Definition

Approach - Two intraoral projection techniques used for periapical radiograph - paralleling - bisecting - These both can appiled to both digital and film based imaging

• The paralleling is preferred because provides imaging with less distortion

• The bisecting is preferred in anatomic constriction because strict adherence of parallel

• image receptor(receptor) refers to

• object
• source

Paralleling technique

Synonyms - right-angle, long-cone technique

Definition - The x-ray receptor is supported parallel to the long axis of teeth and The central ray of the x-ray beam is directed at right angle to the teeth and receptor. - receptor II long axis to tooth and receptor_l_ray beam

Principle - True anatomic relationship by parallel orientation

Faulty - Due to anatomic construction parallel orientation is change into uneven and away from tooth

Bisecting techinque

Definition - The x-ray beam directed at an angle to bisects the angle formed between long axis of the tooth and the receptor - x-ray_l_imaginary bisector from θ of long axis tooth and receptor

Principle - Cieszynski's rule of isometry which states that two triangles are equal with sides and angles when they share a one common side and two equal angles - The common side is a imaginary bisector - Two angles are equal due to Bisecting of parallel lines of x-ray beam Angles

• This leads to projection Geometry
• projection Geometry defined as the positioning and orientation of the x-ray source, patient and the receptor to one another Principles
• synonyms: shadow casting
• Focal spot should small
• Focal spot to object distance is more
• object to receptor distance is less
• Long axis of object and receptor should in parallel
• x-ray beam should strike the object and film in right angle