Proposal of a compact VHEE-linac for FLASH radiotherapy

The present study regards the design of a Very High Electron Energy (VHEE) machine for use in radiotherapy to treat deep tumors in a FLASH regime. The proposed system includes a low energy, high current injector linac followed by high acceleration gradient structures capable of reaching 60–130 MeV energy range. We used the CST code to define the linac’s RF parameters and the codes TSTEP and ASTRA in beam dynamics simulations to optimize the accelerated current and the delivered dose. Preliminary results show a compact VHEE-linac system reaching a peak current of 200 mA, equivalent to 600 nC per pulse. The realization of the prototype for vacuum and brazing tests is ongoing to evaluate the strength and integrity of the joints and connections in the linac and to perform the low-power RF tests. The outcome of these tests helps to make any necessary design adjustments or improvements before developing the final structure.