An Alvarez-Type Linac Configuration for Future Carbon and Helium Ion Therapy Facilities with Parallel Radioisotope Production

The increasing demand for ion beams heavier than protons—particularly carbon and helium ions—for cancer therapy has driven the development of advanced accelerator technologies. Although proton therapy is well established, its physical properties limit its effectiveness against certain tumor types, thereby motivating the use of ions with higher linear energy transfer (LET) and greater biological effectiveness. This study presents the design of an Alvarez-type linear accelerator configuration that combines a Quasi-Alvarez Drift Tube Linac (QA-DTL) and a conventional Alvarez Drift Tube Linac (DTL). The proposed systems are intended for accelerating and injecting carbon or helium ions into a cancer therapy synchrotron, as well as accelerating helium ions for radioisotope production. The optimized QA-DTL and DTL structures provide a versatile and efficient solution for future particle therapy facilities, addressing the growing demand for compact, high-performance, and multifunctional accelerator systems. The proposed linac configurations are designed to operate at 352.2 MHz and consist of three sections. For accelerating low-velocity ions, the first section is a QA-DTL, which is the only section powered during the injection of carbon or helium ions (depending on configuration) into the therapy synchrotron at the energy of 5 MeV/u. The QA-DTL is followed by two DTL cavities forming the second and third sections, which further accelerate helium ions to energies of up to 7.1 MeV/u and 10 MeV/u, respectively. The energy of 7.1 MeV/u is chosen because it represents the production threshold of 211At, one of the most promising alpha emitters for targeted alpha therapy.