Optimization of parameters for reducing artifact and radiation dose in multi-detector computer tomography after pedicle screw internal fixation

Abstract

Objective To assess the correlation between the metal artifact degrees with the tube voltage(in peak kilovolts,kV) and tube current(in milliamperes,mA) in multidetector computed tomography(MDCT),so as to search for proper strategies to reduce metal artifact and the radiation dose.Methods Four lumbar pedicle screws were implanted in the human L4,L5 specimens to establish the pedicle screw fixation model,and the models were hung on the appropriative water mode to assess the artifacts with silk thread.Different scanning parameters(Hnly tube tension,tube current) were used for scanning.The lengths of the artifacts emanating from the anterior tips of the screw were used to evaluate the degree of artifact.Results The tube current change did not significantly affect the metal artifacts(P0.05),but the tube voltage had significant impact on the metal artifacts;the degree of artifacts decreased remarkably with the increase of the tube voltage(100-140 kV,P0.05).Radiation dose rose with tube current and tube voltage increase.Conclusion Simultaneous reduction of the artifact and radiation dose can be achieved with high tube voltages(usually 140 kV) and tube currents should be lower than the generally used values of 250-270 mA.