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X-Ray Acoustic Imaging: Towards Radiation Dose Assessment During Teletherapy

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D Sampaio

D.R.T. Sampaio*, A.A.F. Martins, A.A.O. Carneiro , J.F. Pavoni, T.Z. Pavan, University of Sao Paulo, Ribeirao Preto, Sao Paulo


WE-RAM1-GePD-I-3 (Wednesday, August 2, 2017) 9:30 AM - 10:00 AM Room: Imaging ePoster Lounge

Purpose: The purpose of this work was to form x-ray acoustic images (XAI) using commercial ultrasound system, providing theory considerations and simulations to support XAI as potential tool for real-time measuring dose during teletherapy.

Methods: An experiment was conducted to form x-ray acoustic (XA) images following a megavoltage x-ray pulse of linear accelerator irradiation. The commercial ultrasound system was programed to acquire passively x-ray acoustic signals with a linear array transducer. By placing solid samples of lead, brass and aluminum into a water tank and moving the samples along the central axis of the beam, x-ray acoustic signals at varying water in depth were detected and processed to form XAI. In addition, simulated XAI were obtained using GATE and k-Wave to generate dose profiles and x-ray acoustic pressure waves, respectively.

Results: The spatial pressure distribution of the XA images were in agreement with that obtained for the simulation. Comparison of simulated and experimental images intensity indicates that the accumulated intensity increases with dose deposition. However, a difference between simulation and experiment intensities at higher water in depth was observed. One explanation of this difference was proposed based on XAI contrast mechanism, which could be related with the lower energy electrons that are more often released in higher depth in water.

Conclusion: This work improves the use of x-ray acoustic imaging for teletherapy. The results demonstrated the feasibility of generating x-ray acoustic images for different materials, providing dosimetric information during teletherapy with commercial ultrasound system. This new imaging modality could be used in future as a new real-time dosimetry tool.

Funding Support, Disclosures, and Conflict of Interest: This study was supported by CAPES, CNPq grant (476671/2013-2), FAPESP grant (2013/18854-6; 2015/05684-0) and the USP NAP-FisMed grant. In addition, Mr. Carlos Renato da Silva, Mr. Agnelo Bastos, Mr. Andre Delfini and GPhantom company.

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