Environmental and operational factors affecting 17-month routine ¹⁸F-FDG production: Impact of final purification water cooling and process optimization

Background: In-house ^18F-FDG production is increasingly adopted by hospitals, yet few studies have quantified how environmental and operational factors influence radiochemical yield during real-world clinical operation. In May 2024, our institution launched a new cyclotron facility where all technologists had no prior experience in FDG manufacturing. This study evaluates 17 months of continuous production to identify factors associated with yield stability. Methods: A total of 17 months of consecutive production records were analyzed using a cyclotron (HM-12S) and an automated synthesizer (F300). Environmental variables included ambient temperature, humidity, and weather (Sunny/Cloudy/Rainy). The cooling condition (room temperature vs 4 °C) and implementation of a line-drying procedure were also evaluated. FDG yield, non–decay-corrected to end of bombardment (EOB), was analyzed using univariate comparisons and multivariate linear regression. Results: Temperature and humidity showed weak but consistent correlations with yield (R² < 0.1). Weather demonstrated minimal direct impact. Cooling showed no statistically significant effect but slightly reduced variability, while the drying procedure resulted in a modest improvement in median yield and a reduction in variability. A full multivariate model revealed that no single factor strongly predicted yield; however, the combined contribution of environmental parameters and operational refinements explained a meaningful portion of yield stabilization over time. Notably, FDG production was completed without cancellation throughout the study period. Conclusion: Although individual environmental and operational factors exhibited only small effects on ^18F-FDG yield, their combined influence contributed to greater production stability. This multivariate approach provides practical insights for newly established hospital cyclotron facilities and supports systematic optimization in real-world FDG manufacturing.