Quality of the radiographic image

• Contrast

• Image geometry

• Characteristics of the x-ray beam

• Image sharpness and resolution

Perception of the radiographic image

• Partial images-we all see the same partial images but we don’t necessarily perceive the same object

• Contrast

• Context

Effect of partial image

The effect of contrast

The effect of context

Image geometry

• Positioning of the film, object and x-ray beam

• Focal spot size and principle of line focus

• Focal spot-object distance (FSOD), object-

to film-distance (OFD)

Ideal image geometry requirements

Focal spot size, heat distribution and image sharpness

• Focal spot 1mm

• Heat needs to be distributed over as large

as possible area

• Principle of line focus

Focal spot-to film-distance(FSFD)

FSFD

• Increasing the distance between the focal

spot and the object results in an image

with increased sharpness and less

magnification of the object

Object-to film- distance (OFD)

• Decreasing the distance between the

object and the film increases the

sharpness and result in less magnification

of the object

Image shape distortion

Cont’d

Bisecting angle technique-shape distortion

Cont’d