A medical device includes: a base; a positioner coupled to the base; an accelerator coupled to the positioner, wherein the positioner is operable to rotate the accelerator relative to the base about at least two axes; and a power source coupled to the accelerator, the power source configured to provide microwave power for the accelerator, wherein a position of the power source relative to the base remains fixed during movement of the accelerator. A medical device includes: a base; a positioner coupled to the base; an accelerator coupled to the positioner; a power source configured to provide microwave power for the accelerator, wherein a position of the source relative to the base remains fixed during movement of the accelerator; and a waveguide for coupling the power source and the accelerator; wherein the waveguide has a first segment with a first cross section, the first cross section being a circular cross-section.