Abstract
A compact micro X-ray beam irradiation system has been developed to research the effects of radiation for single cell. A micro radiation beam experimental system is one of the most useful tools to research cellular damages such as chromosome aberrations and mutagenesis. The system was composed of a 50kV micro focus X-ray tube with X-ray guide-tube, an X-ray detector for fluorescent X-ray analysis and a sample stage with an inverted microscope. In the microscope observation, a single cell can be irradiated with the micro X-ray beam. It has been obtained from the beam profile measurement that the X-ray beam diameter was 14 µm[FWHM] and the flux was ~5.0×103 [photon/100mm2/s]. Also, a Monte Carlo photon-electron transport simulation was performed to estimate the dose rate for the irradiated single cell and the maximum dose rate was 0.5 Gy/s. In a preliminary experiment, the single-cell irradiations were performed using the yeast cells. The budding yeast Saccharomyces cerevisiae was irradiated with the micro X-ray beam irradiation system, and the maximum dose for the samples was 60 Gy. After the X-ray irradiation, the irradiated yeast cells were incubated at room temperature, and the time-lapse images of the irradiated cells were collected during incubation. After incubation for 20 hours, cell growth and division were hardly observed. This result shows that the X-ray beam had been delivered to targeted cells, and the irradiated cells had the lethal dose of X-ray.
