Charged Particle Therapy is a non-invasive technique for radio-resistant tumor treatment performed with protons or light ions, aiming to deliver a high precision treatment. Compared to conventional ...radiotherapy, ions allow for a higher dose deposition in the tumor region while sparing the surrounding healthy tissue. To really exploit the potential benefits of this technique, the highest possible accuracy in the calculation of dose and its spatial distribution is required in treatment planning. Commonly used Treatment Planning Software solutions adopt a simplified beam-body interaction model. An alternative is the use of Monte Carlo simulations which explicitly take into account the interaction of charged particles with actual human tissues hence providing highly accurate results. However, Monte Carlo simulations are used in a restricted number of cases due to substantial computational resources required. The code FRED has been developed to allow a fast optimization of the treatment plans in Charged Particle Therapy while profiting from the dose release accuracy of a Monte Carlo tool. Currently, the most refined module is the transport of proton beams in water. A comparison with measurements shows that the lateral dose tails are reproduced within 2% in the field size factor test up to 20 cm. Models for the interaction of ion with the matter are currently under development in the FRED code. The status of new developments and the performance of FRED will be presented.
Organic scintillators are often chosen as radiation detectors for their fast decay time and their low Z, while inorganic ones are used when high light yields are required. In this paper we show that ...a para-terphenyl based detector has a blend of properties of the two categories that can be optimal for energy and position measurements of low-energy charged particles. Using 0.1% diphenylbutadiene doped para-terphenyl samples we measured a light attenuation length λ = 4.73 ±0.06 mm, a quenching factor for α particles Q α = (10.7 ±0.6), and a rejection power ranging between 3 - 11% for 660 keV photons, with respect to electrons of the same energy, depending on the signal threshold. A simulation based on FLUKA properly reproduces the experimental data distributions.
The treatment of deep-seated tumours with electrons of very high energies (VHEE, 70–150 MeV) has already been explored in the past, suggesting that a dosimetric coverage comparable with ...state-of-the-art proton (PT) or photon radiotherapy (RT) could be achieved with a large (
>
10) number of fields and high electron energy. The technical and economical challenges posed by the deployment of such beams in treatment centres, together with the expected small therapeutic gain, prevented the development of such technique. This scenario could radically change in the light of recent developments that occurred in the compact, high-gradient, electron acceleration technology and, additionally, of the experimental evidence of the sparing of organs at risk achieved in ultra-high dose rate irradiation, also referred to as FLASH. Electrons with the energy required to treat intracranial lesions could be provided, at dose rates compatible with what is needed to trigger the FLASH effect, by accelerators that are a few metres long, and the organ sparing could be exploited to significantly simplify the irradiation geometry, decreasing the number of fields needed to treat a patient. In this paper, the case of two patients affected by a chordoma and a meningioma, respectively, treated with protons in Trento (IT) is presented. The proton plans have been compared with VHEE plans and X-ray intensity-modulated radiotherapy (IMRT) plans. The VHEE plans were first evaluated in terms of physical dose distribution and then assuming that the FLASH regimen can be achieved. VHEE beams demonstrated their potential in obtaining plans that have comparable tumour coverage and organs at risk sparing when benchmarked against current state-of-the-art IMRT and PT. These results were obtained with a number of explored fields that was in the range between 3 and 7, consistent with what is routinely performed in IMRT and PT conventional irradiations. The FLASH regimen, in all cases, showed its potential in reducing damage to the organs placed nearby the target volume, allowing, particularly in the chordoma case where the irradiation geometry is more challenging, a better tumour coverage with respect to the conventional treatments.
Hadrontherapy is an emerging technique in cancer therapy that uses beams of charged particles. To meet the improved capability of hadrontherapy in matching the dose release with the cancer position, ...new dose-monitoring techniques need to be developed and introduced into clinical use. The measurement of the fluxes of the secondary particles produced by the hadron beam is of fundamental importance in the design of any dose-monitoring device and is eagerly needed to tune Monte Carlo simulations. We report the measurements carried out with charged secondary particles produced from the interaction of a 80 MeV/u fully stripped carbon ion beam at the INFN Laboratori Nazionali del Sud, Catania, with a poly-methyl methacrylate target. Charged secondary particles, produced at 90° with respect to the beam axis, have been tracked with a drift chamber, while their energy and time of flight have been measured by means of a LYSO scintillator. Secondary protons have been identified exploiting the energy and time-of-flight information, and their emission region has been reconstructed backtracking from the drift chamber to the target. Moreover, a position scan of the target indicates that the reconstructed emission region follows the movement of the expected Bragg peak position. Exploiting the reconstruction of the emission region, an accuracy on the Bragg peak determination in the submillimeter range has been obtained. The measured differential production rate for protons produced with E(Prod)(kin) > 83 MeV and emitted at 90° with respect to the beam line is dN(P)/(dN(C)dΩ) (E(Prod)(kin) > 83 MeV, θ = 90°) = (2.69 ± 0.08(stat) ± 0.12(sys)) × 10⁻⁴ sr⁻¹.
Particle therapy (PT) is a radiation therapy technique in which solid tumors are treated with charged ions and exploits the achievable highly localized dose delivery, allowing to spare healthy ...tissues and organs at risk. The development of a range monitoring technique to be used online, during the treatment, capable to reach millimetric precision is considered one of the important steps toward an optimization of the PT efficacy and of the treatment quality. To this aim, charged secondary particles produced in the nuclear interactions between the beam particles and the patient tissues can be exploited. Besides charged secondaries, neutrons are also produced in nuclear interactions. The secondary neutron component might cause an undesired and not negligible dose deposition far away from the tumor region, enhancing the risk of secondary malignant neoplasms that can develop even years after the treatment. An accurate neutron characterization (flux, energy and emission profile) is, hence, needed for a better evaluation of long-term complications. In this contribution, two tracker detectors, both based on scintillating fibers, are presented. The first one, named dose profiler (DP), is planned to be used as a beam range monitor in PT treatments with heavy ion beams, exploiting the charged secondary fragments production. The DP is currently under development within the Innovative Solutions for In-Beam DosimEtry in Hadrontherapy project. The second one is dedicated to the measurement of the fast and ultrafast neutron component produced in PT treatments, in the framework of the monitor for neutron dose in hadrontherapy project. Results of the first calibration tests performed at the Trento Protontherapy Center and at Centro Nazionale di Adroterapia Oncologica (Italy) are reported, as well as simulation studies.
In Particle Therapy (PT) accelerated charged particles and light ions are used for treating tumors. One of the main limitation to the precision of PT is the emission of secondary particles due to the ...beam interaction with the patient: secondary emitted neutrons can release a significant dose far from the tumor. Therefore, a precise characterization of their flux, production energy and angle distribution is eagerly needed in order to improve the Treatment Planning Systems (TPS) codes. The principal aim of the MONDO (MOnitor for Neutron Dose in hadrOntherapy) project is the development of a tracking device optimized for the detection of fast and ultra-fast secondary neutrons emitted in PT. The detector consists of a matrix of scintillating square fibres coupled with a CMOS-based readout. Here, we present the characterization of the detector tracker prototype and CMOS-based digital SPAD (Single Photon Avalanche Diode) array sensor tested with protons at the Beam Test Facility (Frascati, Italy) and at the Proton Therapy Centre (Trento, Italy), respectively.
Introduction: Charged Particle Therapy plays a key role in the treatment of deep-seated tumours, because of the advantageous energy deposition culminating in the Bragg peak. However, knowledge of the ...dose delivered in the entrance channel is limited by the lack of data on the beam and fragmentation of the target. Methods: The FOOT experiment has been designed to measure the cross sections of the nuclear fragmentation of projectile and target with two different detectors: an electronic setup for the identification of Z ≥ 3 fragments and a nuclear emulsion spectrometer for Z ≤ 3 fragments. In this paper, we analyze the data taken by exposing four nuclear emulsion spectrometers, with C and C 2 H 4 targets, to 200 MeV/n and 400 MeV/n oxygen beams at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany), and we report the charge identification of produced fragments based on the controlled fading induced on nuclear emulsion films. Results: The goal of identifying fragments as heavy as lithium has been achieved. Discussion: The results will contribute to a better understanding of the nuclear fragmentation process in charged particle therapy and have implications for refining treatment planning in the presence of deep-seated tumors.
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