Experiment Design of Secondary Neutron and Charged-Particle Measurement with Stopping Targets Bombarded by 100 and 230 MeV/amu 4He Ions (original) (raw)
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New Journal of Physics, 2008
For applications in heavy-ion radiotherapy, the emission of secondary fragments from 200 MeV u −1 carbon ions was investigated using a 12.78 cm thick water absorber as a tissue-equivalent beam stopping target. Secondary light particles (n, p, d, t, 3 He and 4 He) produced by nuclear fragmentation and emerging from the target in forward direction were detected with a E − E-telescope consisting of NE102 and BaF 2 scintillation detectors. Energy spectra of the fragments at angles of 0 • , 5 • , 10 • , 20 • and 30 • to the beam axis were obtained from time-of-flight measurements. They show a broad maximum at about half of the projectiles energy per nucleon, the shape at high energies is exponential and extends up to the projectiles initial energy per nucleon-for neutrons and protons to about twice the energy of the projectile per nucleon. Comparison of the experimental data with calculations performed with the Monte-Carlo code (partide and heavy ion transport code system (PHITS)) shows fairly good agreement for neutrons, protons and deuterons, but some deviations for tritons and helium fragments. The neutron dose in patient treatments with carbon ions was estimated to be 8 mGy per treatment-Gy based on the measured neutron yield.
Physics in Medicine & Biology
Proton and carbon ion beams are used in the clinical practice for external radiotherapy treatments achieving, for selected indications, promising and superior clinical results with respect to X-ray based radiotherapy. Other ions, like 4 Heare recently being considered as projectiles in particle therapy centres. 4 He ions might represent a good compromise between the linear energy transfer and the radiobiological effectiveness of 12 C ion and proton beams allowing improved tumour control probability and minimizing normal tissue complication probability. Proton, 4 He and 12 C ion beams allow to achieve sharp dose gradients on the boundary of the target volume. At the same time, the accurate dose delivery is more sensitive to the patient positioning and to anatomical variations with respect to photon therapy. This requires beam range and/or dose release measurement during the patient irradiation and therefore the development of dedicated monitoring techniques. 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 4 He and 12 C beams of different therapeutic energies were measured at 60 • and 90 • 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-offlight information, whereas the emission profiles were reconstructed exploiting tracking
2015
Hadrontherapy is a technique that uses accelerated charged ions for cancer treatment. The high irradiation precision and conformity achievable during hadrontherapy treatments allows for local tumor control and sparing of the surrounding healthy tissues. Such a high spatial selectiveness requires the development of new dose monitoring techniques. It has been proved that the beam emits secondary particles in the path to the tumor, namely γ from β+ emitters, prompt γ from nuclear de-excitation and charged particles, that can be used to monitor Bragg Peak (BP) position and the related dose release. In this contribution preliminary results obtained in the study on the neutral and charged secondary particles produced by 12C , 4He and 16O ion beams of therapeutical energy impinging on PMMA phantoms will be presented. The data acquisition have been performed at GSI (Darmstadt, Germany) and HIT (Heidelberg, Germany) facilities. A correlation between the secondary generation regions and BP po...
A multi-scale approach to the physics of ion beam cancer therapy
AIP Conference Proceedings, 2008
We propose a multi-scale approach to understanding physics related to the ion/proton-beam cancer therapy and calculation of the probability of the DNA damage as a result of irradiation of patients with energetic (up to 430 MeV/u) ions. This approach is inclusive with respect to different scales starting from the long scale defined by the ion stopping followed by a smaller scale defined by secondary electrons and radicals ending with the shortest scale defined by interactions of secondaries with the DNA. We present calculations of the probabilities of single and double strand breaks of the DNA and suggest a way of further elaboration of such calculations.
Absorbed Dose in Ion Beams: Comparison of Ionisation- and Fluence-Based Measurements
Radiation Protection Dosimetry, 2014
We present a direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionization chamber. Irradiations were performed at the Heidelberg Ion-Beam Therapy Center (HIT) using monoenergetic protons (142.66 MeV, = 3x10 6 1/cm 2 ) and carbon ions (270.55 MeV/u, = 3x10 6 1/cm 2 ) in the entrance channel of the ion beam. We found that absorbed dose to water values as determined by fluence measurements using FNTDs are in case of protons in good agreement (2.2 %) with ionization chamber measurements when including slower protons and Helium secondaries by an effective stopping power. For carbon, however, we found a discrepancy of 4.6 %. This deviation is significant considering both the uncertainties for ionization chambers as given in the TRS 398 [1] and from experimental design (e.g. inhomogeneous irradiation, machine stability, beam direction). Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not seen.
Uncertainties surround the radiobiological consequences of exposure to charged particles, despite the increasing use of accelerated ion beams for cancer treatment (hadrontherapy). In particular, little is known about the long-term effects on normal tissue at the beam entrance or in the distal part of the Spread-Out Bragg Peak (SOBP). Moreover, although the relative biological effectiveness (RBE) of particle radiation has been traditionally related to the radiation linear energy transfer (LET), it has become increasingly evident that radiation-induced cell death, as well as long term radiation effects, is not adequately described by this parameter. Hence, exploring the effectiveness of various ion beams at or around the Bragg peak of monoenergetic ion beams can prove useful to gain insights into the role played by parameters other than the particle LET in determining the outcome of particle radiation exposures. In this context, the upgrade of the Tandem irradiation facility at Naples University here described, has allowed us to perform a series of preliminary radiobiological measurements using proton and carbon ion beams. The facility is currently used to irradiate normal and cancer cell lines with ion beams such as oxygen and fluorine.
Current status of radiotherapy with proton and light ion beams
Cancer, 2007
Several model studies have shown potential clinical advantages with charged particles (protons and light ions) compared with 3D-conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) in many disease sites. The newly developed intensity-modulated proton therapy (IMPT) often yields superior dose distributions to photon IMRT, with the added advantage of a significant reduction in the volume of healthy normal tissues exposed to low-to-medium doses. Initially, the major emphasis in clinical research for proton and light ion therapy was dose escalation for inherently radioresistant tumors, or for lesions adjacent to critical normal structures that constrained the dose that could be safely delivered with conventional x-ray therapy. Since the advent of IMRT the interest in particle therapy has gradually shifted toward protocols aimed at morbidity reduction. Lately the emphasis has mostly been placed on the potential for reduced risk of radiation-induced carcinogenesis with protons. Compared with 3D-CRT, a 2-fold increase has been theoretically estimated with the use of IMRT due to the larger integral volumes. In the pediatric setting, due to a higher inherent susceptibility of tissues, the risk could be significant, and the benefits of protons have been strongly emphasized in the literature. There is a significant expansion of particle therapy facilities around the world. Increasing public awareness of the potential benefits of particle therapy and wider accessibility for patients require that treating physicians stay abreast of the clinical indications of this radiotherapy modality. The article reviews the available literature for various disease sites in which particle therapy has traditionally been considered to offer clinical advantages and to highlight current lines of clinical research. The issue of radiation-induced second malignancies is examined in the light of the controversial epidemiological evidence available. The cost-effectiveness of particle therapy is also discussed.