A Pragmatic Protocol for Reduction in the Metal Artifact and Radiation Dose in Multislice Computed Tomography of the Spine

Abstract

To assess the correlation between the metal artifact degree and the tube voltage (in peak kilovolts; kVp) and tube current (in milliamperes; mA) in multidetector row computed tomography (MDCT) and evaluate the proper protocols for reduction in the metal artifact and the radiation dose. We performed MDCT examinations for 13 cadavers operated for transpedicular screw insertion from C3 to C7, bilaterally. We used 80, 100, and 120 kVp in all cadavers. For the mA, we arbitrarily applied 100, 150, and 200 in 6 cadavers (experiment 1); 140, 180, and 220 in 4 (experiment 2), and randomly used mAs between 60 and 220 in 3 (experiment 3). The lengths of the artifacts emanating from the anterior and posterior tips of the screw were used for the degree of artifact. In experiment 1, the mA did not significantly affect the metal artifacts (P > 0.05); but the kVp did (P < 0.05). In experiment 2, the mA and kVp did not significantly affect the metal artifact degree (P > 0.05). In experiment 3, the mA did not affect the metal artifacts, but the kVp caused changes in metal artifact degrees (simple quantitative analysis). The proper parameters for the simultaneous reduction in the artifact and radiation dose are suggested to be tube voltages from 100 to 120 kVp and tube currents lower than the generally used values of 200 to 220 mA.