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Design and Fabrication of 3D Printer Based Patient-Specific Intensity Modulated Brachytherapy (IMBT) Tandem for Cervical Cancer

J Jung

J Jung1*, H Zhang2 , S Olberg3 , B Lu4 , J Jung5 , J Kim6 , H Li7 , S Mutic8 , J Park9 , (1) University of Florida, Gainesville, FL, (2) Washington University School of Medicine in St. louis, Saint Louis, MO, (3) Missouri University of Science and Technology, Rolla, Missouri, (4) University of Florida, Gainesville, FL, (5) National Cancer Center, Goyang-si, Gyeonggi-do, (6) Yonsei University College of Medicine, Yonsei Cancer Center, Seoul, Seoul, (7) Washington University School of Medicine, St. Louis, MO, (8) Washington University in St Louis, St Louis, MO, (9) Washington University in St. Louis, St. Louis, MO


WE-AB-605-6 (Wednesday, August 2, 2017) 7:30 AM - 9:30 AM Room: 605

Purpose: To design and fabricate a new tandem device using a 3D metal printer for patient-specific intensity modulated brachytherapy (IMBT).

Methods: The tandem is designed by simultaneously optimizing the wall thickness of the tandem applicator and the dwell time based on a patient’s anatomy. The model parameters are input into 3D modeling software (Cinema 4D) to generate a stereolithographic (STL) file for the final 3D printing. At each dwell position of the HDR source, the surrounding tandem wall is divided into six equiangular sections with varying thicknesses of tungsten. The thickness of each section varies from 0.12 cm to 0.48 cm inwards, such that the exterior surface of the tandem resembles the traditional applicator (d=1.2 cm). This is performed using the ‘inner extrude’ function in the 3D modeling software for all pre-defined dwell positions. This 3D model is exported to the 3D printing software (Simplify3D) and converted from 3D volumetric data into an STL file. A 3D metal printer (ProX DMP 320) finally fabricates the tandem applicator using tungsten. For the feasibility study, the tandem samples were printed by a fused deposition modeling (FDM) 3D printer with polylactic acid (PLA) filament to verify the accuracy and uncertainty of the 3D printing process.

Results: The results indicated that the 3D printing of a tandem is achievable without major discrepancy between the digital and physical models. The comparison between the model parameters and 3D printed model showed that the accuracy was within 0.1 mm.

Conclusion: In this study, we have demonstrated the feasibility of 3D printing a tandem for IMBT application. It is anticipated that our method can be an alternative to conventional tandem when surrounding organs at risk (OARs) limit the tumor-dose coverage during HDR. Also, this method can be adapted to other HDR sites such as rectal, prostate, and breast.

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