Paralleling technique

Question 1

other names for paralleling technique?

Answer 1

extension cone paralleling technique (XCP), right-angle technique, and long-cone technique

Question 2

important terminology!!!

Answer 2

• parallel
• intersecting
• perpendicular
• right angle
• long axis of the tooth
• central ray

Question 3

principles of paralleling technique

Answer 3

• film is places in the mouth to the long axis of the tooth being radiographed
• the central ray of the x-ray beam is directed perpendicular to the film and the long axis of the tooth
• a film holder must be used to keep the film parallel with the long axis of the tooth

Question 4

different film holders (5)

Answer 4

• rinn XCP instruments
• precision film holders
• state bite-block
• eezee-grip film holder
• hemostat with bite-block

Question 5

size 1 film is used for…

Answer 5

• used in the anterior region

- long portion in the vertical direction

Question 6

size 2 film is used for…

Answer 6

• used in the posterior region

- long portion in the horizontal direction

Question 7

rules for paralleling technique

Answer 7

• film placement: tooth and root
• film position: parallel to long axis
• vertical angulations: central ray perpendicular to film 90 degree
• horizontal angulations: through contacts
• film exposure: avoid cone cut

Question 8

step-by-step procedures for radiographs

Answer 8

• patient preparation
• equipment preparation
• exposure sequence for film placements
• film placement

Question 9

how can we prepare the patient?

Answer 9

• explain the procedure
• adjust the chair
• adjust the headrest
• place and secure the LEAD APRON
• remove all object from the mouth

Question 10

how can we prepare equipment?

Answer 10

• set the exposure factors

- BEFORE PLACING, open the sterilized package containing the film holder

Question 11

exposure sequence for film placements

Answer 11

• anterior exposure sequence

- posterior exposure sequence

Question 12

film placement for paralleling technique

Answer 12

• the specific area where the film must be positioned before exposure
• dictated by teeth and surrounding structures

Question 13

how can we ensure a logical sequence in radiographing?

Answer 13

• anterior first - more tolerable for patient
• posteriors: always premolar before molar due to patient comfort
• lay films out in a FMS mount orientation, as you remove films, put in cup. ensure you do not miss an area or double exposure of a film
• review text sequence and reasoning. reduce changing XCP configuration, but move back and forth from right side
• recommended sequence - next

Question 14

recommended sequence

Answer 14

• anteriors first: mx and then mn, which side does not matter
• posterior second: do one sextant at a time (premolar and molar), follow arrangement of films
• put films in cup as they are exposed, ex: Q1 - premolar and molar, Q4 - premolar and molar, Q2 and Q3

Question 15

3 modifications in the paralleling technique

Answer 15

• shallow palate
• bony growths
• mandibular premolar region

Question 16

what is the shallow palate modifications?

Answer 16

• cotton rolls: 2 cotton rolls can be used, one placed on each side of the bite-block
• vertical angulation: the vertical angulation can be increased by 5 to 15 degrees

Question 17

what if we cannot get parallel?

Answer 17

no more than 20 degrees is still generally diagnostic

Question 18

what are bony growth modifications?

Answer 18

• maxillary torus: the film must be placed on the far side of the torus and then exposed
• mandibular tori: the film must be placed between the tori and the tongue and then exposed

Question 19

in placing film for radiographs…

Answer 19

• film will become parallel as the patient closes
• insert on angle
• floor of mouth will relax as patient closes

Question 20

mandibular premolar region: film placement

Answer 20

the film must be placed under the tongue

Question 21

mandibular premolar region: film

Answer 21

the lower edge of the film can be greatly softened to prevent discomfort

Question 22

advantages of the paralleling technique

Answer 22

• accuracy: the image is free of distortion
• simplicity: eliminated the need to determine horizontal and vertical angulation, elicited chances of dimensional distortion
• duplication: comparison of serial radiographs has great validity

Question 23

disadvantages of paralleling technique

Answer 23

• film placement: may be difficult

- discomfort: film-holding device may cause discomfort