Hiroshi Yamaguchi

Accepted for publication in Nuclear Medicine Communications (June 2026). Co-first authors: Masanori Watanabe and Hiroshi Yamaguchi.

2026年8月25日 受理（Accepted）

Purpose The study aimed to develop and evaluate a practical model for determining cyclotron irradiation time based on planned fluorodeoxyglucose (FDG) supply in a hospital-based production setting. Methods Irradiation time was calculated using a composite coefficient of 2.8 min per GBq of planned clinical demand. The coefficient integrated a facility-specific conversion between required end-of-bombardment activity and irradiation time, a conservative synthesis yield of 55%, quality control activity consumption of 11.1%, radioactive decay during an approximately 30-min processing interval, and an operational safety factor of 1.2. Results During a fixed 24-month evaluation period, the model was applied on 516 consecutive scheduled FDG production days. Sufficient FDG activity was supplied for all scheduled examinations on all 516 days (100%), with no activity shortage attributable to underestimation of the required irradiation time. Conclusion A demand-based irradiation model incorporating conservative yield assumptions, quality control consumption, and handling margins enables reliable FDG supply while maintaining an appropriate activity margin. This approach provides a practical framework for hospital-based radiopharmaceutical production.

Accepted for publication in Operational Radiation Safety, a quarterly supplement of Health Physics (25 Aug 2026).

This technical note reports threshold behavior of droplet release in automated [¹⁸F]FDG quality control. During routine operation of an automated QC system, small-volume dispensing showed unstable droplet release, resulting in misplacement on test media. Droplet behavior was sensitive to programmed dispensing volume: 0.011 mL frequently resulted in adhesion to the needle tip, 0.012 mL showed borderline behavior, and 0.013 mL restored stable release. The findings highlight the importance of periodic verification and adaptive adjustment of dispensing parameters in automated radiopharmaceutical quality control.

Routine maintenance of a radio-HPLC detector system resulted in an unintended shift of the detector energy window from 511 keV to approximately 400 keV, causing substantial signal attenuation during radiopharmaceutical quality control. This report describes the incident, root cause analysis, and the role of technologists and site engineers in identifying and resolving the problem.

Accepted for publication in the October–December 2026 issue of the Journal of Clinical Engineering.