Radiation dose optimization in computed tomography with current modulation and Iterative Reconstruction

The study was aimed at evaluating the value of current modulation (mAs) and iterative reconstructions algorithms during Computed Tomography examinations in terms of dose reduction and image quality. The focus was mainly on non-contrast head and chest-abdomen-pelvis examinations. A total of 40 adult patients with weighting between 65 and 80 kg underwent CT examinations (20 head and 20 chest-abdomen-pelvis). All examinations were performed on a 128-slice scanner (Somatom Definition AS from Siemens, Forchheim, Germany) using CARE Dose 4D technology. The radiation dose values were compared with reference levels values recommended for head and chest-abdomen-pelvis regions. Image quality was evaluated both objectively and subjectively using Students' test. The results on the present study showed that through the combination of CARE Dose 4D and SAFIRE; the radiation dose could be reduced by 20.10% and 59 % for the examination of head and chest-abdomen-pelvis respectively. There was a substantial difference in the image quality when using FBP or SAFIRE (p < 0.05). The noise level dropped significantly during SAFIRE when compared to FBP by 14.25% for head and by 27.60% and for chest-abdomen-pelvis scans. We conclude that automatic exposure control mechanism based on tube current modulation CARE Dose 4D when combined with iterative reconstruction SAFIRE delivers good image quality with low dose for non-enhanced head and chest-abdomen-pelvis scans.