A radiotherapy apparatus includes a rotatable drum on which is mounted a gantry arm carrying a radiation source. The arm extending from the drum to a location of the radiation source is offset from the axis of rotation of the drum and oriented towards the axis. The radiotherapy apparatus further includes a mechanism configured to apply a tilt to the arm at one or more rotational orientations of the drum. The rotatable drum is supported on wheels beneath the drum, and the mechanism is an eccentric mechanism within the wheels and is configured to apply the tilt to the arm via the wheels.

Described here are systems, devices, and methods for imaging and radiotherapy procedures. Generally, a radiotherapy system may include a radiotransparent patient platform, a radiation source coupled to a multi-leaf collimator, and a detector facing the collimator. The radiation source may be configured to emit a first beam through the collimator to provide treatment to a patient on the patient platform. A controller may be configured to control the radiotherapy system.