Low kilovoltage and low contrast volume neck CT protocol using iterative reconstruction techniques: A comparison with standard dose protocol

Computed Tomography (CT) is standard imaging modality for evaluation of neck pathologies. The increased radiation risks and effects of contrast media has drawn attention for using low dose and low contrast volume protocols in the recent years. The aim of the study is to evaluate the image quality and radiation dose of 80 kVp (iDose⁴) with low contrast volume Neck CT compared to 120 kVp standard Neck CT. This is prospective study with historical controls. In Group A, twenty-five patients who had undergone Contrast Enhanced Neck CT from August 2019–August 2020 using standard dose protocol (120 kVp, 60 ml Contrast) were included. In Group B twenty-five patients who was referred for Contrast Enhanced Neck CT from September 2020–March 2021 using low dose protocol (80 kVp, 40 ml contrast) were included. The qualitative analysis of standard (120 kVp) and low dose (80 kVp, iDose⁴) images did not show significant difference between two groups (p > 0.05). Contrast to Noise Ratio (CNR) showed significant difference between two groups and was slightly higher in 80 kVp (iDose⁴) images. There was 69.2% reduction in effective dose with 80 kVp (iDose⁴) protocol. The qualitative analysis of low dose protocol with Filtered back projection (FBP) and iDose⁴ of group B showed significant difference between both (p < 0.001). The Image noise (IN) was more, Signal to Noise Ratio (SNR) and CNR was less in FBP compared to iDose⁴ of Group B. The study concludes that low kilovoltage (80 kVp) and low contrast volume Neck CT protocol used with iterative reconstruction technique (iDose⁴) provides optimum diagnostic image quality with reduced radiation dose compared with standard dose protocol (120 kVp).