Encrypted login | home

Program Information

Fourier Space Guided RACT Design and Simulation

no image available
M Klem

M Klem1*, V Moskvin2 , J Farr3 , K Stantz4 , (1) Purdue University, West Lafayette, IN,(2) St. Jude Children's Hospital, Memphis, TN, (3) St. Jude Children's Research Hospital, Memphis, TN, (4) Purdue University, West Lafayette, IN


WE-G-605-4 (Wednesday, August 2, 2017) 4:30 PM - 6:00 PM Room: 605

Purpose: The overall goal of this project is to develop 3D Radiation-Acoustic Computed Tomography (RACT) imaging to verify proton dose and range in phantoms, and ultimately, in IMPT patients. This study reports on a method for RACT scanner design employing acoustic simulation and Fourier image space analysis to optimize transducer placement and bandwidth selection.

Methods: Pressure signals produced by a pulsed proton beam in water as measured by an ultrasonic array with a cylindrical geometry were simulated. 3D FLUKA dose maps were simulated for the proton ranges of 6.5, 12, and 27 cm. The scanner array consisted of 71 detectors aligned along the length and (distal) end of the cylinder, which was rotated (2- and 5-degree increments) about the cylinder’s central axis to obtain 5K+ projections over 3π coverage. A multithreaded approach was employed to compute the received pressure signals for each projection angle, and the data from the array were used to compute the Fourier image space and to reconstruction a 3D image.

Results: Fourier image space demonstrates a dependence of the spatial frequency spectrum on detector position. Nearly axial angles exhibit a strong high-frequency component consistent with the high spatial frequencies required to model the steep drop-off of the distal edge of the Bragg peak. Similarly, at angles normal to the cylindrical axis, a high-frequency component is also seen, indicative of the increased lateral fall off of the Bragg peak.

Conclusion: These results demonstrate the unique characteristics of IMPT proton beams in frequency space, which can be used to optimize the design of a radiation acoustic CT scanner in 3D proton dosimetry. Currently, we are developing a prototype scanner combining low-frequency hydrophones and high-frequency transducers to optimally fill frequency space based on projection angle sampling, detector bandwidth and aperture. Future work will be to investigate clinically viable designs.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by a graduate NRC fellowship administered by Purdue University

Contact Email: