An imaging system includes an identification module, an analysis module, and a determination module. The identification module is configured to identify a scanning mode of operation. The analysis module is configured to determine an attenuation for an object for a scan to be performed on the object. The determination module is configured to determine an image contrast for each of plural setting combinations, determine a corresponding tolerable noise for the image contrast for each of the setting combinations based on the scanning mode of operation, and determine a corresponding diagnostic dosage for each setting combination, the diagnostic dosages corresponding to the image contrast and tolerable noise for the corresponding setting combination. The determination module is also configured to select an operational setting for the scan to be performed using the dosages determined.
