Department of Mechanical Engineering, University of Victoria, Victoria, British Columbia V8P 5C2, Canada.
Axolotl Bioscience, Victoria, British Columbia V8W 2Y2, Canada.
Biomed Phys Eng Express. 2023 Feb 10;9(2). doi: 10.1088/2057-1976/acb7f7.
The goal of this work was to build an anthropomorphic thorax phantom capable of breathing motion with materials mimicking human tissues in x-ray imaging applications. The thorax phantom, named Casper, was composed of resin (body), foam (lungs), glow polyactic acid (bones) and natural polyactic acid (tumours placed in the lungs). X-ray attenuation properties of all materials prior to manufacturing were evaluated by means of photon-counting computed tomography (CT) imaging on a table-top system. Breathing motion was achieved by a scotch-yoke mechanism with diaphragm motion frequencies of 10-20 rpm and displacements of 1 to 2 cm. Casper was manufactured by means of 3D printing of moulds and ribs and assembled in a complex process. The final phantom was then scanned using a clinical CT scanner to evaluate material CT numbers and the extent of tumour motion. Casper CT numbers were close to human CT numbers for soft tissue (46 HU), ribs (125 HU), lungs (-840 HU) and tumours (-45 HU). For a 2 cm diaphragm displacement the largest tumour displacement was 0.7 cm. The five tumour volumes were accurately assessed in the static CT images with a mean absolute error of 4.3%. Tumour sizes were either underestimated for smaller tumours or overestimated for larger tumours in dynamic CT images due to motion blurring with a mean absolute difference from true volumes of 10.3%. More Casper information including a motion movie and manufacturing data can be downloaded from http://web.uvic.ca/~bazalova/Casper/.
这项工作的目标是构建一个具有呼吸运动功能的拟人化胸部体模，其材料在 X 射线成像应用中模仿人体组织。这个名为 Casper 的胸部体模由树脂（主体）、泡沫（肺）、聚乳酸（骨骼）和天然聚乳酸（放置在肺部的肿瘤）组成。在制造之前，所有材料的 X 射线衰减特性都通过在台式系统上进行光子计数计算机断层扫描（CT）成像进行了评估。呼吸运动通过一个带有隔膜运动频率为 10-20rpm 和 1-2cm 位移的 Scotch-yoke 机构实现。Casper 通过模具和肋骨的 3D 打印制造，并通过复杂的过程组装。最后，使用临床 CT 扫描仪对体模进行扫描，以评估材料的 CT 数和肿瘤运动的程度。Casper 的 CT 数与人的软组织（46HU）、肋骨（125HU）、肺（-840HU）和肿瘤（-45HU）的 CT 数接近。对于 2cm 的隔膜位移，最大的肿瘤位移为 0.7cm。在静态 CT 图像中，5 个肿瘤体积的评估非常准确，平均绝对误差为 4.3%。在动态 CT 图像中，由于运动模糊，较小的肿瘤体积可能被低估，较大的肿瘤体积可能被高估，平均绝对差值为真实体积的 10.3%。更多 Casper 的信息，包括运动视频和制造数据，可以从 http://web.uvic.ca/~bazalova/Casper/下载。
