CH 29 DISTORTION

Distortion is the mis representation

misrepresentation of size or shape of the structures being examined can be classified as either

• size or shaped distortion.

Distortion is controlled by

Source to image receptor SID and object to image receptor OID

Magnification size distortion is controlled by positioning, the body part and

Tube to maximize SID while minimizing OID

SID HAS A MAJOR EFFECT ON MAGNIFICATION , the greater SID the smaller?

Greater SID, The smaller the magnification because as SID increases

SID must be maximize to decrease

Must be maximized to decrease magnification.

For example; exams with body parts with large OID’s like Lateral C spine And chest

( use large oid)

OID must be minimized to _____

decrease magnification

For example; exams with large O IDs, like kidneys and chest achieve small O ID as possible

Size distortion or Magnification can be assessed by

Assessed by calculation of magnification factor.

Magnification factor is calculated by the M= SID/SOD

Shape distortion is the

Misrepresentation by the unequal magnification of the actual shape of the structure being examined.

• either elongation, for shortening

elongation refers to

protects the object that it appears to be longer than it really is

• occurs when the tube or image receptorr is a improperly aligned

foreshortening refers to

Refers to projecting an object to appear shorter than it actually is

• Occurs only when the part is improperly aligned

Century away from the specified central rate entrance point is equivalent to

Is equivalent to angling the tube away from the perpendicular because the entire perspective of the anatomical part is distorted

The central rate is normally positioned

Positioned perpendicular to the anatomical part into the image interceptor

The below axis of the anatomical, part or object is intended to be positioned

Position perpendicular to the central ray & parallel to the image receptor

For shortening only occurs when there is

When there is poor alignment of the part

Elongation occurs only

Occurs when the poor alignment of the tube and or the Image receptor

Image perceptive is intended to be positioned

Position perpendicular to the central ray and parallel to the anatomical part.

Angulation refers to the direction.

Refers to the direction and degree of the tube moved from its original position, perpendicular to the image receptor.

The most common direction of tube angle is

Longitudinal angulations

• Cephalic= Tube is angled towards the head

• Caudad= tube is angled towards the feet

Degree refers to

Method of describing the exact amount of angulation and is usually stated as the angle between the central rate and the image of their plane from the standard preference point of perpendicularity.

Shape of distortion involves both elongation and for shortening

T or f

True