Track detection on the cells exposed to high LET heavy-ions by CR-39 plastic and terminal deoxynucleotidyl transferase (TdT)

Background: The fatal effect of ionizing radiation on cells depends on Linear Energy Transfer (LET) level. The distribution of ionizing radiation is sparse and homogeneous for low LET radiations such as X or γ, but it is dense and concentrated for high LET radiation such as heavy-ions radiation. Material and Methods: Chinese hamster ovary cells (CHO-K1) were exposed to 4 Gy Fe-ion 2000 keV/m. The CR-39 is a special and sensitive plastic used to verify exact position of heavy-ions traversal. Terminal deoxynucleotidyl transferase (TdT) is an enzyme labeled with [3H] dATP for detection of cellular DNA damage by autoradiography assay. Results: The track of heavy ions traversals presented by pit size was almost similar for all different doses of radiation. No pits to show the track of traversal were found in 20% of the cell nuclei of the irradiation. Apparently these fractions of cells wave not hit by heavy ions. Conclusion: This study indicated the possible usefulness of both the CR-39 plastics and DNA labeling with TdT method for evaluating the biological effect of heavy-ions in comparison with low LET ionizing radiation.