Low-dose MDCT in the reconstruction of tracheobronchography: an experimental study
LIU Xin *, GUO Qi yong, LIN Ai jun, LIAO Wei, SU Hui qun(Department of Radiology, the Second Hospital of China Medical University, Shenyang 110004, China)
Objective To investigate the feasibility of reducing radiation dose in multi detector spiral CT tracheobronchography. Methods With changed milliampere setting (150, 100, 50, 20 mAs), section thickness (6.5, 3.2 mm), tube voltage (120, 90 kVp) and pitch (1.25, 1.75) while other parameters were keeping stable, each one of 8 dogs underwent 7 series of scanning without holding breath. MPR, SSD and VB reconstructions were performed on sgiO2 workstation. Image quality and displaying rate of 0-4 stages bronchi with the standard dose group were compared. The inner diameters of 0-3 stages of bronchi were measured at four sites, the results were compared with the true bronchial diameters in dogs. Results No differences of images quality and displaying rate of 0-4 stages bronchi were seen versus those in standard dose group ( P 0.05). The 100 mAs, 90 kVp and pitch 1.75 group produced accurate measurements at 0-3 stages of bronchi ( P 0.05 ). There was significant difference on the measurement of lobar bronchi in 20 mAs ( P 0.05), and segmental bronchi in 50 mAs SSD image ( P 0.01). Conclusion Compared with the standard dose, low dose MDCT tracheobronchography can provide sufficient information, with CT dose lowered to 20%-33%. It is suggested that similar parameters should be used in the pediatric or the uncooperative patients.