Centre for Biomedical Cybernetics, Faculty of Engineering, University of Malta, Msida, MSD2080, Malta.
Rehabilitation Engineering Unit, National Rehabilitation Centre, 13122, Ilion, Attica, Greece.
Med Phys. 2020 Jun;47(5):2206-2211. doi: 10.1002/mp.14100. Epub 2020 Mar 10.
The fabrication of a realistic patient-specific skull phantom employing for the first time a new filament extrusion rate method, for the accurate replication of soft and bone tissues both in Hounsfield Units (HU) range and in texture.
An in-house developed software was used for the fabrication of the phantom taking into account all the HU of a patient's Computed Tomography (CT) images, replicating the organs voxel-by-voxel without the need of a uniform three-dimensional printing pattern. Two commercially available materials were used; the polylactic acid (PLA) filament for the soft tissues, and a mixture of 50% of PLA and 50% of gravimetric powdered stone for the bone tissues. Additionally, a layer of small amounts of PLA were also extruded on the fabricated bones.
The replicated anatomy of the phantom was very close to the patient's one, achieving a similar range of HU without creating any air gaps and variations on the replicated HU, which are the main artifacts observed when a standard infill density and pattern is employed. The maximum measured HU values of the replicated bone tissues were at about 900.
The results indicated an accurate replication of the soft tissues HU, and a significant improvement of the bone tissue HU replication. Further investigation on materials of high density in conjunction with the filament extrusion rate method may provide custom-made realistic phantoms for diagnostic and lower energy radiation such as in superficial, orthovoltage, and electron beam radiotherapy.
首次采用新型长丝挤出速率方法，制造逼真的个体化颅骨模型，以准确复制软硬组织的亨氏单位（HU）范围和质地。
开发了一款内部软件，用于制作颅骨模型，考虑到患者 CT 图像的所有 HU，逐像素复制器官，而无需使用统一的三维打印模式。使用了两种市售材料；聚乳酸（PLA）长丝用于软组织，以及 50%PLA 和 50%重量比的石粉混合物用于骨组织。此外，还在制造的骨头上挤出了一层少量的 PLA。
颅骨模型的复制解剖结构与患者的非常相似，实现了相似的 HU 范围，而不会产生任何空气间隙和复制 HU 的变化，这是使用标准填充密度和模式时观察到的主要伪影。复制骨组织的最大测量 HU 值约为 900。
结果表明，软组织 HU 的复制非常准确，骨组织 HU 的复制有了显著提高。进一步研究高密度材料结合长丝挤出速率方法，可能为诊断和低能量辐射（如浅层、正交和电子束放射治疗）提供定制的逼真模型。
