Clinical Pilot Study of Ionizing Radiation Acoustic Imaging for Real-Time Visualization of Radiation Therapy Dose...

This study aimed to evaluate the feasibility of using ionizing radiation acoustic imaging (iRAI) to map the delivered dose in patients receiving radiation therapy (RT) with various treatment techniques, including 3-dimensional conformal RT, intensity modulated RT, and volumetric modulated arc therapy.

Patients with intra-abdominal cancer were enrolled in a prospective clinical trial after providing informed consent. Patients were treated with stereotactic body RT using standard clinical techniques with the addition of volumetric iRAI for real-time mapping of 3-dimensional radiation dose deposition.

The minimal detectable dose was approximately 10 cGy. The overall shape of the dose distribution and the location of dose deposition, as determined by iRAI, matched the corresponding treatment plan. A gamma passing rate of 75.97% ± 11.12% and 90.99% ± 6.61% with a 10 mm/10% distance to agreement/dose difference suggests good agreement between the iRAI measurement and the treatment plan in both the liver volume and the planning target volume under the current system resolution. A structural similarity value of 0.6284 ± 0.1678 demonstrates that the iRAI measurements have shown structural pattern agreement with the treatment plan within the planning target volume.

This study demonstrates the clinical feasibility of iRAI to monitor radiation dose delivery to deep targets in real time during treatment. This information can be integrated into treatment delivery systems to improve safety and facilitate the adaptation of RT. Despite the promising results achieved with the current form of technology, limitations in detection sensitivity, reconstruction accuracy, and acoustic coupling still need to be addressed.