Objective To analyze spectral curves and iodine levels in normal adult thyroid by using dual-source CT scanning technique and provide the basis for the differential diagnosis of thyroid space-occupying lesions.Methods A total of 70 subjects were selected for this study,including 38 females and 32 males.They were excluded from thyroid disease by ultrasound examination and had all taken the dual-source CT scan.The image data were transported to the CT workstation,the analysis of iodine levels and spectral curves were completed in theLiver VNCandMonoenergetic modes respectively.The gender differences in ratio iodine content were compared.Results The iodine ratio of thyroid was (1.35±0.19) mg/mlin plain scan,(1.35±0.23) and (1.35±0.21) mg/ml in left lobe and right lobe respectively.There was no statistically significant difference between left and right lobe (P ＞ 0.05),as well as between females and males (P ＞ 0.05).The slopes of the energy spectrum curve in the left and right lobe of the thyroid were 9.98 ± 2.43 and 9.74 ± 1.63,respectively,and 9.88 ± 1.74 and 9.74 ±0.09 for the male and female,respectively.There was no significant difference of slopes of the energy spectrum curve between the left and right lobe,as well as the male and female.The average dose length product of all patients was (208.29 ±21.80) mGy·cm,and the average effective dose was (1.23 ± 0.13) mSv.Conclusions Dual-source dual-energy CT scanning technique have definitive,diagnostic characteristic in the measurement of spectral curves and calculation of the ratio of iodine in normal adult thyroid tissue,and therefore has guidance value in the diagnosis of thyroid space-occupying lesions.