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Towards in Vivo Dosimetry with X-Ray Acoustic Computed Tomography (XACT)

P Samant1*, Y Chen2 , S Wang1 , L Trevisi1 , S Ahmad2 , H Liu2 , L Xiang1 , (1) University of Oklahoma, Norman, OK, (2) University of Oklahoma Health Science Center, Oklahoma City, OK


(Tuesday, 7/16/2019) 1:45 PM - 3:45 PM

Room: Stars at Night Ballroom 4

Purpose: To present X-ray Acoustic Computed Tomography (XACT), a novel imaging technique that can enable real-time Image-guided radiation therapy with high-resolution dose mapping in 3D.

Methods: XACT works through x-ray induced thermoacoustic emissions of ultrasound waves. These detectable ultrasound signals are proportional to the absorbed x-ray energy, and therefore also the dose. We have designed and implemented simulations of dose mapping via XACT to demonstrate its applications in prostate and breast cancer radiation dosimetry during therapy. Monte-Carlo simulations were used to generate X-ray beam dose maps for both prostate and breast radiation therapy. The MATLAB toolbox k-wave was subsequently used to model acoustic signal generation and propagation in the sample. We have also performed experimental studies using a 2D Ultrasound detector array to verify our simulations, using a pulsed x-ray source. Reconstruction of the dose distributions was then performed via time-reversal reconstruction algorithms.

Results: Our simulations and experiments demonstrate that the x-ray dose can be reconstructed in both the breast and the prostate using XACT imaging techniques in different geometries. Dose maps were reconstructed showing the exact locations of x-ray beams in both tissue types. The resolution of reconstructed images was comparable to that of scouting CT images of the tissues. Reconstruction of the 2D ultrasound transducer array data showed that the dose can properly be reconstructed also in 3D using XACT.

Conclusion: XACT has broad applications in radiation dosimetry which is a crucial monitoring procedure in radiation therapy. XACT’s employment in radiation therapy monitoring thus can enable real-time, high resolution dosimetry in 3D, thereby allowing for accurate radiation therapy. The next step in XACT’s development is to begin the process towards clinical translating to enable image guided radiation dosimetry in various cancers.


Thermoacoustics, X Rays, Radiation Dosimetry


TH- External beam- photons: out of field dosimetry/risk analysis

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