18F-FDG PET Definition of Gross Tumor Volume for Radiotherapy of Lung Cancer: Is the Tumor Uptake Value-Based Approach Appropriate for Lymph Node Delineation?

If a method of automatic delineation shall be applied, this method must be applied to every lesion separately. However, to facilitate the delineation in daily practice, when In/It is ≤25%, lymph nodes could be delineated in accordance with tumor uptake, keeping an absolute difference in radii <5 mm.