Methods and systems are provided for fasting switching a filter of an imaging system during scan. In one embodiment, a method comprises determining a first contrast enhancement of an injected contrast agent; responsive to the first contrast enhancement being higher than a first threshold, acquiring a first dataset by transmitting a radiation beam to an imaging subject via a first filter; switching to a different, second filter; acquiring a second dataset by transmitting the radiation beam to the imaging subject via the second filter, wherein an average contrast enhancement of the injected contrast agent during the acquisition of the first dataset is substantially the same as an average contrast enhancement of the injected contrast agent in the imaging subject during the acquisition of the second dataset.