Designing a lateral applicator for intraoperative electron beam radiotherapy using Monte Carlo simulation

Intraoperative radiotherapy (IORT) delivers precise radiation to tumor beds, minimizing healthy tissue exposure. This study aimed to design a lateral applicator for IORT in esophageal carcinoma, addressing the challenges of vertical tumor bed distribution. The applicator consisted of a collimator, scattering foil, modulator, treatment window, and stopper, designed based on tumor bed geometry. Monte Carlo simulations optimized the scattering foil's angle and thickness, while modulator and shielding designs enhanced dose uniformity and minimized tissue damage. The lateral applicator, shaped as a rectangular prism, featured a 5 cm × 5 cm treatment window and internal components made from tungsten, aluminum, and stainless steel. It delivered a planar dose distribution for a 12 MeV electron beam, with a dose rate of 131.05 cGy/min. At depths of 0.5 cm, the doses ranged from 45.19 % to 65.34 % of the surface dose, demonstrating its suitability for IORT in esophageal carcinoma.