A dedicated compact device has been developed, optimized and realized for treatment of breast cancer in prone position. The prone position increases the separation of the target and critical organs and minimizes target motion caused by breathing; in addition, it decreases dose delivered to Organs at Risk (OARs), such as lung and heart, allowing hypo-fractionated conformal RT treatments. Based on a design made by Monte Carlo simulation, a prototype has been realized at APAM (Accelerators of Particles for Medical Application) Laboratory in the ENEA-Frascati Research Center in the framework of the TECHEA (Technology for Health) Project.......