 +1:3 1:2 0:7) 10 4 ; B( ! h 0 ) = (1:8 0:4 0:2) 10 3 and the 95% C.L. limit B( ! )<6:210 4 has been obtained. The ! and 0 rates and dynamics are found in agreement with the predictions made from e + e annihilation data with the help of isospin invariance (CVC).

Physics Letters B, 2002

Tungsten crystals oriented on their 111 axis, were submitted to 6 and 10 GeV electron beams on th... more Tungsten crystals oriented on their 111 axis, were submitted to 6 and 10 GeV electron beams on the SPS-CERN transfer lines. The crystals, 4 and 8 mm thick, used alone or associated to 4 mm thick amorphous disk, were studied as positron sources. The emerging positrons were detected by a Drift Chamber partially immersed in a magnetic field, where their trajectories were reconstructed providing the energy spectrum and the angular distribution. Significant enhancements were observed for the crystal source when compared to the amorphous one of the same thickness. The gain was larger than 3 and 2 for the 4 mm and 8 mm targets, respectively. The presented results look very promising for e + e − linear colliders. 

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

We investigate, by means of Geant4 simulations, a real-time method to control the position of the... more 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 2mm thick silicon strip detectors and a

2011 IEEE Nuclear Science Symposium Conference Record, 2011

The Compton camera is an imaging device relevant for the detection of prompt photons produced dur... more 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

In order to take advantage of the assets of ion irradiation, the position of the Bragg peak has t... more In order to take advantage of the assets of ion irradiation, the position of the Bragg peak has to be monitored accurately. Here we propose a technique relying on the detection of the prompt with a Compton camera. We reconstruct analytically the prompt- emission points by intersecting the ion trajectories given by a beam hodoscope and the Compton cones reconstructed with the camera. For the Compton camera, we investigate the use of a stack of 2 mm thick silicon strip detectors as a scatterer and one scintillator as an absorber. The answer of the Compton camera to a photon point source with a realistic spectrum (corresponding to the prompt- spectrum emitted during the carbon irradiation of a water phantom) is studied. The goal of this study is to tune the design of the absorber detector. First the absorber detector dimensions are optimized. Then we compare the performances of three scintillators : LYSO, NaI and LaBr3. Finally, we study the influence of the spatial and energy resoluti...

Hadrontherapy treatments require a very high precision on the dose deposition ( 2.5% and 1-2mm) i... more Hadrontherapy treatments require a very high precision on the dose deposition ( 2.5% and 1-2mm) in order to keep the benefits of the precise ions' ballistic. The largest uncertainty on the physical dose deposition is due to ion fragmentation. Up to now, the simulation codes are not able to reproduce the fragmentation process with the required precision. To constraint the nuclear models and complete fragmentation cross sections databases; our collaboration has performed an experiment on May 2008 at GANIL with a 95 MeV/u 12C beam. We have measured the fluence, energy and angular distributions of charged fragments and neutrons coming from nuclear reactions of incident 12C on thick water-like PMMA targets. Preliminary comparisons between GEANT4 (G4BinaryLightIonReaction) simulations and experimental data show huge discrepancies.

We will present the first results obtained on the Radiograaff platform after irradiating two cell... more We will present the first results obtained on the Radiograaff platform after irradiating two cell lines of HNSCC (Head and Neck Squamous Carcinoma Cells). The Radiograaff platform which has been setup at the 4MV Van de Graaff accelerator of the Institut de Physique Nucléaire de Lyon, is a horizontal beam facility dedicated for radiobiological experiments with medium-energy protons. Previous experiments have shown that exposure to radiation with high linear energy transfer (LET) induced clonogenic cell death for SCC61 (radiosensitive) and SQ20B (radioresistant) cells (HNSCC cells), the latter systematically showing less sensitivity (Maalouf et al. 2009). At 3 MeV, the Relative Biological Effectiveness of protons at 10% of cell inactivation was reported for V79 cell line to range between 1 and 1. 6 (Paganetti et al. 2002). Thus, this platform constitutes a tool to study the specific effects of high Linear Energy Transfert (LET) radiations to cells.

Radiation Effects and Defects in Solids, 1993

Radiation Effects and Defects in Solids, 1993

The 132 pb 1 of data collected by ALEPH from 1991 to 1994 have been used to analyze and ! product... more The 132 pb 1 of data collected by ALEPH from 1991 to 1994 have been used to analyze and ! production in decays. The following branching fractions have been measured: B( ! !h ) = (1:91 0:07 0:06) 10 2 ; B( ! !h 0 ) = (4:3 0:6 0:5) 10 3 ; B( ! K ) = (2:9 +1:3 1:2 0:7) 10 4 ; B( ! h 0 ) = (1:8 0:4 0:2) 10 3 and the 95% C.L. limit B( ! )<6:210 4 has been obtained. The ! and 0 rates and dynamics are found in agreement with the predictions made from e + e annihilation data with the help of isospin invariance (CVC).

Physics Letters B, 2002

Tungsten crystals oriented on their 111 axis, were submitted to 6 and 10 GeV electron beams on th... more Tungsten crystals oriented on their 111 axis, were submitted to 6 and 10 GeV electron beams on the SPS-CERN transfer lines. The crystals, 4 and 8 mm thick, used alone or associated to 4 mm thick amorphous disk, were studied as positron sources. The emerging positrons were detected by a Drift Chamber partially immersed in a magnetic field, where their trajectories were reconstructed providing the energy spectrum and the angular distribution. Significant enhancements were observed for the crystal source when compared to the amorphous one of the same thickness. The gain was larger than 3 and 2 for the 4 mm and 8 mm targets, respectively. The presented results look very promising for e + e − linear colliders. 

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

We investigate, by means of Geant4 simulations, a real-time method to control the position of the... more 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 2mm thick silicon strip detectors and a

2011 IEEE Nuclear Science Symposium Conference Record, 2011

The Compton camera is an imaging device relevant for the detection of prompt photons produced dur... more 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