Field-flood requirements for emission computed tomography with an Anger camera.
Field-flood requirements for emission computed tomography with an Anger camera.
复制标题
使用 Anger 相机进行发射计算机断层扫描的现场泛洪要求。
作者：
W. Rogers;N. Clinthorne;B. Harkness;K. Koral;J. Keyes
具有旋转相机的发射计算机断层扫描对相机均匀性和相机响应的稳定性提出了严格的要求。在临床层析成像方面，我们研究了相机洪水校正所需的统计精度，洪水精度的要求，洪水和数据图像平滑的实用性和有效性，以减少随机噪声的影响，以及相机变化的幅度和影响作为角位置，能量窗口和调谐的函数。校正泛光响应的均匀性必须保持在1%以上，以消除在肝脏切片的百万计数图像中明显的图像伪影。这需要使用准确、混合良好的洪水源进行校准。相机响应随旋转的随机波动和变化必须保持在1%以下。为了满足统计限制，需要至少3000万次的泛光校正图像计数。单独平滑泛光图像会引入不可接受的图像伪影。然而，平滑洪水图像和数据似乎是减少噪声影响的好方法。仔细的摄像机调谐和磁屏蔽设计提供了适合当前临床应用的摄像机稳定性。
Emission computed tomography with a rotating camera places stringent requirements on camera uniformity and the stability of camera response. In terms of clinical tomographic imaging, we have studied the statistical accuracy required for camera flood correction, the requirements for flood accuracy, the utility and validity of flood and data image smoothing to reduce random noise effects, and the magnitude and effect of camera variations as a function of angular position, energy window, and tuning. Uniformity of the corrected flood response must be held to better than 1% to eliminate image artifacts that are apparent in a million-count image of a liver slice. This requires calibration with an accurate, well-mixed flood source. Both random fluctuations and variations in camera response with rotation must be kept below 1%. To meet the statistical limit, one requires at least 30 million counts for the flood-correction image. Smoothing the flood image alone introduces unacceptable image artifacts. Smoothing both the flood image and data, however, appears to be a good approach toward reducing noise effects. Careful camera tuning and magnetic shield design provide camera stability suitable for present clinical applications.