Operational reliability of an automated¹⁷⁶Lu-based daily quality control system: a five-month continuous monitoring...

Objective.This study aimed to evaluate the feasibility of background quality control (QC) as a novel approach for monitoring time-of-flight (TOF) and energy drift in uMI 550 positron emission tomography-computed tomography (PET/CT) systems.Methods.Three experiments were conducted to compare¹⁷⁶Lu background QC with conventional radioactive source QC. These included multi-system validation, long-term clinical tracking, and anomaly detection. System performance was assessed by calculating TOF drift, energy drift, TOF deviation, and energy deviation. The Wilcoxon signed-rank test compared energy and TOF drift between¹⁷⁶Lu background QC and¹⁸F-FDG rod phantom QC, while the Friedman rank sum test compared parameters among¹⁷⁶Lu background QC,¹⁸F-FDG rod phantom, and⁶⁸Ge cylinder phantom QC.Results.Long-term tracking and anomaly detects showed, TOF deviation remained below 7.6 ps and energy deviation below 1%. Over the five-month period, TOF drift remained stable, whereas energy drift showed a slight decrease under both¹⁷⁶Lu background and radioactive source QC.¹⁷⁶Lu Background,¹⁸F-FDG rod phantom, and⁶⁸Ge cylinder phantom QC methods all reliably detected variations in system energy and TOF drift.Conclusions.¹⁷⁶Lu Background QC offers a feasible and reliable alternative to¹⁸F-FDG rod phantom QC for daily PET/CT QC. It reduces radiation exposure and simplifies operation, while periodic cross-validation with¹⁸F-FDG rod phantom QC every six to twelve months remains advisable to ensure long-term system stability.