Feasibility of pre-scan size-specific dose estimate in coronary computed tomography angiography

Objective: To investigate the feasibility of optimization of coronary computed tomography angiography (CCTA) with pre-scan size-specific dose estimate(SSDE). Methods: Ninety patients from Quzhou People's Hospital during March and May 2018 who underwent CCTA were defined as modelled patients, the regression equation of body mass index (BMI) and water-equivalent diameter (d_w) were conducted and upper quartile of CTDI_vol values was calculated. Other 67 patients were divided into two groups: control group (CCTA scan protocol, based on CTDI_vol) and study group (CCTA scan protocol using SSDE). The image quality and radiation dose including breast dose (Dose_bre) in two groups were assessed. Results: The positive correlation was found between BMI and d_w with a linear regression equation of d_w = 9.241 + 0.644 × BMI (r = 0.823, P < 0.05), and the upper quartile of CTDI_vol was 7.92 mGy. The proportions of high-level image quality were 94.10% (367/390) and 93.93% (402/428) in the control and study groups, respectively (P > 0.05). The median signal to noise ratio (SNR) and contrast to noise ratio (CNR) were 21.08/24.39, 17.24/19.94 in the control and study groups, respectively (P > 0.05). The CTDI_vol, SSDE and D_bre of the study group were reduced by 37.04%, 35.77% and 37.37% compared with the control group, and statistically significant differences were found (z = -7.041, t = 18.479, 15.079, P < 0.05) among them. Conclusions: The CCTA scan protocol based on the pre-scan SSDE can significantly reduce the radiation dose and provide the diagnostic image quality. (authors)