Department of Physics 'Ettore Pancini', Università di Napoli Federico II, I-80126 Napoli, Italy. INFN Sezione di Napoli, I-80126 Napoli, Italy.
Phys Med Biol. 2019 Mar 27;64(7):075008. doi: 10.1088/1361-6560/ab0670.
3D breast modelling for 2D and 3D breast x-ray imaging would benefit from the availability of digital and physical phantoms that reproduce accurately the complexity of the breast anatomy. While a number of groups have produced digital phantoms with increasing level of complexity, physical phantoms reproducing that software approach have been scarcely developed. One possibility is offered by 3D printing technology. This implies the assessment of the energy dependent absorption index β of 3D printing materials for absorption based imaging, as well as the assessment of the refractive index decrement, δ, of the printing material, for phase contrast imaging studies, at the energies of interest for breast imaging. In this work we set-up a procedure and performed a series of measurements (at 30, 45 and 60 keV, at the European Synchrotron Radiation Facility) for assessing the relative value of δ with respect to that of breast tissues, for twelve 3D printing materials. The method included propagation based phase contrast 2D imaging and retrieval of the estimated phase shift map, using the Paganin's algorithm. Breast glandular, adipose and skin tissues were used as reference materials of known ratio δ/β. A percentage difference Δδ was introduced to assess the suitability of the printing materials as tissue substitutes. The accuracy of the method (about 4%) was assessed based on the properties of PMMA and Nylon, acting as gold standard. Results show that, for the above photon energies, ABS is a good substitute for adipose tissue, Hybrid as a substitute of the glandular tissue and PET-G for simulating the skin. We plan to realize a breast phantom manufactured by fused deposition modelling (FDM) technology using ABS, Hybrid and PET-G as substitutes of the glandular and skin tissue and a second phantom by stereolithography (SLA) technology with the resins Flex, Tough and Black.
3D 乳房建模对于 2D 和 3D 乳房 X 射线成像将受益于数字和物理体模的可用性，这些体模可以准确再现乳房解剖结构的复杂性。虽然许多小组已经制作了具有越来越复杂水平的数字体模，但很少开发出可以再现该软件方法的物理体模。3D 打印技术提供了一种可能性。这意味着需要评估用于基于吸收的成像的 3D 打印材料的能量相关吸收指数β，以及评估用于相衬成像研究的打印材料的折射率衰减δ，在这些能量下对乳房成像感兴趣。在这项工作中，我们建立了一个程序，并进行了一系列测量（在欧洲同步辐射设施的 30、45 和 60keV 处），以评估十二种 3D 打印材料相对于乳房组织的δ的相对值。该方法包括基于传播的相衬 2D 成像和使用 Paganin 算法检索估计的相移图。乳腺腺组织、脂肪组织和皮肤组织被用作已知δ/β 比值的参考材料。引入了百分比差异 Δδ，以评估打印材料作为组织替代物的适用性。该方法的准确性（约 4%）是基于 PMMA 和 Nylon 的特性评估的，它们作为金标准。结果表明，对于上述光子能量，ABS 是脂肪组织的良好替代品，Hybrid 是腺体组织的替代品，而 PET-G 可用于模拟皮肤。我们计划使用 ABS、Hybrid 和 PET-G 作为腺体和皮肤组织的替代品，通过熔丝制造（FDM）技术制造乳房体模，以及通过立体光刻（SLA）技术制造第二个体模，使用树脂 Flex、Tough 和 Black。
