Chapter 20: Exposure and Technique Errors

Chapter 20

1. EXPOSURE AND TECHNIQUE
ERRORS
CHAPTER 20

2. LEARNING OBJECTIVES
LESSON 20.1: RECEPTOR EXPOSURE
AND TECHNIQUE ERRORS
1.Define the key terms associated with exposure and
technique errors.
2.Identify and describe the appearance of the following
exposure errors: unexposed receptor, film exposed to
light, overexposed receptor, and underexposed
receptor.
3.Identify and describe the appearances of the following
periapical technique errors due to receptor placement:
absence of apical structures and dropped receptor
corner.

3. LEARNING OBJECTIVES
LESSON 20.1: RECEPTOR EXPOSURE
AND TECHNIQUE ERRORS (CONT.)
4.Describe horizontal and vertical angulation.
5.Identify and describe the appearances of the following
periapical technique errors due to angulation problems:
incorrect horizontal angulation (overlapped contacts),
incorrect vertical angulation (foreshortened images and
elongated images), and incorrect beam alignment (cone-
cut images).
6.Describe and identify proper receptor placement for bite-
wing images.

4. INTRODUCTION
•Only diagnostic images are useful
•Purpose
•To describe receptor exposure problems and
technique errors that involve periapical and bite-wing
images

5. RECEPTOR EXPOSURE ERRORS
•Receptor exposure errors that result in
nondiagnosticimages include:
•Unexposed receptors
•Overexposed receptors
•Underexposed receptors
•All of these errors produce images that are too
light or too dark.
•Radiographer must be able to recognize
exposure errors, identify causes, and know the
necessary steps to correct such problems.

6. UNEXPOSED RECEPTOR
•Receptor
•May occur with digital sensors or film
•Appearance
•The image appears clear
•Cause
•Failure to turn on the x-ray machine
•Electrical failure
•Malfunction of the x-ray machine
•Correction
•Make certain the x-ray machine is turned on and listen for
the audible exposure signal.

8. FILM EXPOSED TO LIGHT
•Receptor
•Occurs only with film
•Appearance
•The image appears black.
•Cause
•The film was exposed to white light.
•Correction
•Do not unwrap in a room with white light.
•Check the darkroom for light leaks.
•Turn off all lights in the darkroom except the safelight.
•Examine film packs for defects before using.
•Never unwrap films in the presence of white light.

10. OVEREXPOSED RECEPTOR
•Receptor
•May occur with digital sensors or film
•Appearance
•Image appears dark or high in density.
•Cause
•Excessive exposure time, kilovoltage, milliamperage
•Incorrect milliamperes (too low) or time (too long).
•Correction
•Check settings and reduce as needed before exposing
receptor.

12. UNDEREXPOSED RECEPTOR
•Receptor
•May occur with digital sensors or film
•Appearance
•The image appears light or low in density.
•Cause
•The receptor was underexposed
•Incorrect milliamperes (too low) or time (too short)
•Correction
•Check the exposure time, kilovoltage, and milliamperage
settings on the x-ray machine before exposing the
receptor.

14. PERIAPICAL TECHNIQUE ERRORS
•Receptor placement problems
•Correct receptor placement
•Incorrect receptor placement
•Absence of apical structures
•Dropped film corner
•Angulation problems
•Incorrect horizontal angulation
•Incorrect vertical angulation
•PID alignment problems
•Cone-cut with beam alignment device
•Cone-cut without beam alignment device

15. RECEPTOR PLACEMENT PROBLEMS
•Each periapical receptor must be positioned in a
certain way to show specific teeth and related
anatomic structures.
•The edge of the periapical receptor must be placed
parallel to the incisal or occlusal surfaces of the teeth
and extend ⅛ inch beyond the incisal or occlusal
surfaces.
•A nondiagnostic image may result from improper
placement of a receptor over the area of interest,
inadequate coverage of the apical regions, or a
dropped receptor corner.

16. CORRECT PA PLACEMENT

17. ABSENCE OF APICAL STRUCTURES
•Receptor
•May occur with digital sensors or film
•Appearance
•No apices appear on the receptor.
•Cause
•The receptor was not positioned in the patient’s mouth to cover the
apical regions of the teeth.
•Correction
•Make certain no more than ⅛inch of the receptor edge extends
beyond the incisal-occlusal surfaces of the teeth.
•This error occurs with both the paralleling and bisecting
technique.

19. DROPPED RECEPTOR CORNER
•Receptor
•May occur with digital sensors or film
•Appearance
•The occlusal plane appears tipped or tilted.
•Cause
•The edge of the receptor was not placed parallel to the
incisal-occlusal surfaces of the teeth.
•Correction
•Make certain the edge of the receptor is placed parallel to
the incisal-occlusal surfaces of the teeth.

21. ANGULATION PROBLEMS
•Angulation: Describes the alignment of the central ray of the
x-ray beam in the horizontal and vertical planes
•Can be varied by moving the PID in either a horizontal or vertical
direction
•Horizontal angulation: refers to the positioning of the PID in a horizontal,
side-to-side plane
•Vertical angulation: refers to the positioning of the PID in a vertical, up-and-
down plane
•Incorrect vertical angulation results in an image that is not
the same length as that of the tooth; the image instead
appears shorter or longer.
•Overlapped contacts can be defined as the area where the
contact area of one tooth is superimposed over the contact
area of an adjacent tooth.

22. OVERLAPPED CONTACTS: INCORRECT
HORIZONTAL ANGULATION
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with paralleling or bisecting technique
•Appearance
•Overlapped contacts

23. OVERLAPPED CONTACTS: INCORRECT
HORIZONTAL ANGULATION (CONT.)
•Cause
•The central ray was not directed through interproximal
spaces.
•Correction
•Direct the x-ray beam through interproximal regions.
•The proximal surfaces of adjacent teeth appear
overlapped in the periapical exposure.
•This prevents the examination of interproximal
areas.

25. FORESHORTENED IMAGES: INCORRECT
VERTICAL ANGULATION
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with the bisecting technique when beam alignment
is not used
•Appearance
•Short teeth with blunted roots
•Cause
•Excessive vertical angulation
•Correction
•Do not use excessive vertical angulation with the bisecting
technique.

26. FORESHORTENED IMAGES: INCORRECT
VERTICAL ANGULATION (CONT.)

27. ELONGATED IMAGES: INCORRECT
VERTICAL ANGULATION
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with the bisecting technique when a beam alignment
device is not used
•Appearance
•Long, distorted teeth
•Cause
•The vertical angulation was insufficient.
•Correction
•Use adequate vertical angulation with the bisecting technique.

28. ELONGATED IMAGES: INCORRECT
VERTICAL ANGULATION (CONT.)

29. POSITION INDICATING DEVICE (PID)
ALIGNMENT PROBLEMS
•If the PID is misaligned and the x-ray beam is not centered
over the receptor, a partial image results.
•A cone-cut image appears as a clear or white unexposed
area on a dental image and may occur with a rectangular
or round PID.
•If a round PID is used, the cone-cut appears with a curved
border.
•If a rectangular PID is used, the cone-cut appears with a
linear border.

30. CONE-CUT WITH BEAM
ALIGNMENT DEVICE
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with either paralleling or bisecting technique when a
beam alignment device is used
•Appearance
•A clear area appears on the image.
•Cause
•The PID was not properly aligned with the periapical beam
alignment device.
•Correction
•Make certain the x-ray beam is centered over the receptor.

31. CONE-CUT WITH BEAM
ALIGNMENT DEVICE (CONT.)

32. CONE-CUT WITHOUT BEAM
ALIGNMENT DEVICE
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with bisecting technique when a beam alignment device
is not used
•Appearance
•A clear area appears on the image.
•Cause
•The PID was not directed at the center of the receptor.
•Correction
•Make certain the x-ray beam is centered over the receptor.

33. LEARNING OBJECTIVES
LESSON 20.2: BITE-WING EXPOSURE
AND TECHNIQUE ERRORS
7.Identify and describe the appearances of the following
bite-wing technique errors due to receptor placement:
incorrect placement of premolar bite-wing and incorrect
placement of molar bite-wing.
8.Identify and describe the appearances of the following
bite-wing technique errors due to angulation problems:
incorrect horizontal angulation (overlapped contacts),
incorrect vertical angulation (distorted image), and
incorrect position-indicating device (PID) alignment
(cone-cut images).

34. LEARNING OBJECTIVES
LESSON 20.2: BITE-WING EXPOSURE
AND TECHNIQUE ERRORS (CONT.)
9.Identify and describe the appearances of the
following miscellaneous technique errors: bending,
creasing, debris accumulation, phalangioma, double
image, movement, and reversed/backward
placement.

35. BITE-WING TECHNIQUE ERRORS
•Receptor placement problems
•Correct receptor placement
•Incorrect receptor placement
•Angulation problems
•Incorrect horizontal angulation
•Incorrect vertical angulation
•PID alignment problems
•Cone-cut with beam alignment device
•Cone-cut without beam alignment device

36. RECEPTOR PLACEMENT PROBLEMS
•Premolar bite-wing
•The resulting image shows both the maxillary and mandibular
premolars and distal contact areas of both canines.
•Molar bite-wing
•The resulting image shows both the maxillary and mandibular
molars.
•To ensure that the distal surfaces of the canines are
shown on the resulting image, the receptor must be
positioned so that the front edge of the receptor is aligned
with the midline of the mandibular canine.

38. INCORRECT RECEPTOR PLACEMENT
OF PREMOLAR BITE-WING
•Receptor
•May occur with digital sensors (more common)or film
•Technique
•May occur with bite-wing technique when a beam alignment device
or bite-tab is used
•Appearance
•Distal surfaces of the canines are not visible on the image.
•Cause
•The bite-wing receptor was positioned too far posteriorly in the
mouth.
•Correction
•Make certain the anterior edge of the bite-wing receptor is
positioned at the midline of the mandibular canine.

39. INCORRECT RECEPTOR PLACEMENT
OF PREMOLAR BITE-WING (CONT.)

40. INCORRECT PLACEMENT
OF MOLAR BITE-WING
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with the bite-wing technique when a beam alignment
device or bite-tab is used
•Appearance
•Third molar regions are not visible on image.
•Cause
•The bite-wing receptor was positioned too far anteriorly in the
mouth.
•Correction
•Make certain the anterior edge of the bite-wing receptor is
positioned at the midline of the mandibular second premolar.

41. INCORRECT PLACEMENT
OF MOLAR BITE-WING (CONT.)
•The molar bite-wing must be centered over the mandibular second
molar.
•To ensure accuracy, the front edge of the receptor needs to be aligned
with the midline of the mandibular second molar.
•The third molar region is not visible on this image.

42. ANGULATION PROBLEMS
•Dental radiographer must be prepared to choose the
correct horizontal and vertical angulations.
•Incorrect horizontal angulation results in overlapped
interproximal contacts, and incorrect vertical angulation
results in distorted images.

43. OVERLAPPED CONTACTS: INCORRECT
HORIZONTAL ANGULATION
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with the bite-wing technique when a beam alignment
device or bite-tab is used
•Appearance
•Overlapped contacts on the image
•Cause
•The central ray was not directed through the interproximal spaces.
•Correction
•Direct the x-ray beam through the interproximal spaces.

44. OVERLAPPED CONTACTS: INCORRECT
HORIZONTAL ANGULATION (CONT.)
•If the overlapping is more pronounced in the posterior half of the
image, the PID was pointed too much from the mesial toward the
distal.
•Proper use of a Rinn XCP bite-wing instrument minimizes errors in
horizontal angulation.

45. DISTORTED IMAGE: INCORRECT
VERTICAL ANGULATION
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with the bite-wing technique when a bite-tab is used
•Appearance
•Image appears distorted
•Cause
•The vertical angulation was incorrect.
•Correction
•Always use a +10-degree vertical angulation with the bite-wing
technique.

46. DISTORTED IMAGE: INCORRECT
VERTICAL ANGULATION (CONT.)

47. POSITION INDICATING DEVICE (PID)
ALIGNMENT PROBLEMS
•If the PID is misaligned and the x-ray beam is not
centered over the receptor, a partial image results.

48. CONE-CUT WITH BEAM
ALIGNMENT DEVICE
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with bite-wing technique when a beam alignment is used
•Appearance
•A clear area appears on the image.
•Cause
•The PID was not properly aligned with the beam alignment device.
•Correction
•Make certain the PID and the aiming ring are aligned.

49. CONE-CUT WITHOUT BEAM
ALIGNMENT DEVICE
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with bite-wing technique when a bite-tab is used
•Appearance
•A clear area appears on the image.
•Cause
•The PID was not directed at the center of the receptor.
•Correction
•Make certain the x-ray beam is centered over the receptor.

50. MISCELLANEOUS TECHNIQUE ERRORS
•Bending
•Creasing
•Debris accumulation
•Phalangioma
•Double accumulation
•Movement/motion unsharpness
•Reversed/backward placement

51. BENDING
•Receptor
•May occur with indirect digital sensors or film
•Technique
•May occur with the paralleling, bisection, or bite-wing techniques
•Appearance
•Images appear stretched (on a film) and distorted (on PSP
receptors).
•Cause
•Improper handling; receptor damaged
•Correction
•Check receptor placement before exposure.

52. BENDING (CONT.)
•A receptor may be bent because of the curvature of the
hard palate, or as the result of rough and excessive
handling.

53. CREASING
•Receptor
•May occur with indirect digital sensors or film
•Technique
•May occur with paralleling, bisecting, or bite-wing technique
•Appearance
•A thin radiolucent line appears on the image.
•Cause
•Improper handling; receptor creased; film emulsion cracked
•Correction
•Do not overmanipulate the receptor.

54. CREASING (CONT.)
Once a plate receptor is creased, a
permanent artifact occurs and appears
on each resultant image.
Damaged plate receptors must be
replaced.

55. DEBRIS ACCUMULATION
•Receptor
•May occur with digital sensors
•Technique
•May occur with paralleling, bisecting, or bite-wing technique
•Appearance
•Debris on the surface of sensor may cause permanent radiopaque
artifacts or radiolucent scratch marks on the sensor.
•Cause
•Sensors not handled carefully or wiped between uses; debris/dirt
accumulates on the surface of sensor
•Correction
•Extreme care must be used when handling sensors.

56. DEBRIS ACCUMULATION (CONT.)
•Correct infection control
procedures and cleaning
of sensors is important to
prevent debris from
accumulating or
scratching the sensor.

57. PHALANGIOMA
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with the bisecting technique when finger-holding method
is used
•Appearance
•The patient’s finger appears on the image.
•Cause
•The patient’s finger was positioned in front of the receptor.
•Correction
•Make certain the patient’s finger is placed behind the receptor.

58. PHALANGIOMA (CONT.)

59. DOUBLE IMAGE
•Receptor
•May occur with indirect digital sensors or film
•Technique
•May occur with the paralleling, bisecting, or bite-wing techniques
•Appearance
•A double image appears on the image.
•Cause
•The receptor was exposed twice in the patient’s mouth.
•Correction
•Always separate exposed and unexposed receptors.

60. DOUBLE IMAGE (CONT.)

61. MOVEMENT/MOTION UNSHARPNESS
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with the paralleling, bisecting, or bite-wing techniques
•Appearance
•Blurred images appear on the image.
•Cause
•The patient moved during exposure of the receptor.
•Correction
•Instruct the patient to remain still while the receptor is being
exposed.

62. MOVEMENT/MOTION UNSHARPNESS
(CONT.)

63. REVERSED/BACKWARD PLACEMENT
•Receptor
•May occur with digital sensors or film
•Technique
•May occur with paralleling, bisecting, or bite-wing techniques
•Appearance
•Light images with a herringbone pattern appear on the image.
•Cause
•The receptor was placed backward in the mouth and then exposed.
•Correction
•Always place the white side of the receptor adjacent to the teeth.

64. REVERSED/BACKWARD PLACEMENT
(CONT.)

65. QUESTIONS?