An X-ray source transmits X-rays through a subject and a detector receives the X-ray energy after having passed through the subject. A processing system generates a pre-shot image of the subject using low energy X-ray intensity from the X-ray source and determines a plurality of acquisition parameters for a main scan of the subject based on the pre-shot image. A saturation time of the detector for the corresponding acquisition parameters is determined based on detector calibration data and to determine a number of time frames required to reach the targeted dose based on the saturation time. An X-ray dosage level of the subject is then applied using the X-ray source based on the number of time frames and to generate the image of the subject based on the detected X-ray energy at the X-ray detector for the applied X-ray dosage level.