Delineation of organs at risk in radiotherapy and perspectives

The delineation of organs at risk is fundamental in radiotherapy, ensuring optimal tumour targeting while minimizing toxicity to healthy tissues. Advances in imaging, including MRI-based segmentation and functional imaging, have improved contour precision, while artificial intelligence-assisted autosegmentation enhances efficiency and reproducibility. This article presents updated organs at risk delineation guidelines, incorporating emerging critical structures and refined contouring protocols. Despite technological progress, challenges remain in integrating artificial intelligence-driven tools and functional imaging into routine practice, requiring continued validation and standardization. The future of organs at risk delineation lies in a multidisciplinary approach combining automation, adaptive radiotherapy, and personalized treatment planning to optimize patient safety and long-term outcomes.