Radiation-induced double-strand breaks by internal ex vivo irradiation of lymphocytes: Validation of a Monte Carlo simulation model using GATE and Geant4-DNA.
Z Med Phys
; 2023 Aug 18.
Article
en En
| MEDLINE
| ID: mdl-37599196
ABSTRACT
This study describes a method to validate a radiation transport model that quantifies the number of DNA double-strand breaks (DSB) produced in the lymphocyte nucleus by internal ex vivo irradiation of whole blood with the radionuclides 90Y, 99mTc, 123I, 131I, 177Lu, 223Ra, and 225Ac in a test vial using the GATE/Geant4 code at the macroscopic level and the Geant4-DNA code at the microscopic level. METHODS:
The simulation at the macroscopic level reproduces an 8â¯mL cylindrical water-equivalent medium contained in a vial that mimics the geometry for internal ex vivo blood irradiation. The lymphocytes were simulated as spheres of 3.75⯵m radius randomly distributed, with a concentration of 125â¯spheres/mL. A phase-space actor was attached to each sphere to register all the entering particles. The simulation at the microscopic level for each radionuclide was performed using the Geant4-DNA tool kit, which includes the clustering example centered on a density-based spatial clustering of applications with noise (DBSCAN) algorithm. The irradiation source was constructed by generating a single phase space from the sum of all phase spaces. The lymphocyte nucleus was defined as a water sphere of a 3.1⯵m radius. The absorbed dose coefficients for lymphocyte nuclei (dLymph) were calculated and compared with macroscopic whole blood absorbed dose coefficients (dBlood). The DBSCAN algorithm was used to calculate the number of DSBs. Lastly, the number of DSBâcell-1âmGy-1 (simulation) was compared with the number of radiation-induced foci per cell and absorbed dose (RIFâcell-1âmGy-1) provided by experimental data for gamma and beta emitting radionuclides. For alpha emitters, dLymph and the number of α-tracksâ100â¯cell-1âmGy-1 and DBSsâµm-1 were calculated using experiment-based thresholds for the α-track lengths and DBSs/track values. The results were compared with the results of an ex vivo study with 223Ra.RESULTS:
The dLymph values differed from the dBlood values by -1.0% (90Y), -5.2% (99mTc), -22.3% (123I), 0.35% (131I), 2.4% (177Lu), -5.6% (223Ra) and -6.1% (225Ac). The number of DSBâcell-1âmGy-1 for each radionuclide was 0.015 DSBâcell-1âmGy-1 (90Y), 0.012 DSBâcell-1âmGy-1 (99mTc), 0.014DSBâcell-1âmGy-1 (123I), 0.012 DSBâcell-1âmGy-1 (131I), and 0.016 DSBâcell-1âmGy-1 (177Lu). These values agree very well with experimental data. The number of α-tracksâ100â¯cells-1âmGy-1 for 223Ra and 225Ac where 0.144 α-tracksâ100â¯cells-1âmGy-1 and 0.151 α-tracksâ100â¯cells-1âmGy-1, respectively. These values agree very well with experimental data. Moreover, the linear density of DSBs per micrometer α-track length were 11.13⯱â¯0.04 DSB/µm and 10.86⯱â¯0.06 DSB/µm for 223Ra and 225Ac, respectively.CONCLUSION:
This study describes a model to simulate the DNA DSB damage in lymphocyte nuclei validated by experimental data obtained from internal ex vivo blood irradiation with radionuclides frequently used in diagnostic and therapeutic procedures in nuclear medicine.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
Z Med Phys
Asunto de la revista:
RADIOTERAPIA
Año:
2023
Tipo del documento:
Article