OMICS 放射線学ジャーナル

抽象的な

256-Slice Coronary Computed Tomography Angiography Using Low Tube Voltage of 100 KV

Bhojraj Sharma

Purpose: To evaluate the image quality and radiation dose of 100 kV with 1000 mAs retrospective electrocardiography (ECG)-gated CCTA protocol, compared to the standard protocol of 120 kV with 800 mAs retrospective ECG-gated CCTA. Material and Methods: We divided 70 patients into two, a reduced dose group with 35 patients (18 M, 17 F; Mean age 56.94 ± 11.51 years) were examined by 100-kV with 1000 mAs retrospective ECG-gated CCTA, and another as a standard group of 35 patients (21, 14 F; Mean age 54.03 ± 9.81 years) were examined by 120-kV with 800 mAs retrospective ECG-gated CCTA. The two blinded radiologists analyzed the image quality of the coronary arteries independently and they accessed subjective and objective image quality. The radiation dose was also measured as effective radiation dose [ED] and was calculated using CT dose volume index [CTDIvol.], dose-length product [DLP] and conversion coefficient for chest (conversion factor k=0.014 mSv mGy-1cm-1). Results: Although the objective image quality of the 100-kV with 1000 mAs was significantly better than the 120- kV with 800 mAs (mean SNR, 36.65 ± 2.95 vs. 33.47 ± 3.86, P<0.0001; mean CNR, 34.27 ± 2.92 vs. 30.62 ± 3.90, P<0.0001). There was no significant variation in the subjective image quality between two groups (mean image score, 4.54 ± 0.37 vs. 4.56 ± 0.25 for radiologist 1, P = 0.781; 4.52 ± 0.25 vs. 4.56 ± 0.25 for radiologist 2, P=0.486). The radiation dose was found to be reduced by 28% with the 100-kV/1000 mAs protocol than with the 120-kV/800 mAs retrospective ECG-gated CCTA (7.87 ± 0.59 vs. 10.95 ± 1.67 mSv, P<0.0001). Conclusion: The protocol of low tube voltage CCTA using 100 kV/1000 mAs retrospective ECG-gated shows significant reduction of the radiation dose without disturbing the subjective image quality of CCTA.