External beam for the Heavy Ion Accelerator Facility

Abstract

Radiotherapy using protons and heavier ions is emerging as an alternative to traditional photon radiotherapy for cancer treatment. Ions have a depth-dose profile that results in high energy deposition at the end of the particle’s path, with a relatively low dosage elsewhere. However, the specifics of ion interactions with cellular biology are not yet fully understood. To study the induced biological effects of the ions on cell cultures, an external beam is required as biological specimens cannot be placed in vacuum. The Heavy Ion Accelerator Facility (HIAF) at the Australian National University hosts accelerators for a wide variety of ion-beam research applications. However, HIAF does not currently have an external beam capability. Here, we present an initial design for a radiobiological research capability at HIAF. A systems engineering approach was used to develop the architecture of the apparatus and determine the feasibility of adapting the current facilities to external beam applications. This effort included ion optics calculations, coupled to a Geant4 simulation, to characterise ion beam transitions through a thin window into the air. The beam spread, intensity distributions, and energy of proton and carbon ions were studied as a function of distance travelled from the window, as well as the effects of alternative window materials and thicknesses. It was determined that the proposed line at the HIAF would be suitable for the desired applications. Overall, this feasibility study lays the foundations of an external beam design, a simulation test framework, and the basis for a grant application for an external beam at the HIAF.

The Heavy Ion Accelerator Facility: Research Achievements and Aspirations

“…The HIAF supports Australia's only experimental nuclear physics program (both fundamental and applied), a major accelerator mass spectrometry program, and facilities for ion-beam modification and analysis of materials. Newer initiatives include aspects of radiobiology [1][2][3], and detector characterisation for Australia's growing contributions to dark matter particle physics research, particularly for the SABRE experiment [4][5][6].…”

“…detector is planned for new research and applications of heavy-ion irradiation. Projects include material modification and component testing for deployment in space as well as medical physics applications, including research to support hadron therapy and an external beam capability for radiobiology [3].…”

“…Facility development and aspirationsSeveral research and facility development projects, which have already been funded, have been mentioned above (e.g., new ion source for3 He and 4 He beams; upgrades of injection, accelerator tube and column; Enge refurbishment for transfer reactions). Concerning future aspirations, the Research School of Physics Building Plan allocates space for a future stand-alone linear accelerator.…”