. The Monte Carlo simulation software is a valuable tool in radiation therapy, in particular to achieve the needed accuracy in the dose evaluation for the treatment plans optimisation. The current ...challenge in this field is the time reduction to open the way to many clinical applications for which the computational time is an issue. In this manuscript we present an innovative GPU-accelerated Monte Carlo software for dose valuation in electron and photon based radiotherapy, developed as an update of the FRED (Fast paRticle thErapy Dose evaluator) software.
. The code transports particles through a 3D voxel grid, while scoring their energy deposition along their trajectory. The models of electromagnetic interactions in the energy region between 1 MeV-1 GeV available in literature have been implemented to efficiently run on GPUs, allowing to combine a fast tracking while keeping high accuracy in dose assessment. The FRED software has been bench-marked against state-of-art full MC (FLUKA, GEANT4) in the realm of two different radiotherapy applications: Intra-Operative Radio Therapy and Very High Electron Energy radiotherapy applications.
. The single pencil beam dose-depth profiles in water as well as the dose map computed on non-homogeneous phantom agree with full-MCs at 2% level, observing a gain in processing time from 200 to 5000.
. Such performance allows for computing a plan with electron beams in few minutes with an accuracy of ∼%, demonstrating the FRED potential to be adopted for fast plan re-calculation in photon or electron radiotherapy applications.
Tumour control is performed in particle therapy using particles and ions, whose high irradiation precision enhances the effectiveness of the treatment, while sparing the healthy tissue surrounding ...the target volume. Dose range monitoring devices using photons and charged particles produced by the beam interacting with the patient's body have already been proposed, but no attempt has been made yet to exploit the detection of the abundant neutron component. Since neutrons can release a significant dose far away from the tumour region, precise measurements of their flux, production energy and angle distributions are eagerly sought in order to improve the treatment planning system (TPS) software. It will thus be possible to predict not only the normal tissue toxicity in the target region, but also the risk of late complications in the whole body. The aforementioned issues underline the importance of an experimental effort devoted to the precise characterisation of neutron production, aimed at the measurement of their abundance, emission point and production energy. The technical challenges posed by a neutron detector aimed at high detection efficiency and good backtracking precision are addressed within the MONDO (monitor for neutron dose in hadrontherapy) project, whose main goal is to develop a tracking detector that can target fast and ultrafast neutrons. A full reconstruction of two consecutive elastic scattering interactions undergone by the neutrons inside the detector material will be used to measure their energy and direction. The preliminary results of an MC simulation performed using the FLUKA software are presented here, together with the DSiPM (digital SiPM) readout implementation. New detector readout implementations specifically tailored to the MONDO tracker are also discussed, and the neutron detection efficiency attainable with the proposed neutron tracking strategy are reported.
The search for a novel technology, which is able to detect and reconstruct nuclear recoil events in the keV energy range, has become increasingly important now that vast regions of high mass ...weakly-interacting-massive-particle-like dark matter candidates have been excluded. Gaseous time projection chambers (TPC) with optical readout are very promising candidates combining the complete event information provided by the TPC technique with the high sensitivity and granularity of the latest generation light sensors. A TPC with an amplification at the anode, obtained with gas electron multipliers (GEMs), was tested at the Laboratori Nazionali di Frascati. Photons and neutrons from radioactive sources were employed to induce recoiling nuclei and electrons with kinetic energy in the range 1-100 keV. A He-CF4 (60/40) gas mixture was used at atmospheric pressure and the light produced during the multiplication in the GEM channels was acquired by a high-position resolution and low-noise complementary metal-oxide semiconductor camera and a photomultiplier. A multi-stage pattern recognition algorithm based on an advanced clustering technique is presented here. A number of cluster-shaped observables are used to identify nuclear recoils induced by neutrons, which originated from a AmBe source against x-ray 55Fe photoelectrons. An efficiency of 18% to detect nuclear recoils with an energy of about 6 keV is reached, while suppressing 96% of the 55Fe photoelectrons, making this optical read-out gas TPC a very promising candidate for future investigations of ultra-rare events such as directional direct dark matter searches.
Abstract In recent years, there has been a significant focus on improving the effectiveness of radiotherapy (RT) and particle therapy in treating tumors while minimizing damage to healthy tissue. A ...promising development is offered by the observation of the so-called FLASH effect, where ultra-high dose rates delivered in a short time have shown to protect healthy tissues while maintaining anti-tumor efficacy. However, conventional detectors face challenges in monitoring charged beams at these ultra-high dose rates due to non-linear effects. To address this challenge, the FlashDC (Flash Detector beam Counter) has been developed. It uses air fluorescence to monitor beam fluence and spatial distribution in real-time with high accuracy and minimal impact on treatment delivery. This innovative detector offers a linear response for various charged beams, dose rates, and energies, making it a cost-effective solution. Multiple prototypes have been developed and optimized using Monte Carlo simulations. The analysis of data from recent test beam campaigns with electrons delivered at FLASH intensities has demonstrated a linear correlation between the detector signal and the delivered dose per pulse, confirming that fluorescence can be used for beam monitoring in FLASH-RT studies. This contribution introduces the FlashDC monitor, discusses its expected performance, and presents preliminary test beam results obtained with electron beams in FLASH mode.
The radiation used in hadrontherapy treatments interacts with the patient body producing secondary particles, either neutral or charged, that can be used for dose and Bragg peak monitoring and to ...provide a fast feedback on the treatment plans. Recent results obtained from the authors on simplified setups (mono-energetic primary beams interacting with homogeneous tissue-like target) have already indicated the correlation that exists between the flux of these secondaries coming from the target (e.g. protons and photons) and the position of the primary beam Bragg peak. In this paper, the measurements of charged particle fluxes produced by the interaction of a 220 MeV/u carbon ion beam at GSI, Darmstadt, with a polymethyl methacrylate target are reported. The emission region of protons (p), deuterons (d) and tritons (t) has been characterized using a drift chamber while the particle time-of-flight, used to compute the kinetic energy spectra, was measured with a LYSO scintillator. The energy released in the LYSO crystal was used for particle identification purposes. The measurements were repeated with the setup at 60° and 90° with respect to the primary beam direction. The accuracy on the fragments emission profile reconstruction and its relationship with the Bragg peak position have been studied. Based on the acquired experimental evidence, a method to monitor the dose profile and the position of the Bragg peak inside the target is proposed.
The high dose conformity and healthy tissue sparing achievable in Particle Therapy when using C ions calls for safety factors in treatment planning, to prevent the tumor under-dosage related to the ...possible occurrence of inter-fractional morphological changes during a treatment. This limitation could be overcome by a range monitor, still missing in clinical routine, capable of providing on-line feedback. The Dose Profiler (DP) is a detector developed within the INnovative Solution for In-beam Dosimetry in hadronthErapy (INSIDE) collaboration for the monitoring of carbon ion treatments at the CNAO facility (Centro Nazionale di Adroterapia Oncologica) exploiting the detection of charged secondary fragments that escape from the patient. The DP capability to detect inter-fractional changes is demonstrated by comparing the obtained fragment emission maps in different fractions of the treatments enrolled in the first ever clinical trial of such a monitoring system, performed at CNAO. The case of a CNAO patient that underwent a significant morphological change is presented in detail, focusing on the implications that can be drawn for the achievable inter-fractional monitoring DP sensitivity in real clinical conditions. The results have been cross-checked against a simulation study.
The MOnitor for Neutron Dose in hadrOntherapy (MONDO) project addresses the technical challenges posed by a neutron tracker detector aiming for a high detection efficiency and a good backtracking ...precision. The project aims to develop a tracking device capable of fully reconstructing the four momentum of fast and ultrafast secondary neutrons produced, e.g., in particle therapy (PT) treatments or in other physical processes. The MONDO tracker uses, as active material, squared scintillating fibers readout by dedicated CMOS-based digital single-photon avalanche diode (SPAD) array sensors. The expected light output, when operating in neutron monitoring applications, was experimentally evaluated in order to optimize the design of the MONDO detector readout. A small detector prototype (4 × 4 × 4.8 cm) has been built and tested at a test beam facility. The detection capabilities have been measured using a traditional photomultiplier (PMT) and a particle beam of 450-MeV electrons crossing a single layer of fibers. The observed number of photoelectrons in this case is (7.2 ± 1.4). A detector prototype was also tested with an SPAD-based SBAM (SPAD-Based Acquisition readout for MONDO experiment) sensor (SPADnet-I) to study the tracking performances. SBAM is a novel sensor developed to match the need of high single-photon detection efficiency and high spatial resolution and compactness. The sensor expected performance is discussed in view of an operation tailored for PT applications. In this contribution, we also report the results of a simulation performed to optimize the full MONDO detector layout.
The high dose conformity and healthy tissue sparing achievable in Particle Therapy when using C ions calls for safety factors in treatment planning, to prevent the tumor under-dosage related to the ...possible occurrence of inter-fractional morphological changes during a treatment. This limitation could be overcome by a range monitor, still missing in clinical routine, capable of providing on-line feedback. The Dose Profiler (DP) is a detector developed within the INnovative Solution for In-beam Dosimetry in hadronthErapy (INSIDE) collaboration for the monitoring of carbon ion treatments at the CNAO facility (Centro Nazionale di Adroterapia Oncologica) exploiting the detection of charged secondary fragments that escape from the patient. The DP capability to detect inter-fractional changes is demonstrated by comparing the obtained fragment emission maps in different fractions of the treatments enrolled in the first ever clinical trial of such a monitoring system, performed at CNAO. The case of a CNAO patient that underwent a significant morphological change is presented in detail, focusing on the implications that can be drawn for the achievable inter-fractional monitoring DP sensitivity in real clinical conditions. The results have been cross-checked against a simulation study.
Abstract FOOT (FragmentatiOn Of Target) is an applied nuclear physics experiment with the aim of performing high precision cross section measurements for fragmentation reactions of interest in ...hadrontherapy and radiation protection in space. The physics program of the experiment foresees a set of measurements with light ion beams, such as C and O, in the energy range of 100–800 MeV/u interacting with tissue-like and shielding material targets. The setup was initially conceived for the detection of charged fragments and, in 2021, the Collaboration started the study of possible solutions for neutron detection. Two detection systems have been proposed: one based on BC-501A liquid scintillators with neutron/ γ discrimination capabilities and a system based on BGO crystals operated in phoswich mode. In 2022, a dedicated data acquisition campaign was carried out at the n_TOF facility at CERN to evaluate the capabilities of the two systems. First, the neutron/ γ discrimination efficiency of the BC-501A system was studied using radioactive sources. Then, the two systems were placed in the n_TOF experimental area to study their neutron detection efficiency under a well characterized neutron beam. In this work, the first preliminary results concerning the characterization of the two possible neutron detectors of FOOT are presented.
Combined readout of a triple-GEM detector Antochi, V.C.; Baracchini, E.; Cavoto, G. ...
Journal of instrumentation,
05/2018, Letnik:
13, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Optical readout of GEM based devices by means of high granularity and low noise CMOS sensors allows to obtain very interesting tracking performance. Space resolution of the order of tens of μm were ...measured on the GEM plane along with an energy resolution of 20%÷30%. The main limitation of CMOS sensors is represented by their poor information about time structure of the event. In this paper, the use of a concurrent light readout by means of a suitable photomultiplier and the acquisition of the electric signal induced on the GEM electrode are exploited to provide the necessary timing informations. The analysis of the PMT waveform allows a 3D reconstruction of each single clusters with a resolution on z of 100 μm. Moreover, from the PMT signals it is possible to obtain a fast reconstruction of the energy released within the detector with a resolution of the order of 25% even in the tens of keV range useful, for example, for triggering purpose.
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