Comparison of cell repair mechanisms by means of chromosomal aberration induced by proton and gamma irradiation – preliminary results*
Institute of Physics, University of Szczecin,
ul. Wielkopolska 15,
2 Maritime University of Szczecin, Wały Jagielońskie 1-2, 70-500 Szczecin, Poland
3 Joint Institute of Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia
4 Departament of Oncology, Pomeranian Medical University, ul. Strzałowska 22, 71-730 Szczecin, Poland
Received: 13 January 2014
Received in final form: 17 July 2014
Published online: 19 March 2015
DNA damage of peripheral blood lymphocytes exposed to gamma and proton irradiation is studied by means of chromosome aberrations to validate the efficiency of the repair mechanisms of individual cells. A new method based on an observed deviation from the Poisson statistics of the chromosome aberration number is applied for estimation of a repair factor (RF) defined as a ratio between originally damaged cells to the amount of finally observed aberrations. The repair factors are evaluated by studying the variance of individual damage factors in a collective of healthy persons at a given dose as well as by using the chi-square analysis for the dose-effect curves. The blood samples from fifteen donors have been irradiated by Co60 gamma rays and from nine persons by 150 MeV protons with different doses up to 2 Gy. A standard extraction of lymphocyte has been used whereby dicentrics, acentrics and rings have been scored under a microscope. The RF values determined for the proton radiation are slightly larger than for gamma rays, indicating that up to 70% DNA double strand breaks can be repaired.
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