Optimized Electron Guns for MRI-guided Radiotherapy

This technology is a novel design to improve the performance of electron guns used with MRI for real-time image guidance during linear accelerator (linac)-based radiotherapy. This treatment option will offer fast imaging of tumor and normal tissue for unprecedented accuracy in aligning the radiation beam to the tumor. The low energy electron trajectories for a conventional electron gun are heavily influenced by an external magnetic field such as the fringe field of an MRI magnet, with up to 80% of current lost for inline magnetic fields. Design modifications to overcome this loss include changing the electron gun geometry and changing the cathode material to allow higher current per unit area to accommodate the reduced size of the cathode emitting surface.

Schematic representation of the electron gun model and the space charge solution represented by the electron trajectories.

Stage of Research
Stanford University is participating in a $16M project to create an integrated inline MRI-linear accelerator. The refinement of the electron gun design is continuing. The inventors expect to include these designs in the integrated system and perform experimental reduction to practice to characterize the increased system performance.