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
