19 AGO 2020 · BISECTING ANGLE
The film is placed as close as possible to the surface.
Central ray is directed perpendicular to the imaginary bisector.
Advantage – shorter exposure time, more patient acceptance cos we don’t need a beam aligner ring.
Disadvatage – image distortion/ magnification is possible. Angulation problems maybe, coz beam aligner right.
PARALELLING BEAM
It is easy to place using a film holder.
Central ray is perpendicular to both recptor & long axis of the tooth.
To maintain the parallelism between the object & the film, - INCREASE TARGET TO OBJECT DISTANCE *
Advantage – more accurate & Simplicity (no extra calculations required)
Disadvantages – patient discomfort.