Abstract: An apparatus includes a yoke having a first end and a second end. The yoke is configured to hold a device that includes an aperture and a range compensation structure. A catch arm is pivotally secured to the first end of the yoke. The catch arm includes a locking feature. The locking feature and the second end of the yoke interface, respectively, to a first retention feature and a second retention feature defined by the aperture and the range compensation structure. The locking feature is configured to interface to the first retention feature and the second end of the yoke is configured to interface to the second retention feature.

Abstract: Among other things, an accelerator is mounted on a gantry to enable the accelerator to move through a range of positions around a patient on a patient support. The accelerator is configured to produce a proton or ion beam having an energy level sufficient to reach any arbitrary target in the patient from positions within the range. The proton or ion beam passes essentially directly from the accelerator to the patient. In some examples, the synchrocyclotron has a superconducting electromagnetic structure that generates a field strength of at least 6 Tesla, produces a beam of particles having an energy level of at least 150 MeV, has a volume no larger than 4.5 cubic meters, and has a weight less than 30 Tons.