Week 3: Paralleling technique

extension cone paralleling; right-angle technique; long-cone technique

what is paralleling technique also known as?

parallel

moving or lying in the same plane, always separated by the same distance and not intersecting

intersecting

to cut across or through

perpendicular

intersecting at or forming a right angle

right angle

an angle of 90 degrees formed by two lines perpendicular to each other

long axis of the tooth

an imaginary line that divides the tooth longitudinally into two equal halves

central ray

the central portion of the primary beam of x-radiation

1. receptor placement 2. receptor position 3. VA 4. HA 5. film receptor exposure

what are the 5 rules for paralleling technique?

receptor must be positioned to cover the prescribed area of the teeth

rule for receptor placement?

receptor must be positioned parallel to the long axis of the tooth; receptor and beam alignment device must be placed away from the teeth and toward the middle of the oral cavity

rule for receptor position

central ray of xray beam must be directed perpendicular to the receptor and the long axis of the tooth

rule for VA

central ray of xray beam but be directed through the contact areas between the teeth

rule for HA

xray beam must be centered on the receptor to ensure all areas are exposed

rule for receptor exposure

1. accuracy - free of distortion

2. simplicity - eliminates need to determine HA/VA, chances of dimensional distortion

3. duplication - comparison of serial images has great validity

advantages of parallel technique

1. receptor placement - may be difficult

2. discomfort - beam alignment device may cause discomfort

disadvantages of parallel technique