| 摘要 |
A combined radiation therapy and magnetic resonance unit 1 is provided, which is characterised by the beam deflection arrangement for an electron beam accelerator 9 as part of the radiation therapy part 5. The beam deflection arrangement 17 comprises a magnet arrangement providing a first magnetic field BC of equal magnitude and opposite direction to the main magnet field BO of the MRI unit, such that the main magnet field is nullified or cancelled out in the region of the beam deflection set up. A second magnetic field BD is provided, directed perpendicular to the trajectory of the electron beam to cause it to be deflected inward into the interior of the unit, towards the axis and patient when in use. The beam deflection may be achieved through use of an electromagnet, pulsed magnet or permanent magnet. The magnetic arrangement may be essentially tubular and shaped to contain the arcuate path of the electron beam as it is deflected. A separate field cancelling magnet may be provided. |
