Magdi A. Ali, Bothaina A. Kandil, Yasser I. Khedr, Mohamed M. El Safwany and Ayman A. Aly
Computed tomography (CT) examinations have become increasingly popular because of recent multidetector technological developments; concerns have arisen over the increase in the patient dose. We aimed to evaluate the impact of automatic tube current modulation (ATCM) technique in CT multiphasic examinations based on the radiation dose and image quality compared to fixed tube current (FTC) technique. We retrospectively reviewed the images of 50 patients who
underwent multiphasic CT of the liver using a 160 slice CT scanner. The study was performed following scan steps according to hepatic circulatory phases namely arterial, portal, venous, and equilibrium phases. All phases are done using identical scan and reconstruction parameters except for the tube current. The portal phase was done using FTC technique while the venous phase was performed using ATCM technique, the portal and venous phases were compared regarding their radiation dose values and image quality in the same patient. Radiation dose was evaluated by calculation of Dose Index Volume (CTDIvol), Dose Length Product (DLP) and Effective Dose (ED). The image quality was quantitatively evaluated using Signal to Noise Ratio (SNR) and Contrast to Noise ratio (CNR). Although both phases have similar mean scan length, the CTDIvol have decreased by 47.41% in ATCM compared to FTC with the maintenance of good image quality. In conclusion, by using ATCM, the radiation dose could be reduced while maintaining image quality in multiphasic CT examinations of the liver.
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