Department of Imaging Physics, The University of Texas M D Anderson Cancer Center, Houston, TX, USA.
Phys Med Biol. 2014 Mar 7;59(5):1223-38. doi: 10.1088/0031-9155/59/5/1223. Epub 2014 Feb 20.
In this study, we developed a prototype animal PET by applying several novel technologies to use solid-state photomultiplier (SSPM) arrays to measure the depth of interaction (DOI) and improve imaging performance. Each PET detector has an 8 × 8 array of about 1.9 × 1.9 × 30.0 mm(3) lutetium-yttrium-oxyorthosilicate scintillators, with each end optically connected to an SSPM array (16 channels in a 4 × 4 matrix) through a light guide to enable continuous DOI measurement. Each SSPM has an active area of about 3 × 3 mm(2), and its output is read by a custom-developed application-specific integrated circuit to directly convert analogue signals to digital timing pulses that encode the interaction information. These pulses are transferred to and are decoded by a field-programmable gate array-based time-to-digital convertor for coincident event selection and data acquisition. The independent readout of each SSPM and the parallel signal process can significantly improve the signal-to-noise ratio and enable the use of flexible algorithms for different data processes. The prototype PET consists of two rotating detector panels on a portable gantry with four detectors in each panel to provide 16 mm axial and variable transaxial field-of-view (FOV) sizes. List-mode ordered subset expectation maximization image reconstruction was implemented. The measured mean energy, coincidence timing and DOI resolution for a crystal were about 17.6%, 2.8 ns and 5.6 mm, respectively. The measured transaxial resolutions at the center of the FOV were 2.0 mm and 2.3 mm for images reconstructed with and without DOI, respectively. In addition, the resolutions across the FOV with DOI were substantially better than those without DOI. The quality of PET images of both a hot-rod phantom and mouse acquired with DOI was much higher than that of images obtained without DOI. This study demonstrates that SSPM arrays and advanced readout/processing electronics can be used to develop a practical DOI-measureable PET scanner.
在这项研究中，我们应用了几项新技术来开发一种原型动物正电子发射断层扫描仪（PET），使用固态光电倍增管（SSPM）阵列来测量深度信息（DOI）并提高成像性能。每个 PET 探测器都有一个 8×8 的约 1.9×1.9×30.0mm(3) 的硅酸镥-钇-氧（LSO）闪烁体阵列，每个闪烁体的两端都通过光导与 SSPM 阵列（4×4 矩阵中的 16 个通道）光学连接，以实现连续的 DOI 测量。每个 SSPM 的有效面积约为 3×3mm(2)，其输出通过定制开发的专用集成电路直接转换为模拟信号到数字定时脉冲，该脉冲编码交互信息。这些脉冲被传输到基于现场可编程门阵列的时间数字转换器，并进行符合事件选择和数据采集解码。每个 SSPM 的独立读出和并行信号处理可以显著提高信噪比，并允许使用灵活的算法进行不同的数据处理。原型 PET 由一个带有两个旋转探测器面板的便携式龙门架组成，每个面板有四个探测器，提供 16mm 的轴向和可变的横向视野（FOV）大小。实现了列表模式有序子集期望最大化图像重建。测量的晶体平均能量、符合定时和 DOI 分辨率分别约为 17.6%、2.8ns 和 5.6mm。在 FOV 中心测量的横向分辨率分别为 2.0mm 和 2.3mm，分别用于重建有和没有 DOI 的图像。此外，有 DOI 的整个 FOV 的分辨率明显优于没有 DOI 的分辨率。使用 DOI 获得的热棒体模和小鼠的 PET 图像的质量明显高于没有 DOI 的图像。本研究表明，SSPM 阵列和先进的读出/处理电子学可以用于开发实用的 DOI 可测量的 PET 扫描仪。
