Radiotherapy Linear Accelerator-Based X-Ray Acoustic Imaging Using Linear Array Transducer and Its Relationship with Dose: Multidomain Simulation and In Vitro Experiments

As x-ray acoustic imaging (XAI) moves towards the external beam radiation therapy (EBRT) environment, introducing new practical XAI dosimetry systems with clinical ultrasound scanner becomes a significant contribution, especially using noise reduction methods that can increase the typical low signal-to-noise ratio (SNR) of XA images. In addition, experimental validation of multidomain XAI simulation is of great importance for accurate dose estimation. Therefore, in the present study, a XAI system combining a clinical linear particle accelerator (LINAC) and a linear array transducer connected to a clinical ultrasound scanner was developed. The capability of acquiring XA signal and generating images was investigated with simulations and experiments. PENELOPE and k-wave environments were combined to simulate the XAI system, which was used to generate XA images of different metals and bone in a water tank. A Daubechies’s wavelet denoise method was proposed to improve XAI’s SNR, where a threefold improvement in SNR of XA image of the bone sample was achieved. The denoised XA experimental images agreed well with simulations in terms of spatial profiles and signal amplitude dose–response slope values, therefore validating the multidomain simulations.