Size-specific dose estimation in pediatric computed tomography: From dose characterization to individualized...

Pediatric computed tomography (CT) is clinically indispensable for emergency care, neurologic disorders, thoracoabdominal diseases, trauma assessment, and oncologic diagnosis and follow-up. However, children should not be regarded as small adults. They are actively growing and developing, and organs or tissues such as the hematopoietic system, thyroid, breast, gonads, lens, central nervous system, and bone marrow are more sensitive to ionizing radiation. In addition, children have a longer life expectancy, allowing a longer latency window for radiation-related late effects. Epidemiological studies suggest associations between pediatric CT exposure and cumulative-dose-related risks of leukemia, brain tumors, and overall cancer; although the individual absolute risk is generally low, stricter justification, optimization, and dose recording remain necessary in pediatric populations. Conventional volume CT dose index (CTDI_vol) and dose-length product primarily describe scanner output under standard phantom conditions and cannot adequately characterize differences in patient body size, tissue attenuation, organ location, and scan coverage. Size-specific dose estimate (SSDE), which corrects CTDI_vol using a patient-size conversion factor, represents an important intermediate dose descriptor linking scanner output, pediatric body-size characteristics, organ-dose estimation, and scan-protocol optimization. This review focuses on the specific requirements of pediatric CT dose assessment. It summarizes the conceptual evolution of SSDE, the selection of size metrics, applications across examination sites, relationships with organ dose and radiation-risk assessment, pediatric diagnostic reference levels, and future directions in automated dose management. The aim is to provide a conceptual and practical basis for individualized pediatric CT dose optimization.