Distortion

Object thickness

The OID of a thick object changes measurably across the object

Significant

As the object's position is shifted laterally from the central ray, spatial distortion can become ___

Minimal

Distortion is ___ for objects lying along the central ray

Correct patient positioning

Distortion is possible in every radiograph if ___ is not maintained

More distorted

Due to the change of the OID the image of that structure is ___ than an image of a thinner structure

Directly related to positioning

Factors that control distortion are ___

Object thickness, object position and spatial distortion

Geometric Principles Three conditions contribute to image distortion

Diffuse blurring

If sufficient magnification is achieved by a reasonable OID and a short SID, the object may be visualized as a diffuse gray area.

Shape distortion

___ is the misrepresentation by unequal magnification of the actual shape of the structure being examined

Maximize SID while minimizing OID

Magnification size distortion is controlled by positioning the body part and x-ray tube to ___

Definition of distortion

Misrepresentation of the size and shape of the structure being examined

Foreshortening

Projects the object so it appears shorter than it really is. Occurs only when the part being examined is improperly aligned

Elongation

Projects the object so it appears to be longer than it is. Occurs when the tube or IR are improperly aligned

Distortion (Size)

Reduced magnification size distortion increases the resolution of recorded detail

Source to image distance and Object to image distance

Size distortion (magnification) is a function of:

Spatial distortion

The misrepresentation in the image of the actual spatial relationship among objects

Object position

When the object plane and the image plane are parallel, the image is not distorted