Onishi Hideo, Motomura Nobutoku, Fujino Koichi, Natsume Takahiro, Haramoto Yasuhiro
Program in Health and Welfare, Graduate School of Comprehensive Scientific Research, Prefectural University of Hiroshima, 1-1 Gakuenmachi, Mihara, Hiroshima 723-0053, Japan.
Radiol Phys Technol. 2013 Jan;6(1):42-53. doi: 10.1007/s12194-012-0168-z. Epub 2012 Jul 13.
Several resolution recovery (RR) methods have been developed. This study was aimed to validate the following performance of the advanced RR methods: Evolution, Astonish, Flash3D, and 3D-OSEM. We compared the advanced RR method with filtered back projection (FBP) and standard order-subset expectation maximization (OSEM) using resolution (RES), cylinder/sphere (CYS), and myocardial (MYD) digital phantoms. The RES phantom was placed in three spheres. Sixteen spheres (hot and cold) were then placed in a concentric configuration (diameter: 96-9.6 mm) inside the CYS phantom. The MYD phantom was created by computer simulation with the use of an electron γ-shower 4 (EGS4) and it included two left ventricular defects in the myocardium. The performance was evaluated at source-to-detector distances (R-distance) of 166, 200, and 250 mm with reconstruction parameters (product of subset and iteration: SI) with use of the resolution recovery factor, count recovery, normalized mean square error (NMSE), and %CV. According to increased SI updates, the value of the FWHM decreased, and the effect was more obvious as the R-distance increased. The spatial resolution of the advanced RR method was 20 % better than that of FBP and OSEM. The resolution recovery ratio was 80 %, and the count recovery was maintained only in objects with a diameter of >30 mm in the advanced RR method. The NMSE and %CV was 50 and 30 % improved over FBP and OSEM, respectively. The advanced RR method caused overestimation due to Gibbs's phenomenon in the marginal region when the diameter of the sphere was 16-28.8 mm.
已经开发了几种分辨率恢复（RR）方法。本研究旨在验证以下先进RR方法的性能：Evolution、Astonish、Flash3D和3D-OSEM。我们使用分辨率（RES）、圆柱/球体（CYS）和心肌（MYD）数字体模，将先进RR方法与滤波反投影（FBP）和标准序子集期望最大化（OSEM）进行了比较。RES体模放置在三个球体中。然后在CYS体模内以同心配置（直径：96 - 9.6 mm）放置16个球体（热球和冷球）。MYD体模是通过使用电子γ簇射4（EGS4）进行计算机模拟创建的，它包括心肌中的两个左心室缺损。使用分辨率恢复因子、计数恢复、归一化均方误差（NMSE）和%CV，在源到探测器距离（R距离）为166、200和250 mm以及重建参数（子集与迭代的乘积：SI）的情况下评估性能。随着SI更新的增加，半高宽（FWHM）值降低，并且随着R距离增加，这种效果更明显。先进RR方法的空间分辨率比FBP和OSEM高20%。分辨率恢复率为80%，并且在先进RR方法中，仅在直径>30 mm的物体中保持计数恢复。与FBP和OSEM相比，NMSE和%CV分别提高了50%和30%。当球体直径为16 - 28.8 mm时，先进RR方法在边缘区域由于吉布斯现象导致高估。
