Fig. 2.

Two-parameter normal tissue complication probability curves for all regions of interest show significant interactions between age at treatment and development of chronic radiation-associated dysphagia at given dose levels. Abbreviations: NTCP, normal tissue complication probability; ROIs, regions of interest; ADM, anterior digastric muscle; GGM, genioglossus muscle; IPC, inferior pharyngeal constrictor; ITM, intrinsic tongue muscle; MGM, mylo/geniohyoid muscles; MPC, middle pharyngeal constrictor; PDM, posterior digastric muscle; SPC, superior pharyngeal constrictors. Legend – Orange, Age: ≥ 70– Blue, Age: 60–69– Green, Age: 50–59– Red, Age: ≤49 – Gray, All patients.