Individualized Dosimetry for **177Lu-PRRT** in Neuroendocrine Tumors Improves Therapeutic Outcomes

Neuroendocrine tumors (NETs) are increasingly diagnosed malignancies, often affecting the gastroenteropancreatic system, presenting diagnostic and therapeutic challenges due to their asymptomatic development. While nuclear medicine has advanced diagnostics, its role in treatment, particularly with systemic radionuclide therapy using somatostatin analogs labeled with Lutetium-177 (177Lu-PRRT), is growing for advanced-stage disease. A critical gap exists as most patients receive a standard activity of radiopharmaceuticals, unlike external beam radiotherapy. This often leads to suboptimal dosing, underscoring the need for individual internal dosimetry to measure absorbed radiation doses and optimize therapeutic effects.

This narrative literature review synthesized current concepts and clinical relevance of dosimetry in 177Lu-PRRT for neuroendocrine tumors. Researchers systematically searched PubMed/MEDLINE and Embase databases, prioritizing recent publications. The search strategy combined keywords such as "Lutetium-177", "neuroendocrine tumors", "dosimetry", "PRRT", "systemic radionuclide therapy", and "artificial intelligence". Particular emphasis was placed on recent prospective clinical studies, multicenter investigations, systematic reviews, and consensus documents from major nuclear medicine societies like the European Association of Nuclear Medicine (EANM) and the Society of Nuclear Medicine and Molecular Imaging (SNMMI), alongside seminal earlier publications.

The review found increasing evidence demonstrating a strong correlation between the absorbed radiation dose in pathological lesions and the therapeutic efficacy of 177Lu-PRRT. Currently, most patients receive a standard, fixed activity of therapeutic radiopharmaceuticals, which the literature indicates often results in suboptimal dosing for a significant fraction. Internal dosimetry, which measures the patient's absorbed radiation dose post-administration, is crucial for personalizing therapy. > The consensus across recent clinical studies and expert documents is that individual internal dosimetry prior to 177Lu-PRRT is essential to ensure patients receive optimal radioactivity doses, moving beyond the current 'one-size-fits-all' approach. This personalized strategy aims to maximize tumor response while minimizing toxicity to healthy tissues. The review also highlighted the emerging role of artificial intelligence in enhancing dosimetry calculations and treatment planning, suggesting future advancements will further refine this personalized approach.