Lung blocks for total-body irradiation are commonly used to reduce lung dose and prevent radiation pneumonitis. Currently, molten Cerrobend containing toxic materials, specifically lead and cadmium, is poured into molds to construct blocks. We propose a streamlined method to create 3-dimensional (3D)-printed lung block shells and fill them with tungsten ball bearings to remove lead and improve overall accuracy in the block manufacturing workflow. 3D-printed lung block shells were automatically generated using an inhouse software, printed, and filled with 2 to 3 mm diameter tungsten ball bearings. Clinical Cerrobend blocks were compared with the physician drawn blocks as well as our proposed tungsten filled 3D-printed blocks. Physical and dosimetric comparisons were performed on a linac. Dose transmission through the Cerrobend and 3D-printed blocks were measured using point dosimetry (ion-chamber) and the on-board Electronic-Portal-Imaging-Device (EPID). Dose profiles from the EPID images were used to compute the full-width-half-maximum and to compare with the treatment-planning-system. Additionally, the coefficient-of-variation in the central 80% of full-width-half-maximum was computed and compared between Cerrobend and 3D-printed blocks. The geometric difference between treatment-planning-system and 3D-printed blocks was significantly lower than Cerrobend blocks (3D: –0.88 ± 2.21 mm, Cerrobend: –2.28 ± 2.40 mm, = .0002). Dosimetrically, transmission measurements through the 3D-printed and Cerrobend blocks for both ion-chamber and EPID dosimetry were between 42% to 48%, compared with the open field. Additionally, coefficient-of-variation was significantly higher in 3D-printed blocks versus Cerrobend blocks (3D: 4.2% ± 0.6%, Cerrobend: 2.6% ± 0.7%, < .0001). We designed and implemented a tungsten filled 3D-printed workflow for constructing total-body-irradiation lung blocks, which serves as an alternative to the traditional Cerrobend based workflow currently used in clinics. This workflow has the capacity of producing clinically useful lung blocks with minimal effort to facilitate the removal of toxic materials from the clinic.

中文翻译：

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用于全身照射的钨填充 3 维印刷肺块

全身照射的肺阻滞通常用于减少肺部剂量和预防放射性肺炎。目前，含有有毒物质（特别是铅和镉）的熔融塞罗本德被倒入模具中来建造砌块。我们提出了一种简化的方法来创建 3 维 (3D) 打印的肺块外壳，并用钨滚珠轴承填充它们，以去除铅并提高肺块制造工作流程的整体精度。 3D 打印的肺块外壳是使用内部软件自动生成、打印并填充直径 2 至 3 毫米的钨球轴承。将临床 Cerrobend 块与医生绘制的块以及我们提出的钨填充 3D 打印块进行比较。在直线加速器上进行物理和剂量测定比较。使用点剂量测定法（离子室）和机载电子射野成像设备 (EPID) 测量通过 Cerrobend 和 3D 打印块的剂量传输。 EPID 图像的剂量分布用于计算半高全宽并与治疗计划系统进行比较。此外，还计算了 Cerrobend 和 3D 打印块之间全宽半最大值中央 80% 的变异系数并进行了比较。治疗计划系统和 3D 打印模块之间的几何差异显着低于 Cerrobend 模块（3D：–0.88 ± 2.21 mm，Cerrobend：–2.28 ± 2.40 mm，= .0002）。在剂量测定方面，与开放场相比，通过 3D 打印和 Cerrobend 块进行离子室和 EPID 剂量测定的透射测量值在 42% 至 48% 之间。此外，3D 打印块的变异系数显着高于 Cerrobend 块（3D：4.2% ± 0.6%，Cerrobend：2.6% ± 0.7%，< .0001）。我们设计并实施了用于构建全身照射肺块的钨填充 3D 打印工作流程，该工作流程可作为目前临床使用的基于 Cerrobend 的传统工作流程的替代方案。该工作流程能够以最小的努力产生临床上有用的肺块，以促进从诊所去除有毒物质。