The parallel design of the linac-MR system designed to generate an x-ray beam parallel to the main magnetic field of the MR imager.
A summary of each program used in the linac simulation is given along with their respective inputs and outputs.
The derived magnetic fringe field solution resulting from Monte Carlo optimization of current loops. Two coil pairs were used to generate the above continuous field solution.
The transverse phase space at the exit of the electron gun is given when subjected to (a) 0 T, (b) 0.0022 T, (c) 0.0046 T, and (d) 0.011 T longitudinal magnetic fields.
(a) Spatial intensity distribution and (b) energy spectrum at the linac target for simulations of 0, 0.0022, 0.0046, and 0.011 T longitudinal magnetic fields over the electron gun and linac waveguide.
in-line dose profiles at 1.5 cm depth and DD curves resulting from the linac operating in the presence of 0.0022, 0.0046, and 0.011 T longitudinal magnetic fields. The DD curves were initially normalized to but scaled here for visual clarity.
The 3D OPERA-3D/SCALA electron gun and trajectory solution in a 0.06 T longitudinal field is shown. The structure on the right is the anode, while the structures on the left are the focusing electrode and cathode (mostly hidden behind the electron beam). The electron beam color signifies its radial location in mm. Much of the beam is incident on the anode at 0.06 T.
The calculated cathode emission current and injection current with increasing magnetic field strength using OPERA-3D/SCALA is given. A very sharp decrease in the injection current is observed after 0.012 T. At 0.06 T, the injection current is a minimum after which it slowly increases with increasing magnetic field due to beam collimation within the anode beam tube.
The calculated target current with increasing magnetic field strength. The target current decreases even for increasing injection current up to 0.012 T due to a more nonlaminar injected beam.
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