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Abstract：
The aim of this phantom study was to assess the detectability and volumetric accuracy of pulmonary nodules on photon-counting detector CT (PCD-CT) at different low-dose levels compared to conventional energy-integrating detector CT (EID-CT). In-house fabricated artificial nodules of different shapes (spherical, lobulated, spiculated), sizes (2.5-10 mm and 5-1222 mm3), and densities (-330 HU and 100 HU) were randomly inserted into an anthropomorphic thorax phantom. The phantom was scanned with a low-dose chest protocol with PCD-CT and EID-CT, in which the dose with PCD-CT was lowered from 100% to 10% with respect to the EID-CT reference dose. Two blinded observers independently assessed the CT examinations of the nodules. A third observer measured the nodule volumes using commercial software. The influence of the scanner type, dose, observer, physical nodule volume, shape, and density on the detectability and volumetric accuracy was assessed by a multivariable regression analysis. In 120 CT examinations, 642 nodules were present. Observer 1 and 2 detected 367 (57%) and 289 nodules (45%), respectively. With PCD-CT and EID-CT, the nodule detectability was similar. The physical nodule volumes were underestimated by 20% (range 8-52%) with PCD-CT and 24% (range 9-52%) with EID-CT. With PCD-CT, no significant decrease in the detectability and volumetric accuracy was found at dose reductions down to 10% of the reference dose (p > 0.05). The detectability and volumetric accuracy were significantly influenced by the observer, nodule volume, and a spiculated nodule shape (p < 0.05), but not by dose, CT scanner type, and nodule density (p > 0.05). Low-dose PCD-CT demonstrates potential to detect and assess the volumes of pulmonary nodules, even with a radiation dose reduction of up to 90%.
摘要：
这项体模研究的目的是评估与常规能量积分探测器CT（EID-CT）相比，在不同低剂量水平下，光子计数探测器CT（PCD-CT）上肺结节的可检测性和体积准确性。内部制造的不同形状的人工结节(球形，分叶状,针状)，尺寸（2.5-10毫米和5-1222毫米），并将密度（-330HU和100HU）随机插入拟人化的胸模中。体模用低剂量胸部协议用PCD-CT和EID-CT扫描，其中PCD-CT的剂量相对于EID-CT参考剂量从100%降低到10%。两名失明的观察者独立评估了结节的CT检查。第三个观察者使用商业软件测量结节体积。扫描仪类型的影响，剂量,观察者,物理结节体积，形状,和密度对可检测性和体积准确性的影响通过多变量回归分析进行评估。在120次CT检查中,有642个结节。观察者1和2检测到367个（57％）和289个结节（45％），分别。使用PCD-CT和EID-CT，结节可检测性相似。PCD-CT的物理结节体积被低估了20％（范围8-52％），EID-CT的物理结节体积被低估了24％（范围9-52％）。使用PCD-CT,当剂量减少至参考剂量的10%时,检测能力和体积准确度没有显著下降(p>0.05).可检测性和体积精度受到观察者的显著影响，结节体积,结节呈针状（p<0.05），但不是通过剂量，CT扫描仪类型,结节密度(p>0.05)。低剂量PCD-CT显示出检测和评估肺结节体积的潜力，即使辐射剂量减少高达90%。
