KEY POINTS
- This single-center implementation report describes a multidisciplinary patient-specific radiopharmaceutical therapy dosimetry program integrating radiation oncology, nuclear medicine, medical physics, nursing, dosimetry, radiation safety, and nuclear pharmacy.
- The workflow uses quantitative SPECT/CT at approximately 3, 24, and 96 hours, deformable multi-timepoint registration, organ-at-risk and tumor contouring, pharmacokinetic modeling, and GPU-accelerated voxel-level Monte Carlo dose calculation.
- Among the first 19 patients evaluated after cycle 1 of 177Lu-PSMA-617, extrapolated six-cycle mean absorbed doses were 16.1 Gy to the kidneys and 15.9 Gy to the salivary glands.
- Dosimetry supported treatment without modification in 13 patients (68%), while 5 patients (26%) received a 20% activity reduction and 1 patient (5%) had treatment delayed.
- This was a selected high-risk cohort without a comparator or formal efficacy and toxicity endpoints; dosimetric thresholds and patient-selection criteria were institution-specific.
CLINICAL TAKEAWAY
Patient-specific, multi-timepoint radiopharmaceutical dosimetry can be incorporated into routine practice and may influence treatment decisions in patients with renal dysfunction, marrow compromise, prior radiopharmaceutical exposure, or other toxicity concerns. However, this report establishes feasibility rather than improved clinical outcomes, and broader adoption still requires standardized workflows, quality assurance, reimbursement, and prospectively validated dose constraints.