使用新型MURA掩模对扩展源进行信噪比优化
Signal to Noise Ratio optimization for extended sources with a new kind of MURA masks
摘要：
使用编码孔径，用于定位放射性热点，导致提高的效率和在某些配置下的宽视场（FOV）。本文提出了一种易于重构的编码孔径组装技术，并研究了利用该技术构建的编码孔径在定位空间扩展γ辐射源时的本征噪声的降低。具体地，通过将铅球嵌入在透明介质（诸如丙烯酸玻璃）内部加工的位置矩阵中来构造改进的均匀冗余阵列（MURA）编码孔径，从而产生有利的透明与不透明面积比，并因此提高检测效率。这种配置还在相关矩阵的点扩展函数（PSF）上引起系统的、逐元素的噪声。当用这些孔径扩展的热点成像时，半影现象发生并以核滤波器的方式降低该固有噪声。利用快速傅里叶变换（FFT）分析了这种现象对相关矩阵的影响，并解释了在一定范围内热点信号的信噪比最大化的原因。模拟已被用于详细研究的SNR依赖于热点的尺寸，而实验与两个99mTc圆柱形源与11毫米和24毫米直径，分别和1.5 MBq的活动，每个，确认减少的固有噪声。结果定义的方式，优化的成像设置的检测扩展的热点。这种优化例如在核医学中的淋巴结或甲状腺残留成像的情况下可能是有用的。最后，我们提出了一个核滤波器，来自自相关函数（ACF），应用于具有高固有噪声的PSF，以消除它。
英文摘要：
Using coded aperture, for localization of radioactive hot-spots, results in enhanced efficiency and under certain configurations wide Field of View (FOV). We present a coded aperture assembly technique which can be restructured easily, as well as the reduction of the intrinsic noise of coded apertures constructed with this technique, when they localize spatially extended γ-emitters. Specifically, Modified-Uniformly-Redundant-Array (MURA) coded apertures are structured by embedding lead spheres in a matrix of positions machined inside a transparent medium such as acrylic glass, resulting in an advantageous transparent to opaque area ratio and thus an improved detection efficiency. This configuration also induces a systematic, element-wise, noise on the Point-Spread-Function (PSF) of the correlation matrix. When imaging with these apertures extended hot-spots, a penumbra phenomenon occurrs and reduces this intrinsic noise, in the way a kernel filter does. Fast-Fourier-Transform (FFT) is used to analyze the effect of this phenomenon on the correlation matrix and to explain the maximization of its Signal-to-Noise Ratio (SNR) for certain extent of the hot-spots. Simulations have been used for the detailed study of the SNR dependence on the dimensions of the hot-spot, while experiments with two 99mTc cylindrical sources with 11mm and 24mm diameter, respectively and 1.5 MBq activity each, confirm the reduction of the intrinsic noise. The results define the way of optimization of the imaging setup for the detection of extended hot-spots. Such an optimization could be useful for example in the case of lymph nodes or thyroid remnant imaging in nuclear medicine. Finally, we propose a kernel filter, derived by the Auto-Correlation-Function (ACF), to be applied on PSFs with high intrinsic noise, in order to eliminate it.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
