Host: The Japan Radiation Research Society
Co-host: City of Kitakyushu, University of Occupational and Environmental Health, Japan
Accumulating evidence indicates that the biological effects of low dose and low dose-rate radiation are different from those of high dose and high dose-rate radiation. Radiation-induced bystander response is defined as a response in cells that have not been directly targeted by radiation but is in the neighborhood of cells that have been directly exposed. Thus, to elucidate the bystander reponse is important to evaluate the risk of low dose radiation. It has already reported many results of bystander response induced by high-LET charged particle radiations. On the other hand, it has not yet fully recognized that to low-LET photons.
The CRIEPI microbeam X-ray irradiation system is a powerful tool to investigate cellular response to low dose and low dose-rate radiation. X-ray microbeam irradiation system has been developed in March, 2007. Our system is characterized by (1) tabletop (2) X-ray focusing system using Fresnel zone plate (FZP), and (3) on-line confocal laser microscope. Characteristic X-ray of aluminum (1.49 keV) was generated by focused electron bombardment of aluminum target. The FZP was used to focus aluminum K-shell X-ray. The size of X-ray beam is 2-3 microns in diameter.
Using our irradiation system, we identified the dose response of X-ray-induced bystander cell killing of normal human WI-38 cells obtained using our system. In addition, we could observe the induction of complex clustered DNA damage by the high dose of X-ray microbeam irradiation. Recent cell irradiaion studies and the details of the performance of our system will be present.
