Liu Leening P, Pua Rizza, Dieckmeyer Michael, Shapira Nadav, Sahbaee Pooyan, Gang Grace J, Litt Harold I, Noël Peter B
University of Pennsylvania, Perelman School of Medicine, Department of Radiology, Philadelphia, Pennsylvania, United States.
University of Pennsylvania, Department of Bioengineering, Philadelphia, Pennsylvania, United States.
J Med Imaging (Bellingham). 2024 Dec;11(Suppl 1):S12806. doi: 10.1117/1.JMI.11.S1.S12806. Epub 2024 Jul 26.
Evaluation of iodine quantification accuracy with varying iterative reconstruction level, patient habitus, and acquisition mode on a first-generation dual-source photon-counting computed tomography (PCCT) system.
A multi-energy CT phantom with and without its extension ring equipped with various iodine inserts (0.2 to 15.0 mg/ml) was scanned over a range of radiation dose levels ( 0.5 to 15.0 mGy) using two tube voltages (120, 140 kVp) and two different source modes (single-, dual-source). To assess the agreement between nominal and measured iodine concentrations, iodine density maps at different iterative reconstruction levels were utilized to calculate root mean square error (RMSE) and generate Bland-Altman plots by grouping radiation dose levels (ultra-low: ; low: 1.5 to 5; medium: 5 to 15 mGy) and iodine concentrations (low: ; high: 5 to 15 mg/mL).
Overall, quantification of iodine concentrations was accurate and reliable even at ultra-low radiation dose levels. RMSE ranged from 0.25 to 0.37, 0.20 to 0.38, and 0.25 to 0.37 mg/ml for ultra-low, low, and medium radiation dose levels, respectively. Similarly, RMSE was stable at 0.31, 0.28, 0.33, and 0.30 mg/ml for tube voltage and source mode combinations. Ultimately, the accuracy of iodine quantification was higher for the phantom without an extension ring (RMSE 0.21 mg/mL) and did not vary across different levels of iterative reconstruction.
The first-generation PCCT allows for accurate iodine quantification over a wide range of iodine concentrations and radiation dose levels. Stable accuracy across iterative reconstruction levels may allow further radiation exposure reductions without affecting quantitative results.
在第一代双源光子计数计算机断层扫描（PCCT）系统上，评估不同迭代重建水平、患者体型和采集模式下碘定量的准确性。
使用两种管电压（120、140 kVp）和两种不同的源模式（单源、双源），在一系列辐射剂量水平（0.5至15.0 mGy）下，对配备有各种碘插入物（0.2至15.0 mg/ml）且有或没有其延伸环的多能CT体模进行扫描。为了评估标称碘浓度与测量碘浓度之间的一致性，利用不同迭代重建水平下的碘密度图来计算均方根误差（RMSE），并通过对辐射剂量水平（超低：；低：1.5至5；中：5至15 mGy）和碘浓度（低：；高：5至15 mg/mL）进行分组来生成布兰德-奥特曼图。
总体而言，即使在超低辐射剂量水平下，碘浓度的定量也是准确可靠的。超低、低和中辐射剂量水平下的RMSE分别为0.25至0.37、0.20至0.38和0.25至0.37 mg/ml。同样，管电压和源模式组合的RMSE稳定在0.31、0.28、0.33和0.30 mg/ml。最终，没有延伸环的体模碘定量准确性更高（RMSE为0.21 mg/mL），并且在不同的迭代重建水平上没有变化。
第一代PCCT能够在广泛的碘浓度和辐射剂量水平上实现准确的碘定量。迭代重建水平上稳定的准确性可能允许在不影响定量结果的情况下进一步降低辐射暴露。
