Studies of the performance of a detector dedicated to ballistic control during hadrontherapy treatments using Monte-Carlo simulation code

L'utilisation de faisceaux d’ions (protons ou ions légers) permet d'obtenir, lors du traitement, un dépôt d'énergie localisé en fin de parcours dans une zone réduite de l'espace. Les cibles privilégiées pour cette thérapie sont les tumeurs « radiorésistantes » ou les traitements nécessitant une balistique très précise, du fait de la présence d'organes à risques à proximité de la tumeur. Cependant, comme la détermination du parcours des ions et donc de la dose délivrée est dépendante de grandeurs qui restent difficiles à mesurer précisément, d’importantes marges de sécurité doivent être prises lors de la conception du plan de traitement. En conséquence, il est nécessaire de mettre en place un système performant de contrôle balistique afin de garantir la qualité du traitement. Une des possibilités pour le contrôle balistique repose sur la mesure en temps réel de la distribution spatiale des radionucléides émetteurs de positons produits par réaction de fragmentation entre le projectile et la cible et donc sur la détection en coïncidence de deux photons. Pour cela, un premier prototype appelé Détecteur Pixélisé de Grande Acceptance (DPGA) a été conçu puis construit au sein du laboratoire de Physique de Clermont. Dans un premier temps, ce travail a permis de comparer les prédictions de deux modèles hadroniques implémentés dans Geant4 aux mesures expérimentales effectuées par une autre équipe (Dendooven et al.) à 55 MeV. Ensuite, nous nous sommes attachés à caractériser les performances du DPGA et à déterminer son potentiel lors de son utilisation en faisceau clinique. Pour cela nous avons développé une simulation Monte-Carlo dédiée permettant de comprendre la physique associée, le détecteur et les expériences effectuées sur faisceau de protons 65 MeV à l’Institut méditerranéen de Protonthérapie (IMPT) de Nice. Enfin, comme le DPGA sera à terme couplé avec un système d’acquisition à grande bande passante (μTCA) autorisant l’envoi et le traitement des données mesurées en temps réel, nous avons fait une étude des performances attendues sur la ligne PROTEUS ONE de l'IMPT à 120 et 230 MeV.The use of ion beams (protons or light ions) makes it possible to obtain, during treatment, a localised energy deposit at the end of the treatment in a small area of space. The preferred targets for this therapy are "radioresistant" tumours or treatments requiring very precise ballistics, due to the presence of high-risk organs close to the tumour. However, as the determination of the ion path and thus the delivered dose is dependent on quantities that are difficult to measure precisely, large safety margins must be taken into account when designing the treatment plan. Consequently, it is necessary to set up an efficient ballistic control system in order to guarantee the quality of the treatment. One of the possibilities for ballistic control is based on the real-time measurement of the spatial distribution of positron-emitting radionuclides produced by the fragmentation reaction between the projectile and the target and thus on the coincident detection of two photons. For this purpose, a first prototype called Large Area Pixelized Detector (LAPD) was designed and built at the Clermont Physics Laboratory. Initially, this work allowed to compare the predictions of two hadronic models implemented in Geant4 with experimental measurements performed by Dendooven et al. at 55 MeV. We then focused on characterizing the performance of the LAPD and determining its potential when used in a clinical beam. For this purpose, we developed a Monte-Carlo simulation dedicated to understand the associated physics, the detector and the experiments carried out on 65 MeV proton beam at the Institut Mediterranéen de Protonthérapie (IMPT) in Nice. Finally, as the LPAD will eventually be coupled with a high-bandwidth acquisition system (μTCA) allowing the sending and processing of the measured data in real time, we have made a study of the performances expected on the PROTEUS ONE line of the IMPT at 120 and 230 MeV

Etudes des performances d'un détecteur dédié au contrôle balistique lors des traitements d'hadronthérapie par simulation Monte-Carlo

The use of ion beams (protons or light ions) makes it possible to obtain, during treatment, a localised energy deposit at the end of the treatment in a small area of space. The preferred targets for this therapy are "radioresistant" tumours or treatments requiring very precise ballistics, due to the presence of high-risk organs close to the tumour. However, as the determination of the ion path and thus the delivered dose is dependent on quantities that are difficult to measure precisely, large safety margins must be taken into account when designing the treatment plan. Consequently, it is necessary to set up an efficient ballistic control system in order to guarantee the quality of the treatment. One of the possibilities for ballistic control is based on the real-time measurement of the spatial distribution of positron-emitting radionuclides produced by the fragmentation reaction between the projectile and the target and thus on the coincident detection of two photons. For this purpose, a first prototype called Large Area Pixelized Detector (LAPD) was designed and built at the Clermont Physics Laboratory. Initially, this work allowed to compare the predictions of two hadronic models implemented in Geant4 with experimental measurements performed by Dendooven et al. at 55 MeV. We then focused on characterizing the performance of the LAPD and determining its potential when used in a clinical beam. For this purpose, we developed a Monte-Carlo simulation dedicated to understand the associated physics, the detector and the experiments carried out on 65 MeV proton beam at the Institut Mediterranéen de Protonthérapie (IMPT) in Nice. Finally, as the LPAD will eventually be coupled with a high-bandwidth acquisition system (μTCA) allowing the sending and processing of the measured data in real time, we have made a study of the performances expected on the PROTEUS ONE line of the IMPT at 120 and 230 MeV.L'utilisation de faisceaux d’ions (protons ou ions légers) permet d'obtenir, lors du traitement, un dépôt d'énergie localisé en fin de parcours dans une zone réduite de l'espace. Les cibles privilégiées pour cette thérapie sont les tumeurs « radiorésistantes » ou les traitements nécessitant une balistique très précise, du fait de la présence d'organes à risques à proximité de la tumeur. Cependant, comme la détermination du parcours des ions et donc de la dose délivrée est dépendante de grandeurs qui restent difficiles à mesurer précisément, d’importantes marges de sécurité doivent être prises lors de la conception du plan de traitement. En conséquence, il est nécessaire de mettre en place un système performant de contrôle balistique afin de garantir la qualité du traitement. Une des possibilités pour le contrôle balistique repose sur la mesure en temps réel de la distribution spatiale des radionucléides émetteurs de positons produits par réaction de fragmentation entre le projectile et la cible et donc sur la détection en coïncidence de deux photons. Pour cela, un premier prototype appelé Détecteur Pixélisé de Grande Acceptance (DPGA) a été conçu puis construit au sein du laboratoire de Physique de Clermont. Dans un premier temps, ce travail a permis de comparer les prédictions de deux modèles hadroniques implémentés dans Geant4 aux mesures expérimentales effectuées par une autre équipe (Dendooven et al.) à 55 MeV. Ensuite, nous nous sommes attachés à caractériser les performances du DPGA et à déterminer son potentiel lors de son utilisation en faisceau clinique. Pour cela nous avons développé une simulation Monte-Carlo dédiée permettant de comprendre la physique associée, le détecteur et les expériences effectuées sur faisceau de protons 65 MeV à l’Institut méditerranéen de Protonthérapie (IMPT) de Nice. Enfin, comme le DPGA sera à terme couplé avec un système d’acquisition à grande bande passante (μTCA) autorisant l’envoi et le traitement des données mesurées en temps réel, nous avons fait une étude des performances attendues sur la ligne PROTEUS ONE de l'IMPT à 120 et 230 MeV

Projet BePAT : BeaQuant, un autoradiographe numérique au service de la production de radionucléides pour des applications en médecine nucléaire

International audienc

Latest development of α emitter imaging and quantification on a large Field Of View for Targeted Alpha Therapy applications

International audienceIntroductionAlthough very promising, the development of Targeted Alpha Therapy (TAT) requires the use of accurate techniques that can identify and quantify individual radionuclides in different matrices. However, currently, characterization of the nature and spatial distribution of radionuclides in a sample is time consuming and fastidious. Indeed, it necessarily requires the use of two distinct analytical techniques and detectors of different nature. Moreover, the resolutions of the two methods are often different from each other because they also depend on the nature of the detector used, which makes it difficult to integrate and interpret these two types of measurements together. To overcome these limitations, as well as to simplify and to accelerate the measurement process, it is now possible to use a digital autoradiograph capable of combining the measurement of the spatial distribution with the ability to separate and quantify each radionuclide.Description of the Work or ProjectFor this purpose, a set of temporal and energy spectrometry techniques had to be specifically developed. On the one hand, the use of instruments capable of recording the location of each decay product allows to measure the evolution of the activity of the sample and thus, to deduce the contributions of several radionuclides. On the other hand, the development of an innovative method of autoradiography spectroscopy in particle energy also allows to separate them by measuring their initial energy. Even if the efficiency of energy spectrum reconstruction is low (<5%) compared to the efficiency of a simple autoradiograph (50%), this novel measurement approach offers the opportunity to select areas on an autoradiograph to perform an energy spectrum analysis within that area. Although if the samples usable on this type of instrument must generally be of solid nature, recent developments show that it is possible to use fluid samples (liquid or gas) with a cell system. Eventually, the proposed measurement system could allow dynamic imaging of radionuclides of interest.ConclusionsFrom an application point of view, this opens up possibilities for theragnostic applications that typically use two radionuclides. Further upstream, it can optimize the production and distribution challenge of α radionuclides by allowing the identification and characterization of individual radionuclides in radionuclide chains such as 225Ac. Moreover, the measurement system and the associated method could strongly contribute to facilitate research on the biodistribution of α radionuclides.ReferencesLefeuvre, H., Donnard, J., Descostes, M., Billon, S., Duval, S., Oger, T., Toubon, H. & Sardini, P. (2022). Spectroscopic Autoradiography of Alpha Particles Using a Parallel Ionization Multiplier Gaseous Detector. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. https://doi.org/10.1016/j.nima.2022.16680

Projet BePAT : BeaQuant, un autoradiographe numérique au service de la production de radionucléides pour des applications en médecine nucléaire

International audienc

Latest development of α emitter imaging and quantification on a large Field Of View

International audienceCurrently, the characterization of the nature and spatial distribution of radionuclides in a sample is time consuming and fastidious. Indeed, it necessarily requires the use of two distinct analytical techniques and detectors of a different nature. Moreover, the resolutions of the two methods are often different from each other because they also depend on the nature of the detector used, which makes it difficult to integrate and interpret these two types of measurements together.To overcome these limitations and to simplify and accelerate the measurement process, it is now possible to use a digital autoradiograph capable of combining the measurement of the spatial distribution with the ability to separate and quantify each radionuclide.For this purpose, a set of temporal and energy spectrometry techniques had to be specifically developed. On the one hand, the use of instruments capable of recording the location of each decay product allows measuring the evolution of the activity of the sample and thus, to deduce the contributions of several radionuclides. On the other hand, the development of an innovative method of autoradiography spectroscopy in particle energy also allows separating them by measuring their initial energy. Even if the efficiency of energy spectrum reconstruction is low (4.4%) compared to the efficiency of a simple autoradiograph (50%), this novel measurement approach offers the opportunity to select areas on an autoradiograph to perform an energy spectrum analysis within that area.From an application point of view, this opens up possibilities for theragnostic applications that typically use two radionuclides. Further upstream, it can optimize the production and distribution challenge of α radionuclides by allowing the identification and characterization of individual radionuclides in radionuclide chains such as 225Ac

BeaQuant, un autoradiographe numérique au service de la production de radionucléides pour des applications en médecine nucléaire

International audienceOne of the main difficulties in the development of radionuclides in nuclear medicine is related to the optimization of their production. As these are, in most cases, produced using a nuclear reactor or a particle accelerator, it is important to define optimal production methods in order to obtain a final product with the highest possible isotopic and chemical purity. In addition to production and distribution challenges, incomplete identification and spectroscopic characterization can sometimes be a limiting factor in determining the full potential of a radionuclide. This is particularly the case for heavy Auger radionuclides (Z>40) where the number of Auger electrons emitted remains a theoretical value [1].The BePAT project aims to demonstrate that it is possible to overcome these limitations by using a digital autoradiograph. Thus, through the exploratory study of the theragnostic β+/Auger couple, iridium, 187 and 189, we want to show that it is possible to identify and distinguish contaminants efficiently. Indeed, the production of these radionuclide with an alpha beam and a natural rhenium foil is inevitably accompanied by the production of contaminants that are difficult to separate chemically, such as iridium, 188 and 190.In parallel, part of the project will focus on the possibility of performing localized α-spectrometry of irradiated targets. While waiting to be able to acquire elements heavier than bismuth again, the project will also focus on astatine-211, the production of which is well-mastered at the GIP ARRONAX site located in Saint-Herblain.[1] D. Filosofov, E. Kurakina, et V. Radchenko, « Potent candidates for Targeted Auger Therapy : Production and radiochemical considerations », Nucl. Med. Biol., vol. 94‑95, p. 1‑19, mars 2021, doi : 10.1016/j.nucmedbio.2020.12.001Funding : Plan de relance - ANR-21-PRRD-0027-0

A digital real-time high-resolution imaging system to quantify and identify all emitted charged particles

International audienceThis paper describes an instrumentation imaging system that provides, at real-time, localization, quantification and identification of a radioactive source with a precision up to 20μm. The localization of each decay position is obtained with using a parallel ionization multiplier gaseous detector and a reconstruction algorithm. The spatial identification of the composition of the radioactive source is performed by an original specific set of temporal and energy spectrometry techniques. The system allows with a single detector to combine the measurement of the spatial distribution with the ability to separate and quantify at real time each radionuclide. From an application point of view, this system opens up possibilities for theragnostic applications that typically use two radionuclides. Further upstream, it can optimize the production and distribution challenge of α radionuclides by allowing the identification and characterization of individual radionuclides in radionuclide chains such as 225Ac. Moreover, themeasurement system and the associated method could strongly contribute to facilitate research on the biodistribution of αradionuclides that are by their nature difficult to characterize by standard methods

A digital real-time high-resolution imaging system to quantify and identify all emitted charged particles

International audienceThis paper describes an instrumentation imaging system that provides, at real-time, localization, quantification and identification of a radioactive source with a precision up to 20μm. The localization of each decay position is obtained with using a parallel ionization multiplier gaseous detector and a reconstruction algorithm. The spatial identification of the composition of the radioactive source is performed by an original specific set of temporal and energy spectrometry techniques. The system allows with a single detector to combine the measurement of the spatial distribution with the ability to separate and quantify at real time each radionuclide. From an application point of view, this system opens up possibilities for theragnostic applications that typically use two radionuclides. Further upstream, it can optimize the production and distribution challenge of α radionuclides by allowing the identification and characterization of individual radionuclides in radionuclide chains such as 225Ac. Moreover, themeasurement system and the associated method could strongly contribute to facilitate research on the biodistribution of αradionuclides that are by their nature difficult to characterize by standard methods

Latest development of α emitter imaging and quantification on a large Field Of View for Targeted Alpha Therapy applications

International audienceIntroductionAlthough very promising, the development of Targeted Alpha Therapy (TAT) requires the use of accurate techniques that can identify and quantify individual radionuclides in different matrices. However, currently, characterization of the nature and spatial distribution of radionuclides in a sample is time consuming and fastidious. Indeed, it necessarily requires the use of two distinct analytical techniques and detectors of different nature. Moreover, the resolutions of the two methods are often different from each other because they also depend on the nature of the detector used, which makes it difficult to integrate and interpret these two types of measurements together. To overcome these limitations, as well as to simplify and to accelerate the measurement process, it is now possible to use a digital autoradiograph capable of combining the measurement of the spatial distribution with the ability to separate and quantify each radionuclide.Description of the Work or ProjectFor this purpose, a set of temporal and energy spectrometry techniques had to be specifically developed. On the one hand, the use of instruments capable of recording the location of each decay product allows to measure the evolution of the activity of the sample and thus, to deduce the contributions of several radionuclides. On the other hand, the development of an innovative method of autoradiography spectroscopy in particle energy also allows to separate them by measuring their initial energy. Even if the efficiency of energy spectrum reconstruction is low (<5%) compared to the efficiency of a simple autoradiograph (50%), this novel measurement approach offers the opportunity to select areas on an autoradiograph to perform an energy spectrum analysis within that area. Although if the samples usable on this type of instrument must generally be of solid nature, recent developments show that it is possible to use fluid samples (liquid or gas) with a cell system. Eventually, the proposed measurement system could allow dynamic imaging of radionuclides of interest.ConclusionsFrom an application point of view, this opens up possibilities for theragnostic applications that typically use two radionuclides. Further upstream, it can optimize the production and distribution challenge of α radionuclides by allowing the identification and characterization of individual radionuclides in radionuclide chains such as 225Ac. Moreover, the measurement system and the associated method could strongly contribute to facilitate research on the biodistribution of α radionuclides.ReferencesLefeuvre, H., Donnard, J., Descostes, M., Billon, S., Duval, S., Oger, T., Toubon, H. & Sardini, P. (2022). Spectroscopic Autoradiography of Alpha Particles Using a Parallel Ionization Multiplier Gaseous Detector. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. https://doi.org/10.1016/j.nima.2022.16680