Comparisons of DNA damages in physics process caused by protons with different energies / 中华放射医学与防护杂志

ABSTRACT

Objective To compare the difference among DNA damages in physics processes caused by protons with different energies around Bragg peak.Methods By constructing the nucleus and DNA model using Geant4 and simulating the transportation processes of protons with different energies around Bragg peak in nucleus model based on Geant4-DNA,the information of interaction points were recorded.16％ of them were picked randomly to use as the points at which protons interact with DNA.After finding out the points which broke the DNA and writing their information to new files,these new files were treated with density-based spatial clustering of applications with noise (DBSCAN),so as to analyze and calculate the difference of DNA damages caused by protons with different energies.Results With the protons with energies from 20.0 to 0.6 MeV,the numbers of damage points and damage clusters increased from 49.86 to 549.88 and from 2.92 to 82.46,respectively;the numbers of clusters with different sizes had a remarkable increase,and the number of clusters with size not less than 5 increased by 400 times.The average cluster size increased slightly.Simple single strand breaks (SSSBs),complex single strand breaks (CSSBs),simple double strand breaks (SDSBs) and complex double strand breaks (CDSBs) of DNA increased by about 8,26,24 and 64 times,respectively.The proportion of single strand breaks (SSBs) decreased from 96.69％ to 89.37％,and the double strand breaks (DSBs) increased from 3.31％ to 10.63％.Conclusions The lower proton energy would result in the more complex damage to DNA and the harder repair of DNA damage.