Whole-body CT with high heat-capacity X-ray tube and automated tube current modulation - Effect of tube current limitation on contrast enhancement, image quality and radiation dose

Abstract

Purpose To evaluate the effect of tube current limitation on contrast enhancement, image quality, and radiation dose in whole-body 64-detector CT with a high heat-capacity X-ray tube and automated tube current modulation. Materials and methods One hundred eighteen patients were randomized into three whole-body CT protocols: tube current limitation at 210 mA, 450 mA, and no limitation. Signal-to-noise ratio (SNR), dose-length product (DLP), estimated effective dose (ED), and image quality were assessed. Results Mean SNR of aorta was comparable among protocols, but that of liver was somewhat lower in 210-mA than in 450-mA and no-limitation protocols (p < 0.05). Mean DLP with 210-mA (533.8 mGy cm) was reduced by 31% from that with 450-mA (768.4 mGy cm) and by 38% from that with no-limitation protocol (861.3 mGy cm), respectively. Image quality was slightly degraded (p < 0.017) with 210 mA relative to the others in thorax and pelvis, but no difference was found in diagnostic acceptability. Conclusion For whole-body CT using multidetector CT mounted with a high heat-capacity X-ray tube, an appropriate tube current limitation setting may help reduce excessive radiation dose without significant compromise in diagnostic acceptability.