Concept of Monobloc, Traveling Wave, Space Charge Current Limited Linear Accelerator for Radiotherapy in Oncology

Abstract

The number of cancer cases will grow annually and according to WHO it will reach 25 million cases a year by 2035. Radiotherapy (RT) is a key element for the treatment of the 80 % of the cases [1-3] and its development and accessibility are the main routes for further improvement. At the current moment the large percentage of the negative outcomes of the cancer treatment is attributed to either lack of the RT machines or technical personal capable to maintain it. A modular approach to structure such an equipment is one of the ways to resolve the issues. The aim of the studies is to develop a conceptual design of a single module compact accelerator for medical applications and specifically RT of cancers. Development of such a machine is an important step to resolve the RT availability and challenging task from research and design point of view. The studies carried out using analytical and numerical (CST MW studio) approaches. In this paper the conceptual design of such a monobloc traveling wave (12 GHz) accelerator with the space charge limited electron beam current is presented and discussed. The accelerating section made of set of specially designed cell with average constant accelerating potential around 40 MV/m is demonstrated and its properties are discussed. It is shown that the low-relativistic electron beam can reach energy of 10 MeV on the length of the section less than 30 cm. It is shown that the electron beam capture, modulation and transportation takes place inside the accelerating section with the beam transportation efficiency above 80 %. It is illustrated that the main beam losses are taking place at the initial stage of beam formation and ways to optimise the system and minimise the beam losses are discussed. The results of the studies are compared and good agreement is demonstrated.