Flat x-ray—(plain film tomography) provides a two dimensional compressed x-ray. They have a built in distortion & unequal magnification due to super imposition of various structures.
Cat Scan—Traditional Patient scanned slice at a time (axially) and a 2-D image is recreated by stacking slices. Helical CT has multiple detectors allowing 3-D image generation.
Cone Beam CT—Achieve final display utilizing volumetric tomography (voxels not pixels). A 3-D x-ray beam and a 360° scan unite to produce 3-D volumetric image with the help of sophisticated algorithms. This process is exceptionally useful for evaluation of bones of the skull.
Other advantages over conventional CT:
1.Greatly reduced radiation exposure to patient (by 98%!)
2.Rapid Scan time (10-30 sec) result in increased accuracy due to reduced movement by patient.
3.Accurate image—voxels of CBCT are smaller than spiral CT in sub-millimeter resolution (0.4-0.125 mm) which exceeds the highest grade multislice CT.
4.Smaller size of irradiated area.
5.Reduced artifact image due to suppression algorithms and increased number of projections.
6. Unique display modes Software to read data can be made available on CD ROM. This allows real time analysis & measurements & limited planning of treatment modalities.