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Validation of a Novel Therapeutic X-Ray Array Source and Collimation System

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S Trovati

S Trovati1*, P Borchard2 , GJ King1 , CG Limborg3 , BW Loo1 , P Maxim1 , D McCormick3 , LY Nicolas3 , E Schueler1 , S Tantawi3 , J Wang1 , L Wang1 , (1) Stanford University School of Medicine, Palo Alto, California, (2) Tibaray Inc, San Francisco, California, (3) Stanford Linear Accelerator, Menlo Park, CA


TU-H-BRC-9 (Tuesday, August 2, 2016) 4:30 PM - 6:00 PM Room: Ballroom C

Purpose: We have experimentally characterized and simulated the dosimetric properties and spatial fidelity of a novel X-ray array source and collimation system called SPHINX that has the potential to generate complex intensity modulated X-ray beams by varying the electron beam intensity only, and without any moving parts like in multi-leaf collimators.

Methods: We investigated the spatial fidelity and the X-ray performances of a SPHINX prototype in tungsten, using a Cyber Knife and the experimental high-energy electron beam line at XTA at SLAC National Laboratory. Dose distributions were recorded with gafchromic films, placed at the distal end of SPHINX and at several depths in a solid water phantom. The geometry of SPHINX and of the experimental set-ups was also modeled in Monte Carlo (MC) simulations with the FLUKA code, used to reproduce the experimental results and, after validation, to predict and optimize the performance and design of the SPHINX.

Results: The results indicate significant particle leakage through the channels during a single-channel irradiation for high incident energies, followed by a rapid decrease for energies of clinical interest. When the collimator channels are used as target, the photon production increases, however at expense of the beam size that is also enlarged. The illumination of all channels simultaneously shows a fairly even transmission of the beam.

Conclusion: With the measurements we have verified the MC models and the uniformity of beam transmission through SPHINX, and we have evaluated the importance of particle leakage through adjacent channels. These results can be used to optimize SPHINX design through the validated MC simulations.

Funding Support, Disclosures, and Conflict of Interest: Funding: Weston Havens Foundation, Office of the Dean of Medical School and Office of the Provost (Stanford University). Loo, Maxim, Borchard, Tantawi are co-founders of TibaRay Inc. Loo and Tantawi are TibaRay Inc. board members. Loo and Maxim received grants from Varian Medical Systems and RaySearch Laboratory.

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