(Sunday, 7/29/2018) 2:05 PM - 3:00 PM
Room: Karl Dean Ballroom B1
Purpose: The overall goal of this project is to design and construct a prototype 3D Radiation-Acoustic Computed Tomography (RACT) imaging scanner to verify proton Bragg-peak dose and range in phantoms, and ultimately, in patients undergoing IMPT.
Methods: The RACT scanner was designed for to optimally measure the distal edge (range) and the Bragg peak dose from pencil proton beams observed in the clinic.
Results: The RACT scanner consists of 10 0.45-MHz hydrophones and 12 1.0-MHz ultrasound transducers. These detector elements are designed to provide a 15.0-cm field-of-view at isocenter and are positioned to fill k-space. The endcap of the cylindrical transducer array allows the testing of additional ultrasound transducers (0.2, 0.5, 1.0, and 2.2-MHz, with various aperture sizes). Low noise preamplifiers are constructed at the location of the hydrophone to minimize transmission losses, and all signals are acquired by a 128-channel DAS. The transducer-array is rotated to obtain 3Ï€ coverage, and a 3D FBP algorithm reconstructs the thermoacoustic image. Impulse response functions and final calibration of transducer positions are measured using photoacoustic methods. The final design and construction the RACT scanner will be presented, and the measured spatial resolution and relative sensitivity over the field of view of the scanner.
Conclusion: To our knowledge, this study reports on the first prototype Radiation-Acoustic Computed Tomography (RACT) scanner designed to image the 3D dose from a clinical pulsed proton beam in water. We are currently working to test this prototype-RACT scanner in a clinical beam.
Funding Support, Disclosures, and Conflict of Interest: Nuclear Regulatory Commission Graduate Fellowship TRASK Grant from Purdue Office of Technology and Commercialization
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