A radiation apparatus including a support column, a rotatable arm that is configured to rotate around a first pivot relative to the support column, a first arm rotatably attached to one side of the rotatable arm to rotate about a second pivot, the first arm holding a imaging device, and a second arm rotatably attached to an other side of the rotatable arm to rotate about a third pivot, the second arm holding a radiation source, wherein radiation axis of the radiation source is configured to irradiate an imaging plane of the imaging device.

A mobile x-ray device includes a telescopic column including a fixed portion and an telescopic portion vertically moveable relative to the fixed portion, a telescopic arm moveably connected to the upper telescopic portion of the telescopic column, a head assembly for obtaining x-ray images on the telescoping arm, a wire rope connected to the telescopic portion and the telescoping arm for providing the vertical movement of the telescopic portion and telescoping arm, and a counterbalancing mechanism for balancing the weight of the telescopic portion and the telescopic arm during movement thereof. The counterbalancing mechanism includes a block and tackle connected to the wire rope and a compression spring connected to and extending between the fixed portion and the block and tackle for storing potential gravitational energy of the telescopic portion and telescoping arm during either synchronous or non-synchronous movement of the upper telescopic portion and telescoping arm.

A detent method for a medical imaging system. The method comprises obtaining a braking function F(S, V) between a distance S moved by a moveable component of the medical imaging system when a brake is applied to the component and a velocity V of the component and obtaining a measured velocity V.sub.m of the component before the brake is applied. A braking position P.sub.B is determined based on a target position P.sub.T, the measured velocity V.sub.m and the braking function F(S, V), wherein the brake is configured to be actuated when the component reaches the braking position P.sub.B.