CH 17: Paralleling Technique

Rinn Snap-A-Ray Holder

Comes in two versions, one for film and one for digital sensors. This receptor holding device can be used in both anterior and posterior areas

-Receptor placement: may be difficult -Discomfort: beam alignment device may cause discomfort

Disadvantages of paralleling technique: (2)

Set the exposure control factors

Equipment Preparation: Step 1

open the sterilized package containing the beam alignment devices over a covered work area and assemble

Equipment Preparation: Step 2

- Rinn XCP Extension Cone paralleling system - Rinn XCP-ORA One ring & arm positioning system - Rinn XCP-DS FIT universal sensor holder - Rinn Flip ray system - Rinn Snap-A-Ray Holder - Stabe bite block

Examples of commercially available intraoral Beam alignment devices

longest dimension of film placed vertically

Film Packet positioning: Anterior

in the slot

Film Packet positioning: DOT

widest dimension of film placed horizontally

Film Packet positioning: Posterior

flex backing plate to open film slot

Film Packet positioning: XCP

- by preventing cone cuts thus reducing retakes - by allowing the film to be held in place without the aid of the patient's finger in the field of radiation

How do film holders with rings reduce exposure?

3

How many Principles of Paralleling Technique are there

7 total 4 maxillary 3 mandibular

How many anterior placements total? Maxillary? Mandibular?

8 total 4 maxillary 4 mandibular

How many posterior placements total? maxillary? mandibular?

5

How many rules for the paralleling technique are there

receptor must be placed on the far side of the torus and then exposed

How to modify paralleling technique for: Bony Growths: maxillary torus

receptor must be placed between the tori and rhe tongue and then exposed

How to modify paralleling technique for: Bony growths: mandibular tori

lower edge of film can be softened to prevent discomfort; or use of special tabs

How to modify paralleling technique for: Mandibular premolar region: Film

must be placed under the tongue

How to modify paralleling technique for: Mandibular premolar region: Receptor placement:

can tilt film holder to be upright when pt closes

How to modify paralleling technique for: Mandibular premolar region: Sensitive premolar area

- cotton rolls placed on each side of the bite block - increased by 5-15 degrees

How to modify paralleling technique for: Shallow palate Cotton rolls (2) Vertical Angulation:

in the slot helps with mounting

If using film the identification dot should be ___________ Why?

the teeth

If using film the white side of the receptor faces ______________

perpendicular

Intersecting at or forming right angle

Rotating bite-block Ring

Rinn Flip-Ray System

Three plastic bite-blocks Three plastic aiming rings Three metal indicator arms

Rinn XCP Extension Cone Paralleling System

One ring One arm

Rinn XCP-ORA One Ring & Arm Positioning System

anterior vertical

Size 1 receptor is used for ____________ region long portion is the _________ direction

posterior horizontal

Size 2 receptor is used for ____________ region long portion is the _________ direction

slot film vertical horizontal

Stabe Holder film placement: Dot in the _________ center _______ in holder Anterior = ____________ Posterior = ______________

true

T/F: The advantages of the paralleling technique outweigh the disadvantages.

extension cone paralleling

What does XCP stand for

it is disposable and does not need to be sterilized

What is the advantage of using the stabe bite-block

Size 1 receptor; easier for pt to tolerate - less likely to make pt gag

What size receptor is used in anterior exposure sequence

b. 1, 2, and 3

Which are advantages of the paralleling technique? 1. increased accuracy 2. simplicity of use 3. ease of duplication 4. ease of receptor placement

2 and 3

Which are correct? 1. Anterior receptors are placed horizontally 2. Anterior receptors are placed vertically. 3. Posterior receptors are placed horizontally. 4. Posterior receptors are placed vertically

right angle: formed by two parallel lines

Which definition is incorrect?

The receptor is placed away from the tooth and toward the middle of the oral cavity.

Which describes the distance between the receptor and the tooth in the paralleling technique?

The receptor and the tooth are parallel to each other.

Which describes the relationship between the receptor and the long axis of the tooth in the paralleling technique

90 degrees to the receptor and long axis of the tooth

Which describes the relationship of the central ray to the receptor in the paralleling technique?

If the lack of parallelism is less than 20 degrees, the image is generally acceptable.

Which is correct?

Anterior receptors are always exposed before posterior receptors.

Which is incorrect?

to position the receptor parallel to the long axis of the tooth

Why does the paralleling technique require the use of a beam alignment instrument or receptor holding device?

to avoid image magnification

Why is an increased target-receptor distance required in the paralleling technique?

Target-receptor distance

distance between source of x-rays and receptor

object receptor distance

distance between the tooth and receptor

increased

object receptor distance must be ___________ to keep the receptor parallel with the long axis of the tooth

Paralleling Technique (AKA: Extension cone paralleling technique (XCP), right angle technique, long-cone technique)

one method that can be used to expose periapical and bite-wing image receptors

increased

target-receptor distance must be ___________ to ensure that only the most parallel rays will be directed at the tooth and the receptor

central ray

the central portion of the primary beam of x-radiation

perpendicular

the central ray of the x-ray beam is directed _______________ to the film and the long axis of the tooth

parallel

the receptor is placed in the mouth ___________ with the long axis of the tooth being radiographed

less image magnification and increased definition

the use of a long target-receptor distance in the paralleling technique results in

tooth middle of the oral cavity

to achieve parallelism between the receptor and the tooth, the receptor must be placed away from the ___________ and toward the _______________

intersecting

to cut across or through

beam alignment devices

used to position the receptor in the mouth and maintain the receptor in position during exposure

shallow palate bony growths mandibular premolar region

what can cause the clinician to make modifications in paralleling technique

- using cotton rolls - changing vertical angulation and location of the receptor placement

what modifications can be made to the paralleling technique to get a dentle image of radiographic quality

image magnification and loss of definition

what results from receptor being placed away from the tooth

area to be examined

center the receptor over

positioned to cover prescribed area of teeth to be examined

1. receptor placement

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

2. receptor position

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

3. Vertical angulation of PID

The central ray of the x-ray beam must be directed through the contact areas between teeth

4. Horizontal angulation

x-ray beam must be centered on the receptor to ensure all areas are exposed; NO CONE CUT

5. Receptor exposure

parallel

A beam alignment device must be used to keep the receptor ___________ with the long axis of the tooth

bite

Ask pt to slowly ________ on the bite wing tab or bite-block of the beam alignment device

Rinn XCP-DS FIT Universal Sensor Holder

Bite block that includes self adjusting clip that stretches to accommodate size of digital sensor

parallel

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

explain the procedure to the pt

Patient Preparation: Step 1

adjust the chair: Raise it up

Patient Preparation: Step 2

Adjust the headrest; pt occlusion should be parallel to the floor with some exceptions

Patient Preparation: Step 3

place and secure the lead apron

Patient Preparation: Step 4

remove all objects from the mouth that may interfere w/ the procedure

Patient Preparation: Step 5

Stabe bite block

a disposable receptor holder made of Styrofoam and is designed for one time use only

premolars molars

according to the textbook ___________ are exposed before _________________

- accuracy: image free of distortion - simplicity: eliminates need to determine horizontal and vertical angulation, eliminates chances of dimensional distortion - duplication: comparison of serial images has great validity

advantages of paralleling technique (3)

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