Rogers W L, Clinthorne N H, Harkness B A, Koral K F, Keyes J W
J Nucl Med. 1982 Feb;23(2):162-8.
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.
采用旋转相机的发射型计算机断层扫描对相机均匀性和相机响应稳定性提出了严格要求。在临床断层成像方面，我们研究了相机泛源校正所需的统计精度、泛源精度要求、泛源和数据图像平滑以减少随机噪声影响的效用和有效性，以及相机变化随角位置、能量窗和调谐的大小和影响。校正后的泛源响应均匀性必须保持在1%以内，以消除肝脏切片百万计数图像中明显的图像伪影。这需要用精确、充分混合的泛源进行校准。相机响应的随机波动和随旋转的变化都必须保持在1%以下。为了达到统计极限，泛源校正图像至少需要3000万个计数。仅对泛源图像进行平滑会引入不可接受的图像伪影。然而，对泛源图像和数据都进行平滑似乎是减少噪声影响的好方法。仔细的相机调谐和磁屏蔽设计可提供适合当前临床应用的相机稳定性。
