Department of Radiology, University of Washington, Seattle, WA, 98195, USA.
Med Phys. 2019 Dec;46(12):5593-5601. doi: 10.1002/mp.13832. Epub 2019 Oct 10.
Currently, single-photon emission computed tomography (SPECT)/computed tomography (CT) lung phantoms are commonly constructed using polystyrene beads and interstitial radioactive water. However, this approach often results in a phantom with a density (typically -640 HU) that is considerably higher than that of healthy lung (-750 to -850 HU) or diseased lung (-900 to -950 HU). Furthermore, the polystyrene and water phantoms are often quite heterogeneous in both density and activity concentration, especially when reused. This work is devoted to examining methods for creating a more realistic lung phantom for quantitative SPECT/CT using Tc-laced expanding polyurethane foam (EPF).
Numerous aspects of EPF utilization were studied, including stoichiometric mixing to control final foam density and the effect of water during growth. We also tested several ways of molding the foam lung phantoms. The most successful method utilized a three-part silicone mold that allowed for creation of a two-lobe phantom, with a different density and activity concentration in each lobe.
The final phantom design allows for a more anatomically accurate geometry as well as customizable density and activity concentration in the different lobes of the lung. We demonstrated final lung phantom densities between -760 and -690 HU in the "healthy" phantom and -930 to -890 HU in the "unhealthy" phantom tissue. On average, we achieved 15% activity concentration nonuniformity and 12% density nonuniformity within a given lobe.
Final EPF lung phantoms closely matched the densities of both health and diseased lung tissue and had sufficient uniformities in both density and activity concentration for most nuclear medicine applications. Management of component moisture content is critical for phantom reproducibility.
目前，单光子发射计算机断层扫描（SPECT）/计算机断层扫描（CT）肺部体模通常使用聚苯乙烯珠和间质放射性水构建。然而，这种方法通常会导致体模的密度（通常为-640 HU）明显高于健康肺（-750 至-850 HU）或患病肺（-900 至-950 HU）。此外，聚苯乙烯和水体模在密度和放射性浓度方面往往非常不均匀，尤其是在重复使用时。这项工作致力于研究使用 Tc 掺杂膨胀型聚氨酯泡沫（EPF）为定量 SPECT/CT 创建更逼真肺部体模的方法。
研究了 EPF 的多种应用方法，包括通过化学计量混合来控制最终泡沫密度以及在生长过程中加水的影响。我们还测试了几种成型泡沫肺部体模的方法。最成功的方法是使用三部分硅酮模具，该模具可用于创建两个叶的体模，每个叶的密度和放射性浓度不同。
最终的体模设计允许更准确的解剖学几何形状以及在肺部的不同叶中可定制的密度和放射性浓度。我们展示了最终肺部体模的密度在“健康”体模中为-760 至-690 HU，在“不健康”体模组织中为-930 至-890 HU。平均而言，我们在给定的叶中实现了 15%的放射性浓度不均匀性和 12%的密度不均匀性。
最终的 EPF 肺部体模与健康和患病肺组织的密度非常匹配，并且在密度和放射性浓度方面具有足够的均匀性，适用于大多数核医学应用。组件水分含量的管理对于体模的可重复性至关重要。
