High Gradient Accelerating Structure for Low Energy Protons

Currently, the most promising types of radiotherapy is proton or carbon therapy, as they have demonstrated significant improvements in clinical efficiency and reduced toxicity profiles. Unfortunately, the high cost of treatments using both proton and carbon beams is the limiting factor preventing hadron therapy from becoming the standard of care for a wider range of cancers. Designing a linear accelerator with the dimensions allowing to place it on the gantry will reduce the price of the facility dramatically. However, to create such linac, the development of accelerating structure for low energy ions is required. Technical Approach In response to this problem, RadiaBeam System in collaboration with Argonne National Laboratory proposes to design and build a section of S-band accelerating structure for protons or carbon ions with β=0.3 capable of providing >50 MV/m gradient. The proposed structure design will take advantage of the low current requirements, short microwave pulses, and optimized cell geometry and coupling scheme, to maximize the achievable engineering gradient and reduce footprint and eventually cost of the system. Phase I Plans In Phase I, we will perform RF design, engineering design and manufacturing studies of the proposed structure. In the Phase II, the two prototype structures will be manufactured at RadiaBeam, and undergo conditioning and RF breakdown studies at Argonne, to enable final optimization and validation of the design. Commercial Applications and Other Benefits The developed accelerating structure is an enabling omponent of ACCIL, a novel compact proton/carbon radiotherapy machine. A practical implementation of ACCIL system will constitute a major disruption in radiotherapy market, since for multiple types of tumors it would enable a superior clinical efficacy treatment at a relatively modest cost premium. Other commercial applications include upgrades and improvements to the scientific research infrastructure around the world. Key Words: Radiotherapy, proton therapy, carbon therapy, high gradient, backward wave, RF break-down, Kilpatrick criteria.