PANORAMIC RADIOGRAPHY SEMINAR SECOND PART.pptx

SEMINAR

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2. 2 CONTENTS Concepts Errors

3. A CONCEPTUAL APPROACH TO UNDERSTANDING THE PANORAMIC IMAGE A number of peculiarities of the panoramic system result in a unique projection of many anatomic structures in the image. This produces numerous anatomical relationships in the image that are not found in any other kind of radiographic projection. These peculiarities must be understood to accurately interpret pathologic conditions as they differ from normal structures. 3

4. CONCEPT 1: STRUCTURES ARE FLATTENED AND SPREAD OUT The jaws and structures of the maxillofacial complex as well as the spine are portrayed as if they were split vertically in half down the mid- sagittal plane with each half folded outwards such that the nose remains in the middle the right and left sides of the jaws are on each side of the film the spine, having been split in half, appears beyond the rami at the extreme right and left hand edges of the film. 4

5. The midline of the film corresponds to the anterior midline of the patient and that the right and left hand edges of the film correspond to the posterior midline of the patient The right and left halves of the jaws and maxillofacial complex side by side on the film without one half being superimposed on the other and without the distortions that normally occur in plain films when one side is projected out of the image as in the lateral jaw view. DESIRABLE EFFECTS 5

6. UNDESIRABLE EFFECTS When the patient is improperly positioned in the machine. For example, when the chin is tipped too low and the patient is positioned a little back in the machine, the hyoid bone is spread out and projected up, right on top of the mandible. In the same way, the tubinates and meati of the nose are spread out projected across the maxillary sinus. 6

7. CONCEPT 2: MIDLINE STRUCTURES MAY BE PROJECTED AS SINGLE IMAGES AND DOUBLE IMAGES A real image is formed when the object is located between the rotation center of the beam and the film . An object will be portrayed with minimal unsharpness and distortion when it is close to the plane at the center of the layer. It will be portrayed with considerable unsharpness and distortion when it is far away from this plane. 7

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9. The regions where real images are formed relative to typical continuous movement patterns 9

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11. A double image is a pair of real images formed by an object lying within the diamond shaped zone where points are intercepted twice by the beam 11

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14. Structures that produce double images include the hard palate, palatal tori, the body of the hyoid bone and the epiglottis. When the patient is positioned too far back in the machine : The turbinates and meati enter into the diamond area, and double images are produced. These spread across the maxillary sinus, the greater horns of the hyoid bone, which are spread across the mandible. When the patient is positioned too far forward: The spine enters into the diamond area and is projected as a double image on the film and sometimes it is superimposed on the styloid process, ramus, and TMJ areas. 14

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16. CONCEPT 3: GHOST IMAGES ARE FORMED A ghost image is formed when the object is located between the x-ray source and the center of rotation. 16

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18. Ghost images have the following characteristics: The ghost image has the same morphology as its real counterpart. The ghost image appears on the opposite side of the radiograph from its real counterpart. The ghost image appears higher up on the radiograph than its real counterpart. The ghost image is more blurred than its real counterpart. The vertical component of a ghost image is more blurred than the horizontal component. The vertical component of a ghost image is always larger than its real counterpart while the horizontal component of a ghost image mayor may not be severely magnified. 18

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20. In the vertical dimension the ghost image appears higher than the real image since structural details lying between the radiation source and the rotation center are projected at higher levels than structural details at the same height, which lie between the rotation center and the film For objects producing ghost images between the x-ray source and the rotation center blurring is especially severe , since the shadows and the film are actually moving in opposite directions relative to the beam. 20

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22. Narrow structures are more severely affected by motion blurring than are wide structures, because the shadow of a narrow structure, moving a distance with respect to the film that is large relative to its width, will have its density "spread out“. The vertical, narrow details almost vanish from sight The horizontal, wide details are clearly portrayed. 22

23. Panoramic radiographs are characterized by different magnification factors for the horizontal and vertical dimensions. The magnification factors in the two dimensions are equal for those structures lying in the sharply depicted plane at the center of the layer. The vertical magnification factor increases continually as an object is moved closer and closer to the x-ray source. The horizontal magnification factor increases greatly close to the rotation center of the beam. 23

24. In the vertical dimension the ghost image will always appear larger than its real counterpart. The horizontal dimension may be more or less magnified than the vertical dimension depending upon the location of the object between the center of rotation and the x-ray source. 24

25. Anatomic structures that are often ghosted : The hyoid bone The cervical spine Inferior border of the mandible Posterior border of the ramus The meati The turbinates Other objects that ghost are: chin rest right and left markers of some machines earrings, napkin chains, neck chains the shoulder straps of protective aprons 25

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27. CONCEPT 4: SOFT TISSUE OUTLINES ARE SEEN Soft tissue structures visible in the radiograph are: The posterior and superior regions where there are no teeth and in all regions of edentulous patient Fluids and cartilaginous tissues such as the ear, nose, and epiglottis The soft palate and uvula Dorsum of the tongue Posterior pharyngeal wall 27

28. Lips Nasolabial fold Soft tissue of the nasal turbinates Septum Retromolar pad Operculum of erupting teeth 28

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30. 30 Tongue : A radiopaque area superimposed over the maxillary posterior teeth. 2. Soft palate and uvula : A diagonal radiopacity projecting posteriorly and inferiorly from the maxillary tuberosity region. 3. Lip line: • The lip line is seen in the region of the anterior teeth. • The areas of the teeth not covered by the lips appear more radiolucent. • The areas of the teeth covered by the lips appear more radiopaque. 4. Ear: • A radiopaque shadow that projects anteriorly and inferiorly from the mastoid process. • The ear is viewed superimposed over the styloid process.

31. CONCEPT 5: AIR SPACES ARE SEEN The air spaces that may be seen include: Hypopharynx Oropharynx Nasopharynx The maxillary sinus Nasal fossa Mastoid air cells External auditory canal Ethmoid sinuses 31

32. If an air space noted above the dorsum of the tongue: the periapical region of the maxilla will be difficult to interpret and can be avoided by asking the patient to place his tongue taken. If an air space is noted in the region of the against the palate while the radiograph is being anterior teeth, the crowns of these teeth will be difficult to interpret and can be avoided by asking the patient to close his lips around the bite block during the exposure. When the soft tissue outlines of the turbinates are projected across the maxillary sinus, the patient probably has been placed too far back in the machine, causing the turbinates to enter into the diamond area and produce double images 32

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34. 34 1. Palatoglossal air space : A horizontal radiolucent band located above the apices of the maxillary teeth. 2. Nasopharyngeal air space : A diagonal radiolucency located superior to the radiopaque shadow of the soft palate and uvula. 3. Glossopharyngeal air space : A vertical radiolucent band superimposed over the ramus of the mandible. It is continuous with the nasopharyngeal air space superiorly and the palatoglossal air space inferiorly.

35. CONCEPT 6: RELATIVE RADIOLUCENCIES AND RADIOPACITIES ARE SEEN In any image it is important to separate shadows originating from parts of the machine and those coming from the patient. Machine components seen in the image are made of plastic, have a density similar to that of soft tissue and are usually easy to identify due to their geometric or linear configuration. The patient may be thought of as being made up of three basic components: hard tissue (teeth and bone), soft tissue (including cartilage and fluid),air If an area of hard tissue is intersected by an air space, it will appear relatively more radiolucent than an adjacent area that is interrupted by a soft 35

36. To obtain the ideal single real image of the patient's three basic tissue components: identify all other shadows that can be caused by Machine components Double images Ghosts 36

37. If a pathologic process is present, it will consist either of hard tissue or soft tissue, and it will affect one or more of the three tissue components in the patient as follows: Those conditions producing hard tissue will cause all three patient components to become relatively more radiopaque in the region of the disorder. A soft tissue pathologic condition within the mineralized component causes it to become more radiolucent, whereas the soft tissue and air components become more radiopaque when a soft tissue disorder is present. When a soft tissue lesion encroaches upon an airspace such as the nasopharynx or maxillary sinus it be- comes visible as an opacity superimposed on the air space . 37

38. 38 Relative radiolucencies and radiopacities The ramus is relatively more radiolucent due to superimposition of the nasopharyngeal airspace The oral and nasopharyngeal airspaces are interrupted by a soft tissue mass consisting of a hyperplastic palatine tonsil The airspace of the oropharynx The soft tissue of the earlobe superimposed on the airspace of the nasopharynx

39. 39 5. The hyperplastic adenoid tonsil causes the condylar neck and head to appear relatively more radiopaque and the upper portion of the nasopharyngeal airspace to appear relatively radiopaque 6. The artifactual palatoglossal airspace obliterates bony details in the apical region of all of the upper teeth and represents an error in technique 7. Soft tissue of the base of the tongue.

40. 40 The uniqueness of the panoramic technique is that it results in an excellent projection of a variety of structures on a single film which no other imaging system can achieve. CONCEPT 7: PANORAMIC RADIOGRAPHS ARE UNIQUE

41. 41 ZONES OF INTERPRETATION

42. 42 The panoramic image was divided into six anatomical zones for anatomical structure evaluation. Nomenclature for each zone is defined as Zone 1: Dentition Zone 2: Nasal and Sinus Zone 3: Mandibular Body Zone 4: Temporal-mandibular Joint Zone 5: Ramus-spine Zone 6: Hyoid Bone

43. 43 BONY LANDMARKS OF THE MAXILLA AND SURROUNDING STRUCTURES

44. 44 1. Mastoid Process A rounded radiopacity located posterior and inferior to the temporomandibular joint. 2. Styloid process A long radiopaque spine extending from the temporal bone anterior to the mastoid process. 3 . External auditory meatus (External acoustic meatus) A round to oval radiolucency anterior and superior to the mastoid process. 4. Glenoid fossa (Mandibular fossa) A concave radiopacity superior to the mandibular condyle. 5. Articular eminence (Articular tubercle) A rounded radiopaque projection of the bone located anterior to the glenoid fossa. 6. Lateral pterygoid plate A radiopaque projection of bone distal to the maxillary tuberosity region.

45. 45 7. Pterygomaxillary fissure A radiolucent area between the lateral pterygoid plate and the maxilla. 8. Maxillary tuberosity A radiopaque bulge distal to the third molar region. 9. Infraorbital foramen A round or oval radiolucency inferior to the orbit. 10. Orbit A round radiolucent compartment with radiopaque borders located superior to the maxillary sinus 11. Incisive canal (Nasopalatine canal) A tube like radiolucent area with radiopaque borders. 12. Incisive foramen (Nasopalatine foramen) A small ovoid or round radiolucency located between the roots of the maxillary central incisors.

46. 46 13. Anterior nasal spine A “V” shaped radiopaque area located at the inter-section of the floor of the nasal cavity and the nasal septum. 14. Nasal cavity A large radiolucent area above the maxillary incisors. 15. Nasal septum A vertical radiopaque partition that divides the nasal cavity. 16. Hard palate A horizontal radiopaque band superior to the apices of the maxillary teeth. 17. Maxillary sinus A paired radiolucencies located above the apices of the maxillary premolars and molars. 18. Floor of the maxillary sinus The floor of the maxillary sinus is composed of dense cortical bone and appears as a radiopaque line.

47. 47 19. Zygomatic process of the maxilla A “J’ or “U” shaped radiopacity located superior to the maxillary first molar. 20. Zygomatic arch Posterior extension of Zygoma. Formed by Temporal process of Zygomatic bone (Anterior 1/3) and Zygomatic process of Temporal bone (Posterior 2/3). 21. Zygoma A radiopaque band that extends posteriorly from the zygomatic process of the maxilla. It is triangular in shape. 22. Hamulus A radiopaque hook-like projection posterior to the maxillary tuberosity area. 23. Dentition

48. 48 BONY LANDMARKS OF THE MANDIBLE AND SURROUNDING STRUCTURES

49. 49 1. Mandibular condyle A bony rounded, radiopaque projection extending from the posterior border of the ramus of the mandible. 2. Coronoid notch A radiolucent concavity located distal to the coronoid process on the superior border of the ramus. 3. Coronoid process A triangular radiopacity posterior to the maxillary tuberosity region. 4. Mandibular foramen A round or ovoid radiolucency centered within the ramus of the mandible. 5. Ramus Shadows of other structures may be superimposed over the mandibular ramus area 6. Lingula An indistinct radiopacity anterior to the mandibular foramen. 7. Mental foramen A small ovoid or round radiolucency located in the apical region of the mandibular premolars.

50. 50 8. Mandibular Or Inferior alveolar canal A radiolucent band outlined by two thin radiopaque lines representing the cortical walls of the canal. 9. Mental ridge A thick radiopaque band that extends from the mandibular premolar region to the incisor region. 10. Mental fossa A radiolucent area above the mental ridge 11. Lingual foramen A small radiolucent dot located inferior to the apices of the mandibular incisors 12. Genial tubercles A ring shaped radiopacity surrounding the lingual foramen. 13. Inferior border of the mandible A dense radiopaque band that outlines the lower border of the mandible.

51. 51 14. Mylohyoid ridge A dense radiopaque band that extends downward and forward from the molar region. 15. Internal oblique ridge A dense radiopaque band that extends downward and forward from the ramus 16. External oblique ridge A dense radiopaque band that extends downward and forward from the anterior border of the ramus of the mandible 17. Angle of the mandible A radiopaque bony structure where the ramus joins the body of the mandible 18. Dentition 19. Hyoid Bone Bilateral, ‘U’ shaped radiopaque body, just below or at the level of the inferior border of the mandible in line with molars

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53. 53 COMMON ERRORS

54. 54 PATIENT PREPARATION ERRORS

55. 55 These can include: ● Failure to remove jewellery – Earrings, Necklaces, Piercings ● Failure to remove dentures ● Failure to remove orthodontic appliances ● Failure to remove spectacles ● Inappropriate use of the lead apron.

56. 56 PATIENT POSITIONING ERRORS

57. 57 i. Positioning of the lips and teeth: If the lips are not closed on the bite block, a dark radiolucent shadow obscures the anterior teeth. ii. Positioning of the Frankfurt plan 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):

58. 58 – 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. – A 'reverse smile line' is seen on the radiograph (flattening of the occlusal plane).

59. 59 Frankfort plane not horizontal (chin tipped up) creating out-of-focus upper incisors and distorted occlusal plane (arrowed) (so-called grumpy face).

60. 60 b. Downward Ala-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.

61. 61 – 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).

62. 62 iii. Positioning of the teeth: a. Anterior to the focal trough : Patient'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.

63. 63 Patient positioned too far forwards (too close to the image receptor) and frankfort plane not horizontal (chin tipped down) creating narrow, out of focus anterior teeth, distorted occlusal plane (so-called smiley face) and excessive peripheral spinal shadowing.

64. 64 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.

65. 65 Patient positioned too far back (too far away from the image receptor) creating widened, magnified and out of focus anterior teeth.

66. 66 Frankfort plane not horizontal (chin tipped down) creating out of focus lower incisors and excessive ghosting shadows of the contralateral angles of the mandible.

67. 67 iv. Positioning of the midsagittal plane: If the patient's head is not centered, the ramus and the posterior teeth appear unequally magnified. The side farthest from the film appears magnified and the side closest to the film appears smaller. 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.

68. 68 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.

69. 69 Patient asymmetrical, rotated to the RIGHT. The RIGHT molars are closer to the image receptor and smaller, the LEFT molars are further away from the image receptor and larger

70. 70 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

71. 71 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. Failure to position the neck correctly – extension of the neck causing excessive spinal ghosting shadows over the anterior teeth.

72. 72 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.

73. 73 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. Patient positioned too far forwards (too close to the image receptor) creating narrowed incisors and failure to instruct patient to keep their tongue in contact with the palate creating the radiolucent band across the film

74. 74 viii. Distortion due to patient movement: Movement in the same direction as the beam. – There is prolonged exposure of the same area, with increase in horizontal dimension of the image. Continuous shaking movements throughout the cycle

75. 75 b. 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.

76. 76 Sudden movement in the vertical plane – distortion of the image 45 region creating a step-deformity in the lower border Movement in the vertical plane caused by the patient opening their mouth causing distortion in the 43 region

77. 77 Multiple vertical movements while the anterior teeth were being imaged. Sudden side-to-side horizontal movement while the anterior teeth were being imaged causing them to be blurred.

78. 78 Horizontal movement towards the end of the cycle causing horizontal elongation and stretching of the shadow of the developing lower right third molar

79. 79 EQUIPMENT POSITIONING ERRORS

80. 80 2. 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.

81. 81 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 radiopaque broad horizontal line through the middle of the radiograph

82. 82 The X-ray tubehead and image receptor carriage assembly positioned too low relative to the patient – the antra and condyles are not imaged. Cassette positioned back-to-front in the carriage assembly. Name plate and hinge screws are evident

83. 83 Modern cassette positioned back-to-front Cassette inadvertently used twice and double-exposed.

84. 84 Error and Cause Identifying Features Correction Patient too far forward Narrow blurred anterior teeth with pseudospace Superimposition of spine on ramus Bicuspid overlap bilaterally Use incisal bite guide Line up incisal edge of teeth with notch Edentulous patients should bite about 5 mm behind notch Patient too far back Wide, blurred anterior teeth Ghosting of rami; spread-out turbinates, ears, and nose in image; condyles off lateral edges of film Use incisal bite guide Line up incisal edge of teeth with notch

85. 85 Chin tipped too low Excessive curving of the occlusal plane Loss of image of the roots of the lower anterior teeth Narrowing of the intercondylar distance and loss of head of the condyles at the top of the film Tip chin down, but ala-tragus line should not exceed —5 to — 7° downward Use chin rest Chin raised too high Flattening or reverse curvature of occlusal plane Loss of image of the roots of the upper anterior teeth Lengthening of intercondylar distance and loss of head of the condyles at the edges of the film Hard palate shadow wider and superimposed on the apices of the maxillary teeth Tip chin down —5 to —7° Use chin rest.

86. 86 Head twisted Unequal right-left magnification particularly teeth and ramus Severe overlap of contact points and blurring Line up patient’s midline with middle of incisal bite guide Close side guide Head tilted Mandible appears tilted on film Unequal distance between mandible and chin rest at a given point on the right and left sides One condyle is higher and larger than the other Position the chin firmly on both sides of the chin rest Close side guide Slumped position Ghost image of cervical spine superimposed on the anterior region Stand-up machines: have the patient step forward or place feet on markers

87. 87 Chin not on the chin rest Sinus not visible on the film Top of condyles are cut off Excessive distance between inferior border of the mandible and the lower edge of the film Position the chin on the chin rest Bite guide not used Incisal and occlusal surfaces of the upper and lower teeth overlapped Use bite guide Compensate for missing anterior teeth with cotton rolls Tongue not on palate Relative radiolucency obscuring apices of the maxillary teeth (palatoglossal air space) Place the tongue firmly against the palate Ask the patient to swallow or suck on his or her tongue

88. 88 Lips open Relative radiolucency on the coronal portion of the upper and lower teeth Close lips Patient movement Wavy outline of cortex of the interior border of the mandible Blurring of the image above wavy cortical outline Ask the patient to hold still and not swallow Explain the function of the machine to avoid startling the patient Be certain the patient’s clothing will not interfere