Status of development and planning activities on CANS in Korea

This report reviews the overall status of the development and planning activities of compact accelerator-based neutron sources in Korea. For the last decade, the demand for the technology development and application of CANS has significantly increased, and becomes widely accepted by the science, engineering and industry sectors. Since the first technical workshop focused on CANS under the support of the Korea Nuclear Society in fall 2016, there have been numerous efforts to launch projects by several groups. Although unsuccessful, two CANS projects were newly launched in 2020. One is the 30-MeV cyclotron-based neutron source for industrial neutron imaging at the Korea Atomic Energy Research Institute (KAERI), and the other is the BNCT technology development at the Korea Institute of Radiological & Medical Sciences. A project proposal for an expansion of the proton LINAC facility at KAERI to 200 MeV for semiconductor irradiation testing through the produced neutron field is now almost complete and will be submitted to the government funding agency for review. The CANS project for BNCT based on the proton LINAC developed by the Dawonsys consortium is briefly described. The new neutron source based on electron LINAC is prepared by the Pohang Light Source laboratory, and the initial consideration and application targets are also described. A new strategic plan for national R&D on radiation technology and the enforcement of its infrastructure is still under way, and a more systematic approach to the development and application of neutron sources will be implemented through the strategic planning.

Conceptual Design of a Novel Nozzle Combined with a Clinical Proton Linac for Magnetically Focussed Minibeams

(1) Background: Proton minibeam radiation therapy (pMBRT) is a novel therapeutic approach with the potential to significantly increase normal tissue sparing while providing tumour control equivalent or superior to standard proton therapy. For reasons of efficiency, flexibility and minibeam quality, the optimal implementation of pMBRT should use magnetically focussed minibeams which, however, could not yet be generated in a clinical environment. In this study, we evaluated our recently proposed minibeam nozzle together with a new clinical proton linac as a potential implementation. (2) Methods: Monte Carlo simulations were performed to determine under which conditions minibeams can be generated and to evaluate the robustness against focussing magnet errors. Moreover, an example of conventional pencil beam scanning irradiation was simulated. (3) Results: Excellent minibeam sizes between 0.6 and 0.9 mm full width at half maximum could be obtained and a good tolerance to errors was observed. Furthermore, the delivery of a 10 cm × 10 cm field with pencil beams was demonstrated. (4) Conclusion: The combination of the new proton linac and minibeam nozzle could represent an optimal implementation of pMBRT by allowing the generation of magnetically focussed minibeams with clinically relevant parameters. It could furthermore be used for conventional pencil beam scanning.