PDF(Pubmed)
Abstract：
Objective. Photon-counting detector (PCD) CT enables routine virtual-monoenergetic image (VMI) reconstruction. We evaluated the performance of an automatic VMI energy level (keV) selection tool on a clinical PCD-CT system in comparison to an automatic tube potential (kV) selection tool from an energy-integrating-detector (EID) CT system from the same manufacturer.Approach.Four torso-shaped phantoms (20-50 cm width) containing iodine (2, 5, and 10 mg cc-1) and calcium (100 mg cc-1) were scanned on PCD-CT and EID-CT. Dose optimization techniques, task-based VMI energy level and tube-potential selection on PCD-CT (CARE keV) and task-based tube potential selection on EID-CT (CARE kV), were enabled. CT numbers, image noise, and dose-normalized contrast-to-noise ratio (CNRd) were compared.Main results. PCD-CT produced task-specific VMIs at 70, 65, 60, and 55 keV for non-contrast, bone, soft tissue with contrast, and vascular settings, respectively. A 120 kV tube potential was automatically selected on PCD-CT for all scans. In comparison, EID-CT used x-ray tube potentials from 80 to 150 kV based on imaging task and phantom size. PCD-CT achieved consistent dose reduction at 9%, 21% and 39% for bone, soft tissue with contrast, and vascular tasks relative to the non-contrast task, independent of phantom size. On EID-CT, dose reduction factor for contrast tasks relative to the non-contrast task ranged from a 65% decrease (vascular task, 70 kV, 20 cm phantom) to a 21% increase (soft tissue with contrast task, 150 kV, 50 cm phantom) due to size-specific tube potential adaptation. PCD-CT CNRdwas equivalent to or higher than those of EID-CT for all tasks and phantom sizes, except for the vascular task with 20 cm phantom, where 70 kV EID-CT CNRdoutperformed 55 keV PCD-CT images.Significance. PCD-CT produced more consistent CT numbers compared to EID-CT due to standardized VMI output, which greatly benefits standardization efforts and facilitates radiation dose reduction.
摘要：
目的：光子计数探测器（PCD）CT可以实现常规的虚拟单能量图像（VMI）重建。与来自同一制造商的能量积分检测器（EID）CT系统的自动管电势（kV）选择工具相比，我们评估了临床PCD-CT系统上自动VMI能级（keV）选择工具的性能。＆＃xD;方法：在PCD-CT和EID-CT上扫描了四个包含碘（2、5和10-mg/cc）和钙（100mg/cc）的躯干形体模（20-50厘米宽）。剂量优化技术,PCD-CT上基于任务的VMI能级和管电位选择（CAREkeV）和EID-CT上基于任务的管电位选择（CAREkV），已启用。CT数字,图像噪声,和剂量归一化对比噪声比（CNRd）进行比较。＆＃xD;主要结果：PCD-CT在70、65、60和55keV下产生了任务特定的VMI，骨头,软组织对比，和血管设置，分别。对于所有扫描,在PCD-CT上自动选择120kV管电势。相比之下,EID-CT根据成像任务和体模大小使用80kV至150kV的X射线管电势。PCD-CT实现了9%的一致剂量减少，21%和39%的骨，软组织对比，和血管任务相对于非对比任务，独立的幻影大小。在EID-CT上,对比任务相对于非对比任务的剂量减少因子从减少65%(血管任务，70kV,20厘米体模）增加21％（具有对比任务的软组织，150kV,50厘米体模）由于特定尺寸的管电位适应。对于所有任务和体模大小，PCD-CT的CNRd等于或高于EID-CT的CNRd，除了20厘米幻影的血管任务，其中70kVEID-CTCNRd优于55keVPCD-CT图像。＆＃xD;意义：由于标准化的VMI输出，与EID-CT相比，PCD-CT产生了更一致的CT编号，这极大地有利于标准化工作，并有助于减少辐射剂量。
