Various methods and systems are provided for x-ray tube conditioning for a computed tomography imaging method. In one embodiment, x-ray may be generated in an x-ray tube of a radiation source prior to a diagnostic scan to warmup the x-ray tube to a desired temperature for the diagnostic scan. The power delivered to the x-ray tube during warmup may be adjusted in a closed loop system based on an initial temperature of the x-ray tube and the desired temperature for the diagnostic scan. During tube warmup, by placing a blocking plate coupled to a collimator blade in a path of the x-ray beam, the x-ray beam may be blocked from exiting a collimator.