Microdosimetric characteristics of micro X-ray beam for single cell irradiation

A tabletop micro X-ray beam irradiation system has been developed to research radiation effects on living cells. The microbeam system is composed of a micro focus X-ray tube, a capillary for X-ray guide, an X-ray semiconductor detector for fluorescent X-ray analysis and an inverted microscope. A beam profile measurement was performed and the size of the focused beam was 10 mum in diameter (FWHM) with the divergence of 5.1 mrad. The data on the microbeam measurement was approximately in agreement with a simulation of X-ray optical traces for the designed capillary. In addition, the microdosimetric characterization for the single cell irradiation was performed with the beam profile measurement and a photon-electron transport simulation. The maximum of the dose rate for the sample cells set in the system was estimated to be 0.05 Gy/s. In a preliminary experiment, single yeast cell was irradiated with the X-ray microbeam, and the data on the survival rate of the cell samples for the X-ray doses was obtained. Then, the microbeam irradiation system is useful to research the radiation effects to the living cells