BACKGROUND:High-resolution, low-noise detectors with minimal dead-space at chest-wall could improve posterior coverage and microcalcification visibility in the dedicated cone-beam breast CT (CBBCT). However, the smaller field-of-view necessitates laterally-shifted detector geometry to enable optimizing the air-gap for x-ray scatter rejection. OBJECTIVE:To evaluate laterally-shifted detector geometry for CBBCT with clinical projection datasets that provide for anatomical structures and lesions. METHODS:CBBCT projection datasets (n = 17 breasts) acquired with a 40×30 cm detector (1024×768-pixels, 0.388-mm pixels) were truncated along the fan-angle to emulate 20.3×30 cm, 22.2×30 cm and 24.1×30 cm detector formats and correspond to 20, 120, 220 pixels overlap in conjugate views, respectively. Feldkamp-Davis-Kress (FDK) algorithm with 3 different weighting schemes were used for reconstruction. Visual analysis for artifacts and quantitative analysis of root-mean-squared-error (RMSE), absolute difference between truncated and 40×30 cm reconstructions (Diff), and its power spectrum (PSDiff) were performed. RESULTS:Artifacts were observed for 20.3×30 cm, but not for other formats. The 24.1×30 cm provided the best quantitative results with RMSE and Diff (both in units of μ, cm-1) of 4.39×10-3±1.98×10-3 and 4.95×10-4±1.34×10-4, respectively. The PSDiff (>0.3 cycles/mm) was in the order of 10-14μ2mm3 and was spatial-frequency independent. CONCLUSIONS:Laterally-shifted detector CBBCT with at least 220 pixels overlap in conjugate views (24.1×30 cm detector format) provides quantitatively accurate and artifact-free image reconstruction.

中文翻译：

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使用横向移动探测器几何结构的专用锥形束乳房 CT：临床转化可行性的定量分析。

背景：具有最小胸壁死腔的高分辨率、低噪声探测器可以提高专用锥形束乳腺 CT (CBBCT) 的后部覆盖率和微钙化可见度。然而，较小的视场需要横向移动的探测器几何结构，以优化气隙以抑制 X 射线散射。目的：使用提供解剖结构和病变的临床投影数据集评估 CBBCT 的横向移动探测器几何结构。方法：使用 40×30 厘米探测器（1024×768 像素，0.388 毫米像素）获得的 CBBCT 投影数据集（n = 17 个乳房）沿扇角截断以模拟 20.3×30 厘米、22.2×30 厘米和24.1×30 cm 探测器格式，分别对应于共轭视图中 20、120、220 像素的重叠。Feldkamp-Davis-Kress (FDK) 算法具有 3 种不同的加权方案被用于重建。进行了伪影的可视化分析和均方根误差 (RMSE)、截断和 40×30 cm 重建之间的绝对差异 (Diff) 及其功率谱 (PSDiff) 的定量分析。结果：在 20.3 × 30 cm 处观察到伪影，但其他格式未观察到伪影。24.1×30 cm提供了最好的定量结果，RMSE和Diff（均以μ，cm-1为单位）为4.39×10-3±1.98×10-3和4.95×10-4±1.34×10-4，分别。PSDiff (>0.3 周期/mm) 约为 10-14μ2mm3，并且与空间频率无关。结论：在共轭视图中至少有 220 个像素重叠的横向移动检测器 CBBCT（24.1×30 cm 检测器格式）提供了定量准确和无伪影的图像重建。