Effects of multiple-interaction photon events in a high-resolution PET system that uses 3-D positioning detectors
Effects of multiple-interaction photon events in a high-resolution PET system that uses 3-D positioning detectors
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DOI：
10.1118/1.3483262
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发表时间：
2010-10-01
期刊：
影响因子：
3.8
通讯作者：
Levin, Craig S.
中科院分区：
文献类型：
--
作者：
Gu, Yi;Pratx, Guillem;Levin, Craig S.
目的：作者的实验室正在开发一种双面板乳房专用 PET 系统。探测器面板由双 LSO 位置敏感雪崩光电二极管 (PSAPD) 模块构成，单元内装有两个 1 mm(3) LSO 晶体的 8 X 8 阵列，其中每个阵列都耦合到 PSAPD。当堆叠形成成像体积时，这些模块能够记录多重相互作用光子事件 (MIPE) 的各个相互作用的 3D 坐标。所使用的闪烁晶体元件的小尺寸增加了晶体阵列之间光子散射的可能性。在本文中，作者研究了 MIPE 如何影响系统光子灵敏度、数据采集方案以及重建 PET 图像的质量和定量准确性。方法：使用双面板系统在均匀放射性体模上进行蒙特卡罗模拟 PET 扫描，以进行光子灵敏度研究。为了确定 MIPE 对所提出的 PSAPD 复用方案的影响，从用 (22)Na 点源边缘照射的双 LSO-PSAPD 模块收集实验数据，将数据与基于相同设置的模拟数据进行比较。为了评估 MIPE 对双面板 PET 图像的影响，对模型进行了模拟 PET，该模型包含浸入温暖背景中的不同直径的热球形辐射源矩阵。列表模式输出数据用于图像重建，其中使用各种方法来估计 MIPE 中第一个光子相互作用的位置，以实现更准确的响应线定位。重建图像中的对比度恢复系数 (CRC)、对比度噪声比 (CNR) 和球体的半最大空间分辨率全宽被用作品质因数以方便比较。结果：与仅使用具有仅限于一个 LSO 阵列的相互作用的事件的图像重建相比，当总能量落在 +/- 范围内的 MIPE 中，对于均匀体模，潜在的单光子灵敏度增益 >46.9%（重合 >115.7%）。还包括光峰周围 12% 的窗口。实验和模拟数据都表明
Purpose: The authors' laboratory is developing a dual-panel, breast-dedicated PET system. The detector panels are built from dual-LSO-position-sensitive avalanche photodiode (PSAPD) modules-units holding two 8 X 8 arrays of 1 mm(3) LSO crystals, where each array is coupled to a PSAPD. When stacked to form an imaging volume, these modules are capable of recording the 3-D coordinates of individual interactions of a multiple-interaction photon event (MIPE). The small size of the scintillation crystal elements used increases the likelihood of photon scattering between crystal arrays. In this article, the authors investigate how MIPEs impact the system photon sensitivity, the data acquisition scheme, and the quality and quantitative accuracy of reconstructed PET images.Methods: A Monte Carlo simulated PET scan using the dual-panel system was performed on a uniformly radioactive phantom for the photon sensitivity study. To establish the impact of MIPEs on a proposed PSAPD multiplexing scheme, experimental data were collected from a dual-LSO-PSAPD module edge-irradiated with a (22)Na point source, the data were compared against simulation data based on an identical setup. To assess the impact of MIPEs on the dual-panel PET images, a simulated PET of a phantom comprising a matrix of hot spherical radiation sources of varying diameters immersed in a warm background was performed. The list-mode output data were used for image reconstruction, where various methods were used for estimating the location of the first photon interaction in MIPEs for more accurate line of response positioning. The contrast recovery coefficient (CRC), contrast to noise ratio (CNR), and the full width at half maximum spatial resolution of the spheres in the reconstructed images were used as figures of merit to facilitate comparison.Results: Compared to image reconstruction employing only events with interactions confined to one LSO array, a potential single photon sensitivity gain of >46.9% (>115.7% for coincidence) was noted for a uniform phantom when MIPEs with summed-energy falling within a +/- 12% window around the photopeak were also included. Both experimental and simulation data demonstrate that