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

• Whole-body CT without tube current limitation yielded highest DLP of 861.3 ± 374.9 mGy cm.
• Tube current limitation <210 mA with automated mA modulation reduces DLP by 31–38%.
• Image quality and diagnostic acceptability were adequate even with 210-mA tube current limitation.

PurposeTo 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 methodsOne 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.ResultsMean 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.ConclusionFor 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.