1. A computed tomography (CT) imaging system configured to utilize X-rays, the CT imaging system comprising at least one processor and a tangible and non-transitory computer readable medium, the at least one processor directed by instructions stored on the tangible and non-transitory computer readable medium to: identify a scanning mode of operation for a scan to be performed on an object, the scanning mode of operation corresponding to at least one of a clinical task or clinical application, the scanning mode of operation specifying one or more parameters that influences a relationship between contrast and tolerable noise; determine an attenuation for the object for the scan to be performed on the object; determine an image contrast for each of plural setting combinations for the scan to be performed on the object, wherein each of the setting combinations is for a same type of scan on a same type of tissue; determine a corresponding tolerable noise level for the image contrast for each of the setting combinations based on the scanning mode of operation, wherein a contrast to noise ratio (CNR) corresponding to the tolerable noise levels varies among the setting combinations, wherein each tolerable noise level is for the same type of scan on the same type of tissue for the setting combinations; determine a corresponding current for each tolerable noise level based on the tolerable noise level; determine a corresponding diagnostic dosage for each setting combination for the scan to be performed on the object based on the corresponding current and a corresponding voltage, the diagnostic dosages corresponding to the image contrast and tolerable noise for the corresponding setting combination; select an operational setting for the scan to be performed from among the setting combinations using the dosages determined; and perform the scan using the operational setting for the scan to be performed.