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Distortion
The misrepresentation of the size or shape of the structures being examined
2 types of distortion are?
Size distortion
Shape distortion
What is an example of size distortion?
Magnification
Magnification reduced _____
Recorded detail
What are factors affecting size distortion?
OID and SID
The greater the SID, the ____ the magnification
Less
The greater the OID, the _____ the magnification
More
Magnification or size distortion can be calculated by using the
Magnification Factor
Magnification Factor=
SID/ SOD
Object Size=
Image size/ magnification factor
% magnification of the object=
IS-OS/OS x 100
What is shape distortion?
An unequal magnification of the object
Two types of shape distortion?
Elongation and foreshortening
What affects shape distortion?
Tube/part/film alignment
What are the factors affecting shape distortion?
Angulation and alignment
Central ray: beam divergence is _____ at edges of beam due to angle of beam
Greater
Anatomical part: part aligned correctly to ______
Central ray
Image receptor: should lie flat, not _____ or ______ to beam
Angled to part, perpendicular
What is elongation caused by?
Misalignment of the CR and the IR
The greater the angle the ____ the elongation
Greater
Foreshortening is when?
Object appears to be shorter than it really is
Tube or IRS angle will cause elongation, never ______
Foreshortening
What are the ways to minimize distortion?
Use small OID
Use large SID
Insure proper tube/part/film alignment