Low kV CT pulmonary angiography at 64-slice CT for standard body type:a feasibility study

ZHAO Lei; YANG Xiaoguang; BAO Lili; LIU Aishi

doi:10.19300/j.2016.L3343

Abstract：Objebtive The purpose of this study was to compare image quality and radiation dose between low voltage CT pulmonary angiography (CTPA) and conventional CTPA protocols in patients of standard body type. Methods 60 consecutive patients with low body mass index (≤25 kg/m2) and low body mass (≤80 kg) suspected having pulmonary embolism (PE) were prospectively enrolled from February 2013 to August 2014. The patients were divided into two groups. Tube voltage was set at 80 Kv for group A and 120 Kv for group B. Tube current settings were determined by testing bolus peak attenuation. Radiation dose and image quality were compared between the two groups. The relationship between image quality parameter and radiation dose measured at pulmonary artery trunk were analyzed with Pearson correlation. Results The total pulmonary arteries showed significantly higher attenuation and noise in group A than in group B (P=0.000). The total signal-to-noise ratio and total contrast-to-noise ratio did not significantly differ between groups A and B (P=0.187, P=0.309, respectively). The mean effective dose showed significantly lower in group A than in group B (1.69±0.43 mSv vs 5.63± 1.84 mSv, P=0.000). The attenuation or noise and effective dose was negatively correlated. Conclusion Using 80 Kv-CTPA can achieve stable image quality with reduced effective radiation dose compared with 120 Kv-CTPA in patients with low body mass index (≤25 kg/m2) and low body mass (≤80 kg).