P194] Breast cancer radiosurgery with a synchrotron radiation beam

Abstract

Purpose Recently, we proposed the use of the synchrotron radiation (SR) beam for a new rotational radiotherapy technique for breast cancer treatment (SR3T) [1] ;. In this work, we show, via Monte Carlo (MC) simulations, the potential of SR3T also for application in breast radiosurgery with the patient in prone position. Methods We simulated the irradiation condition of the breast rotational radiosurgery with a MC code based on GEANT 4 toolkit. The pendant breast was modeled as a polyethylene cylinder with a diameter of 14 cm and height of 9 cm with a 1-cm tumor simulated in the centre or at 4 cm from the cylinder axis. A monoenergetic laminar SR beam of size 1.5 cm × 1.0 cm with energy ranging between 60 and 120 keV irradiated the phantom during a complete rotation with the center of rotation along the tumor mass. Results A collimated SR beam irradiating a pendant breast produces a dose distribution peaked at the center of rotation. MC simulations showed that is possible to perform partial-breast irradiation with a skin sparing comparable with that from a conventional MV breast radiotherapy. Conclusions We proposed a kV SR beam for partial-breast irradiation, for breast radiosurgery in the treatment of small lesions. We foresee the use of dose-enhancement agents in order to improve the dose to the target volume with proper sparing of healthy tissues.