Determining the Feasibility of Integrating Laser Plasma Accelerated Proton Beams and Thermoacoustic Dose Imaging Into a Small Animal Image-Guided Therapy Platform
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PO-GePV-M-86 (Sunday, 7/10/2022) [Eastern Time (GMT-4)]
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Purpose: To determine the feasibility of using thermoacoustic imaging to measure the 3D dose distribution from protons generated from laser plasma acceleration (LPA).
Methods: The Monte Carlo (MC) program FLUKA was used to simulate a proton beam with LPA characteristics based on literature (50 MeV, 30% FWHM energy spread, 2 degrees angular divergence, 10⁷ protons/pulse). Thermoacoustic waves were simulated on a voxel-wise basis of the MC generated dose and sampled using 2π and sub-2π transducer arrays based on in-house detectors. A 3D filtered backprojection algorithm was used to reconstruct volumetric images of the dose. An iterative reconstruction algorithm was implemented to achieve 4π sampling of projection space. The dose sensitivity of the detectors was determined by adding different noise levels to the signals.
Results: By shifting the water level within the sub-2π detector, the increased angular sampling of the dose distribution in projection space improved the overall image accuracy and reduced artifacts, although with off-isocenter blurring. The iterative reconstruction algorithm was able to significantly improve the image accuracy, with its application to the initial 2π detector image achieving convergence toward the MC dose in magnitude and spatial distribution.
Conclusion: This work demonstrates the feasibility of measuring LPA proton beams with thermoacoustic imaging. The implementation of an iterative reconstruction algorithm enables high accuracy images to be obtained without requiring 4π transducer array angular coverage. Ongoing experiments are being performed to determine the dose sensitivity of our detectors using high frequency transducers and low frequency hydrophones. Future work will correct for off-isocenter blurring to improve dose accuracy and precision when implementing a sub-2π transducer array.
Funding Support, Disclosures, and Conflict of Interest: This work was prepared under an educational institution award from the U.S. Nuclear Regulatory Commission. The statements, findings, conclusions, and recommendations are those of the author(s) and do not necessarily reflect the view of the institution or the U.S. Nuclear Regulatory Commission.
Keywords
Image-guided Therapy, Thermoacoustics, Protons
Taxonomy
Not Applicable / None Entered.
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