Chromosome aberrations induced by protons up to 31 MeV in cultured human cells

Abstract

Chromosome aberrations were induced in cultured human cells by proton beams of 31, 12, and 8 MeV. The frequencies of isochromatid breaks and dicentrics have been analysed as a function of proton energy and dose. Both effects are largely dependent on proton energy; isochromatid breaks increased linearly with the dose, whereas dicentrics show a definite parabolic behaviour. The experimental data were fitted to the analytic form Y = KDn and Y = alpha D + beta D2 and the best fitted values of the parameters are reported and discussed. The values of RBE for the isochromatid breaks are in the ratio 1.7:1.3:1 for 8, 12, and 31 MeV respectively. In the case of the dicentrics the RBE values are dose-dependent function of the type CD-n. The three distributions of dicentrics among the cells do not fit a Poisson distribution.

Modelling Heterogeneous Anomalous Dynamics of Radiation-Induced Double-Strand Breaks in DNA during Non-Homologous End-Joining Pathway

“… Number of dicentrics per cell after 24 h of repair as a function of the dose of proton irradiation for FBM without directed movement ( a ) and HFBM ( b ). HFBM reproduces a trend similar to experimental data from Bettega et al [ 42 ] (blood samples) and Schmid et al [ 43 ] (human heteroploid line with epithelioid morphology). …”

Apparent absence of a proton beam dose rate effect and possible differences in RBE between Bragg peak and plateau

“…In fact, our data suggested that more than 15% of RBE difference exists between Bragg peak ͑L D = 3.19 keV/ m͒ and plateau ͑L D = 0.56 keV/ m͒. In Bettega et al, 21,22 it was shown that proton RBE determined via the formation of micronuclei in a heteroploid cell line with an epithelioid morphology ͑EUE line with a modal number of 60 chromosomes͒ were 1.7, 1.3, and 1.0 for proton beams of 8, 12, and 31 MeV, which had LET of 5.5, 4.0, and 1.8 keV/ m, respectively. 16 Our results, as well as the previous measurement of RBE at SOBP center, 7 were consistent with their results.…”

An analysis of the distribution and dose response of chromosome aberrations in human lymphocytes after in vitro exposure to137Cesium gamma radiation

“…Bauchinger et al [5] showed a good fit to the Poisson distribution for 3 MeV electrons, as did Virsik et al [36] for 30 kV and 150 kV X-rays. Deviations from the Poisson distribution for dicentrics have been found for neutron radiation [17,31] and proton beams [8] as well as for alpha particles [18]. '…”