Abstract: Objective: To investigate the radiation dose levels of adult head and chest CT examinations in a grassroots medical institution in a suburban area of Beijing, evaluate their rationality, and provide a basis for establishing the diagnostic reference level (DRL) for this region. Methods: Based on 15 CT devices of 11 grassroots medical institutions within the jurisdiction, the relevant scanning parameters and radiation dose data of head and chest CT examinations were collected, the dose distribution was statistically analyzed, and comparisons were made with the recommended values of DRL from both domestic and international sources. Results: The DRL of CT dose index (CTDI) and dose-length product (DLP) for head CT was 59.83 mGy and 814.08 mGy·cm, respectively, while the DRL of volume CT dose index (CTDIvol) and DLP for chest CT was 13.68 mGy and 444.51 mGy·cm, both of which were lower than the industry standards in China. The DRL of head CT was superior to most national standards, and the differences in other DRLs were not significant. The radiation dose in tertiary hospitals was significantly lower than that in primary hospitals, and there were significant differences in both scanning parameters and radiation doses. Conclusion: The overall radiation dose of adult head and chest CT in grassroots medical institutions in this region is within a reasonable range. However, the CT scanning parameters of some grassroots hospitals need to be optimized to further reduce the radiation risk for patients.