Effects of Pulsed X-rays on Cancer Cells compared with Conventional X-rays Irradiation.*

It is demonstrated that pulsed X-rays (\textasciitilde 15ns) from a kJ plasma focus (PF-2kJ) device produce larger amount of cell death than conventional continuous X-rays in colorectal colon cancer line, DLD-1, for the similar amount of doses. At first, PF-2kJ was optimized for the maximum X-rays emission. Doses were characterized using thermoluminscent detectors (TLD-600). It was found that 60 pulses of X-rays provide about 0.7 Gy at a distance \textasciitilde 10.0 cm from the top of the PF-2kJ anode. Experiments were performed to irradiate (60 pulses of X-rays) DLD-1 cell line in vitro. Results show that 60 pulses of X-rays induce a significant cell death at 48 h post irradiation, which was \textasciitilde 3-fold greater than that was induced at 0.6 Gy obtained from a conventional continuous X-rays irradiation, and similar to the cell death evoked at 12 Gy (continuous X-rays). Dose rate for pulsed X-rays from PF-2kJ, was found \textasciitilde 10$^{\mathrm{7}}$ Gy/min that was larger than the conventional X-rays source (0.5 Gy/min). Thus, kJ plasma focus have potential applications in the area of cancer research. Results are encouraging to study the pulsed X-rays effects on different cancer cell lines, to study as a possible alternative of conventional radiation therapy.