For purpose of getting the radial electric current density in the medium of the cable due to X-rays illumination, Monte Carlo method and Finite-Difference Time-Domain (FDTD) method are used. Using the radial electric current density as the source of Maxwell functions, center conductor response current is calculated under the condition of matching load of cable ends. Distributed charges in center conductor, medium and shielding are considered in this method. The results show that the center conductor response current is proportional to the length of the illumination, and it is in the opposite direction of the source. In source zone, there is static field. The distributed charge of the center conductor is calculated using electric field, and it is about 20% less than the solution of Monte Ca