Indian Journal of Public Health Research & Development

To evaluate the feasibility of using clinically low-dose computed tomography (CT) with an iterative reconstruction (IR) algorithm in CT angiography (CTA) with various contrast media (CM) concentrations. We performed a phantom study using 128-channel MDCT with 270, 300, and 350 mg iodine/ml, first at 120 kV tube voltage combined with a conventional algorithm (standard protocol), and then at clinically low dose (80 kV), combined with conventional (filtered back-projection; FBP) and IR (ASIR-V) algorithms. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the tube centre and background were measured and the clinical radiation dose (CTDI_VoL) determined.

In all phantom studies, the higher the CM concentration was, the higher was the CT value. At all concentrations of iodine CM, clinically low-dose radiation with an IR algorithm significantly increased the SNR and CNR of the phantom study (P <.001). Compared to the standard protocol using a CM of 350 mg iodine/ml, the low-tube voltage with an IR algorithm using a CM of 300 mg iodine/ml significantly increased the SNR (43 ± 7 vs. 82 ± 22, respectively; P <. 001) and CNR (32 ± 7 vs. 70 ± 21, respectively; P <.001). The radiation dose (CTDI_VoL) with the low-tube voltage and IR algorithm was 32% lower than that with the low-tube voltage with FBP algorithm, and 65% lower than the standard protocol (P <.001). Low CM concentrations improve images. Clinically low-dose CT with an IR algorithm is superior to the conventional protocol in phantom image contrast and exposure dose and is feasible for CTA.