RTDs were recorded four to seven times per second, depending on the size of the ROI (longer times needed to process images for larger ROIs). A typical ROI was selected to include the external skin of the treatment area. For each patient, the RTD recording frequency is approximately the same throughout the treatment course. At each recorded instance, the three translational and three rotational RTDs were calculated, and these RTDs represented the breath‐hold motion. Since the RTDs were calculated against the same reference ROI (the default was the planning CT skin rendering) for each fraction for both setup and treatment, the interfraction variations in breath‐hold position would not propagate to treatment RTDs. The RTDs along with their corresponding beam‐on/off status were saved in a motion log file, and only the beam‐on portions were considered. For each patient, RTDs from all treatments were included, and then the mean, standard deviation, maximum, and minimum of the RTDs were calculated (for each of the three translational and three rotational parameters). The average motion (the mean and standard deviation) was calculated using the absolute values of the RTDs. The signed RTDs were used to estimate the delivered dose.