Figure 2.

Application of activatable imaging probes in radiotherapy workflow. Before treatment: (i) diagnosing early-stage lesions; (ii) imaging different tumor sub-volumes for dose-escalation; (iii) monitoring the receptor expression for the selection of treatment methods. During radiotherapy courses: (i) assessing early tumor response; (ii) measuring the radiosensitivity index of radiotherapy; (iii) determining radiation dosimetry for optimizing treatment regimes. After treatment: (i) monitoring tumor progression and differentiating imaging results; (ii) predicting radiotherapy-induced toxicity for early interventions; (iii) predicting radioresistance for re-scheduling or changing treatment methods. BTV: biological target volume; GTV: gross tumor target volume; CTV: clinical target volume; PTV: planning target volume; FAP: fibroblast activation protein; LVEF: left ventricular ejection fraction; CAFs: cancer-associated fibroblasts.