Phantom study of the influence of CareDose 4D and Care kV on CT pulmonary ground glass nodule with respect to image quality and radiation dose

Abstract

Objective To investigate the effect of CareDose 4D combined with Care kV on CT pulmonary ground glass nodule (GGN) with respect to quality and radiation dose. Methods The thoracic model containing 6 GGN was performed by using 7 low-dose schemes. The CareDose 4D + Care kV was adopted in scheme 1. In schemes 2, 3 and 4, the tube voltage was 120 kV, and the tube current 30, 20 and 10 mAs respectively. In schemes 5, 6 and 7, the tube voltage was 100 kV, and the tube current was 30, 20 and 10 mAs, respectively. The image quality [CT value, contrast noise ratio (CNR), noise value (SD) and subjective score] and effective dose (E) were compared. Results There was no statistically significant difference in CT value of GGN among different schemes (P>0.05). The SD of scheme 1 was higher than those of schemes 2, 3 and 5, but lower than those f scheme 7, while the CNR of scheme 1 was lower than those of schemes 2, 3 and 5, but higher than that of scheme 7 (t=13.020, 9.560, 8.120, -5.720, -7.849, -5.192, -4.130, 1.361, P 0.05). The subjective scores of each GGN of schemes 1, 2, 3, 5 and 6 was over 3 points, but and the subjective scores of one GGN of each of schemes 4 and 7 were below 3 points. The value E of the scheme 1 was reduced by 63.0%, 44.4%, 38.8%, and 9.1%, compared with the schemes 2, 3, 5 and 6, respectively. Conclusions CareDose 4D combined with Care kV in low-dose lung CT scan can ensure the image quality of GGN and reduce the radiation dose effectively. Key words: CareDose 4D; Care kV; Ground glass nodule; Radiation dose; Image quality