scholarly journals Ionization Dosimetry Principles for Conventional and Laser-Driven Clinical Particle Beams

2018 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Ionizing Radiation ◽  
Heavy Particle ◽  
Absorbed Dose ◽  
High Energy ◽  
Particle Energy ◽  
Particle Accelerators ◽  
Carbon Ions ◽  
Particle Beams ◽  
Radiation Fields ◽  
Number Of Particles

In this paper after mentioning the clinical radiation fields of 20 keV-450 MeV/u, they are characterized by the number of particles and their energy. Particle energy is the quantity that determines radiation penetration at the depth at which the tumor is situated (Fig. 1). The number of particles (or beam intensity) is the second major quantity that assures the administration of the absorbed dose in the tumor. The first application shows the radiation levels planned for various radiation fields. Prior to interacting with the medium, the intensity (or energy fluence rate) allows the determination of energy density, energy, power and relativistic force. In the interaction process, it determines the absorbed dose, kerma and exposure. Non-ionizing radiations in the EM spectrum are used as negative energy waves to accelerate particles charged into special installations called particle accelerators. The particles extracted from the accelerator are the source of the corpuscular radiation for high-energy radiotherapy. Of these, light particle beams (electrons and photons) for radiotherapy are generated by betatron, linac, microtron, and synchrotron and heavy particle beams (protons and heavy ions) are generated by cyclotron, isochronous cyclotron, synchro-cyclotron and synchrotron. The ionization dosimetry method used is the ionization chamber for both indirectly ionizing radiation (photons and neutrons) and for directly ionizing radiation (electrons, protons and carbon ions). Because the necessary energies for hadrons therapy are relatively high, 50-250 MeV for protons and 100-450 MeV/u for carbon ions, the alternative to replace non-ionizing radiation with relativistic laser radiation for generating clinical corpuscular radiation through radiation pressure acceleration mechanism (RPA) is presented.

Modeling of Laboratory Animals Exposure Conditions behind Local Concrete Shielding Bombarded by 650-MeV Protons

2021 ◽  
Vol 65 (5) ◽  
pp. 77-86
Author(s):  
A Ivanov ◽  
A Krylov ◽  
A. Molokanov ◽  
A. Bushmanov ◽  
A. Samoylov
Keyword(s):  
Absorbed Dose ◽  
High Energy ◽  
Laboratory Animals ◽  
Diamond Detector ◽  
Radiation Fields ◽  
The Monte Carlo Method ◽  
Direct Measurements ◽  
Pass Through ◽  
Protective Structures ◽  
Dose Measurements

Purpose: To estimate the radiation fields formed after the passage of high-energy protons through the concrete protection for subsequent radiobiological experiments on animals on this model. Material and methods: The results of the calculation of the secondary characteristics of a field of mixed radiation behind the local concrete with thickness 20, 40, and 80 cm, bombarded by a proton beam of 650 MeV at the JINR Phasotron and experimental estimation of the values of the absorbed dose phantoms of mice irradiated for protection during radiobiological experiments. The calculation was performed by the Monte Carlo method according to the MCNPX program for secondary protons, neutrons, π-mesons, and gamma rays. To verify the adequacy of calculations was performed the comparison of calculated and measured in the experiment spatial distribution of activation threshold detectors for aluminum protection, as well as a comparison of the calculated values of absorbed dose for radiation protection with the results of absorbed dose measurements with a diamond detector. Results: The calculations made it possible to obtain the characteristics of the fields of mixed secondary radiation behind local concrete shields of different thickness irradiated with protons with an energy of 650 MeV and to estimate the values of absorbed doses in the irradiation sites of mice in the radiobiological experiment. The reliability of the calculations was confirmed by experimental verification of the activation of aluminum threshold detectors behind a 20 cm thick protection, as well as direct measurements using a diamond detector. Conclusion: The calculated assessment of radiation fields formed after protons pass through the concrete protection and its comparison with the results of radiation dose measurements for the subsequent radiobiological experiment on animals on this model in the interests of designing protective structures on the Moon and other space bodies, as well as biological defenses on charged-particles accelerators.

scholarly journals Beam loss monitoring with unfolding techniques

2021 ◽  
Vol 136 (2) ◽  
Author(s):  
M. Caresana ◽  
M. Ferrarini ◽  
M. Frosini ◽  
M. Reginatto
Keyword(s):  
Radiation Protection ◽  
Particle Beam ◽  
High Energy ◽  
Monte Carlo Code ◽  
Carbon Ions ◽  
Particle Beams ◽  
Beam Loss ◽  
Main Instrument ◽  
Mixed Fields ◽  
Pulsed Neutron

AbstractSince the first particle accelerator’s construction in 1931, an exponential spread of these machines occurred worldwide, in different kinds of applications. Nowadays, these are mainly used for industrial (60%) and medical (35%) purposes and for scientific research (5%). High energy secondary mixed fields produced by the particle beams interaction with matter imply a complex environmental dosimetry and special radiation protection regulations able to guarantee workers and population safety. In the medical field, this aspect is particularly emphasized in hadrontherapy centres, where high energy charged particles such as protons and carbon ions modify environmental doses, with a significant increase in the neutron contribution. This work proposes a technique to identify points of losses of the primary particle beam around an acceleration ring and has been developed within the radiation protection section at the National Centre for Oncological Hadrontherapy situated in Pavia. In the first part, the radiation field produced by protons and carbon ions interactions with structural materials at different energies was investigated. The main instrument of analysis is the Monte Carlo code for particle transport FLUKA, supported by experimental measurements in the treatment room carried out with the rem counter LUPIN, designed for pulsed neutron fields dosimetry. This first step allowed an analysis of both the angular and energetic instrumental response and a comparison of experimental results with simulations. The second part proposes a description of the technique for beam loss positions reconstruction around the acceleration ring at CNAO based on the application of unfolding codes.

Effect of ionizing radiation on the kinetics of hydrogenation on the Ni-MgO mixed catalyst

1982 ◽  
Vol 47 (7) ◽  
pp. 1780-1786 ◽  
Author(s):  
Rostislav Kudláček ◽  
Jan Lokoč
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Liquid Phase ◽  
Ionizing Radiation ◽  
Oxide Catalyst ◽  
Absorbed Dose ◽  
Hydrogenation Rate ◽  
Solution Composition ◽  
Mixed Catalyst ◽  
Kinetics Of

The effect of gamma pre-irradiation of the mixed nickel-magnesium oxide catalyst on the kinetics of hydrogenation of maleic acid in the liquid phase has been studied. The changes of the hydrogenation rate are compared with the changes of the adsorbed amount of the acid and with the changes of the solution composition, activation energy, and absorbed dose of the ionizing radiation. From this comparison and from the interpretation of the experimental data it can be deduced that two types of centers can be distinguished on the surface of the catalyst under study, namely the sorption centres for the acid and hydrogen and the reaction centres.

scholarly journals Development and characterization of Nb3Sn/Al2O3 superconducting multilayers for particle accelerators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Sundahl ◽  
Junki Makita ◽  
Paul B. Welander ◽  
Yi-Feng Su ◽  
Fumitake Kametani ◽  
...  
Keyword(s):  
High Performance ◽  
High Energy ◽  
Particle Accelerators ◽  
Quality Factors ◽  
Critical Fields ◽  
Linear Accelerators ◽  
Cross Sectional ◽  
Low Field ◽  
Superconducting Radio Frequency

AbstractSuperconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1–2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200–240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration field in Nb3Sn, it has been proposed to coat Nb cavities with thin film Nb3Sn multilayers with dielectric interlayers. Here, we report the growth and multi-technique characterization of stoichiometric Nb3Sn/Al2O3 multilayers with good superconducting and RF properties. We developed an adsorption-controlled growth process by co-sputtering Nb and Sn at high temperatures with a high overpressure of Sn. The cross-sectional scanning electron transmission microscope images show no interdiffusion between Al2O3 and Nb3Sn. Low-field RF measurements suggest that our multilayers have quality factor comparable with cavity-grade Nb at 4.2 K. These results provide a materials platform for the development and optimization of high-performance SIS multilayers which could overcome the intrinsic limits of the Nb cavity technology.

Dosimetry of High-Energy Photon Beams Based on Standards of Absorbed Dose to Water: Abstract

2001 ◽  
Vol 1 (1) ◽  
pp. 8-8 ◽  
Author(s):  
K. Hohlfeld ◽  
P. Andreo ◽  
O. Mattsson ◽  
J. P. Simoen
Keyword(s):  
Reference Conditions ◽  
International Comparisons ◽  
Absorbed Dose ◽  
High Energy ◽  
National Standards ◽  
Photon Radiation ◽  
Photon Beams ◽  
Radiation Induced ◽  
Absorbed Dose To Water ◽  
Primary Standards

This report examines the methods by which absorbed dose to water can be determined for photon radiations with maximum energies from approximately 1 MeV to 50 MeV, the beam qualities most commonly used for radiation therapy. The report is primarily concerned with methods of measurement for photon radiation, but many aspects are also relevant to the dosimetry of other therapeutic beams (high-energy electrons, protons, etc.). It deals with methods that are sufficiently precise and well established to be incorporated into the dosimetric measurement chain as primary standards (i.e., methods based on ionisation, radiation-induced chemical changes, and calorimetry using either graphite or water). The report discusses the primary dose standards used in several national standards laboratories and reviews the international comparisons that have been made. The report also describes the reference conditions that are suitable for establishing primary standards and provides a formalism for determining absorbed dose, including a discussion of correction factors needed under conditions other than those used to calibrate an instrument at the standards laboratory.

scholarly journals IPEM code of practice for high-energy photon therapy dosimetry based on the NPL absorbed dose calibration service

2020 ◽  
Vol 65 (19) ◽  
pp. 195006
Author(s):  
David J Eaton ◽  
Graham Bass ◽  
Paul Booker ◽  
John Byrne ◽  
Simon Duane ◽  
...  
Keyword(s):  
Absorbed Dose ◽  
High Energy ◽  
High Energy Photon ◽  
Energy Photon ◽  
Code Of Practice

Synchronized Periodic Solutions of a Class of Periodically Driven Nonlinear Oscillators

1988 ◽  
Vol 55 (3) ◽  
pp. 721-728 ◽  
Author(s):  
Gamal M. Mahmoud ◽  
Tassos Bountis
Keyword(s):  
Periodic Solutions ◽  
Periodic Orbits ◽  
Nonlinear Oscillators ◽  
High Energy ◽  
Second Order ◽  
Multiple Time ◽  
Particle Beams ◽  
Periodically Driven ◽  
Time Scaling ◽  
A New Technique

We consider a class of parametrically driven nonlinear oscillators: x¨ + k1x + k2f(x,x˙)P(Ωt) = 0, P(Ωt + 2π) = P(Ωt)(*) which can be used to describe, e.g., a pendulum with vibrating length, or the displacements of colliding particle beams in high energy accelerators. Here we study numerically and analytically the subharmonic periodic solutions of (*), with frequency 1/m ≅ √k1, m = 1, 2, 3,…. In the cases of f(x,x˙) = x3 and f(x,x˙) = x4, with P(Ωt) = cost, all of these so called synchronized periodic orbits are obtained numerically, by a new technique, which we refer to here as the indicatrix method. The theory of generalized averaging is then applied to derive highly accurate expressions for these orbits, valid to the second order in k2. Finally, these analytical results are used, together with the perturbation methods of multiple time scaling, to obtain second order expressions for regions of instability of synchronized periodic orbits in the k1, k2 plane, which agree very well with the results of numerical experiments.

Medical Cyclotrons

2009 ◽  
Vol 02 (01) ◽  
pp. 133-156 ◽  
Author(s):  
D. L. Friesel ◽  
T. A. Antaya
Keyword(s):  
Cancer Therapy ◽  
Scientific Research ◽  
High Energy ◽  
Industrial Applications ◽  
Medical Applications ◽  
Particle Accelerators ◽  
Radioisotope Production ◽  
Practical Applications ◽  
Medical Radioisotope ◽  
High Energy Particles

Particle accelerators were initially developed to address specific scientific research goals, yet they were used for practical applications, particularly medical applications, within a few years of their invention. The cyclotron's potential for producing beams for cancer therapy and medical radioisotope production was realized with the early Lawrence cyclotrons and has continued with their more technically advanced successors — synchrocyclotrons, sector-focused cyclotrons and superconducting cyclotrons. While a variety of other accelerator technologies were developed to achieve today's high energy particles, this article will chronicle the development of one type of accelerator — the cyclotron, and its medical applications. These medical and industrial applications eventually led to the commercial manufacture of both small and large cyclotrons and facilities specifically designed for applications other than scientific research.

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