IMAGINE UR UM 103, Montpellier University, Department of Medical Imaging, Nîmes University Hospital, 30029 Nîmes, France.
Department of Computed Tomography, Siemens Healthineers AG, 91301 Forchheim, Germany.
Diagn Interv Imaging. 2024 Sep;105(9):311-318. doi: 10.1016/j.diii.2024.02.009. Epub 2024 Mar 1.
The purpose of this study was to assess image quality and dose level using a photon-counting CT (PCCT) scanner by comparison with a dual-source CT (DSCT) scanner on virtual monoenergetic images (VMIs) at low energy levels.
A phantom was scanned using a DSCT and a PCCT with a volume CT dose index of 11 mGy, and additionally at 6 mGy and 1.8 mGy for PCCT. Noise power spectrum and task-based transfer function were evaluated from 40 to 70 keV on VMIs to assess noise magnitude and noise texture (f) and spatial resolution on two iodine inserts (f), respectively. A detectability index (d') was computed to assess the detection of two contrast-enhanced lesions according to the energy level used.
For all energy levels, noise magnitude values were lower with PCCT than with DSCT at 11 and 6 mGy, but greater at 1.8 mGy. f values were higher with PCCT than with DSCT at 11 mGy (8.6 ± 1.5 [standard deviation [SD]%), similar at 6 mGy (1.6 ± 1.5 [SD]%) and lower at 1.8 mGy (-17.8 ± 2.2 [SD]%). For both inserts, f values were higher with PCCT than DSCT at 11- and 6 mGy for all keV levels, except at 6 mGy and 40 keV. d' values were higher with PCCT than with DSCT at 11- and 6 mGy for all keV and both simulated lesions. Similar d' values to those of the DSCT at 11 mGy, were obtained at 2.25 mGy for iodine insert at 2 mg/mL and at 0.96 mGy for iodine insert at 4 mg/mL at 40 keV.
Compared to DSCT, PCCT reduces noise magnitude and improves noise texture, spatial resolution and detectability on VMIs for all low-keV levels.
本研究旨在通过比较光子计数 CT（PCCT）扫描仪与双源 CT（DSCT）扫描仪在低能级虚拟单能量图像（VMI）上的图像质量和剂量水平，评估光子计数 CT 扫描仪的性能。
使用 DSCT 和 PCCT 对体模进行扫描，管电流分别为 11 mGy，PCCT 还分别在 6 mGy 和 1.8 mGy 下进行扫描。在 VMI 上从 40 keV 到 70 keV 评估噪声功率谱和基于任务的传递函数，以评估噪声幅度和噪声纹理（f）以及两个碘插塞的空间分辨率（f）。根据使用的能量水平计算检测指数（d'），以评估对两个增强病变的检测能力。
在所有能级下，PCCT 在 11 mGy 和 6 mGy 时的噪声幅度值均低于 DSCT，但在 1.8 mGy 时更高。在 11 mGy 时，PCCT 的 f 值高于 DSCT（8.6 ± 1.5[标准差[SD]%），在 6 mGy 时相似（1.6 ± 1.5[SD]%），在 1.8 mGy 时更低（-17.8 ± 2.2[SD]%）。对于两个插件，在所有 keV 水平下，除了在 6 mGy 和 40 keV 下，PCCT 的 f 值均高于 DSCT。在 11 mGy 和 6 mGy 下，PCCT 的 d'值均高于 DSCT，在所有 keV 和两个模拟病变下均如此。在 40 keV 时，对于碘插塞浓度为 2 mg/mL，PCCT 在 2.25 mGy 时可获得与 DSCT 相似的 d'值，对于碘插塞浓度为 4 mg/mL，PCCT 在 0.96 mGy 时可获得与 DSCT 相似的 d'值。
与 DSCT 相比，PCCT 可降低 VMI 上的噪声幅度，改善噪声纹理、空间分辨率和检测能力，适用于所有低能级。
