Paul Scherrer Institute, Center for Proton Therapy, Villigen, Switzerland. Author to whom any correspondence should be addressed.
Phys Med Biol. 2020 Apr 2;65(7):07NT02. doi: 10.1088/1361-6560/ab7508.
In this study, a functioning and ventilated anthropomorphic phantom was further enhanced for the purpose of CT and MR imaging of the lung and liver. A deformable lung, including respiratory tract was 3D printed. Within the lung's inner structures is a solid region shaped from a patient's lung tumour and six nitro-glycerine capsules as reference landmarks. The full internal mesh was coated, and the tumour filled, with polyorganosiloxane based gel. A moulded liver was created with an external casing of silicon filled with polyorganosiloxane gel and flexible plastic internal structures. The liver, fitted to the inferior portion of the right lung, moves along with the lung's ventilation. In the contralateral side, a cavity is designed to host a dosimeter, whose motion is correlated to the lung pressure. A 4DCT of the phantom was performed along with static and 4D T1 weighted MR images. The CT Hounsfield units (HU) for the flexible 3D printed material were -600-100 HU (lung and liver structures), for the polyorganosiloxane gel 30-120 HU (lung coating and liver filling) and for the silicon 650-800 HU (liver casing). The MR image intensity units were 0-40, 210-280 and 80-130, respectively. The maximum range of motion in the 4D imaging for the superior lung was 1-3.5 mm and 3.5-8 mm in the inferior portion. The liver motion was 5.5-8.0 mm at the tip and 5.7-10.0 mm at the dome. No measurable drift in motion was observed over a 2 h session and motion was reproducible over three different sessions for sin(t), sin(t) and a patient-like breathing curve with the interquartile range of amplitudes for all breathing cycles within 0.5 mm. The addition of features within the lung and of a deformable liver will allow the phantom to be used for imaging studies such as validation of 4DMRI and pseudo CT methods.
在这项研究中，进一步增强了一个功能齐全且通风的拟人化模型，以进行肺部和肝脏的 CT 和 MR 成像。3D 打印了一个可变形的肺，包括呼吸道。在肺部的内部结构中，有一个由患者肺部肿瘤和六个硝化甘油胶囊形成的固体区域作为参考标志。全内部网格被涂覆，肿瘤充满了基于聚有机硅氧烷的凝胶。用充满聚有机硅氧烷凝胶和柔性塑料内部结构的硅制成模制的肝脏。肝脏安装在右肺的下部，随肺的通气而移动。在对侧，设计了一个腔室来容纳剂量计，其运动与肺压相关。对模型进行了 4DCT 扫描，并进行了静态和 4D T1 加权 MR 图像扫描。柔性 3D 打印材料的 CT 亨氏单位（HU）为-600-100 HU（肺部和肝脏结构），聚有机硅氧烷凝胶为 30-120 HU（肺部涂层和肝脏填充），硅为 650-800 HU（肝脏外壳）。MR 图像强度单位分别为 0-40、210-280 和 80-130。上肺 4D 成像的最大运动范围为 1-3.5 毫米，下肺为 3.5-8 毫米。肝脏运动在尖端为 5.5-8.0 毫米，在穹顶为 5.7-10.0 毫米。在 2 小时的测试过程中，未观察到运动漂移，在三个不同的测试过程中，运动是可重复的，使用了正弦函数、正弦函数和具有患者样呼吸曲线的函数，所有呼吸周期的四分位间距幅度为 0.5 毫米。在肺部添加特征和可变形肝脏将使该模型能够用于成像研究，例如验证 4DMRI 和伪 CT 方法。
