Using an independent cohort of 71 NSCLC patients treated uniformly with 55 Gy in 20 fractions (no systemic therapy), this study found that tumor volume regression at the end of RT could be predicted from the first ~10 days of CBCT data with impressive accuracy using the Proliferation Saturation Index model (R² 0.87, PCC 0.93 with 4 scans; improving to R² 0.94, PCC 0.97 with 5), while also identifying limited responders (≤10% regression) with 78% sensitivity and 91% NPV. | Barrett, Int J Radiat Oncol Biol Phys 2026
