Integrating Longitudinal Complete Blood Count Surveillance with Occupational Hp(10) Monitoring in Healthcare Workers Exposed to Low-Dose Ionizing Radiation: A Six-Year Retrospective Pilot Study

This six-year retrospective pilot evaluated the operational and analytical feasibility of linking longitudinal complete blood count (CBC) surveillance with occupational personal dose equivalent at a depth of 10 mm, Hp(10), without inferring biological safety. Among 368 screened workers, 358 had linkable dosimetry and 34 met the complete annual CBC criterion for 2018–2023. The cohort contributed 204/204 CBC and 182/204 annual Hp(10) observations. Median cumulative Hp(10) was 0.911 mSv (IQR 0.550–1.739; range 0.242–99.105), and 32/34 workers accumulated less than 15 mSv. Maximum-likelihood random-intercept models treated annual Hp(10) as a time-varying exposure and included prespecified confounder and sensitivity analyses. No annual lymphocyte trend was detected (β = 0.009 ×10 ³ /µL/year; p = 0.563), and annual Hp(10) was not associated with lymphocyte count in crude, age- and sex-adjusted, high-dose exclusion, complete-dose, or occupational-area models. Hemoglobin showed a small annual trend without dose dependence. Although record linkage and analysis were operationally achievable, 9.5% cohort retention, small sample size, narrow exposure range for most workers, influential high-dose observations, residual confounding, and incomplete annual dosimetry preclude biological or safety conclusions. The study provides a reproducible surveillance-linkage workflow and specifies data requirements for larger prospective multicenter research.