论文标题
设计和CT成像Casper，拟人化呼吸胸腔幻影
Design and CT imaging of Casper, an anthropomorphic breathing thorax phantom
论文作者
论文摘要
这项工作的目的是建立一个拟人化胸腔幻影，能够用模仿人体组织在X射线成像应用中呼吸运动的幻象。胸腔幻影，名为Casper，由树脂（身体），泡沫（肺），发光多胎酸（骨骼）和天然多胎酸（放置在肺中）组成。制造前所有材料的X射线衰减特性通过台式系统上的光子计算机层析成像（CT）成像评估。通过隔膜运动频率为10-20 rpm，位移1至2 cm，呼吸运动是通过Scotch射击机制实现的。 Casper是通过3D打印模具和肋骨制造的，并在复杂的过程中组装。然后使用临床CT扫描仪扫描最终的幻影，以评估材料CT数量和肿瘤运动的程度。 Casper CT数接近软组织（46 HU），肋骨（125 HU），肺（-840 HU）和肿瘤（-45 HU）的人类CT数。对于2 cm的膜片位移，最大的肿瘤位移为0.7 cm。在静态CT图像中准确评估了五个肿瘤体积，平均绝对误差为4.3％。由于运动模糊而导致动态CT图像中较大肿瘤的肿瘤大小低估了较小的肿瘤，或者被高估了较大的肿瘤，其平均绝对差异与10.3％的真实体积的平均绝对差异。
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%.
