Geometric distortions in magnetic resonance can introduce significant uncertainties into applications such as radiotherapy treatment planning and need to be assessed as part of a comprehensive quality assurance program. We report the design, fabrication, and imaging of a custom 3D printed unibody MR distortion phantom along with quantitative image analysis. Methods: The internal cavity of the phantom is an orthogonal three-dimensional planar lattice, composed of 3 mm diameter rods spaced equidistantly at a 20 mm centre-centre offset repeating along the X, Y, and Z axes. The phantom featured an overall length of 308.5 mm, a width of 246 mm, and a height of 264 mm with lines on the external surface for phantom positioning matched to external lasers. The MR phantom was 3D printed in Nylon-12 using an advancement on traditional selective laser sintering (SLS) (HP Jet Fusion 3D—4200 machine). The phantom was scanned on a Toshiba Aquilion CT scanner to check the integrity of the 3D print and correct for any resultant issues. The phantom was then filled with NiSO₄ solution and scanned on a 3T PET-MR Siemens scanner for selected T1 and T2 sequences, from which distortion vectors were generated and analysed using in-house software written in Python. Results: All deviations of the node positions from the print design were less than 1 mm, with an average displacement of 0.228 mm. The majority of the deviations were smaller than the 0.692 mm pixel size for this dataset. Conclusion: A customised 3D printed MRI-phantom was successfully printed and tested for assessing geometric distortion on MRI scanners. 3D printed phantoms can be considered for clinics wishing to assess geometric distortions under specific conditions, but require resources for design, fabrication, commissioning, and verification.

磁共振中的几何变形会给放射治疗计划等应用带来很大的不确定性，需要作为综合质量保证计划的一部分进行评估。我们报告了定制 3D 打印一体式 MR 畸变体模的设计、制造和成像以及定量图像分析。方法：模型的内腔是一个正交的 3 维平面晶格，由 3 毫米直径的棒组成，这些棒在 X、Y 和 Z 轴上以 20 毫米的中心偏移等距分布。该模型的总长度为 308.5 毫米，宽度为 246 毫米，高度为 264 毫米，外表面上带有线条，用于与外部激光器匹配的模型定位。MR 模型是在 Nylon-12 中使用传统选择性激光烧结 (SLS)（HP Jet Fusion 3D-4200 机器）的进步进行 3D 打印的。模型在东芝 Aquilion CT 扫描仪上进行扫描，以检查 3D 打印的完整性并纠正任何由此产生的问题。然后用 NiSO _{4填充模型}解决方案并在 3T PET-MR Siemens 扫描仪上扫描选定的 T1 和 T2 序列，使用 Python 编写的内部软件从中生成和分析失真向量。结果：所有节点位置与打印设计的偏差均小于 1 mm，平均位移为 0.228 mm。大多数偏差小于该数据集的 0.692 mm 像素大小。结论：成功打印并测试了定制的 3D 打印 MRI 模型，用于评估 MRI 扫描仪的几何变形。对于希望在特定条件下评估几何变形但需要设计、制造、调试和验证资源的诊所，可以考虑使用 3D 打印模型。