Abstract

In the present work, a kilojoule plasma focus device, PF-2 kJ, is adopted as a pulsed x-ray source to study the effects of pulsed radiation in cancer cells. Low dose hyper-radiosensitivity (LDHRS) effects have been explored in various cancer cell lines using conventional x-ray irradiation. To the best of our knowledge, the LDHRS effects have not yet been explored using pulsed x-rays. Cell death was evaluated in human colorectal (DLD-1 and HCT-116) and breast (MCF-7) cancer cell lines (monolayer cell cultures) irradiated with 10 (similar to 0.24 Gy), 20 (0.61 Gy), and 40 (similar to 1.1 Gy) pulses (FWHM similar to 90 ns, dose rate similar to 10(7) Gy/min with a dose of 0.025 Gy per pulse). The LDHRS cell death effect in the DLD-1 cell line irradiated with pulsed x-ray is three times higher than the reported for a conventional continuous x-ray source at two times higher doses. LDHRS was also observed in HCT-116 and MCF-7 cells exposed to 10 and 20 x-ray pulses, respectively, which are reported not to exhibit LDHRS when conventional continuous x-ray sources are used. Besides, a normal colorectal cell line, CCD-841-CoN, does not show a significant cell death at 10 pulses. These preliminary results suggest a selective effect of low-dose pulsed x-rays on cancer cells. The present work demonstrates the applicability of plasma focus devices for cancer research. Further possibilities in the exploration of pulsed x ray of high-dose rate and low total dose in radiotherapy research are opened.