M. Bajard

Institut de Physique Nucléaire de Lyon, Lyons, Rhône-Alpes, France

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Publications (38)34.28 Total impact

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    ABSTRACT: This paper gives a short review of the past and recent activities of the Atomic Collisions in Solids Lyon-group, in collaboration with other groups, in the field of high energy channelling. The ion-channelling programme was performed at GANIL-Caen and at GSI-Darmstadt. The electron-channelling programme started at ALS-Saclay for relativistic incident energies and was then extended to SPS-CERN for ultra-relativistic energies. The last part of this paper presents the electron-channelling experiments performed originally at ALS-Saclay, then at BTF-Frascati and more recently at LS-Saga, in order to observe the electron “internal clock” predicted in 1924 by L. de Broglie.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 02/2015; 355. DOI:10.1016/j.nimb.2015.02.005 · 1.19 Impact Factor
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    ABSTRACT: Prompt-gamma emission detection is a promising technique for hadrontherapy monitoring purposes. In this regard, obtaining prompt-gamma yields that can be used to develop monitoring systems based on this principle is of utmost importance since any camera design must cope with the available signal. Herein, a comprehensive study of the data from ten single-slit experiments is presented, five consisting in the irradiation of either PMMA or water targets with lower and higher energy carbon ions, and another five experiments using PMMA targets and proton beams. Analysis techniques such as background subtraction methods, geometrical normalization, and systematic uncertainty estimation were applied to the data in order to obtain absolute prompt-gamma yields in units of prompt-gamma counts per incident ion, unit of field of view, and unit of solid angle. At the entrance of a PMMA target, where the contribution of secondary nuclear reactions is negligible, prompt-gamma counts per incident ion, per millimetre and per steradian equal to (124 ± 0.7stat ± 30sys) × 10(-6) for 95 MeV u(-1) carbon ions, (79 ± 2stat ± 23sys) × 10(-6) for 310 MeV u(-1) carbon ions, and (16 ± 0.07stat ± 1sys) × 10(-6) for 160 MeV protons were found for prompt gammas with energies higher than 1 MeV. This shows a factor 5 between the yields of two different ions species with the same range in water (160 MeV protons and 310 MeV u(-1) carbon ions). The target composition was also found to influence the prompt-gamma yield since, for 300/310 MeV u(-1) carbon ions, a 42% greater yield ((112 ± 1stat ± 22sys) × 10(-6) counts ion(-1) mm(-1) sr(-1)) was obtained with a water target compared to a PMMA one.
    Physics in Medicine and Biology 12/2014; 60(2):565-594. DOI:10.1088/0031-9155/60/2/565 · 2.92 Impact Factor
  • 50th International PTCOG meeting (Particle Therapy Co-Operative Group); 05/2011
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    ABSTRACT: Monte Carlo simulations based on the Geant4 toolkit (version 9.1) were performed to study the emission of secondary prompt-gamma rays produced by nuclear reactions during carbon ion-beam therapy. These simulations were performed along with an experimental program and instrumentation developments which aim at designing a prompt-gamma ray device for real-time control of hadrontherapy. The objective of the present study is twofold: firstly, to present the features of the prompt-gamma radiation in the case of carbon ion irradiation; secondly, to simulate the experimental setup and to compare measured and simulated counting rates corresponding to four different experiments. For each experiment, we found that simulations overestimate prompt-gamma ray detection yields by a factor of 12. Uncertainties in fragmentation cross sections and binary cascade model cannot explain such discrepancies. The so-called “photon evaporation” model is therefore questionable and its modification is currently in progress.
    IEEE Transactions on Nuclear Science 11/2010; DOI:10.1109/TNS.2010.2048042 · 1.46 Impact Factor
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    ABSTRACT: The increased effectiveness of highly conformal ion beam therapy requires a higher precision in the dose monitoring and location than in conventional radiation therapy. To monitor in real time the longitudinal position of the Bragg peak we proposed a novel non invasive technique that exploits the detection of prompt gamma-rays issued from nuclear fragmentation. In our first experiment with a 73 MeV/u 13C6+ ion beam we showed that i) the ion depth-dose profile is correlated with the prompt-gamma-ray profile and that ii) the use of the time-of-flight (TOF) technique allows to use a compact device which makes it possible to increase the detection solid angle by 2 or 3 orders of magnitude. We could therefore obtain counting rates high enough for real-time control of the Bragg peak position as compared to the passive neutron-shielded camera previously developed by Min et al. We have recently carried out two series of experiments at the GANIL and GSI facilities with 95 MeV/u and 310 MeV/u 12C6+ ion beams, respectively. The carbon beam was stopped in a PMMA or water target. In both experiments, our collimated detectors were placed at 90 degrees from the beam direction and aimed at the target. The target was placed on a translating table, moving along the beam axis, to allow a full scan of the beam profile inside the target. To discriminate the prompt photons from the background radiation, mainly due or induced by neutrons, we used the TOF and the Pulse Shape Discrimination (PSD) techniques. We showed that TOF could make real-time treatment monitoring with prompt gamma-rays feasible, since it avoids the use of bulky neutron shielding. On the contrary no correlation between the neutron production and the ion path was found. The proposed technique remains valid with patient-like target volumes and the gamma profile is still correlated with the ion depth of penetration. We present our recent developments of a beam monitor, based on scintillating fibres read out by a flat-panel multi-channel photomultiplier, to allow precise beam tagging in time and position in the plane transverse to the beam. A prototype of such a beam hodoscope with 1 mm square scintillating fibres was tested at GANIL, providing encouraging performances concerning the time resolution (rms 350 ps), and sufficient radiation hardness to make their use possible in routine clinical conditions.
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    ABSTRACT: Hadrontherapy treatments require a very high precision on the location of the dose in order to keep the benefits of the precise ions' ballistic. The largest uncertainty on physical dose is due to ion fragmentation. Up to now, the simulation codes are not able to reproduce the fragmentation process with the required precision. The constraints on nuclear models and fragmentation cross sections between 30 and 100MeV/u are not sufficient. We have performed an experiment on May 2008 at GANIL,France with a 95 MeV/u 12C beam. The goals were the measurement of the fluence, energy and angular distributions of the fragments coming from the nuclear reaction between 12C and waterlike PMMA targets of different thicknesses : from 0.5 to 4 cm. At 95MeV/u, the 12C Bragg Peak depth in PMMA is 2 cm. Production rates, from proton to carbons, have been obtained at 10 different angles for the six different PMMA thicknesses. The setup also included DEMON detectors to measure the neutrons at four different angles (15, 25, 45 and 70 degrees). Comparisons between our data and Geant4 simulations have been achieved in order to evaluate the accuracy of the models (eg. G4BinaryLightIonReaction, G4BinaryCascade) included in GEANT4 for hadrontherapy purposes (light ion on light target; energy range: 80-400MeV/u). While we are in good agreement with the angular distribution of proton, beryum and bore ions, these comparisons show some discrepancies for helium lithium and carbon ions. Further studies are underway to find a model in good agreement with all our data. We also have another experiment accepted on thin targets at GANIL (C-C, C-H, C-O, C-Ca from 40 to 95 MeV/u). These double differential cross sections of charged fragments and neutrons are necessary to improve the models and reach the precision required for a reference simulation code for hadrontherapy. These activities will experience a boost with the arrival of a new resource center in hadrontherapy, Archade in Caen, France.
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    ABSTRACT: For real-time monitoring of the longitudinal position of the Bragg-peak during an ion therapy treatment, a novel non-invasive technique has been recently proposed that exploits the detection of prompt gamma-rays issued from nuclear fragmentation. Two series of experiments have been performed at the GANIL and GSI facilities with 95 and 305 MeV/u (12)C(6+) ion beams stopped in PMMA and water phantoms. In both experiments, a clear correlation was obtained between the carbon ion range and the prompt photon profile. Additionally, an extensive study has been performed to investigate whether a prompt neutron component may be correlated with the carbon ion range. No such correlation was found. The present paper demonstrates that a collimated set-up can be used to detect single photons by means of time-of-flight measurements, at those high energies typical for ion therapy. Moreover, the applicability of the technique both at cyclotron and at synchrotron facilities is shown. It is concluded that the detected photon count rates provide sufficiently high statistics to allow real-time control of the longitudinal position of the Bragg-peak under clinical conditions.
    Biophysik 03/2010; 49(3):337-43. DOI:10.1007/s00411-010-0276-2 · 1.58 Impact Factor
  • First International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications (ANIMMA); 06/2009
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    ABSTRACT: We initiated studies on the mechanisms of cell death in head and neck squamous cell carcinoma cell lines (HNSCC) since recent clinical trials have shown that local treatment of HNSCC by carbon hadrontherapy is less efficient than it is in other radioresistant cancers. Two p53-mutated HNSCC cell lines displaying opposite radiosensitivity were used. Different types of cell death were determined after exposure to carbon ions (33.6 and 184 keV/microm) or X-rays. Exposure to radiation with high linear energy transfer (LET) induced clonogenic cell death for SCC61 (radiosensitive) and SQ20B (radioresistant) cells, the latter systematically showing less sensitivity. Activation of an early p53-independent apoptotic process occurred in SCC61 cells after both types of irradiation, which increased with time, dose and LET. In contrast, SQ20B cells underwent G2/M arrest associated with Chk1 activation and Cdc2 phosphorylation. This inhibition was transient after X-rays, compared with a more prolonged and LET-dependent accumulation after carbon irradiation. After release, a LET-dependent increase of polyploid and multinucleated cells, both typical signs of mitotic catastrophe, was identified. However, a subpopulation of SQ20B cells was able to escape mitotic catastrophe and continue to proliferate. High LET irradiation induced distinct types of cell death in HNSCC cell lines and showed an increased effectiveness compared with X-rays. However, the reproliferation of SQ20B may explain the potential locoregional recurrence observed among some HNSCC patients treated by hadrontherapy. An adjuvant treatment forcing the tumor cells to enter apoptosis may therefore be necessary to improve the outcome of radiotherapy.
    International journal of radiation oncology, biology, physics 06/2009; 74(1):200-9. DOI:10.1016/j.ijrobp.2009.01.012 · 4.18 Impact Factor
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    ABSTRACT: 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.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 03/2009; DOI:10.1016/j.nimb.2009.02.031 · 1.19 Impact Factor
  • International Workshop on Hadron Beam Therapy of cancer, Erice, Italie, 24 avril - 1er mai 2009; 01/2009
  • International Conference - Heavy Ions in Therapy and Space Symposium 2009, 12th Workshop on Ion Beams in Biology and Medicine (IBIBAM), Cologne, 6-10 juillet 2009; 01/2009
  • IEEE Nuclear Science Symposium, Medical Imaging Conference; 10/2008
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    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.
    Applied Physics Letters 10/2008; 93(9). DOI:10.1063/1.2975841 · 3.52 Impact Factor
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    ABSTRACT: To establish the radiobiologic parameters of head-and-neck squamous cell carcinomas (HNSCC) in response to ion irradiation with various linear energy transfer (LET) values and to evaluate the relevance of the local effect model (LEM) in HNSCC. Cell survival curves were established in radiosensitive SCC61 and radioresistant SQ20B cell lines irradiated with [33.6 and 184 keV/n] carbon, [302 keV/n] argon, and X-rays. The results of ion experiments were confronted to LEM predictions. The relative biologic efficiency ranged from 1.5 to 4.2 for SCC61 and 2.1 to 2.8 for SQ20B cells. Fixing an arbitrary D(0) parameter, which characterized survival to X-ray at high doses (>10 Gy), gave unsatisfying LEM predictions for both cell lines. For D(0) = 10 Gy, the error on survival fraction at 2 Gy amounted to a factor of 10 for [184 keV/n] carbon in SCC61 cells. We showed that the slope (s(max)) of the survival curve at high doses was much more reliable than D(0). Fitting s(max) to 2.5 Gy(-1) gave better predictions for both cell lines. Nevertheless, LEM could not predict the responses to fast and slow ions with the same accuracy. The LEM could predict the main trends of these experimental data with correct orders of magnitude while s(max) was optimized. Thus the efficiency of carbon ions cannot be simply extracted from the clinical response of a patient to X-rays. LEM should help to optimize planning for hadrontherapy if a set of experimental data is available for high-LET radiations in various types of tumors.
    International Journal of Radiation OncologyBiologyPhysics 07/2008; 71(2):635-42. DOI:10.1016/j.ijrobp.2007.10.050 · 4.18 Impact Factor
  • Radioprotection 01/2008; 43(5). DOI:10.1051/radiopro:2008720 · 0.60 Impact Factor
  • Cancer/Radiothérapie 11/2007; 11(6):397-398. DOI:10.1016/j.canrad.2007.09.058 · 1.11 Impact Factor
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    ABSTRACT: It is proposed to build a national centre for light-ion hadrontherapy in France, located in Lyon in the Rhône-Alpes region. Under the auspices of University Claude Bemard Lyon-I and with the support of a research contract between Rhône-Alpes region and the Minister of Research, a design has been elaborated. This paper reviews the medical and technical characteristics of the project, called ETOILE (Espace de Traitement Oncologique par Ions Légers dans le cadre Européen). The research programs associated with ETOILE concern mainly the tracking of moving organs, the design of an in-beam PET detector, the simulation of the interaction of carbon ions with tissues and radiobiological studies on the radiosensitivity and tolerance of normal tissues and on the radioresistance of tumours. The capital cost needed to realize ETOILE is about 90 M Euro. We expect a definitive decision to build ETOILE at the end of 2004. In that case the centre will treat its first patients in 2009. A routine flux of 1000 patients per year will be reached after 3 years with an operation cost of 15 M Euro.
    Radiotherapy and Oncology 01/2005; 73 Suppl 2:S211-5. DOI:10.1016/S0167-8140(04)80050-1 · 4.86 Impact Factor
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    Joseph Remillieux, Marcel Bajard
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    ABSTRACT: Dès 1947, R. Wilson proposa d'utiliser les propriétés balistiques et ionisantes des ions pénétrant dans la matière (pic de Bragg) pour traiter les tumeurs cancéreuses par «hadronthérapie». Cette idée ne fut exploitée cliniquement qu'à partir de 1954 à Berkeley aux USA, où l'on traita dans un laboratoire de physique jusqu'en 1993, date d'arrêt de l'accélérateur, plus de 2500 patients par divers faisceaux d'ions (du proton au néon). Depuis cet arrêt, de nombreux centres cliniques dédiés uniquement à la «protonthérapie» ont été implantés à travers le monde, notamment en France à Orsay et à Nice. Actuellement, seuls le Japon et l'Allemagne sont dotés d'installations plus lourdes permettant l'hadronthérapie par des faisceaux d'ions carbone, projectiles aux propriétés balistiques et radiobiologiques notablement plus performantes que celles des protons. Cinq projets d'implantation de centres cliniques d'hadronthérapie par ions carbone sont en cours en Europe (Allemagne, Autriche, France, Italie et Suède). La réalisation du centre allemand vient de commencer à Heidelberg. Quant au projet français ETOILE (Espace de Traitement Oncologique par Ions Légers dans le cadre Européen) il vient d'être publié et ce sont ses principales caractéristiques qui sont présentées ici : nombre de patients qui pourront être traités (1000/an), mode d'accélération (synchrotron de 75 m de circonférence), nombre de salles de traitement (3), coûts d'investissement (80 M€) et d'exploitation (12 M€/an), taille des équipes médicales (58 personnes) et techniques (16), site d'implantation de référence (pôle médical Est de Lyon).

Publication Stats

190 Citations
34.28 Total Impact Points


  • 1970–2015
    • Institut de Physique Nucléaire de Lyon
      Lyons, Rhône-Alpes, France
  • 2008–2014
    • University of Lyon
      Lyons, Rhône-Alpes, France
  • 2009
    • Polytech Marseille
      Marsiglia, Provence-Alpes-Côte d'Azur, France
  • 1972–2009
    • Claude Bernard University Lyon 1
      • Institut de physique nucléaire de Lyon (IPNL)
      Villeurbanne, Rhône-Alpes, France
  • 1993–1998
    • GANIL
      Caen, Lower Normandy, France
  • 1994
    • Australian National University
      • Department of Nuclear Physics
      Canberra, Australian Capital Territory, Australia