Chapter 17

1. Paralleling Technique
Chapter 17
1

2. 1. Define the key terms associated with the paralleling
technique.
2. State the basic principle of the paralleling technique
and illustrate the placement of the receptor, beam
alignment device, position-indicating device (PID), and
central ray.
3. Discuss how object-receptor distance affects the image
and how target-receptor distance is used to
compensate for such changes.
2
LEARNING OBJECTIVES
LESSON 17.1: PARALLELING TECHNIQUE

3. 4. Describe why a beam alignment device is necessary
with the paralleling technique.
5. List the beam alignment devices that can be used with
the paralleling technique.
6. Identify and label the parts of the Rinn XCP
instruments.
7. Describe the different sizes of receptors used with the
paralleling technique and how each receptor is placed
in the bite-block.
3
LEARNING OBJECTIVES
LESSON 17.1: PARALLELING TECHNIQUE
(CONT.)

4. 8. State the five basic rules of the paralleling technique.
9. Describe the patient and equipment preparations that
are necessary before using the paralleling technique.
10. Discuss the exposure sequence for 15 periapical
receptor placements using the paralleling technique;
describe each of the 15 periapical receptor placements
recommended for use with the Rinn XCP instruments.
4
LEARNING OBJECTIVES
LESSON 17.1: PARALLELING TECHNIQUE
(CONT.)

5. 11. Summarize the guidelines for periapical receptor
positioning.
12. Explain the modifications in the paralleling technique
that are used for a patient with a shallow palate, bony
growths, or a sensitive premolar region.
13. List the advantages and disadvantages of the
paralleling technique.
5
LEARNING OBJECTIVES
LESSON 17.1: PARALLELING TECHNIQUE
(CONT.)

6. Purpose
To present basic concepts and to describe patient
preparation, equipment preparation, and receptor
placement procedures used in the paralleling
technique
6
INTRODUCTION

7. Paralleling technique is also known as:
Extension cone paralleling technique
Right-angle technique
Long-cone technique
Paralleling technique is one method that can be used
to expose periapical and bite-wing image receptors.
7
BASIC CONCEPTS

8. Parallel (A)
Intersecting (B)
Perpendicular (C)
8
TERMINOLOGY

9. Right angle (D)
Long axis of the tooth
(A) Incisor
(B) Molar
9

10. The receptor is placed in the mouth parallel 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 beam alignment device must be used to
keep the receptor parallel with the long axis of
the tooth.
10
PRINCIPLES OF PARALLELING
TECHNIQUE

11. 11

12. Object-receptor distance
Must be increased to keep the receptor
parallel with the long axis of the tooth
Target-receptor distance
Must be increased to ensure that only the
most parallel rays will be directed at the tooth
Rules must be followed to obtain
accurate images.
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PRINCIPLES OF PARALLELING
TECHNIQUE (CONT.)

13. 13
(A) Receptor is too close
to the tooth
(B) Increase object
receptor distance

14. A device used to position the receptor in the
mouth and retain the receptor in position
during exposure
14
BEAM ALIGNMENT DEVICES
AND RECEPTOR HOLDING DEVICES

15. Examples of commercially available intraoral
beam alignment devices
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
15
BEAM ALIGNMENT DEVICES
AND RECEPTOR HOLDING DEVICES (CONT.)

16. Size 1 receptor
Used in the anterior region
Long portion in the vertical direction
Size 2 receptor
Used in the posterior region
Long portion in the horizontal direction
16
RECEPTORS USED
FOR PARALLELING TECHNIQUE

17.  Receptor placement
Receptor must be positioned to cover the prescribed
area of teeth to be examined
 Receptor position
Receptor must be positioned parallel to the long axis
of the tooth
17
RULES FOR PARALLELING TECHNIQUE

18. Vertical angulation
Central ray of the x-ray beam must be directed
perpendicular to the receptor and long axis of the
tooth
18
RULES CONTINUED

19.  Horizontal angulation
 The central ray of the x-ray beam must be directed through he
contact areas between teeth
19
RULES CONTINUED

20. Film receptor exposure
The x-ray beam must be centered on the receptor to
ensure that all areas are exposed
 Failure results in cone-cut
20
RULES CONTINUED

21. Patient preparation
Equipment preparation
Exposure sequence for receptor placements
Receptor placement for paralleling technique
21
STEP-BY-STEP PROCEDURES

22. Procedure
Explain the procedures.
Adjust the chair.
Adjust the headrest.
Place and secure the lead apron.
Remove all objects from the mouth
Should tongue rings be removed?
The midsagittal plane should be
perpendicular to the floor.
22
PATIENT PREPARATION

23. Set the exposure control factors.
Open the sterilized package containing the
beam alignment devices, and assemble the
devices over a covered work area.
23
EQUIPMENT PREPARATION

24.  Anterior exposure sequence (always start with the anterior teeth)
 Size 1 receptor is small and easier for patient to tolerate
 Less likely to cause patient to gag
 Eight anterior placements
 5 maxillary; 3 mandibular
 Posterior exposure sequence
 Eight posterior placements
 Four maxillary exposures; four mandibular exposures
 Stick to a sequence: Do not interchange from patient
to patient.
 Make this sequence a habit for all imaging exposures.
 In each quadrant, why should you always expose the
premolar receptor first and then the molar receptor?24
EXPOSURE SEQUENCE
FOR RECEPTOR PLACEMENTS

25. The specific area where the receptor must be
positioned before exposure
Dictated by teeth and surrounding structures
Specific placements described in the chapter are
for 15-receptor periapical series using size 1
receptors for anterior exposures and size 2
receptors for posterior exposures. (How many
Pa’s are in our paralleling FMX?)
Have the PID close to the patient so positioning
of the ring will be quick.
Remind patient to hold still during exposure. 25
RECEPTOR PLACEMENT
FOR PARALLELING TECHNIQUE

26. It is very important for the dental radiographer
to be competent in dealing with these types of
situations.
Using cotton rolls and changing the vertical
angulation and the location of the receptor
placement will assist the radiographer in
taking a dental image of diagnostic quality.
Shallow palate
Bony growths
Mandibular premolar region
26
MODIFICATIONS IN PARALLELING TECHNIQUE

27.  Cotton rolls
 Two 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.
27
SHALLOW PALATE

28.  Maxillary torus
 The receptor must be placed on the far side of the torus and then
exposed.
 Mandibular tori
 The receptor must be placed between the tori and the tongue
and then exposed.
28
BONY GROWTHS

29. 29

30. Receptor placement
The receptor must be
placed under the tongue.
Film
The lower edge of the film
can be gently softened to
prevent discomfort.
30
MANDIBULAR PREMOLAR REGION

31. Accuracy
The image is free of distortion.
Simplicity
It eliminates the need to determine horizontal and
vertical angulation.
It eliminates chances of dimensional distortion.
Duplication
Comparison of serial images has great validity.
*The primary advantage of the paralleling
technique is that it produces an image
without dimensional distortion*
31
ADVANTAGES
OF PARALLELING TECHNIQUE

32. Receptor placement
May be difficult
Discomfort
Beam alignment device may cause discomfort.
32
DISADVANTAGES
OF PARALLELING TECHNIQUE

33. 33
QUESTIONS?