Forward- and variable-offset hoop for beam scanning

1. An apparatus for forming a beam of energetic particles and for scanning the beam of particles with respect to an inspected object, the apparatus comprising:

a. a source of energetic particles characterized by an effective beam origin;

b. a rotating hoop having at least one aperture, the rotating hoop characterized by an axis of rotation; and

c. a collimating structure disposed interior to the rotating hoop for collimating emission by the source into a fan beam prior to impinging on the rotating hoop,

wherein the effective beam origin of the source is closer to the inspected object than the axis of rotation of the rotating hoop.

2. An apparatus in accordance with claim 1 , wherein the effective beam origin is a target of an x-ray tube.

3. An apparatus in accordance with claim 1 , wherein the effective beam origin is adapted to be moved with respect to the axis of rotation of the rotating hoop.

4. An apparatus in accordance with claim 1 wherein the collimating structure includes a plurality of moveable shielding devices for varying an angle of the fan beam emitted from the collimating structure.

5. An apparatus in accordance with claim 3 , wherein the effective beam origin is adapted to be moved with respect to the axis of rotation of the rotating hoop during the course of inspection operation.