CT scanners: dose reduction techniques and technology

CT scanners are used to image all parts of the body. Some areas in which CT scanning include internal organs within abdomen and chest, bone scanning, brain scanning and vascular imaging. Inside a doughnut shaped gantry of a CT scanner there is a X-ray tube. It rotates around the patient taking hundreds of X-ray pictures of a thin section of the body. CT scanning has been recognised as a high radiation dose modality when compared to diagnostic X-ray techniques. The comparison of doses from CT and X-ray for different examination is brought out in the paper. Percentage of examinations from total and dose from total in the last five years are estimated in the paper. Techniques like scan protocol optimization like Kv collimation slice width helical pitch mAs, tailored exposure parameters such as weight/age based paediatric protocols, gantry tilt, shielding sensitive organs, extra rotation in helical scanning comparison with references doses are discussed. Main technology being developed in CT affecting patient dose is automated tube current adjustments and the current availability of this technology in different types of scanners are discussed