Dnadamage1 - underestimation of indirect SB after irradiation with alpha-partciles

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Geant4 Version: 11.2.2
Operating System: Centos8
Compiler/Version:
CMake Version: 3.25.1


I am running dnadamage1 example (extented-medical-dna-dnadamage1)

Voxel model irradiated with alpha particles with energy 1 MeV. About 4000 particles shots.

Obtained result reveals a significant uderestimation of Indirect Strand Breaks.

Total direct strand breaks SSBd=299843

total indirect strad breaks SSBi=15792


So, the number of indirect SB 20-times smaller, than number of direct SB. But as we know from literature, for alpha particles with 1 MeV enegry, it should be approximatly equal to the amound of direct SB.

That is the reason of such underestimation?

Dear,

This is interesting! This example is done for a short chromatical fiber. It could be this reason. Maybe you want to try moleculedna or dsbandrepair examples ( advanced/dna)?

I have also tried dsbandrepair-example and find out the same underestimation for indirect SB.

Here is the output of dsbandrepair geant 11.2.2 example. Only 1 option changed from original - I have choose G4emDNA_option2 instead of G4emDNA.

Alpha particles 10 MeV, 5000 ions shot


#=========================== Strand Breaks ============================#
Name of Cell Nucleus: Undefined
Volume of Cell Nucleus: 7.32358e-16 (m3)
Mass Density of Cell Nucleus: 1000 (kg/m3)
Mass of Cell Nucleus: 7.32358e-13 (kg)
Energy deposited in Cell Nucleus: 1.67964e+08 (eV)
Dose delivered in Cell Nucleus: 36.6955 (Gy)
Minimum Distance between two clusters: 10 (bp)
Number of basepairs in Cell Nucleus: 6.23368e+09 (bp)
Threshold Energy for direct damage selection: 17.5 (eV)
Propability for indirect damage selection: 40 (%)
#======================================================================#

#Un-normalized results:
TotalSB [SB] 12972 +/- 478.52
DirSB [SB] 10665 +/- 394.82
IndirSB [SB] 2307 +/- 120.567
SSB [SB] 10676 +/- 394.094
DSB [SB] 680 +/- 35.2364
cDSB [SB] 135 +/- 12.8027
sDSB [SB] 545 +/- 58.8973
DSBdir [SB] 675 +/- 35.1667
DSBind [SB] 152 +/- 18.2394
DSBdirIn [SB] 147 +/- 18.1719

#Normalized results:
TotalSB [SB/Gy/Gbp] 56.7086 +/- 2.0919
DirSB [SB/Gy/Gbp] 46.6233 +/- 1.726
IndirSB [SB/Gy/Gbp] 10.0853 +/- 0.527074
SSB [SB/Gy/Gbp] 46.6714 +/- 1.72283
DSB [SB/Gy/Gbp] 2.9727 +/- 0.15404
cDSB [SB/Gy/Gbp] 0.590168 +/- 0.0559685
sDSB [SB/Gy/Gbp] 2.38253 +/- 0.257476
DSBdir [SB/Gy/Gbp] 2.95084 +/- 0.153735
DSBind [SB/Gy/Gbp] 0.664486 +/- 0.0797358
DSBdirIn [SB/Gy/Gbp] 0.642628 +/- 0.0794407
#======================================================================#
where:
-----> TotalSB: Total strand-breaks
-----> DirSB: Direct strand-breaks
-----> IndirSB: Indirect strand-breaks
-----> SSB: Single strand-breaks
-----> DSB: Double strand-breaks
-----> cDSB: Complex DSB
-----> sDSB: Simple DSB
-----> DSBdir: DSB that contains at least one direct SB
-----> DSBdind: DSB that contains at least one indirect SB
-----> DSBdirIn: DSB that contains at both direct and indirect SB
#============================== End ===================================#

DirSB =10665

IndirSB=2307

Alpha particles 2.9 MeV 5000 particles shot:


#=========================== Strand Breaks ============================#
Name of Cell Nucleus: Undefined
Volume of Cell Nucleus: 7.32358e-16 (m3)
Mass Density of Cell Nucleus: 1000 (kg/m3)
Mass of Cell Nucleus: 7.32358e-13 (kg)
Energy deposited in Cell Nucleus: 4.62892e+08 (eV)
Dose delivered in Cell Nucleus: 101.129 (Gy)
Minimum Distance between two clusters: 10 (bp)
Number of basepairs in Cell Nucleus: 6.23368e+09 (bp)
Threshold Energy for direct damage selection: 17.5 (eV)
Propability for indirect damage selection: 40 (%)
#======================================================================#

#Un-normalized results:
TotalSB [SB] 36830 +/- 1323.07
DirSB [SB] 35790 +/- 1285.72
IndirSB [SB] 1040 +/- 52.8362
SSB [SB] 20481 +/- 736.263
DSB [SB] 4431 +/- 177.13
cDSB [SB] 1986 +/- 86.3021
sDSB [SB] 2445 +/- 144.366
DSBdir [SB] 4430 +/- 177.091
DSBind [SB] 228 +/- 35.9627
DSBdirIn [SB] 227 +/- 35.8072

#Normalized results:
TotalSB [SB/Gy/Gbp] 58.4226 +/- 2.09876
DirSB [SB/Gy/Gbp] 56.7729 +/- 2.03951
IndirSB [SB/Gy/Gbp] 1.64973 +/- 0.0838128
SSB [SB/Gy/Gbp] 32.4885 +/- 1.16792
DSB [SB/Gy/Gbp] 7.02879 +/- 0.280978
cDSB [SB/Gy/Gbp] 3.15035 +/- 0.136899
sDSB [SB/Gy/Gbp] 3.87845 +/- 0.229005
DSBdir [SB/Gy/Gbp] 7.02721 +/- 0.280915
DSBind [SB/Gy/Gbp] 0.361671 +/- 0.0570468
DSBdirIn [SB/Gy/Gbp] 0.360085 +/- 0.0568002
#======================================================================#
where:
-----> TotalSB: Total strand-breaks
-----> DirSB: Direct strand-breaks
-----> IndirSB: Indirect strand-breaks
-----> SSB: Single strand-breaks
-----> DSB: Double strand-breaks
-----> cDSB: Complex DSB
-----> sDSB: Simple DSB
-----> DSBdir: DSB that contains at least one direct SB
-----> DSBdind: DSB that contains at least one indirect SB
-----> DSBdirIn: DSB that contains at both direct and indirect SB
#============================== End ===================================#

DirSB [SB] 35790
IndirSB [SB] 1040

This is interesting! This example is done for a short chromatical fiber. It could be this reason. Maybe you want to try moleculedna or dsbandrepair examples ( advanced/dna)?


Thank you for your reply. dnadamage1 is the simplest example developed for counting direct-indirect strand breaks with Voxel_straight model, so first of all i have run the simplest example

Thanks for your result! In this example, if some DNA molecules are involved in direct damage, they are no longer engaged in indirect damage. At this LET, this may have happened a lot. Can you cite some papers for equal damage ?