scholarly journals Microdosimetry and Dose-Averaged LET Calculations of Protons in Liquid Water: A Novel Geant4-DNA Application

2021 ◽  
Vol 9 ◽  
Author(s):  
Anna Baratto-Roldán ◽  
Alejandro Bertolet ◽  
Giorgio Baiocco ◽  
Alejandro Carabe ◽  
Miguel Antonio Cortés-Giraldo

The spatial distribution of energy deposition events is an essential aspect in the determination of the radiobiological effects of ionizing radiation at the cellular level. Microdosimetry provides a theoretical framework for the description of these events, and has been used in several studies to address problems such as the characterization of Linear Energy Transfer (LET) and Relative Biological Effectiveness (RBE) of ion beams for proton therapy applications. Microdosimetry quantities and their distributions can be obtained by means of Monte Carlo simulations. In this work, we present a track structure Monte Carlo (MC) application, based on Geant4-DNA, for the computation of microdosimetric distributions of protons in liquid water. This application provides two sampling methods uniform and weighted, for the scoring of the quantities of interest in spherical sites, with diameters ranging from 1 to 10 μm. As an element of novelty, the work shows the approach followed to calculate, without resorting to dedicated simulations, the distribution of energy imparted to the site per electronic collision of the proton, which can be used to obtain the macroscopic dose-averaged LET as proposed by Kellerer. Furthermore, in this work the concept of effective mean chord length is proposed to take into account δ-ray influx and escape in the calculation of macroscopic dose-averaged LET for proton track segments and retrieve the agreement predicted by Kellerer’s formula. Finally, the results obtained demonstrate that our MC application is reliable and computational-efficient to perform calculations of microdosimetric distributions and dose-averaged LET of proton track segments in liquid water.

2001 ◽  
Vol 79 (2) ◽  
pp. 189-195 ◽  
Author(s):  
Jean-Philippe Pignol ◽  
Jakobus Slabbert

Fast neutrons (FN) have a higher radio-biological effectiveness (RBE) compared with photons, however the mechanism of this increase remains a controversial issue. RBE variations are seen among various FN facilities and at the same facility when different tissue depths or thicknesses of hardening filters are used. These variations lead to uncertainties in dose reporting as well as in the comparisons of clinical results. Besides radiobiology and microdosimetry, another powerful method for the characterization of FN beams is the calculation of total proton and heavy ion kerma spectra. FLUKA and MCNP Monte Carlo code were used to simulate these kerma spectra following a set of microdosimetry measurements performed at the National Accelerator Centre. The calculated spectra confirmed major classical statements: RBE increase is linked to both slow energy protons and alpha particles yielded by (n,α) reactions on carbon and oxygen nuclei. The slow energy protons are produced by neutrons having an energy between 10 keV and 10 MeV, while the alpha particles are produced by neutrons having an energy between 10 keV and 15 MeV. Looking at the heavy ion kerma from <15 MeV and the proton kerma from neutrons <10 MeV, it is possible to anticipate y* and RBE trends.Key words: fast neutron, kerma, microdosimetry, RBE, Monte Carlo.


2004 ◽  
Vol 22 (1) ◽  
pp. 91-94 ◽  
Author(s):  
Tan Zhen-Yu ◽  
Xia Yue-Yuan ◽  
Zhao Ming-Wen ◽  
Liu Xiang-Dong ◽  
Huang Bo-Da ◽  
...  

1996 ◽  
Vol 100 (20) ◽  
pp. 8595-8606 ◽  
Author(s):  
Simon M. Pimblott ◽  
Jay A. LaVerne ◽  
Asokendu Mozumder

2011 ◽  
Vol 56 (19) ◽  
pp. 6475-6493 ◽  
Author(s):  
Rafael Garcia-Molina ◽  
Isabel Abril ◽  
Santiago Heredia-Avalos ◽  
Ioanna Kyriakou ◽  
Dimitris Emfietzoglou

2001 ◽  
Vol 19 (3) ◽  
pp. 229-236 ◽  
Author(s):  
F. Bulnes ◽  
A.J. Ramirez-Pastor ◽  
G. Zgrablich

The adsorption of particles with repulsive nearest-neighbour interactions was studied through Monte Carlo simulation on bivariate surfaces characterized by patches of weak and strong adsorbing sites of size l. Patches were either arranged in a deterministic chessboard structure or in a random way. Quantities were identified which scale obeying power laws as a function of the scale length l. The consequences of these findings were discussed for the determination of the energetic topography of the surface from adsorption measurements.


1994 ◽  
Vol 52 (1-4) ◽  
pp. 165-169 ◽  
Author(s):  
H. Nikjoo ◽  
M. Terrissol ◽  
R.N. Hamm ◽  
J.E. Turner ◽  
S. Uehara ◽  
...  

Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.


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