Dosimetric characterization and experimental validation for a low-kV FPXS electronic brachytherapy system

This study aims to evaluate the feasibility of using flat-panel X-ray source (FPXS) for brachytherapy through preclinical animal irradiation experiments.

A low-kV FPXS electronic brachytherapy (EB) system was constructed for dosimetry measurements and experimental validation. The surface and depth dose characteristics of FPXS were measured employing a 34013 chamber. An FPXS-based EB workflow was established, enabling the calculation of required exposure times for FPXS at a given prescription dose. The accuracy of the delivered dose and the therapeutic efficacy of FPXS irradiation were validated through brachytherapy experiments conducted on murine models with breast cancer.

The FPXS operates with a maximum voltage of up to 50 kV and a maximum surface dose rate exceeding 2.30 Gy/min. The surface dose rate and current demonstrate an exponential increase with voltage, and the dose rate exhibits a linear correlation with the current. The calculated cumulative dose delivered to mice in the experimental group was slightly higher than the average in-field dose measured by film (21.88±0.61 Gy vs. 20.83 ± 1.03 Gy). Following FPXS irradiation, the increase in tumor volume of mice in the experimental group was markedly less pronounced than that observed in the control group, and the survival rate of mice in the experimental group over time was significantly higher than that of the control group (66.67% vs 12.50%).

The intensity of FPXS is comparable to current EB systems, and its surface dose rate is adequate for therapeutic applications. Animal irradiation experiments confirm the accuracy of FPXS-delivered doses and demonstrate its efficacy in tumor irradiation.