Diagram of OMB differences of CMR each channel over time. (a-c): based on APC method; (d-f): based on neural network.

Figure 2 illustrates the OMB difference of CMR for each channel over time, based on the APC method (left panel) and based on the neural network (right panel). Notably, after calibration, the bias between the calibrated TB and the TB,simu are obviously removed, especially, the neural network exhibits significant improvements both in mean deviation and standard deviation of the OMB difference for all three channels when compared to the APC method.