Nohara Norimasa
Emeritus Researcher, National Institute of Radiological Sciences.
Former Professor, Department of Radiological Sciences, Faculty of Health, International University of Health and Welfare.
Igaku Butsuri. 2022;42(1):23-32. doi: 10.11323/jjmp.42.1_23.
This article gives a commentary on the development of positron emission tomography scanners based on Positology which was proposed by Dr. Eiichi Tanaka. Circular detector rings of an equally spaced detector arrangement have a problem of linear sampling density distributions in the projections. The problem can be solved by Positology in which a continuously rotating detector ring of an unequally spaced detector arrangement obtained by computer iterative searching provides a fine and uniform sampling density distribution. The imaging performance of multilayer positron emission tomography scanners for extended sources is evaluated analytically. The analysis is simplified by "rotation transform," by which three-dimensional photon detection problems are solved by two-dimensional treatment. Event rates of singles, unscattered true coincidence, and single- and double-scattered coincidence are formulated for a uniform cylindrical phantom. Positron emission tomography scanners based on Positology, named Positologica, were developed for brain, whole-body and animal study. A high resolution stationary PET scanner, SHR-1200 was also developed for brain study.
本文对基于田中英一博士提出的正子学的正电子发射断层扫描仪的发展进行了评论。等间距探测器排列的圆形探测器环在投影中存在线性采样密度分布的问题。该问题可以通过正子学解决，其中通过计算机迭代搜索获得的不等间距探测器排列的连续旋转探测器环可提供精细且均匀的采样密度分布。对用于扩展源的多层正电子发射断层扫描仪的成像性能进行了分析评估。通过“旋转变换”简化了分析，通过该变换二维处理解决了三维光子探测问题。针对均匀圆柱形体模制定了单事件、无散射真符合以及单散射和双散射符合的事件率。开发了基于正子学的正电子发射断层扫描仪，名为Positologica，用于脑部、全身和动物研究。还开发了用于脑部研究的高分辨率固定式正电子发射断层扫描仪SHR - 1200。
