Objective:To study the effect of reducing mA or kV on the quality of image and the radiation dose of the patients when undergoing temporal bone CT.To compare the radiation dose and image quality between spiral and non-spiral Temporal bone CT scan.Methods:Four groups of 15 patients each underwent temporal bone CT using spiral and non-spiral scan.The different parameters were following:120 kV and 150mA,or 120 kV and 60 mA respectively.The volume CT dose index (CTDIvol/CTDIw) and calculated the average dose-length produce (DLP)were recorded.Image quality of those four groups was compared and scored by two radiologists,and SPSS was uesed to calculate the result.Image quality was evaluated for the anatomical structures,including cochlea,semicircular canal,auditory ossicle,the facial nerve canal,tympanic tegmen.Results:At the same scan mode,the radiation exposure of the low-mA scaning was significantly reduced comparing with non-spiral(P<0.001).Using the same mA,the radiation dose in axial spiral was obviously lower than that of non-spiral(P<0.001).No difference was found of the quality of image betwwen group of low mA and conventional scanning.The quality of image with spiral-scan was much higher than that of non-spiral scan.Conclusions:Compared with non-spiral CT,the low-mA temporal bone spiral-CT technology might decrease the radiation exposure and guarantee the image quality to meet the need of clinician.