Towards quantitative ionizing radiation acoustic imaging for in vivo radiotherapy dosimetry in a human abdominal phantom

Ionizing radiation acoustic imaging (iRAI) enables real-time visualization of radiotherapy (RT) dose deposition, but prior implementations often assume homogeneous acoustic properties, limiting dose mapping accuracy in heterogeneous anatomy. This study reports the first experimental validation of iRAI- based dose mapping using images reconstructed with a full-wave iterative reconstruction (FWIR) approach that incorporates CT-derived acoustic property maps. A human abdominal phantom was used in two experimental designs. In the first, three spherical targets at distinct anatomical sites were treated with the same dose delivery method. In the second, a single target was treated with different dose delivery methods. The dose mapping accuracy of FWIR- and delay-and-sum (DAS)-based reconstructions was assessed by comparing each to the treatment plan using clinical evaluation metrics, including similarity metrics, dose– volume histograms, and gamma index analysis. Results highlight the potential of iRAI to support quantitative assessment of dose deposition within patient anatomy.