Thesis opportunities
Topics:
Modeling parameters of interest in radiobiology (LET, RBE) using a Monte Carlo approach at both macro and micro-dosimetric scale.
Supervisors:
GA Pablo Cirrone (INFN-LNS), pablo.cirrone@lns.infn.it
Giada Petringa (INFN-LNS), giada.petringa@lns.infn.it
A reliable prediction of the spatial Linear Energy Transfer (LET) distribution in biological tissue is a crucial point for the estimation of the radiobiological parameters on which are based the current treatment planning. Nowadays, the accuracy and approach for the LET calculation can significantly affect the reliability of the calculated Relative Biological Effectiveness (RBE).
Monte Carlo (MC) technique is considered the most accurate method to account for complex radiation transport effects and energy losses in a medium. However, as a computation method, the accuracy and precision of the MC calculation result strongly depend on the physics interaction cross sections applied as well as the simulation algorithms used and the transport parameters are chosen. In this framework, the goal of the project consists on the development, study and validation of a completely new open source tool based on Geant4 code for the calculation of the LET-track, LET-dose and RBE distributions of therapeutic proton and ion beam completely independent to transport parameters.
Laser-matter acceleration project: dosimetry, diagnostic and generation of radiation beam from laser-matter interaction
Supervisors:
GA Pablo Cirrone (INFN-LNS), pablo.cirrone@lns.infn.it
Giada Petringa (INFN-LNS), giada.petringa@lns.infn.it
** This is a thesis work envisaging experimental measurements campaigns at International laboratories
INFN-LNS realized the first Users'-open beamline (called ELIMED) completed dedicated to the transport of proton/ion beams generated in the laser-matter interaction. The ELIMED beamline is now installed at the ELI-Beamlines facility (Prague, CZ) and first experiments with this new accelerated beams will start within the end of 2019.
INFN-LNS also developed and realized the dosimetric system of the beamline and will be responsible for the first cells irradiations that will be carried out within 2020.
The thesis work will be focused on the characterization of the developed dosimetric devices (ionization chambers, Faraday cup, Gafchromic films, ...) and on the preparation of the first experimental runs at the ELI-Beamline facility.
Travels to ELI-Beamlines (CZ) and other facilities will be expected
Investigation of new irradiation and imaging approaches to enhance the radiobiological effectiveness of proton beam using nuclear reactions. Experimental and simulation activities
Supervisors:
Giacomo Cuttone (INFN-LNS), cuttone@lns.infn.it
GA Pablo Cirrone (INFN-LNS), pablo.cirrone@lns.infn.it
** This is a thesis work envisaging experimental measurements campaigns at International laboratories
A charged particle inverted dose-depth profile represents the physical pillar of protontherapy. Reduced integral dose to healthy tissues entails lessened risk of adverse effects. On the other hand, there is no obvious radiobiological advantage in the use of protons since their LET in the clinical energy range (a few keV/micron) is too low to achieve a cell-killing effect significantly greater than in conventional radiotherapy. Thus, enhancing proton RBE is desirable. To this end, the INFN-funded NEPTUNE (Nuclear process-driven Enhancement of Proton Therapy UNravEled) project will exploit the possibility to use the p + 11B → 3α reaction to generate high-LET alpha particles with a clinical proton beam. The p-11B reaction will be studied in all their relevant aspects: from modeling (using analytical and Monte Carlo approaches) to microdosimetry and radiobiology.
Dosimetric approaches and detector developments for "Flash radiotherapy"
Supervisors:
GA Pablo Cirrone (INFN-LNS), pablo.cirrone@lns.infn.it
Giada Petringa (INFN-LNS), giada.petringa@lns.infn.it
** This is a thesis work envisaging experimental measurements campaigns at International laboratories
In the last decades, ion acceleration from laser-plasma interaction has become a popular topic for multidisciplinary applications and opened new scenarios in the protontherapy framework, representing a possible future alternative to classic acceleration schema. The high-intensity dose rate regime that can be obtained with this approach is also strongly attracting the radiation oncologist community thanks to the evident reduction of the normal tissue complication probability, this new radiotherapy technique was called “flash radiotherapy”. One of the many challenges to bring laser acceleration to a clinical setting consists in the development techniques and technologies that allow for accurate dosimetry of a short and intense ion bunch length. In comparison with conventional accelerators, dosimetry of laser-accelerated beams is an ambitious task. Conventional accelerators typically operate at quasi-continuous milliampere currents rather than proton bunches with a temporal structure of the order of nanoseconds. Several international collaborations and experiments have been launched in the last years aiming at exploring the feasibility of using laser-driven sources for potential medical applications. A collaboration between the LNS-INFN, ELI-Beamlines (Czech Republic) and Queen’s University (Ireland) was recently established to develop and investigate new devices for diagnostic and dosimetric purposes for laser-driven ion beams.
New transport solution for eye-protontherapy beamlines
Supervisors:
GA Pablo Cirrone (INFN-LNS), pablo.cirrone@lns.infn.it
G. Milluzzo (LNS-INFN), gmilluzzo@lns.infn.it
Nowadays, the use of particle beams in clinical radiotherapy is applied in an increasing number of particle therapy centers worldwide. In particular, hadrontherapy, based on the use of protons and ions for cancer treatment, shows many physical and biological advantages with respect to the conventional radiotherapy with X- and gamma rays, such as the higher ballistic precision in the radiation release which allows maximizing the damage to the cancer volume while sparing the surrounding healthy tissues.
Recently, a collaboration between the INFN-LNS and the BEST Cyclotron company has been established for the development and the commercialization of a new protontherapy beamline for the eye treatment with the 70 MeV protons accelerated from a BEST Cyclotron. The beamline component will be designed by the LNS-INFN also providing a complete Monte Carlo Geant4 simulation of the beam transport. The Monte Carlo simulation will serve to choose the beam line element characteristics in terms of material, thickness and shape in order to respect the clinical tolerances of the beam parameters for protontherapy. New solutions are currently under investigation for making the beamline as compact and automatic as possible as for instance for what concern the modulation and the degradation section of the beam line. Moreover, in order to open to the possibility to use the beam line with high-dose rate proton beams (>40 Gy/s in the so-called flash regime) the implementation of an innovative ionization monitor chamber for the relative dosimetry along the beam line which would allow correcting for the ion recombination effect due to the high-dose rate, is currently under discussion.
Investigation of the aneutronic proton-boron fusion reaction in plasma for energetic studies
Supervisors:
GA Pablo Cirrone (INFN-LNS), pablo.cirrone@lns.infn.it
G. Milluzzo (LNS-INFN), gmilluzzo@lns.infn.it or G. Petringa (LNS-INFN) giada.petringa@lns.infn.it
The interaction of protons with 11B atoms triggers the following aneutronic fusion reaction: 11B + p → 3α + 8.7 MeV In such reaction, the final product is the generation of three energetic α-particles having a large energy spectrum strongly peaked around 4 MeV. In particular, the main resonance occurs at 675 keV proton energy in the lab frame, with a maximum cross section of 1.2 barn.
The absence of produced neutrons makes the pB fusion reaction particularly appealing involving the possibility to build an ultraclean nuclear-fusion reactor where no activation of the material and no radioactive wastes are expected. Recently, the pB fusion reaction has become an interesting topic also for applications in the space domain as well as for the medical physics with the possibility to use the alpha particles generated by the reaction to improve the biological efficiency of proton therapy
In this context, a huge effort of the researchers has been addressed on the possibility to induce the pB fusion reaction in plasma using the high power-laser matter interaction. The extremely high flux (up to 1012 p/s) typical of laser-accelerated proton beams [4], is indeed a great advantage allowing to enhance the reaction rate and the alpha particle production yield, which might be interesting also for the applications previously mentioned. Moreover, the theoretical as well as the experimental investigation of the energy and angular distribution of the reaction products, i.e. alpha particles, are particularly interesting for the study of the fusion reaction in plasma induced by high power lasers. Many experiments have been carried out so far demonstrating the increase of the alpha particle production (up to1011) in the laser-induced pB reaction in comparison with the classical scheme [5,6]. The activity here proposed, regards the experimental study of the pB fusion reaction in plasma and of the alpha particles yield, angular and energy spectrum using innovative detectors through the systematic variation of the following fundamental parameters: laser energy and pulse duration, contrast, target thickness, target material and structure. A particular effort will be addressed to develop new solutions for the on-line and simultaneous diagnostics of protons and alpha particles. A part of the experimental as well as theoretical (through Monte Carlo simulations) activity could also be dedicated to the study the possible modification on the stopping power values of protons and ions when traversing extremely high-density and hot plasma.
Detectors development for 2D dosimetry of conventional and laser-accelerated ion beams
Supervisors:
GA Pablo Cirrone (INFN-LNS, UNICT), pablo.cirrone@lns.infn.it
Roberto Catalano (INFN-LNS), catalano@lns.infn.it
** This is a thesis work envisaging experimental measurements campaigns at International laboratories
Hadrontherapy currently represents the most advanced form of external radiation modality in tumor treatments, thanks to the increased selectivity of charged particles in terms of dose released and biological effectiveness compared to photons. It makes use of high energetic proton/ion beams accelerated by cyclotrons or synchrotrons, while, in the last years, many efforts have been addressed to validate the clinical feasibility of laser-driven beams. We propose the development of a device for 2D relative dosimetry of both conventional and laser-accelerated ion beams based on innovative optical and geometrical solutions. The system will allow the on-lime determination of all clinical-relevant beam quality parameters and will be characterized by extremely high efficiency and spatial resolution. The validation of the system will be carried out with both conventional and laser-accelerated proton beams at the TIFPA-INFN (Trento, Italy) and ELIMED (Prague, Czech Republic) beamlines, through an inter-comparison with other routinely-used devices for QA tests.
PRAGUE: Proton Range Measure Using Silicon Carbide
Supervisors:
GA Pablo Cirrone (INFN-LNS, UNICT), pablo.cirrone@lns.infn.it
G. Petringa (INFN-LNS), giada.petringa@lns.infn.it
** This is a thesis work envisaging experimental measurements campaigns at International laboratories
Measuring and verifying the reliability and stability of the dosimetric properties of a radiotherapeutic beam, is the most important task of any external-beam radiotherapy quality assurance program. The beam characteristics can be assessed in terms of several different parameters, such as the percentage depth-dose distribution, flatness, symmetry, and absolute dose output. The depth-dose-distribution measure is today performed, adopting commercial systems whose main advantage is the short operational time. The aim of PRAGUE (Proton RAnGe measure Using silicon carbidE) project is to design and construct a detector, based on a new generation of Silicon Carbide (SiC) devices, to measure proton depth dose distributions in real-time and with high spatial resolution (10 μm). The extreme radiation hardness of such devices and the independence of their response with the proton beam energy, makes them capable to operate with clinical hadrontherapy beams and flash proton beams, where extremely high dose rates are delivered. The detector will be composed by a stack of new generation, large area SiC devices with an active thickness of 10 μm. A first detector protype was already designed and tested. The obtained results indicate the SiC detector as a suitable detector for relative dosimetry with charged particles. It showed, in fact, a stable and reproducible response and an extremely good behavior in terms of linearity as respect to absorbed dose was found. The negligible dependence of its response against energy and dose-rate and the high radiation hardness, represent advantageous features as respect other commercial solid-state detectors for ion beams dosimetry. A thesis work on this topic can include more than one of the following aspects: Geant4 simulation of the entire system; experimental runs in different facilities (the detector will be tested with conventional and laser-driven proton beams); electrical characterization of Silicon Carbides.
Silicon Carbide as microdosimeter
Supervisors:
GA Pablo Cirrone (INFN-LNS, UNICT), pablo.cirrone@lns.infn.it
G. Petringa (INFN-LNS), giada.petringa@lns.infn.it
** This is a thesis work envisaging experimental measurements campaigns at International laboratories
Silicon Carbide (SiC) has been recently proposed and patented as a material for the realization of radiation dosimetry and microdosimetry detectors. SiC properties, including its high sensitivity and radiation damage resistance, make it an amazing device susceptible to radiation dosimetric applications of direct ionizing radiations.
The SiC detector developed at LNS-INFN for microdosimetric purposes has been designed by IMM-CNR and manufactured by ST-Microelectronics company (Production site of Catania, I). It has a 0.3 um thick p-layer with a doping concentration NA = 10^19 cm^3 and a 10-um thick n-layer with a doping concentration ND = 0:5–1 10^14 cm^3. The detector has an active thickness of 10 um and was mounted on a PCB board housed in an aluminium box. Depletion is obtained already at 10V while it was operated in an over-depletion condition, applying a 50V positive bias. The voltage applied is about 10 times higher than the depletion voltage to ensure a maximum drift velocity, necessary for a fast and complete charge collection.
The SiC detector was preliminary irradiated in two different facilities: at the CATANA (Centro di Adroterapia e Applicazioni Nucleare Avanzate) facility (IT) with 62 MeV clinical proton beams and with 35 MeV proton beam at Ústav Jaderné Fyziky Av Čr (CZ). The experimental measurements were performed at different depths to reconstruct the microdosimetric spectra along entire the Bragg peak. A thesis work on this topic can include more than one of the following aspects: Geant4 simulation of the detector; experimental tests in different facilities (the detector will be tested with proton and ion beams); electrical characterization of Silicon Carbides.
Microdosimetry for LET and biological damage estimation
Supervisors:
GA Pablo Cirrone (INFN-LNS, UNICT), pablo.cirrone@lns.infn.it
G. Petringa (INFN-LNS), giada.petringa@lns.infn.it
** This is a thesis work envisaging experimental measurements campaigns at International laboratories
Biological and clinical properties of positively charged particles derive from the physical properties of their interaction with the target volume. When ions penetrate the biological matter, they lose part of their energy, they slow down and the ionization density along the particle track increases. Because of the increased ionization density, also the amount and complexity of damage to critical cellular structures increases. The relative biological effectiveness (RBE) of ionizing particles is defined as the ratio of the reference radiation dose to the target to the particle radiation dose producing the same biological effect. RBE depends on several variables, which include radiation type, charge and velocity of the charged particles, dose, fractionation, cell type, biologic endpoint, etc. The RBE of different radiation qualities is most frequently represented as a function of the linear energy transfer, LET, both in radiation biology experiments and RBE models. In this context microdosimetry, measuring the random processes of energy deposition in micrometric
sites, offers valuable tools to supplement LET or RBE-based treatment planning with protons or ions. The researcher from LNS-INFN are involved in LET experimental test and Monte Carlo simulations to predict the biological damage both with clinical proton and ion beams. The silicon detector used is the Bridge Microdosimeter, designed by the Centre for Medical Radiation Physics (CMRP), University of Wollongong, Australia. The Bridge microdosimeter consists of an array of 3D right parallelepiped (RPP) shape SVs with area 30 μmX30 μm each, constructed on a silicon-on-insulator (SOI) wafer with an active silicon thickness of 10 μm. A thesis work on this topic can include Monte Carlo simulations dedicated to predict the LET and RBE distribution and/or experimental measurements in National and International facilities.