A study on the effects of long-term radiation exposure on superconducting magnets in MRI-Guided proton therapy

Abstract

In this publication, we offer the first assessment of the long-term radiation impact on superconducting magnets utilized in MRI-guided proton therapy. We explore both uniform and non-uniform magnetic fields and create three improved therapy plans for shallow (brain), medium (liver), and deep (prostate) targets. The evaluation of radiation damage in superconducting magnets using therapy plans is carried out through the implementation of the Monte Carlo method, molecular dynamics method, and modified NRT model. The results of the three plans show that a large amount of particles do enter the superconducting magnet during the treatment, with a preponderance of photons and neutrons. For superconducting magnets in MRI systems, the closer the coil is to the target area, the greater the radiation damage, and the extent of radiation damage increases with the energy of the incident proton beam. The PKA with high energy can induce temperature fluctuations locally in the superconducting coils, but does not pose a threat to its mechanical properties. Following 20 years of continuous operation, the DPA of the internal coils is about 2.3097E-17, and the maximum dose to insulating layer is about 1.25 Gy. The results of this paper show that MRI-guided proton therapy poses no threat to the long-term operation of superconducting magnets.