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Effect of Heterogeneous Media On Proton Ionoacoustic Range Determination by 3-D Image Reconstruction Algorithms Based On First-Order K-Space Model

H Lin1*, B Zhang2 , J Jing3 , L Xu4 , (1)School of Electronic Science & Application Physics, Hefei University of Technology,Hefei,China (2) School of Electronic Science & Application Physics, Hefei University of Technology,Hefei,China (3)School of Electronic Science & Application Physics, Hefei University of Technology,Hefei,China (4)School of Computer and Information,Hefei University of Technology,Hefei,China

Presentations

(Sunday, 7/29/2018) 3:00 PM - 6:00 PM

Room: Exhibit Hall

Purpose: Proton is a naturally preference to treat tumor for its pronounced maximum at the end of range. The precise positioning of Bragg peak in the patient mandatory is very critical for tumor therapy and normal tissue protection. Dose monitoring through acoustic waves during radiation therapy is a wise choice to replace bulky & expensive nuclear technique detectors. Currently the work all are based on the homogeneous water model. This work evaluates the effect of heterogeneous media on proton ionoacoustic range determination by 3-D FFT and TR (Time Reversal) image reconstruction algorithms based on First-order k-space model.

Methods: The proton pencil beams with energies from 70 to 250 MeV were studied. A water-lung-water model and a water-bone-water model with varying lung or bone thickness were built. The surface sensor for FFT and TR algorithm was placed on the side face. The spherical sensor for TR algorithm also was studied. The implant first-order k-space model kspaceFirstOrder3D was used to calculate the acoustic wave propagation. The 3-D correction-based FFT and the model-based TR image reconstruction algorithms were used to reconstruct the Bragg position. A versatile simulation program with heterogeneous phantom constructing and dose-based pressure map read-in based on k-Wave example was developed.

Results: There are significant deviations for FFT without correction by only using the wave speed of homogeneous water. The equivalent path method can partly compensate the deviation. But the requirement of less than 2mm is not easy to satisfy. The model-based TR reconstruction algorithm show well coincident with the initial acoustic wave source position (less than 1mm). There are no influences of surface or spherical sensor on the reconstruction results.

Conclusion: The model-based TR reconstruction algorithm shows advantage over the 3-D correction-based FFT algorithm. A versatile simulation program was developed for acoustic wave source position reconstruction in heterogeneous Media.

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