Improvements in dose efficiency with high resolution scan modes in photon counting CT.
Improvements in dose efficiency with high resolution scan modes in photon counting CT.
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光子计数 CT 中高分辨率扫描模式提高了剂量效率。
DOI：
10.1117/12.2654334
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Hsieh,ScottS
中科院分区：
文献类型：
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作者：
Shunhavanich,Picha;Rajendran,Kishore;Fan,Mingdong;McCollough,CynthiaH;Leng,Shuai;Yu,Lifeng;Hsieh,ScottS
对于非常小的物体的探测，高分辨率探测器有望提供更高的剂量效率。我们通过比较临床光子计数探测器CT(PCD-CT)在高分辨率和标准分辨率(2×2装仓和更大焦斑)模式下的检测能力，评估了分辨率提高对PCD-CT的影响。将一根50μm的细金属丝放置在胸部体模中，在两种模式下以三种曝光水平(12、15和18 mAs)进行扫描；采集的数据用三个重建核(Br40、Br68和Br76，从平滑到尖锐)进行重建。扫描非预白化模型观察者独立地搜索每个切片内的导线位置。检测性能被量化为自由响应ROC曲线的指数变换下的面积。高分辨率模式的18mAs平均AUC值分别为0.45、0.49和0.65，分别是标准分辨率模式的2倍、3.6倍和4.6倍。对于每个重建核，高分辨率模式在12 mA时比标准分辨率模式在18 mA时获得了更大的AUC，但在更尖锐的核上改善更大。结果与高分辨率CT在较高频率时预期对噪声混叠的更大抑制是一致的。这项工作表明，PCD-CT可以为小的、高对比度病变的检测任务提供大的剂量效率增益。
For the detection of very small objects, high resolution detectors are expected to provide higher dose efficiency. We assessed this impact of increased resolution on a clinical photon counting detector CT (PCD-CT) by comparing its detectability in high resolution and standard resolution (with 2×2 binning and larger focal spot) modes. A 50μm-thin metal wire was placed in a thorax phantom and scanned in both modes at three exposure levels (12, 15, and 18 mAs); acquired data were reconstructed with three reconstruction kernels (Br40, Br68, and Br76, from smooth to sharp). A scanning nonprewhitening model observer searched for the wire location within each slice independently. Detection performance was quantified as area under the exponential transform of the free response ROC curve. The high-resolution mode had the mean AUCs at 18 mAs of 0.45, 0.49, and 0.65 for Br40, Br68, and Br76, respectively, which were 2 times, 3.6 times, and 4.6 times those of the standard resolution mode. The high-resolution mode achieved greater AUC at 12 mAs than the standard resolution mode at 18 mAs for every reconstruction kernel, but improvements were larger at sharper kernels. The results are consistent with the greater suppression of noise aliasing expected at higher frequencies with high resolution CT. This work illustrates that PCD-CT can provide large dose efficiency gains for detection tasks of small, high contrast lesions.