It hereafter relates in general to use magnetic resonance (MR) imaging as the guidance in radiation therapy, and is more particularly to use MR imagings as the guidance in proton therapeutic. In some embodiments, cryogenic Dewar bottle is provided with the multiple channels for allowing the proton beamlets from proton beamlets source to pass through. The proton beamlets can be aligned with first passage first, and then the Dewar bottle can be rotated together with the proton beamlets. Then the Dewar bottle can be rotated to for second channel being aligned with the proton beamlets.
