Patent Number: 
Section: claims

1. A radiation emitting device comprising:a radiation emitter configured for emitting X-rays;an emitter switch, the radiation emitter being secured to the emitter switch;a disk-shaped collimator, the collimator having a central axial through-hole portion and a plurality of radial apertures configured for collimating the X-rays emitted from the radiation emitter into pencil beams, the through-hole portion receiving the radiation emitter and the emitter switch therein;a rotating mechanism coupled to the through-hole portion of the collimator for rotating the collimator;an annular shielding enclosure having an opening configured for allowing the pencil beams to exit therethrough, wherein the shielding enclosure encloses the collimator, the radiation emitter and the emitter switch therein; whereinthe radiation emitter is jointly and axially movable with respect to the emitter switch in the through-hole portion between an off position and an on position, wherein in the off position, the radiation emitter is misaligned with any one of the radial apertures thus ensuring the X-rays emitted from the radiation emitter blocked by the shielding enclosure, and wherein in the on position, the radiation emitter is aligned with one of the radial apertures therefore ensuring the X-rays emitted from the radiation emitter exit from the opening of the shielding enclosure. 2. The radiation emitting device, as recited in claim 1, wherein the radiation emitter is radially engaged with the collimator such that the radiation emitter, the emitter switch and the collimator are collectively rotatable relative to the shielding enclosure. 3. The radiation emitting device as recited in claim 1, wherein in an on position, the radiation emitter and the emitter switch are at rest relative to the shielding enclosure. 4. The radiation source device as recited in claim 1, further comprising a frame movable along a predetermined direction, the shielding enclosure being mounted on the frame.