We are developing a multi-detector pinhole-based stationary brain-dedicated SPECT system: AdaptiSPECT-C. In this work, we introduced a new design prototype with multiple adaptable pinhole apertures for each detector to modulate the multiplexing by employing temporal shuttering of apertures. Temporal shuttering of apertures over the scan time provides the AdaptiSPECT-C with the capability of multiple-frame acquisition. We investigated, through analytic simulation, the impact of projection multiplexing on image quality using several digital phantoms and a customized anthropomorphic phantom emulating brain perfusion clinical distribution. The 105 pinholes in the collimator of the system were categorized into central, axial, and lateral apertures. We generated, through simulation, collimators of different multiplexing levels. Several data acquisition schemes were also created by changing the imaging time share of the acquisition frames. Sensitivity increased by 35% compared to the single-pinhole-per-detector base configuration of the AdaptiSPECT-C when using the central, axial, and lateral apertures with equal acquisition time shares within a triple-frame scheme with a high multiplexing scenario. Axial and angular sampling of the base configuration was enhanced by adding the axial and lateral apertures. We showed that the temporal shuttering of apertures can be exploited, trading the sensitivity, to modulate the multiplexing and to acquire a set of non-multiplexed non-truncated projections. Our results suggested that reconstruction benefited from utilizing both non-multiplexed projections and projections with modulated multiplexing resulting in a noticeably reduction in the multiplexing-induced image artefacts. Contrast recovery factor improved by 20% (9%) compared to the base configuration for a Defrise (hot-rod) phantom study when the central and axial (lateral) apertures with equal time shares were combined. The results revealed that, as an overall trend at each simulated multiplexing level, lowest normalized root-mean-square errors for the brain gray-matter regions were achieved with the combined usage of the central apertures and axial/lateral apertures.

我们正在开发一种基于多探测器针孔的固定脑专用 SPECT 系统：AdaptiSPECT-C。在这项工作中，我们引入了一个新的设计原型，每个探测器具有多个自适应针孔孔径，通过使用孔径的时间快门来调制多路复用。扫描时间内孔径的暂时关闭为 AdaptiSPECT-C 提供了多帧采集的能力。我们通过分析模拟研究了投影多路复用对使用多个数字幻影和模拟脑灌注临床分布的定制拟人化幻影的图像质量的影响。系统准直器中的 105 个针孔分为中心孔、轴向孔和侧孔。我们通过仿真生成了不同多路复用级别的准直器。还通过更改采集帧的成像时间份额创建了几种数据采集方案。当在具有高多路复用场景的三帧方案中使用具有相等采集时间共享的中央、轴向和横向孔径时，与 AdaptiSPECT-C 的每个检测器单针孔配置相比，灵敏度提高了 35%。通过添加轴向和横向孔，增强了基本配置的轴向和角度采样。我们表明可以利用孔径的时间快门，交换灵敏度，调制多路复用并获取一组非多路复用的非截断投影。我们的结果表明，重建受益于利用非多路复用投影和调制多路复用投影，从而显着减少多路复用引起的图像伪影。与 Defrise（热棒）体模研究的基本配置相比，当具有相同时间份额的中央和轴向（横向）孔径组合时，对比恢复因子提高了 20% (9%)。结果显示，作为每个模拟复用级别的总体趋势，结合使用中央孔径和轴向/横向孔径，大脑灰质区域的归一化均方根误差最低。与 Defrise（热棒）体模研究的基本配置相比，当具有相同时间份额的中央和轴向（横向）孔径组合时，对比恢复因子提高了 20% (9%)。结果显示，作为每个模拟复用级别的总体趋势，结合使用中央孔径和轴向/横向孔径，大脑灰质区域的归一化均方根误差最低。与 Defrise（热棒）体模研究的基本配置相比，当具有相同时间份额的中央和轴向（横向）孔径组合时，对比恢复因子提高了 20% (9%)。结果显示，作为每个模拟复用级别的总体趋势，结合使用中央孔径和轴向/横向孔径，大脑灰质区域的归一化均方根误差最低。