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Patient Specific Soft Compensators Design and Fabrication for Electron Modulated Radiotherapy

T Chiu

T Chiu*, J Tan , T Long , B Zhao , K Westover , T Strom , S Jiang , W Lu , X Gu , The University of Texas Southwestern Medical Center, Dallas, TX


TU-RPM-GePD-T-4 (Tuesday, August 1, 2017) 3:45 PM - 4:15 PM Room: Therapy ePoster Lounge

Purpose: To develop a 3D patient specific soft compensator design and fabrication procedure to facilitate electron modulated radiotherapy for the treatment of complex superficial tumors.

Methods: There are three steps in the patient specific soft compensator generation workflow: design, molding and casting. To facilitate compensator design and fabrication, we developed a software package, BolusVision. It uses fast electron beam range optimization and Monte Carlo dose calculation engines to provide dosimetric-driven automatic / interactive compensator shape design functionality. After achieving a desirable compensator design, BolusVision automatically generate a compensator mold, split the mold into two pieces, and send the 2-piece molds to a standard 3D printer for printing. Finally, the 2-piece mold is used to cast soft compensator with skin-safe silicone rubber. Dosimetric properties of the soft compensators (CT number, profiles and PDDs) were investigated. Plan comparison was conducted between soft compensator enabled one-beam electron modulated plans and modulated-volumetric-arc plans in head-and-neck (HN) patient cases.

Results: Compared to solid water and Superflab bolus material, CT and dosimetric properties of the soft compensator were close to water. The transverse profiles and PDD comparison between flat soft compensator and TPS at three different energies are in good agreements with each other. In-vivo OSLD (optically stimulated luminescence dosimeter) measurements obtained in five treated HN patients agreed with Eclipse Monte Carlo dose calculation within 5%. Highly conformal one-beam electron plan was achieved by utilizing the compensator designed by BolusVision. Comparing to the photon plan, the dose fall-off was much quicker and sharper. It suggests the soft compensators could control the electron range effectively.

Conclusion: The developed BolusVision software facilitates efficient compensator design and fabrication to achieve high quality modulated electron treatment plans. The constructed 3D soft compensator enable comfort and accurate electron beam treatment for disease involving complex surfaces.

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