Abstract: Objective: To study the effect of different tube pitches on neck CTA radiation dose and image quality under automatic tube current modulation technology. Data and methods: A total of 120 patients were selected for neck CTA examination in Tinglin Hospital of Jinshan District, Shanghai from September 2022 to May 2023, including 52 males and 68 females, aged 45~86 years, with an average age of 66.76 years. According to different pitches, patients were assigned to three groups: A, B and C, with a total of 40 cases of 0.8 pitch in group A, 40 cases with 1.0 pitch in group B, and 40 cases with 1.2 pitch in group C. Univariate ANOVA test was used to compare gender, age, height, weight, and total scan duration between the three groups. CT value, SD value, SNR, CNR of the carotid artery bifurcation between the three groups and the jugular vein and sternocleidomastoid muscle in the same layer; Subjective scoring of image quality between the three groups; TDLP automatically generated by the device and calculated ED. Kappa test was used to test the consistency of subjective scores of the two physicians. Results: There were no significant differences in gender, age, height and weight between the three groups, and there was no significant difference in automatic TDLP and calculated ED. There were no significant differences in CT values at the carotid bifurcation and CT values of the same layer of sternocleidomastoid muscle, SD, SCR, CNR and SD values of the carotid artery bifurcation between the three groups, and the modified score between the three groups. Conclusion: Based on the premise of automatic tube current modulation technology, radiation dose can be effectively reduced. Even if different pitches are used, radiation dose will not increase or decrease. However, as the pitch increases, the scanning time is shorter, which can effectively reduce the interference of veins on image quality, reduce motion artifacts, and improve the image quality of neck CTA.