Design of support structure for nozzle components in heavy ion therapy gantry

Hadron therapy is a form of radiation therapy for cancer treatment. This cancer treatment approach shows multiple advantages to conventional radiotherapy such as higher precision, better effectiveness, minimal healthy tissue damage. Unfortunately, currently hadron therapy is hardly accessible due to complexity and high cost of infrastructure needed to accelerate and direct the beam of heavy particles. One of the most mechanically complex parts of this infrastructure is machine called gantry. It allows tumour irradiation from multiple desired angles by supporting part of beam transfer line that rotates around patient. “HITRIplus” is a project with the aim to introduce new technologies and improvements in hadron therapy providing the blueprint for the next state of the art hadron therapy center, hence improving the accessibility to the treatment. As a part of this project, this work proposes, the mechanical design of a gantry component called gantry nozzle that supports last part of beam transfer line. Topology optimisation is used as initial design followed by iterative manual optimisation for final design proposals. Two possible solutions of nozzle design are developed and compared. The total mass supported by the nozzle structure is estimated to be around 1.2t and the achieved mass of both proposals is lower than 1t while keeping transfer line component displacements within estimated required linear and angular tolerance of ± 0.2𝑚𝑚 and ±0.5 𝑚𝑟𝑎𝑑 respectively. In addition to that, a design workflow is developed foreseeing its use to update the nozzle structure designs due to ongoing development of the whole system. Key words: hadron therapy; hadron therapy gantry; heavy ion therapy gantry; gantry nozzle; structure optimisation; support structure; scanning magnet; dose delivery system