Isnaini Ismet, Obi Takashi, Yoshida Eiji, Yamaya Taiga
Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan,
Radiol Phys Technol. 2014 Jul;7(2):203-10. doi: 10.1007/s12194-013-0253-y. Epub 2013 Dec 24.
The current positron emission tomography (PET) design is aimed toward establishing an entire-body PET scanner. An entire-body PET scanner is a scanner whose axial field of view (FOV) covers the whole body of a patient, whereas whole-body PET scanner can be of any axial FOV length, but was designed for a whole-body scan. Despite its high production cost, an entire-body depth-of-interaction PET scanner offers many benefits, such as shorter and dynamic PET time acquisition, as well as higher sensitivity and count rate performance. This PET scanner may be cost-effective for clinical PET scanners with high scan throughput. In this work, we evaluated the sensitivity and count rate performance of a 2-m-long PET scanner with conventional data acquisition (DAQ) architecture, using Monte Carlo simulation, and we evaluated two ring diameters (60 and 80 cm) to reduce the scanner cost. From simulation of scanning with a 2-m axial FOV, the sensitivity for a 2-m-long PET scanner of 60 and 80-cm diameter is around 80 and 68 times higher, respectively, than that of the conventional PET scanner. In addition, for the 2-m-long PET scanner with 60-cm diameter, the peak noise equivalent count rate (NECR) was 843 kcps at 125 MBq, whereas the peak for the 80-cm diameter was 989 kcps at 200 MBq. This shows gains of 15.3 and 17.95, respectively, in comparison with that of the conventional PET scanner. The 2-m-long PET scanner with 60-cm ring diameter could not only reduce the number of detectors by 21 %, but also had a 17 % higher sensitivity compared to that with an 80-cm ring diameter. On the other hand, despite the higher sensitivity, the NECR of the 60-cm ring diameter was smaller than that of the 80-cm ring diameter. This results from the single data loss due to dead time, whereas grouping of axially stacked detectors was used in the conventional DAQ architecture. Parallelization of the DAQ architecture is therefore important for the 2-m-long PET scanner to achieve its optimal performance.
当前的正电子发射断层扫描（PET）设计旨在打造一台全身PET扫描仪。全身PET扫描仪是指其轴向视野（FOV）能覆盖患者全身的扫描仪，而全身PET扫描仪的轴向FOV长度可以是任意的，但它是为全身扫描而设计的。尽管其生产成本高昂，但全身交互深度PET扫描仪具有诸多优势，比如PET采集时间更短且具有动态性，以及更高的灵敏度和计数率性能。对于具有高扫描通量的临床PET扫描仪而言，这种PET扫描仪可能具有成本效益。在这项工作中，我们使用蒙特卡罗模拟评估了具有传统数据采集（DAQ）架构的2米长PET扫描仪的灵敏度和计数率性能，并且我们评估了两种环直径（60厘米和80厘米）以降低扫描仪成本。通过对2米轴向FOV扫描的模拟，直径为60厘米和80厘米的2米长PET扫描仪的灵敏度分别比传统PET扫描仪高约80倍和68倍。此外，对于直径为60厘米的2米长PET扫描仪，在125 MBq时的峰值噪声等效计数率（NECR）为843 kcps，而直径为80厘米的在200 MBq时的峰值为989 kcps。与传统PET扫描仪相比，这分别显示出15.3和17.95的增益。直径为60厘米环的2米长PET扫描仪不仅可以将探测器数量减少21%，而且与直径为80厘米环的相比，灵敏度还高17%。另一方面，尽管灵敏度较高，但直径为60厘米环的NECR小于直径为80厘米环的。这是由于死时间导致的单个数据丢失，而在传统DAQ架构中使用了轴向堆叠探测器的分组。因此，DAQ架构的并行化对于2米长PET扫描仪实现其最佳性能很重要。
