A reproducible framework for constructing a longitudinal low-dose CT screening image database: implementation using 11 years of real-world data.

This study presents a reproducible methodological framework for constructing a longitudinal low-dose computed tomography (LDCT) screening image database and demonstrates its implementation using 11 years of real-world data from a single region in Japan. The framework integrates hierarchical identifier design, deterministic metadata linkage, structured anonymization, and a minimal metadata specification to enable consistent organization of longitudinal imaging data. The implemented database comprises 45,337 LDCT examinations from 23,065 examinees, with 47.0% undergoing repeated screening. All examinations were acquired using a standardized CT scanner and protocol and were linked to screening assessment categories and smoking exposure information. The resulting structure supports reproducible subject-level aggregation, temporal tracking, and quantitative image analysis. This framework provides a transferable model for institutions seeking to construct longitudinal screening imaging repositories.