Toward Personalized Radiopharmaceutical Therapy: Radiobiologic Insights Compared with External-Beam Radiotherapy

Radiopharmaceutical therapy differs from external-beam radiation therapy through systemic delivery, a heterogeneous dose distribution, and a low dose rate, challenging conventional radiobiology and dose–effect relationships. These features complicate dose constraints and support dosimetry-guided strategies. Integrating personalized dosimetry into clinical trials is key to optimizing efficacy and limiting toxicity. We emphasize the need for radiopharmaceutical therapy–specific models and trial designs incorporating spatial heterogeneity, radiosensitivity, and patient-specific factors to improve the therapeutic index.