Ding Yijun, Caucci Luca, Barrett Harrison H
Department of Physics, University of Arizona, Tucson, AZ, USA.
Department of Medical Imaging, University of Arizona, Tucson, AZ, USA.
Sci Rep. 2017 Nov 17;7(1):15807. doi: 10.1038/s41598-017-16111-z.
Null functions of an imaging system are functions in the object space that give exactly zero data. Hence, they represent the intrinsic limitations of the imaging system. Null functions exist in all digital imaging systems, because these systems map continuous objects to discrete data. However, the emergence of detectors that measure continuous data, e.g. particle-processing (PP) detectors, has the potential to eliminate null functions. PP detectors process signals produced by each particle and estimate particle attributes, which include two position coordinates and three components of momentum, as continuous variables. We consider Charged-Particle Emission Tomography (CPET), which relies on data collected by a PP detector to reconstruct the 3D distribution of a radioisotope that emits alpha or beta particles, and show empirically that the null functions are significantly reduced for alpha particles if ≥3 attributes are measured or for beta particles with five attributes measured.
成像系统的零函数是物空间中产生恰好为零的数据的函数。因此，它们代表了成像系统的固有局限性。所有数字成像系统中都存在零函数，因为这些系统将连续的物体映射为离散的数据。然而，能够测量连续数据的探测器的出现，例如粒子处理（PP）探测器，有可能消除零函数。PP探测器处理每个粒子产生的信号，并将粒子属性（包括两个位置坐标和三个动量分量）作为连续变量进行估计。我们考虑带电粒子发射断层扫描（CPET），它依靠PP探测器收集的数据来重建发射α或β粒子的放射性同位素的三维分布，并通过实验表明，如果测量≥3个属性，对于α粒子，或者测量5个属性对于β粒子，零函数会显著减少。
