Department of Physics, Khalifa University, Abu Dhabi, United Arab Emirates.
Department of Biomedical Engineering & Sciences, National University of Sciences and Technology, Islamabad, Pakistan.
PLoS One. 2024 Sep 13;19(9):e0308658. doi: 10.1371/journal.pone.0308658. eCollection 2024.
Spectral Photon Counting Computed Tomography (SPCCT), a ground-breaking development in CT technology, has immense potential to address the persistent problem of metal artefacts in CT images. This study aims to evaluate the potential of Mars photon-counting CT technology in reducing metal artefacts. It focuses on identifying and quantifying clinically significant materials in the presence of metal objects. A multi-material phantom was used, containing inserts of varying concentrations of hydroxyapatite (a mineral present in teeth, bones, and calcified plaque), iodine (used as a contrast agent), CT water (to mimic soft tissue), and adipose (as a fat substitute). Three sets of scans were acquired: with aluminium, with stainless steel, and without a metal insert as a reference dataset. Data acquisition was performed using a Mars SPCCT scanner (Microlab 5×120); operated at 118 kVp and 80 μA. The images were subsequently reconstructed into five energy bins: 7-40, 40-50, 50-60, 60-79, and 79-118 keV. Evaluation metrics including signal-to-noise ratio (SNR), linearity of attenuation profiles, root mean square error (RMSE), and area under the curve (AUC) were employed to assess the energy and material-density images with and without metal inserts. Results show decreased metal artefacts and a better signal-to-noise ratio (up to 25%) with increased energy bins as compared to reference data. The attenuation profile also demonstrated high linearity (R2 >0.95) and lower RMSE across all material concentrations, even in the presence of aluminium and steel. Material identification accuracy for iodine and hydroxyapatite (with and without metal inserts) remained consistent, minimally impacting AUC values. For demonstration purposes, the biological sample was also scanned with the stainless steel volar implant and cortical bone screw, and the images were objectively assessed to indicate the potential effectiveness of SPCCT in replicating real-world clinical scenarios.
光谱光子计数计算机断层扫描（SPCCT）是 CT 技术的一项突破性发展，具有极大的潜力可以解决 CT 图像中金属伪影的问题。本研究旨在评估 Mars 光子计数 CT 技术在减少金属伪影方面的潜力。它侧重于在存在金属物体的情况下识别和量化具有临床意义的材料。使用多材料模型，其中包含不同浓度羟磷灰石（存在于牙齿、骨骼和钙化斑块中的矿物质）、碘（用作造影剂）、CT 水（模拟软组织）和脂肪（作为脂肪替代品）的插入物。采集了三组扫描：一组含有铝、一组含有不锈钢，还有一组没有金属插入物作为参考数据集。数据采集使用 Mars SPCCT 扫描仪（Microlab 5×120）在 118 kVp 和 80 μA 下进行。随后将图像重建为五个能量bins：7-40、40-50、50-60、60-79 和 79-118 keV。使用信噪比（SNR）、衰减曲线线性度、均方根误差（RMSE）和曲线下面积（AUC）等评估指标来评估有无金属插入物的能量和材料密度图像。结果表明，与参考数据相比，随着能量bins的增加，金属伪影减少，信噪比提高（高达 25%）。衰减曲线也表现出较高的线性度（R2 >0.95）和较低的 RMSE，即使在存在铝和钢的情况下也是如此。碘和羟磷灰石的材料识别精度（有和没有金属插入物）保持一致，对 AUC 值的影响最小。为了展示目的，还对含有不锈钢掌侧植入物和皮质骨螺钉的生物样本进行了扫描，并客观地评估了图像，以表明 SPCCT 在复制真实临床场景方面的潜在有效性。
