TY - JOUR AU - Lu, Xiaomei AU - Lu, Zaiming AU - Yin, Jiandong AU - Gao, Yuying AU - Chen, Xingbiao AU - Guo, Qiyong PY - 2018 TI - Effects of radiation dose levels and spectral iterative reconstruction levels on the accuracy of iodine quantification and virtual monochromatic CT numbers in dual-layer spectral detector CT: an iodine phantom study JF - Quantitative Imaging in Medicine and Surgery; Vol 9, No 2 (February 28, 2019): Quantitative Imaging in Medicine and Surgery Y2 - 2018 KW - N2 - Background: The purpose of this study is to investigate the accuracy of iodine quantification and virtual monochromatic CT numbers obtained with the dual-layer spectral CT (DLCT) using a phantom at different radiation dose levels and spectral iterative reconstruction (IR) levels. Methods: An abdomen phantom with seven iodine inserts (2.0, 2.5, 5.0, 7.5, 10.0, 15.0, 20.0 mg/mL) was imaged using a DLCT scanner. Five repeated scans were performed at computed tomography dose index volume (CTDI vol ) levels of 5, 10, 15, 20, 25 mGy at tube voltages of 120 and 140 kVp, respectively. Spectral-based images were reconstructed using four spectral IR levels (spectral level of 0, 2, 4, 6). Iodine density images and virtual monochromatic images (VMI) at energy levels of 50, 70 and 120 keV were created. The absolute percentage bias (APB) of the measured iodine concentration and the true iodine concentration, and the measured VMI CT numbers and the theoretical VMI CT numbers were compared to determine the difference of radiation dose levels and different spectral IR levels. Results: At CTDI vol levels of 25, 20, 15, 10 mGy, radiation dose levels had no effect on the accuracy of iodine quantitation; at CTDI vol level of 5 mGy, the accuracy of iodine quantification was the poorest, with the mean APB iodine of 4.33% (P vol levels of 25, 20 and 15 mGy. However, the accuracy of VMI CT numbers was significantly degraded at the CTDI vol levels of 10 and 5 mGy (P vs . 2.99% for 70 keV (P vs . 9.28% for 120 keV (P Conclusions: The accuracy of iodine quantification and VMI CT numbers was only affected by very low radiation dose levels. At the clinically applied radiation dose levels of >10 mGy, the accuracy of both iodine quantification and VMI CT numbers is relatively stable and high. UR - https://qims.amegroups.org/article/view/22850