In Vivo Demonstration of 3D-Dosimetry and Radiation Beam Localization Via Ionizing Radiation Acoustics Imaging (iRAI) in a Rabbit Model
I Oraiqat1*, I El Naqa1,2, W Zhang2, N Ba Sunbul2, C Tichacek1, K Chang2, X Wang2, E Moros1, K Cuneo2, M Matuszak2, P Carson2, D Litzenberg2, (1) H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, (2) University of Michigan, Ann Arbor, MI
Presentations
TU-GH-BRB-9 (Tuesday, 7/12/2022) 1:45 PM - 3:45 PM [Eastern Time (GMT-4)]
Ballroom B
Purpose: Ionizing Radiation Acoustics Imaging (iRAI) is an emerging imaging modality that can be used for both real-time deep tissue dosimetry and beam localization with respect to soft tissue anatomy during Radiotherapy (RT). Current methods of in vivo dosimetry are limited to patient surface measurements and lack the ability to measure radiation dose within a patient depth (i.e., deep seated tumors). This work demonstrates the use of iRAI for in vivo 3D dosimetry in an in vivo rabbit model.
Methods: IRAI measurements were conducted on the liver of a white New Zealand rabbit using a custom 32x32 element 2D ultrasound transducer array with a central frequency of 350 kHz. To ensure adequate acoustic coupling, the fur from the abdominal region of the rabbit was removed and a water balloon was placed between the abdomen and the transducer. A treatment plan was developed specifically for the rabbit and delivered using a Varian TrueBeam. The treatment plan consisted of five 3x3 cm² 6FFF beams at various angles along the sagittal plane to generate an isocentric 3D shaped dose distribution with a dose of 500cGy delivered to the liver center. IRAI intensity maps (which correspond to dose) were generated from a 3D image reconstruction and subsequently overlayed with the rabbit sim CT to visualize radiation dose with respect to anatomy.
Results: iRAI signals originating from the radiation dose were successfully detected during treatment and recovered the dose distribution for the delivered radiation beam boundaries parallel to the transducer. When compared with the expected integrated dose distribution from the treatment planning system, the measured iRAI dose distribution had a gamma passing rate of 84.4% with 3%/3mm for the multibeam treatment plan.
Conclusion: This work shows the feasibility of the clinical translation of iRAI for 3D in vivo dosimetry during radiotherapy.
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