From the Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg.
Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne.
Invest Radiol. 2022 Dec 1;57(12):819-825. doi: 10.1097/RLI.0000000000000901. Epub 2022 Jun 24.
Hardening the x-ray beam, tin prefiltration is established for imaging of high-contrast subjects in energy-integrating detector computed tomography (EID-CT). With this work, we aimed to investigate the dose-saving potential of spectral shaping via tin prefiltration in photon-counting detector CT (PCD-CT) of the temporal bone.
Deploying dose-matched scan protocols with and without tin prefiltration on a PCD-CT and EID-CT system (low-/intermediate-/full-dose: 4.8/7.6-7.7/27.0-27.1 mGy), 12 ultra-high-resolution examinations were performed on each of 5 cadaveric heads. While 120 kVp was applied for standard imaging, the protocols with spectral shaping used the highest potential available with tin prefiltration (EID-CT: Sn 150 kVp, PCD-CT: Sn 140 kVp). Contrast-to-noise ratios and dose-saving potential by spectral shaping were computed for each scanner. Three radiologists independently assessed the image quality of each examination with the intraclass correlation coefficient being computed to measure interrater agreement.
Regardless of tin prefiltration, PCD-CT with low (171.2 ± 10.3 HU) and intermediate radiation dose (134.7 ± 4.5 HU) provided less image noise than full-dose EID-CT (177.0 ± 14.2 HU; P < 0.001). Targeting matched image noise to 120 kVp EID-CT, mean dose reduction of 79.3% ± 3.9% could be realized in 120 kVp PCD-CT. Subjective image quality of PCD-CT was better than of EID-CT on each dose level ( P < 0.050). While no distinction was found between dose-matched PCD-CT with and without tin prefiltration ( P ≥ 0.928), Sn 150 kVp EID-CT provided better image quality than 120 kVp EID-CT at high and intermediate dose levels ( P > 0.050). The majority of low-dose EID-CT examinations were considered not diagnostic, whereas PCD-CT scans of the same dose level received satisfactory or better ratings. Interrater reliability was excellent (intraclass correlation coefficient 0.903).
PCD-CT provides superior image quality and significant dose savings compared with EID-CT for ultra-high-resolution examinations of the temporal bone. Aiming for matched image noise, high-voltage scan protocols with tin prefiltration facilitate additional dose saving in EID-CT, whereas superior inherent denoising decreases the dose reduction potential of spectral shaping in PCD-CT.
在能量积分探测器计算机断层扫描（EID-CT）中，锡预过滤用于高对比度物体的成像，以增强 X 射线束的硬度。通过这项工作，我们旨在研究通过锡预过滤在光子计数探测器 CT（PCD-CT）中对颞骨进行光谱整形的潜在剂量节省。
在 PCD-CT 和 EID-CT 系统上使用剂量匹配的扫描方案（低/中/全剂量：4.8/7.6-7.7/27.0-27.1 mGy），对 5 个头骨的每个头进行了 12 次超高分辨率检查。在应用 120 kVp 进行标准成像的同时，使用光谱整形的方案采用了锡预过滤的最大潜力（EID-CT：Sn 150 kVp，PCD-CT：Sn 140 kVp）。计算了每个扫描仪的对比噪声比和光谱整形的剂量节省潜力。三位放射科医生独立评估了每个检查的图像质量，并计算了组内相关系数以衡量组内一致性。
无论是否使用锡预过滤，低（171.2 ± 10.3 HU）和中剂量（134.7 ± 4.5 HU）的 PCD-CT 提供的图像噪声均小于全剂量 EID-CT（177.0 ± 14.2 HU；P < 0.001）。将图像噪声目标对准 120 kVp EID-CT，120 kVp PCD-CT 可实现 79.3%±3.9%的平均剂量降低。在每个剂量水平上，PCD-CT 的主观图像质量均优于 EID-CT（P < 0.050）。虽然在剂量匹配的 PCD-CT 中未发现锡预过滤与不预过滤之间的差异（P≥0.928），但 Sn 150 kVp EID-CT 在高剂量和中剂量水平上提供的图像质量优于 120 kVp EID-CT（P>0.050）。大多数低剂量 EID-CT 检查被认为不可诊断，而相同剂量水平的 PCD-CT 扫描则获得了满意或更好的评分。组内相关性极好（组内相关系数 0.903）。
与 EID-CT 相比，PCD-CT 可为颞骨的超高分辨率检查提供更好的图像质量和显著的剂量节省。为了匹配图像噪声，使用锡预过滤的高电压扫描方案可在 EID-CT 中进一步节省剂量，而内在的优越降噪则降低了 PCD-CT 中光谱整形的剂量降低潜力。
