Research for Absorbed Dose of Patients by IGRT on Varian Accelerator

Objective:To measure the absorbed dose of patients by different image-guide methods.Methods:Two perpendicular fields(0°270°),with MV and kV X ray,acquired 2D images and measured the absorbed dose in the phantom.The 3D imaging dose for CBCT was also measured in the phantom.Results:The imaging dose for MV/MV was ranged from 82.08 mGy to 100.99 mGy and 89.76 mGy at the center in the head phantom.The imaging dose for kV/kV was ranged from 0.461 mGy to 1.044 mGy and 0.737 mGy at the center.For a CBCT,the imaging dose was in the range of 2.998 mGy～6.426 mGy,and the center was 4.676mGy.For low dose mode,the imaging dose was 50% of the standard mode.Conclusions:For the OBI system,the imaging dose is lower and image quality is better than EPID.The CBCT is well suited for daily position verification.During treatment positioning,the appropriate image-guide methods and scanning parameters should be selected in order to assure the patients precise and safety.