Fig. 7.

Reference kV image without MV beam irradiation (kV only), concurrent kV image during MV beam irradiation (MV + kV), kV‐scatter‐corrected image (kVScorr), MV‐scatter‐corrected image (MVScorr), MV‐ and kV‐scatter‐corrected image (MVkVScorr) for flat panel detectors1 (FPD1) and FPD2 obtained at segments 2 and 11, and EPID images of Field 4. x‐ray path of FPD2 was longer than that of FPD1. The window levels and widths for EPID images are 3500 and 7000. The window levels and widths for FPD images are 300 and 600.