Reducing effective radiation dose with improved image quality of abdominal computed tomography scans for overweight patients

Purpose: This work aimed to explore the effective radiation dose reduction for two Computed Tomography (CT) protocols for overweight and obese patients by using relevant physical techniques, all while obtaining acceptable image quality. Materials and methods: Two CT protocols (A: n = 50, 120 kV/190 +/- 60 mAs and B: n = 50, 100 kV/190 +/- 60 mAs) were used when imaging a total of 100 patients. For the two groups, the Computed Tomography Dose Index (CTDI) and Dose -Length Product (DLP) data were collected to calculate the effective dose (ED), as well as standard deviation (SD). The Hounsfield Unit (HU) details were collected to calculate the image quality coefficients noise (N), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Results: Noise, SNR and CNR were significantly different (p -value <0.05) in group B against group A. CTDIvol (A: 12.5 mGy; B: 7.11 mGy, p -value <0.05), DLP (A: 516.11 mGy cm; B: 258.6 mGy cm, p -value <0.05) and the effective dose (A: 7.73 mSv; B: 3.87 mSv, p -value <0.05). Conclusions: The proposed CT protocol for overweight patients, especially for the abdominal area, included dose adjustment (reducing the voltage from 120 kV to 100 kV, mAs Auto). This reduced the exposure dose by half when compared to the standard protocol, with the reductions in CTDIvol, DLP, and ED all being statistically significant (p -values <0.05). The image quality also improved by 37% where changes in N, SNR and CNR were also statistically significant.