Study of the RBE depth dependence of protons using a damage diagnostic algorithm and its application in proton therapy based on Monte Carlo simulation

2021 ◽  
Vol 16 (12) ◽  
pp. P12027
Author(s):  
Z. Ahmadi Ganjeh ◽  
M. Eslami-Kalantari ◽  
M. Ebrahimi Loushab
Keyword(s):  
Proton Therapy ◽  
Threshold Energy ◽  
Diagnostic Algorithm ◽  
Dna Breaks ◽  
Damage Classification ◽  
Depth Dependence ◽  
Biological Effectiveness ◽  
Different Depths ◽  
Dna Break ◽  
Threshold Energies

Abstract The present study aimed to calculate the yields of DNA breaks and the variation of relative biological effectiveness (RBE) at different depths for protons using Geant4-DNA. For this purpose, an atomic model of DNA and a DNA damage classification matrix were used to calculate different DNA break yields for 62-MeV protons. As the reference radiation, the secondary electron spectrum produced by 60Co was evaluated. This helped to calculate the SSB and DSB yields. Moreover, RBE was found to be between 1.1 at the first point and 1.51 in the Bragg peak region. In this region, it was 37% greater than the 5-mm depth in the plateau region. Considering different threshold energies, the energy deposition at 10.79 eV had the most contribution to the total damage. As the results suggested, the depth dependence of RBE should be taken into account for proton therapy. It was also found that DNA break yields significantly depend on the threshold energy value.

Anisotropy of damage productions in electron irradiated molybdenum

1978 ◽  
Vol 36 (1) ◽  
pp. 354-355
Author(s):  
K. Izui ◽  
S. Furuno ◽  
H. Otsu ◽  
T. Nishida ◽  
H. Maeta
Keyword(s):  
Electron Flux ◽  
Threshold Energy ◽  
High Energy ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
Displacement Threshold ◽  
The Mean ◽  
Channeling Effect ◽  
Different Origins ◽  
Threshold Energies

Anisotropy of damage productions in crystals due to high energy electron bombardment are caused from two different origins. One is an anisotropic displacement threshold energy, and the other is an anisotropic distribution of electron flux near the atomic rows in crystals due to the electron channeling effect. By the n-beam dynamical calculations for germanium and molybdenum we have shown that electron flux at the atomic positions are from ∽4 to ∽7 times larger than the mean incident flux for the principal zone axis directions of incident 1 MeV electron beams, and concluded that such a locally increased electron flux results in an enhanced damage production. The present paper reports the experimental evidence for the enhanced damage production due to the locally increased electron flux and also the results of measurements of the displacement threshold energies for the <100>,<110> and <111> directions in molybdenum crystals by using a high voltage electron microscope.

scholarly journals HPF1 dynamically controls the PARP1/2 balance between initiating and elongating ADP-ribose modifications

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marie-France Langelier ◽  
Ramya Billur ◽  
Aleksandr Sverzhinsky ◽  
Ben E. Black ◽  
John M. Pascal
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Chain Elongation ◽  
Dna Breaks ◽  
Data Support ◽  
Damage Response ◽  
Hit And Run ◽  
Dna Break ◽  
Structural Insights ◽  
In Cells

AbstractPARP1 and PARP2 produce poly(ADP-ribose) in response to DNA breaks. HPF1 regulates PARP1/2 catalytic output, most notably permitting serine modification with ADP-ribose. However, PARP1 is substantially more abundant in cells than HPF1, challenging whether HPF1 can pervasively modulate PARP1. Here, we show biochemically that HPF1 efficiently regulates PARP1/2 catalytic output at sub-stoichiometric ratios matching their relative cellular abundances. HPF1 rapidly associates/dissociates from multiple PARP1 molecules, initiating serine modification before modification initiates on glutamate/aspartate, and accelerating initiation to be more comparable to elongation reactions forming poly(ADP-ribose). This “hit and run” mechanism ensures HPF1 contributions to PARP1/2 during initiation do not persist and interfere with PAR chain elongation. We provide structural insights into HPF1/PARP1 assembled on a DNA break, and assess HPF1 impact on PARP1 retention on DNA. Our data support the prevalence of serine-ADP-ribose modification in cells and the efficiency of serine-ADP-ribose modification required for an acute DNA damage response.

scholarly journals Impact of range uncertainty on clinical distributions of linear energy transfer and biological effectiveness in proton therapy

2020 ◽  
Author(s):  
Christian Hahn ◽  
Jan Eulitz ◽  
Nils Peters ◽  
Patrick Wohlfahrt ◽  
Wolfgang Enghardt ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Proton Therapy ◽  
Linear Energy Transfer ◽  
Biological Effectiveness

scholarly journals Clinically relevant nanodosimetric simulation of DNA damage complexity from photons and protons

RSC Advances ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 6845-6858 ◽  
Author(s):  
N. T. Henthorn ◽  
J. W. Warmenhoven ◽  
M. Sotiropoulos ◽  
A. H. Aitkenhead ◽  
E. A. K. Smith ◽  
...  
Keyword(s):  
Dna Damage ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Proton Therapy ◽  
Relative Biological Effectiveness ◽  
Biological Effectiveness ◽  
Mechanistic Understanding

Relative Biological Effectiveness (RBE) is a controversial and important topic in proton therapy. This work uses Monte Carlo simulations of DNA damage for protons and photons to probe this phenomenon, providing a plausible mechanistic understanding.

scholarly journals Variation in relative biological effectiveness for cognitive structures in proton therapy of pediatric brain tumors

2020 ◽  
pp. 1-8
Author(s):  
Ole Marius Otterlei ◽  
Daniel J. Indelicato ◽  
Laura Toussaint ◽  
Kristian S. Ytre-Hauge ◽  
Sara Pilskog ◽  
...  
Keyword(s):  
Brain Tumors ◽  
Proton Therapy ◽  
Relative Biological Effectiveness ◽  
Pediatric Brain Tumors ◽  
Cognitive Structures ◽  
Biological Effectiveness ◽  
Pediatric Brain
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