| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1875869 | Applied Radiation and Isotopes | 2014 | 5 Pages |
•We found that greater dose-rate effect were observed in T98G cells underwent BNCT than gamma-ray.•Time dependence of 53BP1 foci was not direct evidence of dose-rate effect of BNCT.•The difference of 53BP1 foci reflected the difference of the survival rate results.•The dose-rate effect of BNCT was not that of alpha particles or 7Li nuclei produced by 10B (n,α) 7Li reaction.
BackgroundIt is generally said that low LET radiation produce high dose-rate effect, on the other hand, no significant dose rate effect is observed in high LET radiation. Although high LET radiations are produced in BNCT, little is known about dose-rate effect of BNCT.Materials and methodsT98G cells, which were tumor cells, were irradiated by neutron mixed beam with BPA. As normal tissue derived cells, Chinese hamster ovary (CHO-K1) cells and DNA double strand breaks (DNA-DSBs) repair deficient cells, xrs5 cells were irradiated by the neutrons (not including BPA). To DNA-DSBs analysis, T98G cells were stained immunochemically with 53BP1 antibody. The number of DNA-DSBs was determined by counting 53BP1 foci.ResultsThere was no dose-rate effect in xrs5 cells. D0 difference between 4 cGy/min and 20 cGy/min irradiation were 0.5 and 5.9 at the neutron and gamma-ray irradiation for CHO-K1, and 0.3 at the neutron for T98G cells. D0 difference between 20 cGy/min and 80 cGy/min irradiation for T98G cells were 1.2 and 0.6 at neutron irradiation plus BPA and gamma-ray. The differences between neutron irradiations at the dose rate in T98G cells were supported by not only the cell viability but also 53BP1 foci assay at 24 h following irradiation to monitor DNA-DSBs.ConclusionDose-rate effect of BNCT when T98G cells include 20 ppm BPA was greater than that of gamma-ray irradiation. Moreover, Dose-rate effect of the neutron beam when CHO-K1 cells did not include BPA was less than that of gamma-ray irradiation These present results may suggest the importance of dose-rate effect for more efficient BNCT and the side effect reduction.
