Showing papers by "G.A.P. Cirrone published in 2023"

Proton boron capture therapy (PBCT) induces cell death and mitophagy in a heterotopic glioblastoma model

Abstract: Abstract Despite aggressive therapeutic regimens, glioblastoma (GBM) represents a deadly brain tumor with significant aggressiveness, radioresistance and chemoresistance, leading to dismal prognosis. Hypoxic microenvironment, which characterizes GBM, is associated with reduced therapeutic effectiveness. Moreover, current irradiation approaches are limited by uncertain tumor delineation and severe side effects that comprehensively lead to unsuccessful treatment and to a worsening of the quality of life of GBM patients. Proton beam offers the opportunity of reduced side effects and a depth-dose profile, which, unfortunately, are coupled with low relative biological effectiveness (RBE). The use of radiosensitizing agents, such as boron-containing molecules, enhances proton RBE and increases the effectiveness on proton beam-hit targets. We report a first preclinical evaluation of proton boron capture therapy (PBCT) in a preclinical model of GBM analyzed via μ-positron emission tomography/computed tomography (μPET-CT) assisted live imaging, finding a significant increased therapeutic effectiveness of PBCT versus proton coupled with an increased cell death and mitophagy. Our work supports PBCT and radiosensitizing agents as a scalable strategy to treat GBM exploiting ballistic advances of proton beam and increasing therapeutic effectiveness and quality of life in GBM patients.

A Methodology for the Discrimination of Alpha Particles from Other Ions in Laser-Driven Proton-Boron Reactions Using CR-39 Detectors Coupled in a Thomson Parabola Spectrometer

Abstract: Solid-state nuclear track detectors (CR-39 type) are frequently used for the detection of ions accelerated by laser-plasma interaction because they are sensitive to each single particle. To the present day, CR-39 detectors are the main diagnostics in experiments focused on laser-driven proton-boron (p11B) fusion reactions to detect alpha particles, which are the main products of such a nuclear reaction, and to reconstruct their energy distribution. However, the acceleration of multispecies ions in the laser-generated plasma makes this spectroscopic method complex and often does not allow to unambiguously discriminate the alpha particles generated from p11B fusion events from the laser-driven ions. In this experimental work, performed at the PALS laser facility (600 J, 300 ps, laser intensity 1016 W/cm2), CR-39 detectors were used as main detectors for the angular distribution of the produced alpha particles during a p11B fusion dedicated experimental campaign. Additionally, a CR-39 detector was set inside a Thomson Parabola (TP) spectrometer with the aim to calibrate the CR-39 response for low energetic laser-driven ions originating from the plasma in the given experimental conditions. The detected ion energies were ranging from hundreds of keV to a few MeV, and the ion track diameters were measured for etching times up to 9 hours. The goal of the test was the evaluation of the detectors’ ability to discriminate the alpha particles from the aforementioned ions. Within this study, the calibration curves for protons and silicon low energy ions are accomplished, the overlapping of the proton tracks and alpha particles is verified, and a methodology to avoid this problem is realized.

A New Approach for NaI(Tl) Detector Efficiency Calibration Using 41Ar Radionuclide for Air Exhaust Systems

Abstract: Argon-41 is an essential gaseous radionuclide that must be monitored in gaseous effluents from nuclear facilities. Therefore, a precise evaluation of 41Ar activity is highly desired. Gamma spectroscopy with a NaI(Tl) scintillation detector coupled with a multichannel analyzer (MCA) is one of the widely used techniques for the identification and activity measurements of radioisotopes. However, the efficiency calibration of these kinds of monitoring systems highly depends on the source-detector geometry, and a large amount of uncertainty may complicate the calibration. This paper presents the evaluation of the full peak efficiency of a 2 × 2-in. NaI(Tl) scintillation detector coupled with a stable MCA for a 41Ar source with 1293.5 keV energy in two different source-detector geometries, duct and Marinelli beaker, using the FLUKA code. A new experimental technique is considered to produce 41Ar in a controlled geometry, like a Marinelli beaker, through neutron irradiation of natural argon inside a cyclotron bunker. The simulation data were compared with the experimental results for Marinelli beaker geometry, and the ratio was evaluated as 0.99 ± 0.07. The ratio was considered a scaling factor for the final efficiency calibration of duct geometry.

Design of a compact Thomson Parabola Spectrometer for diagnostics of proton-boron fusion reaction products initiated by laser

Abstract: The proton-boron aneutronic fusion reaction has numerous potential applications varying from controlled nuclear fusion reactor to broad-energy spectrum α-particle source, as well as uses in medicine, where it can serve as a source for radioisotope production, or directly in proton boron capture therapy. However, proton-boron fusion reaction and its by-products should be investigated extensively to provide a stable and controlled secondary ion source. In order to monitor the multi-ion beam emitted and accelerated from the target surface after interaction with laser pulses, a new Thomson Parabola Spectrometer (TPS) has been designed to differentiate proton and alpha traces in the energy ranges 0.5–5 MeV and 1–10 MeV respectively, with a high energy resolution (≤ 1%), while maintaining compactness of the spectrometer (∼ 20 cm).

Liquid jet target system for laser-plasma interactions at kHz repetition rate

Abstract: We have developed a compact liquid target setup that produces a continuous ø50 µm cylindrical water jet, capable of operating at high vacuum. It has been tested with a commercial ultrashort-pulse laser in a series of proof-of-principle laser-driven ion acceleration and x-ray generation experiments at repetition rates up to 1 kHz. In optimized conditions, measurements by the time-of-flight (TOF) method have demonstrated a proton signal cut-off energy of 179±9 keV. The laser-generated x-ray emission was characterized in the range 2-36 keV and used as excitation for x-ray fluorescence spectroscopy (XRF) measurements.

Hydrogenated amorphous silicon high flux x-ray detectors for synchrotron microbeam radiation therapy

Abstract: Objective. Microbeam radiation therapy (MRT) is an alternative emerging radiotherapy treatment modality which has demonstrated effective radioresistant tumour control while sparing surrounding healthy tissue in preclinical trials. This apparent selectivity is achieved through MRT combining ultra-high dose rates with micron-scale spatial fractionation of the delivered x-ray treatment field. Quality assurance dosimetry for MRT must therefore overcome a significant challenge, as detectors require both a high dynamic range and a high spatial resolution to perform accurately. Approach. In this work, a series of radiation hard a-Si:H diodes, with different thicknesses and carrier selective contact configurations, have been characterised for x-ray dosimetry and real-time beam monitoring applications in extremely high flux beamlines utilised for MRT at the Australian Synchrotron. Results. These devices displayed superior radiation hardness under constant high dose-rate irradiations on the order of 6000 Gy s−1, with a variation in response of 10% over a delivered dose range of approximately 600 kGy. Dose linearity of each detector to x-rays with a peak energy of 117 keV is reported, with sensitivities ranging from (2.74 ± 0.02) nC/Gy to (4.96 ± 0.02) nC/Gy. For detectors with 0.8 μm thick active a-Si:H layer, their operation in an edge-on orientation allows for the reconstruction of micron-size beam profiles (microbeams). The microbeams, with a nominal full-width-half-max of 50 μm and a peak-to-peak separation of 400 μm, were reconstructed with extreme accuracy. The full-width-half-max was observed as 55 ± 1 μm. Evaluation of the peak-to-valley dose ratio and dose-rate dependence of the devices, as well as an x-ray induced charge (XBIC) map of a single pixel is also reported. Significance. These devices based on novel a-Si:H technology possess a unique combination of accurate dosimetric performance and radiation resistance, making them an ideal candidate for x-ray dosimetry in high dose-rate environments such as FLASH and MRT.

Array of time-of-flight diamond detectors for particle discrimination in laser driven p-11B fusion experiments

Abstract: The detection of radiation emission in laser induced plasma experiments is an helpful method for gaining information on the physics of laser-matter interaction. Time-of-Flight (TOF) approach is a powerful and effective method to obtain timely spectra of particles accelerated from laser-generated plasma. To this respect, diamond-based detectors are very attractive due to their interesting features such as fast signal collection time, signal proportional to the energy deposited by the incident radiation, blindness to visible radiation, high radiation hardness and low leakage current at room temperature operation. Unfortunately, they cannot supply discrimination on the species of the incoming ions, but only their energies. This may be overcome using specific filtering foils to exploit the different stopping powers of ions of different species and energies. In this work we describe the method to distinguish particles using an array of TOF diamond detectors. A first prototype array, consisting of 2×2 diamond detectors, nominally identical and featuring by aluminum filters of different thicknesses, was developed and preliminary tested at PALS facility in Prague.

X-ray qualification of hydrogenated amorphous silicon sensors on flexible substrate

Abstract: Hydrogenated amorphous silicon (a-Si:H) is a well known material for its radiation resistance and for the possibility of deposition on flexible substrates like Polyimide (PI), polyethylene terephthalate (PET) or polyethylene naphthalate (PEN). Due to the properties of a-Si:H its usage for dosimetry, beam monitoring for particle physics and nuclear medicine, as well as, radiation flux measurement for space applications and neutron flux measurement can be foreseen. In this paper the dosimetric X-ray response of p-i-n diodes deposited on Polyimide will be studied. In particular we will study the linearity of the photocurrent response to X-rays versus dose-rate from which we will extract the dosimetric sensitivity at various bias voltages. We will repeat this study for devices having two different areas (2 mm x 2 mm and 5 mm x 5 mm) also a measurement of stability of X-ray response versus time will be shown.

High-Sensitivity Thomson Spectrometry in Experiments of Laser-Driven Low-Rate NeutronLess Fusion Reactions

Abstract: The aneutronic 11B(p, α)2α fusion reaction driven by the interaction of high-energy lasers with matter has become a popular topic of research, since it represents a potential long-term goal alternative to the most studied deuterium-tritium reaction. However, the detection of the typical ionic products, especially alpha particles, of this low-rate fusion reaction is a challenging issue, due to their low flux. One of the diagnostic devices that can be implemented in laser-driven proton-boron fusion experiments is a Thomson spectrometer (TS), which is capable of detecting and discriminating ions according to their mass-to-charge ratio ( A / Z , where A is the mass number and Z is the atomic number of the ions). In this work, we report on the ultimate test of a TS, which was designed and developed at the ENEA Research Centre in Frascati, Italy, in the context of a p + 11B fusion experiment. Our device—designed to have high sensitivity and a robust shielding against electromagnetic pulses (EMPs)—was implemented at the PALS laser facility (∼700 J in ∼350 ps pulses) at a distance of 367 mm from the laser-plasma interaction point. We analyse here the measured signals obtained with our device, focusing on the assessment of their signal-to-background ratio. Despite the presence of strong EMPs and background radiation at such a short distance from the laser-irradiated target, the TS proved to be suitable for effectively detecting protons and heavier ions stemming from the plasma source.

A Hydrogenated amorphous silicon detector for Space Weather Applications

Abstract: The characteristics of a hydrogenated amorphous silicon (a-Si:H) detector are presented here for monitoring in space solar flares and the evolution of large energetic proton events up to hundreds of MeV. The a-Si:H presents an excellent radiation hardness and finds application in harsh radiation environments for medical pur-poses, for particle beam characterization and in space weather science and applications. The critical flux detection threshold for solar X rays, soft gamma rays, electrons and protons is discussed in detail