Purpose. A compact and mobile hybrid c-arm scanner, capable of simultaneously acquiring nuclear and fluoroscopic projections and SPECT/CBCT, was developed to aid fluoroscopy-guided interventional procedures involving the administration of radionuclides (e.g. hepatic radioembolization). However, as in conventional SPECT/CT, the acquired nuclear images may be deteriorated by patient respiratory motion. We propose to perform compensation for respiratory motion by extracting the motion signal from fluoroscopic projections so that the nuclear counts can be gated into motion bins. The purpose of this study is to quantify the performance of this motion compensation technique with phantom experiments. Methods. Anthropomorphic phantom configurations that are representative of distributions obtained during the pre-treatment procedure of hepatic radioembolization were placed on a stage that translated with three different motion patterns. Fluoroscopic projections and nuclear counts were simultaneously acquired under planar and SPECT/CBCT imaging. The planar projections were visually assessed. The SPECT reconstructions were visually assessed and quantitatively assessed by calculating the activity recovery of the spherical inserts in the phantom. Results. The planar nuclear projections of the translating anthropomorphic phantom were blurry when no motion compensation was applied. With motion compensation, the nuclear projections became representative of the stationary phantom nuclear projection. Similar behavior was observed for the visual quality of SPECT reconstructions. The mean error of the activity recovery in the uncompensated SPECT reconstructions was 15.8%0.9% for stable motion, 11.9%0.9% for small variations, and 11.0%0.9% for large variations. When applying motion compensation, the mean error decreased to 1.8%1.6% for stable motion, 2.2%1.5% for small variations, and 5.2%2.5% for large variations. Conclusion. A compact and mobile hybrid c-arm scanner, capable of simultaneously acquiring nuclear and fluoroscopic projections, can perform compensation for respiratory motion. Such motion compensation results in sharper planar nuclear projections and increases the quantitative accuracy of the SPECT reconstructions.

目的。开发了一种紧凑且移动的混合 c 臂扫描仪，能够同时获取核和透视投影以及 SPECT/CBCT，以帮助涉及放射性核素给药的透视引导介入程序（例如肝放射性栓塞）。然而，与传统的 SPECT/CT 一样，所获得的核图像可能会因患者的呼吸运动而恶化。我们建议通过从透视投影中提取运动信号来对呼吸运动进行补偿，以便可以将核计数选通到运动箱中。本研究的目的是通过幻象实验量化这种运动补偿技术的性能。方法. 代表肝脏放射栓塞预处理过程中获得的分布的拟人化体模配置被放置在以三种不同运动模式平移的平台上。在平面和 SPECT/CBCT 成像下同时获得荧光透视投影和核计数。视觉评估平面投影。通过计算体模中球形插入物的活动恢复，对 SPECT 重建进行视觉评估和定量评估。结果. 当没有应用运动补偿时，平移拟人模型的平面核投影是模糊的。通过运动补偿，核投影成为静止幻影核投影的代表。对于 SPECT 重建的视觉质量，也观察到了类似的行为。在未补偿的 SPECT 重建中，活动恢复的平均误差对于稳定运动为 15.8%0.9%，对于小变化为 11.9%0.9%，对于大变化为 11.0%0.9%。应用运动补偿时，平均误差下降到稳定运动的 1.8%1.6%，小变化的 2.2%1.5%，大变化的 5.2%2.5%。结论. 紧凑且移动的混合 c 臂扫描仪，能够同时获取核和透视投影，可以对呼吸运动进行补偿。这种运动补偿导致更清晰的平面核投影并增加 SPECT 重建的定量精度。