Latest advantages in computed tomography (CT) come with enhanced diagnostic imaging and also sophisticated dose reduction techniques. However, overall exposure to ionizing radiation of patients in Germany rises slightly, which is mainly based on the growing number of performed CT scans. Furthermore, new possibilities in modern imaging, including 4D scans or perfusion protocols, offer new medical insights but require additional scans.In this study, we reevaluated data sets from patients undergoing CT examinations because of suspected pulmonary embolism and compared doses and diagnostic results of the standard protocol to the additional modern CT subtraction technique. Two groups of single-blinded radiologists were provided with CT data sets from 50 patients. One group (G1) had access to full datasets including CT subtraction with perfusion map. The other group (G2) only evaluated conventional CT angiography. Results were compared to final clinical diagnosis. Dose length product (DLP) of CT angiography was compared to CT subtraction technique, which consists of an additional non-contrast-enhanced scan and perfusion map. Effective dose was calculated using a Monte Carlo simulation-based software tool (ImpactDose). Inter-rater agreement of both groups was strong in G1 with κ = .896 and minimal in G2 (κ = .307). Agreement to final diagnosis was strong in both groups (G1, κ = .848; G2, κ = .767). Doses applied using the CT subtraction technique were 34.8% higher than for CT angiography alone (G1 DLP 337.6 ± 171.3 mGy x cm; G2 DLP 220.2 ± 192.8 mGy x cm; p < .001). Calculated effective dose was therefore significantly higher for G1 (G1 4.82 ± 2.20 mSv; G2 3.04 ± 1.33 mSv; p < .001). Our results indicate a benefit of the CT subtraction technique for the detection of pulmonary embolisms in clinical routine, accompanied by an increase in the dose administered. Although CT protocols should always be applied carefully to specific clinical indications in order to maximize the potential for dose reduction and keep the administered dose as low as reasonably achievable, one should never lose sight of the diagnostic benefit, especially in vital clinical indications.

中文翻译：

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在肺栓塞检测中使用额外的CTA减法技术是对患者的益处还是仅增加剂量？

计算机断层扫描（CT）的最新优势在于增强的诊断成像以及先进的剂量减少技术。但是，德国患者对电离辐射的总体暴露量略有增加，这主要是基于进行CT扫描的人数不断增加。此外，现代影像学的新可能性（包括4D扫描或灌注方案）提供了新的医学见解，但需要进行其他扫描。在本研究中，由于怀疑有肺栓塞，我们重新评估了接受CT检查的患者的数据集，并比较了剂量和诊断结果。附加现代CT减法技术的标准协议。为两组单盲放射科医生提供了50例患者的CT数据集。一组（G1）可以访问完整的数据集，包括CT减影和灌注图。另一组（G2）仅评估常规CT血管造影。将结果与最终临床诊断进行比较。将CT血管造影的剂量长度乘积（DLP）与CT减影技术进行了比较，该技术由一个附加的非对比增强扫描和灌注图组成。使用基于蒙特卡洛模拟的软件工具（ImpactDose）计算有效剂量。两组的评分者之间的一致性在G1中很强，κ= 0.896，在G2中极小（κ= .307）。在两组中，最终诊断的一致性都很高（G1，κ= .848； G2，κ= .767）。使用CT减影技术所施加的剂量比单独使用CT血管造影术的剂量高出34.8％（G1 DLP 337.6±171.3 mGy x cm; G2 DLP 220.2±192.8 mGy x cm; p <0.001）。因此，G1的计算有效剂量明显更高（G1为4.82±2.20 mSv； G2为3.04±1.33 mSv； p <.001）。我们的结果表明，CT减影技术可在临床常规检查中检测出肺栓塞，同时增加给药剂量。尽管应始终将CT方案小心地应用于特定的临床适应症，以最大程度地降低剂量，并使给药剂量保持在合理可达到的最低水平，但绝不能忽视诊断的益处，尤其是在重要的临床适应症中。