Objective To evaluate and compare the radiation dose and image quality of the new generation of whole body mobile CT (BodyTom CT) with commonly used fixed CT.Methods The image quality was evaluated with CATPHAN 500 performance test body model.The radiation dose was measured by conventional 100 mm pen ionization chamber and PMMA body phantom and head phantom (head diameter 160 mm,phantom diameter 320 rm and width 140 mm).Results The spatial and contrast resolution of BodyTom CT images were similar to two kinds of fixed CT(P ＞ 0.05).The CNR of image with BodyTom CT decreased by about 20％:In head scan mode,significantly lower than that with Philps 64 slice CT and Toshiba 320 slice CT (with soft,t =-4.82,-6.98,P ＜ 0.05;with standard,t =-20.60,-20.09,P ＜0.05);in body scan mode,significantly lower than that with Philps 64 slice CT and Toshiba 320 slice CT (with soft,t =-5.67,-12.82,P ＜ 0.05;with standard,t =-3.39,-9.18,P ＜ 0.05;with sharp,t =-3.88,-3.21,P ＜0.05).The radiation dose with BodyTom CT was significantly higher than that with fixed CT:in body model,22.97％ than that with Philps 64(t=9.48,P＜0.05),29.6％ than that with Toshiba 320 slice CT(t =11.66,P ＜0.05);in head model,29.76％ than that with Philps 64 slice CT(t=23.44,P＜0.05),33.22％ than that with Toshiba 320 slice CT(t=23.11,P＜0.05).Conclusions The radiation dose with mobile CT was over 20％ higher than that with routine multi-row CT while with the similar image quality.