Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Charitéplatz 1, 10117, Berlin, Germany.
Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Charitéplatz 1, 10117, Berlin, Germany.
Eur J Radiol. 2021 Jun;139:109692. doi: 10.1016/j.ejrad.2021.109692. Epub 2021 Apr 1.
To derive optimal scanning parameters for single-source dual-energy computed tomography (DECT) in the detection of urate by analyzing influence of tube current ratio (TCR) and total radiation exposure in a phantom.
Specimens with different urate concentrations in a realistic porcine bio-phantom were repeatedly imaged with sequential single-source DECT scans at 80 kVp (16.5-220 mA s) and 135 kVp (2.75-19.25 mA s). Detection index (DI - true positive minus false positive urate volume) was calculated for every possible tube current combination. Optimal tube current combinations reaching at least 85 % of the highest measured DI of all combinations without exceeding 150 % of equivalent single-energy radiation dose were identified. TCR, DLP and DI were plotted and compared.
Cubic regression analysis showed a flattening increase in the DI with increasing tube currents. Five out of the 100 tube current combinations analyzed achieved the detection target: the lowest DLP of 53.9 mGycm at 19.25/16.5 mAs (135/80 kVp) achieved a DI of 2.07 mL and the highest DI of 2.11 mL at a dose of 65.3 mGycm and 8.25/79.75 mAs. The optimal TCR is between two and four, while both, higher and lower ratios decreased DI.
A minimum tube current of the high-energy scans is needed before an acceptable overall sensitivity is achieved and before increases in low-energy exposure result in more urate detection. High TCRs above 10 are not beneficial while the optimal TCR ranges between two and four, indicating that special care has to be taken in designing a suitable DECT protocol.
通过分析管电流比（TCR）和总辐射暴露量对猪生物模型中尿酸检测的影响，为单源双能 CT（DECT）的尿酸检测得出最佳扫描参数。
使用连续的单源 DECT 扫描，在 80 kVp（16.5-220 mA s）和 135 kVp（2.75-19.25 mA s）下对具有不同尿酸浓度的猪生物模型进行重复成像。计算每种可能的管电流组合的检测指标（DI-真阳性减去假阳性尿酸体积）。识别出达到所有组合中最高测量 DI 的至少 85%，且不超过等效单能辐射剂量 150%的最佳管电流组合。绘制 TCR、DLP 和 DI 并进行比较。
三次回归分析显示 DI 随管电流的增加而呈平坦增加。在分析的 100 个管电流组合中有 5 个达到了检测目标：最低剂量长度乘积（DLP）为 53.9 mGycm，在 19.25/16.5 mAs（135/80 kVp）时 DI 为 2.07 mL，剂量为 65.3 mGycm 时 DI 最高，为 2.11 mL。最佳 TCR 介于 2 和 4 之间，而更高和更低的比值都会降低 DI。
在获得可接受的整体灵敏度之前，需要高能扫描的最小管电流，并且在低能暴露增加导致更多尿酸检测之前。高于 10 的高 TCR 没有好处，而最佳 TCR 范围在 2 到 4 之间，这表明在设计合适的 DECT 方案时必须特别注意。
