Department of Chemistry, Duke University, Durham, North Carolina, USA.
Medical Physics Graduate Program, Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University School of Medicine, Durham, North Carolina, USA.
Med Phys. 2022 Apr;49(4):2582-2589. doi: 10.1002/mp.15494. Epub 2022 Mar 7.
The purpose of this work was to characterize and improve the ability of fused filament fabrication to create anthropomorphic physical phantoms for CT research. Specifically, we sought to develop the ability to create multiple levels of X-ray attenuation with a single material.
CT images of 3D printed cylinders with different infill angles and printing patterns were assessed by comparing their 2D noise power spectra to determine the conditions that produced minimal and uniform noise. A backfilling approach in which additional polymer was extruded into an existing 3D printed background layer was developed to create multiple levels of image contrast.
A print with nine infill angles and a rectilinear infill pattern was found to have the best uniformity, but the printed objects were not as uniform as a commercial phantom. An HU dynamic range of 600 was achieved by changing the infill percentage from 40% to 100%. The backfilling technique enabled control of up to eight levels of contrast within one object across a range of 200 HU, similar to the range of soft tissue. A contrast detail phantom with six levels of contrast and an anthropomorphic liver phantom with four levels of contrast were printed with a single material.
This work improves the uniformity and levels of contrast that can be achieved with fused filament fabrication, thereby enabling researchers to easily create more detailed physical phantoms, including realistic, anthropomorphic textures.
本工作旨在对熔融沉积制造（FFF）技术创建用于 CT 研究的拟人化物理体模的能力进行评估和改进。具体而言，我们旨在开发使用单一材料创建多个 X 射线衰减水平的能力。
通过比较不同填充角度和打印模式的 3D 打印圆柱体的 2D 噪声功率谱，评估其 CT 图像，以确定产生最小和均匀噪声的条件。开发了一种后填充方法，即将额外的聚合物挤出到现有 3D 打印背景层中，以创建多个图像对比度级别。
发现具有九个填充角度和直线填充模式的打印品具有最佳的均匀性，但打印品不如商业体模均匀。通过将填充百分比从 40%改变到 100%，实现了 600 的 HU 动态范围。后填充技术可在一个物体内实现多达 8 个级别的对比度控制，其范围为 200HU，类似于软组织的范围。使用单一材料打印了具有六个对比度级别的对比细节体模和具有四个对比度级别的拟人化肝脏体模。
这项工作提高了熔融沉积制造技术的均匀性和对比度水平，从而使研究人员能够轻松创建更详细的物理体模，包括逼真的、拟人化的纹理。
