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Register a new userSecondary radiation measurements for particle therapy applications: nuclear fragmentation produced by $^4$He ion beams in a PMMA target
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Nowadays there is a growing interest in Particle Therapy treatments exploiting light ion beams against tumors due to their enhanced Relative Biological Effectiveness and high space selectivity. In particular promising results are obtained by the use of $^4$He projectiles. Unlike the treatments performed using protons, the beam ions can undergo a fragmentation process when interacting with the atomic nuclei in the patient body. In this paper the results of measurements performed at the Heidelberg Ion-Beam Therapy center are reported. For the first time the absolute fluxes and the energy spectra of the fragments - protons, deuterons, and tritons - produced by $^4$He ion beams of 102, 125 and 145 MeV/u energies on a poly-methyl methacrylate target were evaluated at different angles. The obtained results are particularly relevant in view of the necessary optimization and review of the Treatment Planning Software being developed for clinical use of $^4$He beams in clinical routine and the relative benchmarking of Monte Carlo algorithm predictions.
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Charged particle beams are used in Particle Therapy (PT) to treat oncological patients due to their selective dose deposition in tissues and to their high biological effect in killing cancer cells with respect to photons and electrons used in conventional radiotherapy. Nowadays, protons and carbon ions are used in PT clinical routine but, recently, the interest on the potential application of helium and oxygen beams is growing due to their reduced multiple scattering inside the body and increased linear energy transfer, relative biological effectiveness and oxygen enhancement ratio. The precision of PT demands for online dose monitoring techniques, crucial to improve the quality assurance of treatments. The beam range confined in the irradiated target can be monitored thanks to the neutral or charged secondary radiation emitted by the interactions of hadron beams with matter. Prompt photons are produced by nuclear de-excitation processes and, at present, different dose monitoring and beam range verification techniques based on the prompt {gamma} detection have been proposed. It is hence of importance to perform the {gamma} yield measurement in therapeutical-like conditions. In this paper we report the yields of prompt photons produced by the interaction of helium, carbon and oxygen ion beams with a PMMA target. The measurements were performed at the Heidelberg Ion-beam Therapy center (HIT) with beams of different energies. A LYSO scintillator has been used as photon detector. The obtained {gamma} yields for $^{12}$C ion beams are compared with results from literature, while no other results from $^{4}$He and $^{16}$O beams have been published yet. A discussion on the expected resolution of a slit camera detector is presented, demonstrating the feasibility of a prompt-{gamma} based monitoring technique for PT treatments using helium, carbon and oxygen ion beams.
Measurements performed with the purpose of characterizing the charged secondary radiation for dose release monitoring in particle therapy are reported. Charged secondary yields, energy spectra and emission profiles produced in poly-methyl methacrylate (PMMA) target by 4He and 12C beams of different therapeutic energies were measured at 60 and 90 degree with respect to the primary beam direction. The secondary yields of protons produced along the primary beam path in PMMA target were obtained. The energy spectra of charged secondaries were obtained from time-of-flight information, whereas the emission profiles were reconstructed exploiting tracking detector information. The measured charged secondary yields and emission profiles are in agreement with the results reported in literature and confirm the feasibility of ion beam therapy range monitoring using 12C ion beam. The feasibility of range monitoring using charged secondary particles is also suggested for 4He ion beam.
We study the spatial distributions of $beta^+$-activity produced by therapeutic beams of $^3$He and $^{12}$C ions in various tissue-like materials. The calculations were performed within a Monte Carlo model for Heavy-Ion Therapy (MCHIT) based on the GEANT4 toolkit. The contributions from $^{10,11}$C, $^{13}$N, $^{14,15}$O, $^{17,18}$F and $^{30}$P positron-emitting nuclei were calculated and compared with experimental data obtained during and after irradiation. Positron emitting nuclei are created by $^{12}$C beam in fragmentation reactions of projectile and target nuclei. This leads to a $beta^+$-activity profile characterised by a noticeable peak located close to the Bragg peak in the corresponding depth-dose distribution. On the contrary, as the most of positron-emitting nuclei are produced by $^3$He beam in target fragmentation reactions, the calculated total $beta^+$-activity during or soon after the irradiation period is evenly distributed within the projectile range. However, we predict also the presence of $^{13}$N, $^{14}$O, $^{17,18}$F created in charge-transfer reactions by low-energy $^3$He ions close to the end of their range in several tissue-like media. The time evolution of $beta^+$-activity profiles was investigated for both kinds of beams. Due to the production of $^{18}$F nuclide the $beta^+$-activity profile measured 2 or 3 hours after irradiation with $^{3}$He ions will have a distinct peak correlated with the maximum of depth-dose distribution. We found certain advantages of low-energy $^{3}$He beams over low-energy proton beams for reliable PET monitoring during particle therapy of shallow located tumours. In this case the distal edge of $beta^+$-activity distribution from $^{17}$F nuclei clearly marks the range of $^{3}$He in tissues.
Nuclear masses are the most fundamental of all nuclear properties, yet they can provide a wealth of knowledge, including information on astrophysical sites, constraints on existing theory, and fundamental symmetries. In nearly all applications, it is necessary to measure nuclear masses with very high precision. As mass measurements push to more short-lived and more massive nuclei, the practical constraints on mass measurement techniques become more exacting. Various techniques used to measure nuclear masses, including their advantages and disadvantages are described. Descriptions of some of the world facilities at which the nuclear mass measurements are performed are given, and brief summaries of planned facilities are presented. Future directions are mentioned, and conclusions are presented which provide a possible outlook and emphasis on upcoming plans for nuclear mass measurements at existing facilities, those under construction, and those being planned.
The advent of high-intensity pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei, by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments.
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