Limitations of Mono-Exponential Individual Fitting as a Reference Model for Single-Time-Point Dosimetry in [177Lu]Lu-PSMA-617 Therapy

PURPOSE: Lu]Lu-PSMA-617 therapy, and to compare the resulting STP accuracy rankings with those obtained using population-based model selection with non-linear mixed-effects modelling (PBMS NLMEM). METHODS: ) were evaluated at (47.7±2.2) h post-injection. Accuracy was assessed using relative deviation (RD), mean absolute percentage error (MAPE), and root mean square error (RMSE). RESULTS: underestimated absorbed dose (mean RD -14.1%, -13.1% and -17.8%; MAPE 15.2%, 13.1% and 17.8%; RMSE 17.3%, 14.8% and 19.1%, respectively). CONCLUSION: showed the closest agreement with it. To ensure broader applicability, this approach should also be evaluated for salivary glands and tumours, which may require tailored fitting strategies, thereby supporting the development of a generalisable STP method for personalised treatment. Prospective validation in larger cohorts remains necessary.