CT pulmonary angiography using organ dose modulation with an iterative reconstruction algorithm and 3D Smart mA in different body mass indices: image quality and radiation dose.

ABSTRACT

OBJECTIVE: To investigate the differences in imaging quality and radiation dose in CT pulmonary angiography (CTPA) by organ dose modulation and 3D Smart mA modulation in different body mass indices (BMIs) with an adaptive statistical iterative reconstruction (ASiR-V) algorithm. METHODS: Three hundred female patients who underwent CTPA were equally divided into three groups A (18.5 kg/m2 ≦ BMI < 24.9 kg/m2), B (24.9 kg/m2 ≦ BMI < 29.9 kg/m2) and C (29.9 kg/m2 ≦ BMI≦ 34.9 kg/m2). The groups were randomly subdivided into two subgroups (n = 50) A1-A2, B1-B2 and C1-C2. The patients in subgroups A1, B1 and C1 underwent organ dose modulation with the ASiR-V algorithm. The other patients underwent 3D Smart mA modulation. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were calculated after CTPA. Images were then subjectively evaluated using a 5-point scale. The volume CT dose index and dose-length product (DLP) were recorded and their means calculated. The DLP was converted to the effective dose (ED). RESULTS: In group A, the SNR, CNR, and subjective image scores showed no statistical differences (P > 0.05). The ED in subgroup A1 was 33.36% lower than that in A2. In group B and C, the variables showed no significant differences between the subgroups B1 and B2 (P > 0.05), and the subgroups C1 and C2 (P > 0.05), respectively. The ED in subgroup B1 and C1 was 36.15 and 38.22% lower than that in B2 and C2, respectively. CONCLUSIONS: Using organ dose modulation and applying the ASiR-V algorithm can more effectively reduce the radiation dose in CTPA than in 3D Smart mA modulation, while maintaining image quality.