SUBMITTED TO –

SUBMITTED BY -HARKARANPREET SINGH

1. GHOST IMAGES This is a radiopaque artifact seen on a panoramic film

that is produced when a radiodense object is penetrated twice by the Xray beam

The characteristics of a ghost image are:i. A ghost image resembles it's real counterpart and has the

same morphology.ii. It is found on the opposite side of the film from it's real

counterpart.iii. It appears indistinct, the horizontal components are more

blurred than the vertical components of a ghost image.iv. The ghost image is always larger than the real counterpart,

the horizontal component is severly magnified, whereas the vertical component is not as severly magnified.

v. It is usually placed higher than its actual counterpart.vi. Ghost images are always reversed. Left and right being

sifted.

Anatomical structures which are most oftenghosted are:

i. Hyoid bone

ii. Cervical spine

iii. Inferior border of the mandible

iv. Posterior border of the mandible

v. The Meatuses

vi. The turbinates

• Non-anatomical structures which are often ghosted are:

i. Chin rest

ii. (R) or (L) Markers of the machine

iii. Neck chains

iv. Napkin chains

v. Earrings

vi. Shoulder straps of protective aprons.

2. LEAD APRON ARTIFACT

Lead apron artifact appears as a large coneshaped radiopacity obscuring the mandible

3.PATIENT POSITIONING ERRORS:I. POSITIONING OF THE LIPS AND

TEETHIf the lips are not closed on the bite block, a dark radiolucent shadow obscures the anterior teeth

II.POSITIONING OF THE FRANKFURT PLANE

a. Upward :If the patient's chin is positioned too high or tipped up (i.e. the chin is

too far forward while the forehead is titled towards the back):– The hard palate and the floor of the nasal cavity appear superimposed

over the roots of the maxillary teeth.– Loss of density in the middle of the radio-graph, usually characterized

by an hour glass shape.– There is a loss of detail in the maxillary incisor region, magnification.– The maxillary incisors appear blurred and magnified.– Loss of one or both condyles at the side of the film.

The chin and the occlusal plane are rotated upward, resulting in the overlapping of the images of the teeth and an opaque shadow (the hard palate) obscuring the roots of the maxillary teeth

b. DownwardAla-tragus line greater than 5° downward, the patient's chin is positioned too low or is tipped down (i.e. chin positioned back and the forehead is positioned forward);

– The mandibular incisors appear blurred.– There is a loss of detail in the anterior apical region of the mandible.

The apices of the lower incisors are out of focus and blurred.– The condyles may not be visible, as they may be cut off at the top of the

radiograph.– Shadow of the hyoid bone is superimposed on the anterior aspect of the

mandible.– Premolars are severly overlapped.– An 'exaggerated smile line' is seen on the radiograph (severe curvature

of the occlusal plane).

An exaggerated smile seen on a panoramic filmwhen the patient’s chin is tipped down

III. POSITIONING OF THE TEETH:a. Anterior to the focal troughPatient's head is positioned too far forward.– If the anterior teeth are not positioned in the

groove of the bite block, the teeth appear blurred.– If the teeth are positioned too far Forward on the

bite block, the anterior teeth appear 'skinny' and out of focus (Blurred and narrow).

– Spine is superimposed on the ramus areas.– Premolars are severely overlapped.

The anterior teeth appear narrow and blurred on a panoramic filmwhen the patient is positioned too far forward on the bite block

b. Posterior to the focal trough:

Patient's head is positioned too far back

– If the anterior teeth are not positioned in the groove of the bite block, the teeth appear blurred.

– If the teeth are positioned too far back on the bite block, the anterior teeth appear 'fat' and out of focus (blurred and wide).

– Excessive ghosting of mandible and spine.

The anterior teeth appear widened and blurred on a panoramicfilm when the patient is positioned too far back on the bite block

IV. POSITIONING OF THE MIDSAGITTAL PLANE:

If the patient's head is not centered, the ramus

and the posterior teeth appear unequallymagnified. The side farthest from the filmappears magnified and the side closest to

thefilm appears smaller.

The patient’s posterior teeth and ramus appear to bemagnified on the panoramic film when the head is not centered

a. Patient's head is tilted to one side.

– The side tilted towards the X-ray tube is enlarged.

– One condyle appears larger than the opposite one, the neck also appears longer on the larger side.

– Image appears to be tilted, one angle of the mandible is higher than the other.

b. Patient's head is twisted to one side causing the mandible to fall outside the image layer, (one side is in front of the image layer while the other side is behind the image layer).

– Teeth on one side of the midline appear wide and have severe overlapping of contacts, whereas the teeth on the other side appear very narrow.

– Ramus on one side is much wider than the other side.

– Condyles differ in size

c. Whole head is off center position (patient

biting the block off center with lateral incisors or cuspids).

– The molar teeth and the mandibular ramus are magnified on the side farther from the film.

– Anterior teeth are blurred with overlapping

V. POSITIONING OF THE SPINE

If the patient is not sitting or standing with a

straight spine, the cervical spine appears as a

pyramid shaped radiopacity in the center of

the film and obscures diagnostic information.

If the patient is not standing erect, superimposition of the cervicalspine may be seen on the center of the panoramic film

VI. PATIENT'S SHOULDER TOUCHING THE CASSETTE DURING EXPOSURE:This will slow the cassette rotation, resulting in

prolonged exposure or completely stop the film movement.

– Produces a dense black band, which is the area of overexposure or a dense black edge may be seen at the end of the radiographic image, due to eventual stoppage of rotation.

VII. POSITION OF PATIENT'S TONGUE DURING EXPOSURE:

If the tongue is not fully placed against the

roof of the mouth.

– A dark shadow appears in the maxilla

below the palate, and the apices of the

maxillary incisors are obscured.

If the tongue is not placed on the roof of the mouth, a radiolucent shadow will be superimposed over the apices of the maxillary teeth

VIII. DISTORTION DUE TO PATIENT MOVEMENT

a. Movement in the same direction as the beam.– There is prolonged exposure of the same area, with

increase in horizontal dimension of the imageb. Movement in the opposite direction as the

beam.– The horizontal dimension of the image in the

region is decreased

c. Sudden jerky movement in the same direction as the beam.

– The area may be portrayed twice.

d. Sudden jerky movement in the direction opposite the beam movement.

– A part of the object may be missing in the image.

e. If the patient moves up or down during exposure.

– Indentation in the lower border of the mandible (mimicing a fracture)

– Blurring and unsharpness.

4. CASSETTE POSITIONING ERRORS:i. Patient's shoulders touching the cassette during the

movement in the exposure cycle. This may happen if the patient has a short neck and well developed shoulders.

– Alternating vertical dark and light bands appear on the radiograph due to improper movement of the cassette behind the slit in the cassette holder or the tube head cassette holder assembly around the patient's head.

ii. Cassette placed too high.

– Lower border of the mandible is cut off.

iii. Cassette placed too low.

– Diagnostic information in the maxilla will be cut off.

iv. Two exposures on a single film.

Undiagnostic radiograph, with unnecessary exposure to the patient.

v. Cassette placed backwards.

– This is common in panorex the X-rays must penetrate the metal latch, which will present as a radiopaquebroad horizontal line through the middle of the radiograph