技术说明：用于调强适形放射治疗的3D打印铈镧合金铅挡块制造：一项可行性研究。
Technical Note: Fabricating Cerrobend grids with 3D printing for spatially modulated radiation therapy: A feasibility study.
作者信息
Zhu Xiaofeng, Driewer Joseph, Li Sicong, Verma Vivek, Lei Yu, Zhang Mutian, Zhang Qinghui, Zheng Dandan, Cullip Timothy, Chang Sha X, Wang Andrew Z, Zhou Sumin, Enke Charles A
机构信息
Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska 68154.
Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514.
出版信息
Med Phys. 2015 Nov;42(11):6269-73. doi: 10.1118/1.4932223.
PURPOSE
Grid therapy has promising applications in the radiation treatment of large tumors. However, research and applications of grid therapy are limited by the accessibility of the specialized blocks that produce the grid of pencil-like radiation beams. In this study, a Cerrobend grid block was fabricated using the 3D printing technique.
METHODS
A grid block mold was designed with flared tubes which follow the divergence of the beam. The mold was 3D printed using a resin with the working temperature below 230 °C. The melted Cerrobend liquid at 120 °C was cast into the resin mold to yield a block with a thickness of 7.4 cm. At the isocenter plane, the grid had a hexagonal pattern, with each pencil beam diameter of 1.4 cm; the distance between the beam centers was 2.1 cm.
RESULTS
The dosimetric properties of the grid block were studied using small field dosimeters: a pinpoint ionization chamber and a stereotactic diode. For a 6 MV photon beam, its valley-to-peak ratio was 20% at dmax and 30% at 10 cm depth; the output factor was 84.9% at dmax and 65.1% at 10 cm depth.
CONCLUSIONS
This study demonstrates that it is feasible to implement 3D printing technique in applying grid therapy in clinic.
目的
格栅疗法在大肿瘤的放射治疗中具有广阔的应用前景。然而，格栅疗法的研究和应用受到产生铅笔状辐射束格栅的专用挡块可及性的限制。在本研究中，使用3D打印技术制作了一种铈镧合金格栅挡块。
方法
设计了一种带有喇叭形管的格栅挡块模具，该喇叭形管与射束的发散方向一致。使用工作温度低于230°C的树脂对模具进行3D打印。将120°C的熔化铈镧合金液体浇铸到树脂模具中，得到厚度为7.4 cm的挡块。在等中心平面上，格栅呈六边形图案，每个铅笔束直径为1.4 cm；束中心之间的距离为2.1 cm。
结果
使用小场剂量计（一个针点电离室和一个立体定向二极管）研究了格栅挡块的剂量学特性。对于6 MV光子束，其谷峰比在dmax处为20%，在10 cm深度处为30%；输出因子在dmax处为84.9%，在10 cm深度处为65.1%。
结论
本研究表明，在临床应用格栅疗法中实施3D打印技术是可行的。
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