In vitro irradiation of colorectal cancer cells by pulsed radiation emitted from a hundred joules plasma focus device and its comparison with continuous irradiation

In the last years, pulsed reduced low dose radiation has been proposed as an alternative for treatment of recurrent cancer. Nonetheless, distinction between the effects of low dose pulsed and continuous radiation is barely known at cellular level. In order to study the effects of low dose pulsed radiation at cellular level, in vitro experiments are important to further advance the basic understanding in this area. In the present work we demonstrate the usefulness of a low-energy plasma focus device PF-400J as a potential source of low-dose pulsed radiation for in vitro cancer cell experiments. Colorectal cancer cell line, DLD-1, were irradiated by pulsed x-rays. Fifty pulses of x-rays provide ∼0.12 Gy dosis, which were measured using thermoluminescence detectors (TLD-100 dosimeters). Irradiation-induced DNA damage was assessed at different time points after irradiation. A statistically significant double strand break (DSB) DNA damage was observed at 30 minutes after irradiation. A comparison of DSB induced by continuous source in the same type cancer cells and pulsed irradiation is made at 30 minutes post-irradiation. In the case of pulsed irradiation, DSB per unit dose found higher. Our findings suggest that low-energy plasma focus devices could have potential application as pulsed radiation source in the area of in vitro cancer cell experiments. (paper)