Objective To explore and establish a technical pathway for size-specific dose estimate (SSDE) in pediatric CT patients of different age groups based on structured dose files and DICOM files, and to provide an effective method for precise monitoring of medical radiation exposure in pediatric CT scans. Methods Structured radiation dose reports (SR files) for pediatric patients aged 15 and under, who underwent CT scans between January and December 2023, were exported from the hospital information system. Scanning parameters and dose information were extracted using specialized software, and SSDE was calculated based on the patient body size parameters. The data were grouped by age (0- < 1 year, 1- < 5 years, 5- < 10 years, and 10-15 years) for statistical analysis. Results From January to December 2023, a total of 2706 pediatric CT scans were performed at the hospital, including 385 (14.23%) head scans, 1990 (73.54%) chest scans, 143 (5.28%) abdominal scans, 112 (4.14%) limb scans, and 76 (2.81%) other scans. The typical volume CT dose index (CTDI_vol) for head CT in the age groups of 0- < 1 year, 1- < 5 years, 5- < 10 years, and 10-15 years were 36.21, 35.29, 37.27, and 41.18 mGy, respectively; the corresponding SSDE values were 41.27, 32.82, 30.56, and 28.41 mGy, respectively. For chest CT scans, the typical CTDI_vol for the age groups of 1- < 5 years, 5- < 10 years, and 10-15 years were 1.91, 2.11, and 2.51 mGy, respectively; the corresponding SSDE values were 2.36, 2.21, and 3.50 mGy, respectively. For abdominal CT scans, the typical CTDI_vol for the age groups of 1- < 5 years, 5- < 10 years, and 10-15 years were 3.94, 4.33, and 6.26 mGy, respectively; the corresponding SSDE values were 5.77, 7.10, and 9.79 mGy, respectively. Conclusion This study developed a technical pathway to estimate the medical radiation doses of pediatric CT patients of different ages based on structured dose files and DICOM files. The feasibility of this approach was validated using data collected over a one-year period.