BACKGROUND Iterative reconstruction is well-established in diagnostic multidetector computed tomography (MDCT) for dose reduction and image quality enhancement. Its application to diagnostic cone beam computed tomography (CBCT) is only emerging and warrants a quantitative evaluation. METHODS Several phantoms and a canine head specimen were imaged using a commercially available small-field CBCT scanner. Raw projection data were reconstructed using the Feldkamp-Davis-Kress (FDK) method with different filters, including denoising via total variation (TV) minimization (FDK-TV). Iterative reconstruction was carried out using the TV-regularized ordered subsets convex technique (OSC-TV). Signal-to-noise ratio (SNR), noise power spectrum (NPS) and spatial resolution of images were estimated. Dose levels were measured via the weighted computed tomography dose index, while low-dose image quality degradation was estimated via structural similarity (SSIM). RESULTS OSC-TV and FDK-TV were shown to significantly improve image signal-to-noise ratio (SNR) compared to FDK with a standard filter, 5.8 and 4.0 times, respectively. Spatial resolution attained with different algorithms varied moderately across different experiments. For low-dose acquisitions, image quality decreased dramatically for FDK but not for FDK-TV nor OSC-TV. For low-dose canine head images acquired using about 1/5 of the dose compared to a reference image, SSIM dropped to about 0.3 for FDK, while remaining at 0.92 for FDK-TV and 0.96 for OSC-TV. CONCLUSION OSC-TV was shown to improve image quality compared to FDK and FDK-TV. Moreover, this iterative approach allowed for significant dose reduction while maintaining image quality.

中文翻译：

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用于诊断锥束CT成像中图像增强和剂量减少的迭代重建。

背景技术在诊断多检测器计算机断层摄影（MDCT）中，为了减少剂量和提高图像质量，已经很好地建立了迭代重建。它在诊断锥形束计算机断层扫描（CBCT）中的应用才刚刚出现，需要进行定量评估。方法使用市售的小视野CBCT扫描仪对几个体模和犬头标本成像。原始投影数据使用Feldkamp-Davis-Kress（FDK）方法和不同的滤波器进行重建，包括通过总变化（TV）最小化（FDK-TV）进行降噪。迭代重建使用电视规则化有序子集凸技术（OSC-TV）进行。估计了信噪比（SNR），噪声功率谱（NPS）和图像的空间分辨率。通过加权计算机断层摄影剂量指数测量剂量水平，而通过结构相似性（SSIM）估算低剂量图像质量下降。结果与采用标准滤波器的FDK相比，OSC-TV和FDK-TV显着提高了图像信噪比（SNR），分别为5.8和4.0倍。在不同的实验中，使用不同算法获得的空间分辨率会略有不同。对于低剂量采集，FDK的图像质量急剧下降，但FDK-TV和OSC-TV的图像质量却没有下降。对于与参考图像相比使用约1/5剂量获得的小剂量犬头图像，对于FDK，SSIM下降到约0.3，而对于FDK-TV，SSIM保持在0.92，对于OSC-TV，SSIM保持在0.96。结论与FDK和FDK-TV相比，OSC-TV可以提高图像质量。此外，