Radiograph sem


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  • But since the patients oral anatomy varies, the principles become difficult to be followed at times.
  • Image characteristics are needed to get an image with good image clarity.They are- Sharpness, resolution, size distortion and shape distortion.It should be kept in mind that we are not looking at the type of radiograph being used but the characteristics and their significance as a whole.We can see how the image on the left has less sharpness and resolution than the one on the right; making judgement and diagnosis difficult.
  • In the same way, we can see how the distinct edges and lines are visible in the second OPG making it a better radiograph.
  • Here in the 1st two images, we see how a magnified image can diminish the quality of a radiograph.But at the same time, there have been studies, where in, deliberately increasing the size of the image makes the detection of caries possible.
  • We can see elongation of the 1st radiograph and the second one shows distortion of the premolar region elongated and molar region forshortened. These images cannot give us precise information.
  • A few concepts need to be kept in mind to get a good radiograph. They are, the focal spot, blurring, magnmification and distortion.
  • Umbra- Complete shadow region, just below the objectPenumbra- partial shadow- some rays reachBeyond penumbra, all rays reach, fully blackened.
  • Ideally a point source focal spot should be used. But because of the heating up and burning out, the size is increased and an angulation is given.
  • To reduce mag, inc FS to object distance or reduce FS to film distance.
  • intensities vary in such a manner causes visible differences in the density produced on the radiographs. This phenomenon is called heel effect.The decreased intensity at C results from emission which is nearly parallel to the angled target where there is increasing absorption of the x-ray photons by the target itself. This phenomenon is readily apparent in rotating anode tubes because they utilize steeply angled anodes of generally 17 degrees or less. Generally, the steeper the anode, the more severe or noticeable the heel effect becomes.
  • Another use-- To demonstrate & evaluate the integrity of anterior, medial & lateral outlines of maxillary sinus.
  • A general guide for chin positioning is to place the patient so that a line from the tragus of the ear to the outer canthus of the eye is parallel with the floor.
  • Radiograph sem

    1. 1. Radiographic techniques R.Hemalatha 1st year Dept. Of Pedodontcs and Preventive Dentistry
    2. 2. Contents… 1. 2. 3. • • • • • • 3. • Introduction Parts of X-ray tube Projection Geometry Principles of projection geometry Terms Focal spot Magnification Distortion Heel effect Intra oral radiographs Periapical radiography 1. Paralleling technique 2. Bisecting angle technique • Bite wing radiography • Occlusal radiography
    3. 3. Contents… • Placement of the film in children and its management • Full mouth radiography • Object localisation technique • Radiographic faults 4. Extraoral techniques • Lateral cephalometric projections • Submentovertex projections • Waters • Posteroanterior cephalometric • Reverse-towne projections 5. Digital radiography and advanced imaging techiques 6.Effects of dental radiographs in oral cavity 7.Radiation protection 8. Conclusion 9.Refrences
    4. 4. Introduction • Radiograph is a 2D image of a 3D object. • A good radiograph is required for use as a good diagnostic aid. • Principles of projection geometry teach us how to reach perfection during radiography. • The intraoral radiograph, when correlated with the case history and clinical examination, is one of the most important diagnostic aids to the dental practitioner.
    5. 5. Parts of X-Ray An X-ray tube is a vacuum tube that produces X-rays. They are used in X ray machines. X-rays are part of the electromagnetic spectrum, an ionizing radiation with wavelengths shorter than ultraviolet light.
    6. 6. • • • • • As with any vacuum tube, there is a cathode, which emits electrons into the vacuum and an anode to collect the electrons, thus establishing a flow of electrical current, known as the beam, through the tube. A high voltage power source is connected across cathode and anode to accelerate the electrons. The X-Ray spectrum depends on the anode material and the accelerating voltage. Electrons from the cathode collide with the anode material, usually tungsten, molybdenum or copper, and accelerate other electrons, ions and nuclei within the anode material. About 1% of the energy generated is emitted/radiated, perpendicular, rest of the energy is released as heat.
    7. 7. • • • • • tungsten will be deposited from the target onto the interior surface of the tube, including the glass surface. The arc will jump from the cathode to the tungsten deposit, and then to the anode. This arcing causes an effect called "crazing" on the interior glass of the X-ray window, tube becomes unstable even at lower voltages, and must be replaced. The X-ray photon-generating effect is generally called the Bremsstrahlung effect. emitted X-ray photons, or dose, are adjusted by controlling the current flow and exposure time (high voltage controls X-ray penetration, and thus the contrast of the image and tube current and exposure time affect the dose and darkness of the image. Aluminum filters are installed in the path of the X-ray beam to remove "soft" (non-penetrating) radiation.
    8. 8. • Fundamentals of radiography areCentral beam should pass through the area to be examined. The x-ray film should be placed in position so as to record the image with the least amount of image distortion
    9. 9. Principles of Projection Geometry… Object and Film should be in contact or as close together as possible. Object and film should be parallel to one another. X-ray tube head should be positioned that, beam meets both the object and film at right angles.
    10. 10. “Terms and conditions apply” • Image sharpnessThe ability of a radiograph to reveal the boundary between two areas of different radiodensity; or to define an edge precisely. • Image spatial resolutionOPG- 5line Ability of a radiograph to reveal pairs/mm. small objects that are close together. IOPAR- 20line Line pairs per mm. pairs/mm.
    11. 11. • Image size distortionIt is the increase in size of the image on the radiograph compared with the actual size of the object.
    12. 12. • Image shape distortionIt is the unequal magnification of different parts of the same object on a single radiograph.
    13. 13. For a good radiograph…
    14. 14. • Actual focal spot size= 1x3mm. • Effective focal spot size= 1x1mm. • Size of the EFS- Angulation of the anode target to the long axis of the incident electron beam from the cathode. • Ideal angle= 10-20o • Smaller effective focal spot size, increased image sharpness and resolution. Focal spot
    15. 15. • Dec. heat production • Inc. X-ray tube life • Dec. sharpness and resolution • Dec. clarity • Inc. “geometric unsharpness” • Inc. heat production • Dec. X-ray tube life • Inc. sharpness and resolution • Inc. clarity
    16. 16. Umbra and Penumbra BLURRING To have sharp edge of image: • Longer “a” • Reduced “b” • Smaller EFS Fuzzy edgeGeometric Unsharpness
    17. 17. Magnification • Formula= Size of the image = Focal spot to film distance Size of the object Focal spot to object distance • When an image is magnified, the shape is maintained because every dimension of the object is magnified to the same extent, provided the object is placed parallel to the film.
    18. 18.  Use large FS to object distance  Use small object to film distance
    19. 19. Distortion • Results from unequal magnification of different parts of the same object. • When not all the parts of the object are at the same FS to object distance.  Position the film parallel to the object.  Orient the central ray perpendicular to the film and the object.
    20. 20. Foreshortening Ray perpendicular to the film but not the object Elongation Ray perpendicular to the object but not the film
    21. 21. Heel effect • Intensity of x-rays are not uniform over the area irradiated. • Due to the electrons having to travel more through the anode, less energy and intensity beam is seen towards the anode than towards the cathode , photons get absorbed by the target anode it self.. Biobrain article
    22. 22. Increases with increase in anode angle steepness Increases with increase in roughness of the anode Heel Effect Decreases with increase in focal spot to film distance Decreases with decrease in film size
    23. 23. Periapical radiographs INTRA ORAL RADIOGR APHS Occlusal radiographs Bite wing radiographs
    24. 24. Intra Oral Periapical Radiography… • • • • • • • Includes the teeth and the tissues around the apices. UsesDetection of apical infection/ inflammation. Assessment of periodontal status Assessment of an unerupted tooth Assessment of root morphology Evaluate position and prognosis of implants
    25. 25. • Ideal positioning requirements• Tooth and film should be as close to each other as possible. • Tooth and film should be parallel to each other. • The film is positioned with its long axis vertical for anterior teeth and horizontal for posterior teeth. • Beam must be directed at 90o to both the teeth and the film. • Positioning must be reproducible.
    26. 26. Placement of the film… • The white side of the film always faces the teeth. • Anterior films are always placed vertically. • Posterior films are always placed horizontally. • The identification dot on the film is always made to face the operator and on the occlusal end of the radiograph. • The film is always centred over the areas to be examined. • Ideally 2mm of the alveolar bone must be seen periapically.
    27. 27. Landmarks used… Inner canthus Pupil Outer canthus Occlusal Plane
    28. 28. Paralleling Technique • C. Edmund Kells in 1896 • developed by Gordon M. Fitzgerald in 1947. • Used by Franklin W. McCormack in practical dental radiography. • It was so named because the object (tooth), receptor (film packet), and end of the position indicating device (PID) are all kept on parallel planes.
    29. 29. PRINCIPLE The image sharpness is primarily affected by the distance from the focal spot within the tube head and the film, object-film distance, motion, and the effective focal spot size of the x-ray tube. • Long axis of the tooth is parallel to long axis of the film • Central ray at 90o to both. • Film holder and x-ray tube head positions can be reproduced. • Film placed at same distance away from the tooth. • Long open ended aiming cylinder Long con tech Right Angled tech Dentomaxillofacial Radiology (2011) 40, 385-389 The British Institute of Rdiology
    30. 30. • Projection method• Maxillary projections, superior border of the film placed at the height of the palatal vault. • Mandibular projections, inferior border of the film placed on the floor of the mouth. • Vertical angulation- 90o • Horizontal angulation- 0o Now more commonly used method
    31. 31. • Film holders• Rinn XCP, Rinn stabe film holders, Precision film holders, EEZEE grip film holders. • Most preferred is Rinn XCP film holder • Parts- Plastic ring and plastic bite block, metal indicator arms, addable ring collimators.
    32. 32. -Film placement in children or small mouths or shallow palate is difficult. -Discomfort -Apices of the teeth may appear close to the edge of the film. -Film holder needs autoclaving. DISADVANTAGES distortion -Simplicity -Duplication is possible due to standardisation -Periodontal bone levels are well depicted. -Angulations and positions are reproducible. -The technique reduces the risk of cone cuts. ADVANTAGES -Accuracy, minimal
    33. 33. Bisecting Angle Technique • Developed by Weston Price in 1904. PRINCIPLEWhen the rule of isometry is used, the length of the tooth is equal to the length of the image on the radiograph.
    34. 34. Multirooted teeth- Angled differently for each root Ciezynski‟s rule of isometry
    35. 35. • Projection method• For maxillary projections- Patient‟s head must be upright, with the sagittal plane vertical and the occlusal plane horizontal. • For mandibular projections- Head is tilted back slightly.
    36. 36. +400 +450 +30 +20 0 0
    37. 37. -150 -100 -200 50
    38. 38. • Size of Intraoral films • Size 0 (22x35mm) used for bitewing and periapical radiographs of small children • Size 1 (24x40mm) used for radiographing anterior teeth in adults. • Size 2 (31x41mm) used for anterior occlusal radiograph,periapical radiograph and bitewing survey in mixed and permanent dentition. • Occlusal films have a size of 57x76 mm and are taken for viewing entire maxillary and mandibular arches
    39. 39. DISADVANTAGES ADVANTAGES - Can be used without a film holder. - Decreased exposure time. - Positioning of the film is relatively more comfortable to the patient in all areas of the mouth. - Image distortion. - Angulation problems. - Unnecessary exposure. - Shadow of the zygomatic bone is frequently seen over the apex of the maxillary molars. - Difficulty in angulation. - Not reproducible.
    40. 40. Comparison of Parelleling technique and bisecting angle technique
    41. 41. Bite wing radiographs… • Also called as the INTERPROXIMAL TECHNIQUE. • Developed by Howard Riley Raper in 1925. • Shows crowns of maxillary and mandibular teeth, interproximal areas, and areas of crestal bone on the same radiograph. • Name originated as the patient bites on the wing to stabilize the film.
    42. 42. • Uses• Checking the interproximal areas of teeth • Checking the alveolar bone on the radiograph. • Caries in deciduous and transitional dentiton phase AAAPD guideline for prescribing dental radiographs
    43. 43. • Vertical angulation- recommended angulation of +10o. Used to compensate for slight bend of the upper portion of the film and tilt of maxillary teeth. • Horizontal angulation- central ray is directed perpendicular to the curvature of the arch and through the contact areas. • Vertical bite wings are used to visualise the level of the alveolar bone, normally used as post treatment films after periodontal treatment.
    44. 44. Occlusal radiograph… • Occlusal radiography is defined as those intraoral radiographic techniques taken using a dental X-ray set where the film packet (5.7 x 7.6 cm) or a small intraoral cassette is placed in the occlusal plane. USES I. II. III. To precisely locate roots, supernumerary, unerupted & impacted teeth. To localize foreign bodies in the jaw & stones in the duct of sublingual & submandibular gland duct. Another use-- To demonstrate & evaluate the integrity of anterior, medial & lateral outlines of maxillary sinus. To obtain information about location, nature, extent & displacement of fractures of mandible & maxilla. v Patients with reduced mouth opening vi. Cleft palate cases IV.
    45. 45. Maxillary and Mandibular Occlusal Projections i. Topographic projections Shows anterior part of maxilla or mandible and the anterior teeth. The cone is placed between the eye brows on the bridge of the nose.
    46. 46. Mandibular Occlusal Projections i. Topographic projections Shows anterior part of maxilla or mandible and the anterior teeth.
    47. 47. • ii. Vertex projection Shows the entire teeth present in the arch.
    48. 48. ii. Vertex Mandibular projection ( cross sectional projection)
    49. 49. iii. Posterior Lateral projection Shows the posterior part of the maxilla and the upper posterior teeth on one side. iv. Pediatric projection Shows the anterior part of the maxilla, used in children of 5years age or younger.
    50. 50. • iii. Posterior Oblique Mandibular Occlusal projection
    51. 51. • Positioning the Radiograph • Positioning the radiograph vertically in the mouth for both periapical and bitewing radiographs reduces the distal extension of the radiograph and may result in greater tolerance by patients, especially those with a mild gag reflex. • The vertical bitewing radiograph provides greater detail of the periapical area.
    52. 52. Primary dentition (3 to 6 years) Maxillary anterior occlusal projection • Place no. 2 film with its long axis perpendicular to the sagittal plane and the pebbled surface towards maxillary teeth. • Direct the central ray at a vertical angulation of +60 degrees through the tip of the nose towards the center of the film Mandibular anterior occlusal projection • Seat the child with the head tipped back so that the occlusal plane is about 25 degrees above the plane of the floor. • Place a no. 2 film with the long axis perpendicular to the sagital plane and the pebbled surface towards the mandibular teeth. • Orient the central ray at -30 degrees vertical angulation and through the tip of the chin towards the film.
    53. 53. Bitewing projection • Use no. 0 film with paper loop holder. • Place the film in the child’s mouth as in the adult premolar bitewing projection. • The image field should include the distal half ofthe canine and the deciduous molars. • Positive vertical angulation of +5 to +10 degrees. Decidious maxillary molar periapical projection • Use no. 0 film , Position the film in the midline of the palate with anterior border extending to the maxillary primary canine. • The image field should include the distal half of the primary canine and both primary molars
    54. 54. • Deciduous mandibular molar projection Projection a no. 0 film The exposed radiograph should show the distal half of the mandibular primary canine and the primary molar teeth. • Mixed dentition(7 to 12 years) Maxillary anterior periapical projection Center a no.1 film on the embrasure between the central incisors in the mouth behind the maxillary central and lateral incisors.Center the film on the midline.
    55. 55. • Mandibular anterior periapcal projection Position no.1 film behind the mandibular central and lateral incisors • Canine periapical projection Position no. 1 film behind each of the canines. Decidious and permanent molar periapical projection Position no.1 or no. 2 film with anterior edge behind the canine • Posterior bitewing projection Use no.1 or no. 2 films as previously described Expose four bitewings projections when the second permanent molars have erupted
    56. 56. • 1. 2. 3. 4. 5. 6. Probable Technical Errors Improper placements of films. Cone cutting Incorrect horizontal angulations Incorrect vertical angulations Over exposure due to defective devices. A high exposure of the patient to radiation because of repetition of taking X-rays due to an uncooperative child.
    57. 57. Radiation hygiene measures • • • • • • • • • Proper registration and maintenance of radiographic units. Training of personnel who are associated with radiography Dosage monitoring Radiation protection of the child patients by using lead apron with thyroid collar. Use of long lead-lined cylinder and cone positioning devices Use of electronically controlled exposure timer Use of high speed films Use of automatic processing machines that give good consistent result Employing proper technique to avoid the chances of repeating exposure
    58. 58. • The Snap-A-Ray is also useful for those patients that have a fear of swallowing the radiograph. • By biting on the large positioning device and watching in a mirror they are assured they will not swallow the radiograph A self sticking sponge tab may also reduce impingement of the radiograph on the intraoral soft tissue. For patients frightened of the procedure itself,desensitization techniques may be necessary to gain the patient cooperation
    59. 59. Desensitization Techniques • Desensitization is defined as gradually exposing the child to new stimuli or experiences of increasing intensity. • An example of this is introducing the patient to x-rays by initially taking an anterior radiograph which is easier to tolerate than a posterior radiograph. “Lollipop Radiograph Technique.”The child is given a lollipop to lick (preferably sugarless). • After a few licks, the lollipop is taken from the child and a radiograph is attached to the lollipop using an orthodontic rubber band. • The lollipop with the attached film is returned to the child, who is told to lick the lollipop again. • After a few licks, the child is told to hold the lollipop in his mouth while we take a tooth picture.The exposure is made
    60. 60. Procuring Posterior Radiographs • Procuring posterior radiographs can be made more pleasant by associating it with a pleasurable taste….bubble gum. • Before placing the radiograph in the patient’s mouth apply bubble gum flavored toothpaste to the film. • The child will be more accepting of the radiograph
    61. 61. Gag reflex • Some patients, young and old, have an exaggerated gag reflex. • The etiology of an exaggerated gag reflex had been attributed to psychological and physical factors. • The easiest is through diversion and positive suggestion. • The operator suggests to the patient the gag reflex can be reduced by concentrating on something other than the procedure. • The patient’s palate can be sprayed with a topical anesthetic to reduce the sensation of the radiograph on the palate and tongue. • An alternative is the use of nitrous oxide analgesia
    62. 62. Newman and Friedman Extraoral Radiographic Technique • Another alternative is to place the radiograph in such a manner to not come in contact with the palate or tongue. • This is accomplished by either extraoral placement of the film or placing the film between the cheek and the tooth and exposing the film from the opposite jaw. • The film side of the packet (the solid color side) is facing the buccal surface of the tooth • The x-ray head is placed at the opposing side, and the coneis positioned under the angle of the ramus on the opposite side. • As the x-ray beam is traveling a longer distance to the film than in the typical positioning, it is necessary to double the exposure time. • It is imperative that after mounting radiographs are Reversed. • Incorrect mounting and labeling of the reverse radiograph can result in misdiagnosis and treatment of the wrong tooth Newman M, Friedman, S. Extraoral Radiographic Technique: An Alternative Approach. Journal Of Endodontics 2003;29:419-421
    63. 63. Modified Newman and Friedman Extraoral Radiographic Technique • Eshagali Saberi, Ladan Hafezi, Narges Farhadmolashahi, Manoochehr Mokhtari The patient sitting upright and the Frankfort plane being horizontal to the floor and when the head was tilted 10 degrees toward the side being examined. For the upper posterior teeth the center of the image receptor was placed on the intersection of the alatragus and a parasagittal line while the upper border of receptor was parallel to the canthomeatal line. The cone was positioned a negative 25 degrees from the horizontal plane.
    64. 64. Modified Newman and Friedman Extraoral Radiographic Technique The central beam was directed from midway between maxillary and mandibular premolars and molars of the opposite side.. For the lower posterior teeth, the receptor was placed against the cheek on the side of interest and its lower border was parallel and 2 cm above the inferior border of the mandible The cone was angled -20 degrees from the horizontal plane while the central beam was directed towards the mandibular molarpremolar region. Saberi1, Hafezi L, Farhadmolashahi1 N, Mokhtari M. Modified Newman And Friedman Extraoral Radiographic Technique
    65. 65. Type of encounter Child with primary dentition (prior erruption of 1st molar) Child with Transitional Dentition (after eruption of first permanent tooth) Adolescent with Permanent Dentition (prior to eruption of third molars) New patient* being evaluated for dental diseases and dental development Individualized radiographic exam consisting of selected periapical/occlusal views and/or posterior bitewings if proximal surfaces cannot be visualized or probed. Patients without evidence of disease and with open proximal contacts may not require a radiographic exam at this time. Individualized radiographic exam consisting of posterior bitewings with panoramic exam or posterior bitewings and selected periapical images. Individualized radiographic exam consisting of Recall patient* with clinical caries or at increased risk for caries** Posterior bitewing exam at 6-12 month intervals if proximal surfaces cannot be examined visually or with a probe. . Recall patient* with no clinical caries and not at increased risk for caries Posterior bitewing exam at 12-24 month intervals if proximal surfaces cannot be examined visually or with a probe Recall patient* with periodontal disease Clinical judgment as to the need for and type of radiographic images for the evaluation of periodontal disease. Imaging may consist of, but is not limited to, selected bitewing and/or periapical images of areas where periodontal disease (other than nonspecific gingivitis) can be identified clinically. posterior bitewings with panoramic exam or posterior bitewings and selected periapical images. A full mouth intraoral radiographic exam is preferred when the patient has clinical evidence of generalized dental disease or a history of extensive dental treatment. Posterior bitewing exam at 18-36 month intervals.
    66. 66. Type of Encounter Child with Primary Dentition (prior to eruption of first permanent tooth) Child with Transitional Dentition (after eruption of first permanent tooth Adolescent with Permanent Dentition (prior to eruption of third molar Patient for monitoring of growth and development Clinical judgment as to need for and type of radiographic images for evaluation and/or monitoring of dentofacial growth and development. Patient with other circumstances including, but not limited to, proposed or existing implants, pathology, restorative/endodontic needs, treated periodontal disease and caries Clinical judgment as to need for and type of radiographic images for evaluation and/or monitoring in these circumstances Clinical judgment as to need for and type of radiographic images for evaluation and/or monitoring of dentofacial growth and development. Panoramic or periapical exam to assess developing third molars
    67. 67. • Large or deep restorations Indications for pediatric radiographs • Malposed or clinically •Poor oral hygiene impacted teeth •Inadequate fluoride exposureft in • Mobilty of teeth diet • Sinus tract/ fistula •Poor family dental health • Clinically suspected sinus •developmentrequentl high sucrose pathology content • Oral involvement in known or •Prolonged nursing bottle or breast suspected systemic disease feeding • Unxplained bleeding, •developmental or acquired enamel sensistivity of tooth, defects • Unusual erruption,spacing or • Developmental or acquired migration of teeth, tooth disability morphology, calcification or • Xerostomia colour, absence of teeth • Genetic abnormality of teeth • Clinical erosion • Many multisurface restorations • High level fo caries experience • Chemo/radiation therapy • Eating disorders • h/o of reccurent caries • Drug/alcohol abuse • High titre of cariogenic titre • Irregular dental care • Exsisting restoration of poor quality AMERICAN ACADEMY OF PEDIATRIC DENTISTRY-2012
    68. 68. Radiographic Surveys • The three most common series of radiographs taken in the dental office are • Bitewing Surveys- consist of a premolar view and a molar view for each side of the mouth taken in occlusion (2 or 4 films) taken to examine the contact areas of the premolar and molar regions, and periapicals for the other teeth and edentulous areas. • Full Mouth Surveys - series of x-rays that properly represent every tooth in the patient's mouth (with 3 to 4 millimeters of surrounding bone) and all other tooth bearing areas of the mouth even if edentulous • panoramic film.
    69. 69. Full Mouth Radiographs 22 total=18 IOPA + 4 Bite wings
    70. 70. 12= 10 IOPA+2 bite wings
    71. 71. Deciduous Dentition 8 film= 6 IOPA + 2 Bitewings
    72. 72. Object localisation techniques… •To determine the location of a foreign object or an impacted tooth in the jaw. •Two methods are used for localizing the object; • • • • • Perpendicular techniqueUsed to localize an object in or about the maxilla or mandible in three dimensions. In clinical practice the position of an object on each radiograph is noted relative to anatomic landmarks. The right angle or cross section technique is best in mandible An IOPAR and an occlusal radiograph are used.
    73. 73. B. Tube shift technique (SLOB Method) This method is also known as “buccal object rule” or “Clark‟s rule”(1910) Rationale for this technique derives from the manner in which the relative positions of radiographic images of two separate objects change when projection angle at which the images are made is change. Two radiographs are taken with different horizontal angulations.
    74. 74. Radiographic Faults…
    75. 75. Quality Assessment… • • • • • • Depends onX-Ray equipment Focusing Image processing Patient Operator and radiographic technique. • If radiograph quality is poor, diagnostic information is lost.
    76. 76. i. Light radiographs Underexposure• Insufficient milliamperage • Insufficient peak kilovoltage • Insufficient exposure time • FS- Film distance to much • Film packet reversed Processing errors• Underdevelopment (Low temp, short time) • Depleted developer solution • Diluted or contaminated developer • Excessive fixation
    77. 77. ii. Dark radiographs Overexposure• Excessive milliamperage • Excessive peak kilovoltage • Excessive exposure time • FS- Film distance to short Processing errors• Overdevelopment (high temp, long time) • Developer concentration high • Inadequate fixation • Improper safe lighting • Accidental exposure to light
    78. 78. iii. Insufficient contrast • Underdevelopment • Underexposure • Excessive peak kilovoltage • Excessive film fog iv. Film Fog • • • • • Improper safe lighting Light leaks Over development Contaminated solutions Deteriorated films
    79. 79. • Light leaks • Turning on the overhead white light too soon Light fog Deterio ration Radiatio n fog of the film • Temperature of • Improper storage storage area too • Insufficient Chemical fog high protection • Too high • Developer humidity temperature too high • Overdevelopment
    80. 80. v. Dark spots or line • Finger print contamination • Black wrapping paper sticking to the film • Film in contact with tank or another film during fixing • Film contaminated with developer before developing • Excessive bending • Static charge to film before processing • Excessive roller pressure or dirty rollers
    81. 81. vii. Light spots • Film contaminated with fixer before processing • Film in contact with tank or another film during development • Excessive bending of the film
    82. 82. viii. Yellow or Brown stains • Depleted developer • Depleted fixer • Insufficient washing • Contaminated solutions
    83. 83. ix. Herring bone or tire track appearence • Placement of the film backwards, with the lead foil facing the xray tube.
    84. 84. x. Blurring Motion blurring Head rest Short exposure time Image receptor blurring Slow speed films Finer grain size Close contact between film and screen Geometric blurring Double Parallax exposure Wet film viewing avoided Intensifying screens
    85. 85. xi. Partial images • Top of the film not immersed in the developing solution • Misalignment of the x-ray tube head (Cone cut).
    86. 86. x. Emulsion peel • Abrasion of the film during processing. • Excessive time in wash water. • Improper handling of the film. xi. Typical positioning faults Incorrect positioning of the x-ray tube Incorrect placement of the film packet head Foreshortening Reverse placement Elongation Double exposure Overlapping Cone cut
    87. 87. Overlapping crown regions due to faulty horizontal angulation of the tube head. Double exposure of the same film.
    89. 89. • Extraoral radiograph are examination made of the head and facial region using films located outside the mouth. • They are taken when large areas of the skull or jaw must be examined or when patients are unable to open their mouths for film placement and areas not fully covered by IOPA. • Images are not as defined or sharp as intraoral films.
    90. 90. Extraoral radiographs can be used alone or in conjunction with intra oral radiographs. Except for the panoramic radiographs, extraoral radiographs are not frequently used by General practitioners. Major users are orthodontistic, prosthodontic and oral surgeries
    91. 91. Purpose and use of extraoral radiographs Examine large areas of the jaws and Skull. Evaluate TMJ Disorders. Detect and evaluate impacted teeth. Detect pathological lesions and Diseases of the jaws. Cervical spine for diseases Detect fractures and evaluate trauma Study growth and development of bone and teeth
    92. 92. TECHNIQUE Many film positions and techniques require …..special equipment's and …a sound knowledge of the anatomical structures through which the radiation beam is directed. …produced with conventional dental x-ray machines, certain models of panoramic machines or higher capacity medical x-ray units. Cassette, Films, Intensifying Screens . grids
    93. 93. Image receptor • Cephalometric and skull views - 20x25cm (8x10 inch) image receptor. • Lateral oblique projections of the mandible 13x18cm (5x7 inch) image receptor. • Panoramic views - 12.7x30.5cm (5x12 inch) or 15x30cm (6x12 inch)image receptor.
    94. 94.  It is critical to correctly and clearly label the right and left sides of the image.  It is done by placing a metal marker of R or L on the outside of the cassette in a corner in which the marker does not obstruct diagnostic information.  The proper exposure parameters depend 10 on the patient‟s size, anatomy and 65 mA head orientation,image receptor Kvp speeds,x-ray source to receptor 3 to distance and the use of grids. 4 sec
    95. 95. The main anatomical landmark used in patient positioning is the CANTHOMEATAL LINE. The canthomeatal line forms approximately a 10degree angle with the FRANKFORT PLANE.
    96. 96. Lateral cephalometric projection of the sagittal or median plane. Submentovertex projection of the transverse or horizontal plane. Water‟s of the coronal or frontal plane. Posteroanterior cephalometric projection of the coronal or frontal plane. Reverse-Towne projection of the coronal or frontal plane. Lateral oblique projection of the mandibular body and ramus. Temperomandibular joint projections Newman and Friedman Technique Orthopantomography
    97. 97. Cephalometric Radiographs Cephalometric means measurements of the head. Either conventional x-ray machines modified for Cephalometric work or special units are needed Frontal (Posteroanterior) Lateral skull projections.
    98. 98. LATERAL SKULL PROJECTION (LATERAL CEPHALOMETRIC PROJECTION) It shows the entire skull from the side •Measure and compare changes in Growth and development of bone and the teeth through pre & progress and post treatment records. Facial soft tissue profile of the face 1. The contour of the lips and the face. 2. The relation ship of the teeth before removal, this will helps to construct prosthetic appliances that look natural. •Evaluate trauma. •To determine the location and extent of fractures. •Malignancies. •injuries to TMJ
    99. 99. LATERAL SKULL PROJECTION (LATERAL CEPHALOMETRIC PROJECTION) Image receptor and patient placement A wedge filter at the tube head is positioned over the The image receptor The site of interest The patient is anterior aspect of is positioned is placed towards placed with the left the beam to absorb parallel to the the image receptors side towards the some of the patient‟s to minimize radiation and to image receptor midsagittal plane distortion allow visualization of soft tissues of the face.
    100. 100. Position of the central x-ray beam The central beam is perpendicular to the midsagittal plane of the patient and the plane of the image receptor and is central over the external auditory meatus
    101. 101. Cephalostats have ear rods that stabilizes the patient‟s head parallel to the film and at right angle to the direction of the beam The Cephalometer allows the exposure to be taken several times for the same patient in the same head position
    102. 102. Cephalostat Film X-ray source 5 feet • For cephalometric applications the distance should be 152.4 cm (60 inches) between the x-ray source and the midcoronal plane. • This increased distance provides an resultant image with a broader gray scale of the patient.
    103. 103. Resultant image Exact superimposition of right and left sides is impossible because Bilateral structures close to the structures on the midsagittal plane demonstrate less side near the image discrepancy in size compared with receptor are bilateral structures farther away from magnified less than the midsagittal plane. the same structure on the side far from the image receptor. Structures close to the midsagittal plane (e.g., the clinoid processes and inferior turbinate's) should be nearly superimposed.
    104. 104. Posteroanterior (PA) cephalometric projection Shows the entire skull in a Posteroanterior plane. The beam passes through the skull in a posterior to anterior direction. USES • Asymmetry • Trauma • Developmental abnormalities • Fractures of skull vault • Investigation of frontal sinus • Conditions affecting cranium( Paget's disease, multiple myeloma, hyperparathyroidism. ) • Intracranial calcification
    105. 105. • The image receptor is placed in front of the patient, perpendicular to the midsagittal plane and parallel to the coronal plane. • The patient is positioned so that the canthomeatal line forms a 10-degree angle with the horizontal plane and the frankfort plane is perpendicular to the image receptor.
    106. 106. The central beam is perpendicular to the image receptor, directed from the posterior to the anterior (hence the name postero-anterior) parallel to patient‟s midsagittal plane and is centred at the level of the bridge of the nose
    107. 107. The midsagittal plane should divide the skull into two symmetric halves. The superior border of the petrous ridge should lie in the lower third of the orbit. Resultant image
    108. 108. Water‟s view projection Also known as sinus projection. It‟s similar to the postero-anterior projection except that the center of interest is focused on the middle third of the face. To Evaluate the maxillary, frontal and ethmoid sinuses.. Detecting the lefort‟s fractures, zygomaticcomplex, nasoethmoidal fractures, orbital blow out fractures.
    109. 109. technique The image receptor is placed in front of the patient and perpendicular to the midsagittal plane.. The patient‟s head is tilted upwards so that the canthomeatal line forms a 37-degree angle with the image receptor. The central beam is perpendicular to the image receptor and centered in the area of the maxillary sinuses. If the patient‟s mouth is open, the sphenoid sinus will be seen superimposed over the palate.
    110. 110. The midsagittal plane should divide the skull image in to two symmetrical halves. The petrous ridge of the temporal bone should be projected below the floor of the maxillary sinus Resultant image
    111. 111. Reverse –towne (open mouth) projection Purpose: To examine fractures of the condylar neck of the mandible. Intracapsular fractures of the TMJ. Condylar hyperplasia or hypoplasia.
    112. 112. technique The image receptor is placed in front of the patient, perpendicular to the midsagittal and parallel to the coronal plane. The patient‟s head is tilted downward so that the canthomeatal line forms a 25 to 30-degree angle with the image receptor. The central beam is perpendicular to the image receptor and parallel to patient‟s midsagittal plane and it is centered at the level of the condyles. To improve the visualization of the condyles, the patient‟s mouth is opened so that the condylar heads are located inferior to the articular eminence.
    113. 113. The midsagittal plane (imaginary line extending from the middle of the foramen magnum and the posterior arch of the atlas through the middle of the bridge of the nose and the nasal septum) should divide the skull image into two symmetric halves. The petrous ridge of the temporal bone should be superimposed at the inferior part of the occipital bone and the condylar heads should be projected inferior to the articular eminence. Resultant image
    114. 114. Submentovertex (base) projection Purpose: Used to show the base of the skull. The position and orientation of the condyles Sphenoid sinus Fractures of the Zygomatic arch.
    115. 115. technique The image receptor is positioned parallel to patient‟s transverse plane and perpendicular to the midsagittal and coronal plane. To achieve this, the patient‟s neck is extended as far backward as possible with the canthomeatal line forming a 10-degree angle with the image receptor. The central beam is perpendicular to the image receptor, directed from below the mandible towards the vertex of the skull (hence the name) and centred about 2cm anterior to a line connecting the right and left condyles.
    116. 116. The midsagittal plane should divide the skull image into two symmetrical halves. The buccal and lingual cortical plates of the mandible should be projected as uniform opaque lines. An underexposed view is required for the evaluation of the zygomatic arches because they will be over exposed or “burned out” on radiography obtained with normal exposure factors. Resultant image
    117. 117. Lateral jaw (lateral oblique) projection It has been largely replacead by panoramic radiographs but still taken when image details is needed. Two types Mandibular body projection. Mandibular ramus projection
    118. 118. To Examine the posterior region of the mandible. Patients who have fractures or swelling. Valuable in children, or Senile patients who can’t withstand intraoral films. It evaluate the condition of the bone and to locate impacted teeth or large lesions.
    119. 119. Mandibular body projection – Film placement and head position Cassette is positioned flat against the cheek and centered in the molar- premolar area. The lower border of the cassette is parallel and at least 2 cm below the inferior border of the mandible Head position is tilted about 10 to 20 degree toward the side to be examined and the chin is protruded.
    120. 120. The central ray is directed toward the molar-premolar region of the mandible from a point 2cm below the angle of the opposite side of the mandible
    121. 121. A clear image of the teeth, the alveolar ridge and the body of the mandible should be obtained. If significant distortion is present, the head was tilted excessively. If the contra-lateral side of the mandible is superimposed over the area of interest, the head was not tilted sufficiently. Resultant image
    122. 122. Mandibular ramus projection Image receptor is placed over the ramus and far enough posteriorly to include the condyle. The central beam is directed the center of the imaged ramus, from 2cm below the inferior border of the opposite side of the mandible at the area of the first molar. The lower border of the cassette is parallel and at least 2cm below the inferior border of the mandible. The head is tilted toward the side being examined so that the condyle of the area of interest and the contra-lateral angle of the mandible form a horizontal line. The mandible is protruded.
    123. 123. Resultant image •A clear image of the third molar-retro molar area, angle of the mandible, ramus and condylar head should be obtained. •If significant distortion – head was tilted excessively •If contralateral side of the mandible is superimposed over the area of interest – head was not tilted sufficiently
    124. 124. Trans cranial • It provides a sagittal view of the lateral aspects of condyle and temporal component. Used for Identifying gross osseous changes on the lateral aspect of the joint Range of motion Displaced condylar fractures
    125. 125. Trans pharyngeal ( Parma) projection • It provides a sagittal view of the medial pole of the condyle. • Used for visualizing erosive changes of the condyle -5 degree though the sigmoid notch of the opposite side
    126. 126. Trans orbital It is similar to trans maxillary projection in that both provide an anterior view of the TMJ, perpendicular to trans cranial and trans pharyngeal. Uses: To detect condylar neck fractures
    127. 127. Evaluation of the image • Extra oral images should first be evaluated for overall quality • Interpreting poor quality images can lead to diagnostic errors and subsequent treatment errors. A thorough knowledge of normal radiographic anatomy and the appearance of normal variants is critical for the identification of pathology Abnormalities cause disruption of normal anatomy Detecting the altered anatomy precedes classifying the type of change and developing a DD
    128. 128. Extra-oral Near Parallel Technique This technique is an alternative to the bisecting angle technique, for the maxillary molars. It is of particular use in cats, where the zygomatic arch superimposes over standard intra-oral bisecting angle views. The patient is in lateral recumbency The long axis of the target teeth is as near parallel to the film as possible and the beam is angled at approximately 70 degrees to the film and the target. The mouth is opened, with a prop, to direct the beam onto the film without superimposing the maxillary teeth on the mandibular teeth
    129. 129. Accuracy is dependent on the ability to keep teeth as near parallel to film as possible and to prevent superimposing the maxillary teeth on the mandibular teeth.
    130. 130. OPG
    131. 131. Orthopantomography iIt is a technique for producing single tomographic image of facial structures that includes both maxillary and mandibular dental arches & their supporting structures. • Ortho – correct/straight • Panorama-“an unobstructed view of a region in every direction” • Tomography- “X-ray technique of making radiographs of layer of tissue depth, without interference of tissues above and below it.”
    132. 132. Historical milestones for digital panoramic systems : 1985-1991-The first dental digital panoramic systems were designed by McDavid et al. 1995-DXIS, the first dental digital panoramic x-rays system available in the market, was introduced by Signet of France. Digipan of trophy radiology (France) offered a digital option for the OP 100 panoramic made by instrumentarium (Finland). 1997-SIDEXIS, of siemens (currently sirona dental systems, germany) offered a digital option for ortophos plus panoramic unit. 1998-2004- Many panoramic manufacturers offered their own digital systems. 2006- SCAN300FP, of „Ajat‟ (Finland) is the latest innovation offered
    133. 133. Patero working independently, Numata were the first to describe the principles of panoramic radiography. Dr.PAATERO 1934 Dr. NUMATA 1934 Father of Panoramic Radiography
    134. 134. To interpret OPG competently one must have a thorough understanding of the following : 1. Principles of Panoramic image formation. 2. 3. 4. Techniques for Patient positioning with head alignment and their rationale. Radiographic appearance of normal anatomic structures.
    135. 135. Principles of Panoramic image formation
    136. 136. tube head angled upward film rotation center
    137. 137. ROTATION CENTER is the pivotal point, or Split image axis, around which the cassette carrier and x-ray tube head Moving center rotation – Ellipso pantomography Single-center rotation rotate. * Depending on the ROTATION CENTER manufacturer, the number and location of the rotational center differ: Triple-center rotation Double-center rotation
    138. 138. Double-Center rotation
    139. 139. Triple-center rotation
    140. 140. Parts of the machine X-ray tube head Cassette and carriage assembly Patient positioning device Exposure control
    141. 141. Scanora multimodality Panoramic machine. Orthopantomogra phy op 100 panoramic machine. ProMax (PLANMECA) Panoramic machine.
    142. 142. Focal Trough, focal corridor Three-dimensional curved zone or image layer in which structures are reasonably well defined Depends upon : 1. Arch path 2. velocity of receptor and Tube head 3. Cassette size
    143. 143. The occlusal plane is aligned so that it is lower anteriorly, angled 20 to 30 degrees below the horizontal plane.
    144. 144. Dentoalveolar region Maxillary region Mandibular region The four Diagnosti c regions in OPG TMJ including retro maxillary and cervical region 149
    145. 145. Maxillary region 150
    146. 146. Mandibular region 151
    147. 147. Dentoalveolar region • Shape and angulation of roots. • Alveolar bone and periodontium • Shows gentle curve of occlusal plane 152
    148. 148. Soft tissue images 153
    149. 149. Air spaces 154
    150. 150. Broad coverage of the facial bones and teeth. Ability to be used in patients unable to open their mouths. Low patient radiation dose. Convenience of the examination for the patient. Patient's readily understand of panoramic films, making them a useful visual aid in patient education and case presentation. Short time required - 3 to 4 minutes Easy to store, compared to the large set of intra oral xrays which are typically used Principle advantages of panoramic Images:
    151. 151. D I S A D V A N T A G E S Magnification, Geometric distortion and overlapped images. Resolution of fine anatomic details of peri-apical area and periodontal structures is less. Poor image is obtained when sharp inclination of anterior teeth towards labial or lingual side. The spinal cord superimpose on anterior region. Common to have overlapped teeth images, particularly in premolar area. Artefacts are common and may easily be misinterpreted. Expensive
    152. 152. • First examination of new patients (patients with multiple deep carious lesions, with orthodontic and periodontal problems) U S E S • Early diagnosis of dental anomalies (recommended especially at ages of 10, 15 and 20 years), to check dentition and to provide a timely diagnosis of the odontogenic tumors or cysts • Establishing the exact cause of missing teeth • Radiographic examination of the teeth with endodontic treatment • Odontogenic sinus disease suspicion • Disorders of TMJ caused by malocclusion (in such cases, the Orthopantomogram should be performed with the patient in habitual occlusion) • Facial and maxillary asymmetry • Painful or asymptomatic swelling
    153. 153. • Multiple dental extractions, with suspected osteomyelitis • Examination of non-odontogenic cysts, tumors and tumor-like lesions of bone tumors • Suspicion of invasive bone tumors or bone metastases • Neural tumors • Unusual sensitivity of teeth, unusual eruption, spacing or migration of teeth • Radiographic examination of the oromaxillo-facial area in systemic diseases and syndromes • Maxillo-facial fractures and suspected post-traumatic fractures • Before and after surgery in the oromaxillo-facial surgery.
    154. 154. Panoramic Technique Errors
    155. 155. Ghost image:- A ghost image looks like the real object except that it appears on the opposite side of the film.
    156. 156. Shadow of vertebral column, usually from patient not standing straight
    157. 157. Lead apron shadow
    158. 158. Anterior teeth narrower and blurred
    159. 159. Teeth too posterior Anterior teeth wider and blurred
    160. 160. Structures smaller on the side to which head is turned; larger on opposite side.
    161. 161. HEAD TIPPED DOWN Mandibular incisors shortened, V-shaped mandible
    162. 162. HEAD TIPPED UP Squared-off mandible, palate superimposed over maxillary teeth
    163. 163. REVERSE OPG: Reverse panoramic radiography is a radiographic technique to view the lateral aspect of the condylar head and its neighboring structures more clearly and with less distortion. The technique is simple to perform with the patient in the reverse position in an Orthopantomogram The chin rest was removed so that the patient can be positioned posteriorly such that the condylar region is moved closer to the lateral centre of rotation within a fixed distance between the X ray source and the cassette.
    164. 164. Advances in radiogrpahic techniques
    165. 165. Digital Radiogrpahy •Sustantial amount of bone loss is required in conventional radiograph to be detected in radiograph. •Enables use of computerized images, can be stored, manipulated and corrected. •Image is constructed using pixels •These pixels are arranged in grids and rows on the sensor
    166. 166. Image acquisition Two systems are there Direct Indirect Direct digiital radiogrpahy •Uses (CCD) sensor linked with a fiber optic to the computer system •Real time imaging radiography Disadvantages •Limited sensor area depics one or two teeth •Sensor rigidity
    167. 167. Direct Digital radiography • nondestructive test (NDT) • image is produced electronically, rather than on film, • very little lag time occurs between the item being exposed to radiation and the resulting image. • the electronic image that is viewed results from the radiation passing through the object being inspected and interacting with a screen of material that fluoresces or gives off light when the interaction occurs. • Fluorescent elements of the screen form the image much as the grains of silver form the image in film radiography.
    168. 168. Indirect Digital radiography •Commercial digora system •Uses phosphor luminescence flexible film like radiation sensor placed •Intraorally and exposed to x ray tubes •A laser scanner reads exposed plates offline and reveals digital image data.
    169. 169. Advantages •Dose reduction •Image manipulation •Measurements •3-D reconstruction can be done •Storage •Environmental friendly •contrast, density • magnification of area of interest • edge enhancement Disadvantages • color rendering •Expensive •Sensor cannot be sterlized, barriers can be used but if contamined they have to be discared •Medicolegal purposes- images can be manipulated, there are concerns about their use
    170. 170. • The image formed is a "positive image" since brighter areas on the image indicate where higher levels of transmitted radiation reached the screen. • This image is the opposite of the negative image produced in film radiography. • The lighter, brighter areas represent thinner sections or less dense sections of the test object.
    171. 171. Radio-visography • X rays takes using sensor that transmit images directly onto computer monitor • Helps patient understand the doctors explanation more easily • Enables the doctor to zoom in on a digitizes specific area of tooth • digitizes ionizing radiation • Provides an instantaneous image on video monitor • Reduces exposure by 90% • Equipment has fiber optic intra oral sensor (with selenium coated plate)
    172. 172. Radio-visiography Parts • The radio- hypersenitve intra oral sensor and conventional X-ray unit. • The visio-> video moniter and display processing u • The graphy>high resolution video printer that instantly provides a hard copy of screen images using same video signal.
    173. 173. • • • • • Advantages Elimination of xray film Significant reduction in exposure time Instantaneous image display RVG System appears to be promising for the future of dentistry. Disadvantages •Resolution is slightly lower than convenional films •Exposure above .15s at 75Kp reults in pixels saturation that results in shortening in saturation of the length of the intrument
    174. 174. Digital Substraction Radiography • Image enhancement method • Area under focus being clearly displayed against a neutral gray black background or it is superimposed on the radiographic itself. • Relies on conversion of serial radiogrpahs into digital images • Quantitative changes can be accompalished by eans of a computer (Computer Assisted Substraction Radiography
    175. 175. • Advantages • reduced radiation up to 80% • faster imaging without X-ray film and developing images • digital intraoral sensor is used instead of X-ray film • immediate imaging on the computer screen • high quality of the digital image that can be analyzed and processed • saving images in the patient's file • children friendly for reduced radiation, if imaging is necessary • Evaluation of success of treatment • Changes in alveolar bone levels • Progress of an incipient carious lesion to DEJ Disadvantages or expansion of periapical lesion after RCT • Assessing healing •Need to be close to identical porjection alignment during the exposure of sequential radiographs •Makes this method very impractical in a clinical setting.
    176. 176. • Recently , new image substraction methods DIAGNOSTIC SUBSTRACTION RADIOGRAPHY (DSR) have been introduced combining use of a positioning device during film exposure with a specialized software.
    177. 177. Computed Tomography • powerful nondestructive evaluation (NDE) technique for producing 2-D and 3-D cross-sectional images of an object from flat X-ray images. • Characteristics of the internal structure of an object such as dimensions, shape, internal defects, and density are readily available from CT images.
    178. 178. • The test component is placed on a turntable stage that is between a radiation source and an imaging system. • The turntable and the imaging system are connected to a computer • 2-dimensional shadowgraph image of the specimen just like a film radiograph. • Specialized computer software produces cross-sectional images of the test component as if it was being sliced.
    179. 179. Indications • Investigation of intracranial disease including tumours, haemorrhage & infarcts. • Suspected intra cranial, spinal cord damage. • Fractures-In the orbit, naso- ethmoid complex. - Cranial base. -Odontoid peg - Cervical spine • Cyst-Site, size & extent. • Disease within para nasal air sinuses.• Tumor staging- site, size, extent of affecting different regions. • Tumour and tumour like discreet swellings both intrinsic and extrinsic to salivary glands. • Investigation of osteomyelitis. • Investigation of TMJ. • Preoperative assessment of maxillary and mandibular alveolar bone height.
    180. 180. Advantages  Very small amounts and differences in x-ray thus detailed imaging of intra cranial lesions, imaging of hard and soft tissues both hard and soft tissues.  Axial tomographic sections are obtainable.  Reconstructed images can be obtained from information obtained I the axial plane.  Images an be enhanced by the use of IV contrast media to delineate blood vessels. Disadvantages • Equipment is very expensive. • Very thin contiguous or overlapping slices result in very high dose investigation. • Metallic objects produce marked streak or artifacts. • Inherent risks associated with IV contrast agents.
    181. 181. CONE BEAM CT •Also known as digital volume tomography/(CBCT) are a variation of traditional CTsystems. •used by dental professionals •rotate around the patient, capturing data using a coneshaped X-ray beam. •reconstruct a three-dimensional (3D) image of the following regions of the patient‟s anatomy: dental (teeth); oral and maxillofacial region (mouth, jaw, and neck); and ears, nose, and throat. •One an is 20-40secs, and in one scan image I cylindrical in volume described as field of view. •Field of view of 15cm diameter is used for scanning maxillofacial skeleton
    182. 182. . When compared with ortho pantamogram CT CBCT 200-300 conventional radiographs. 2-8 conventional panoramic radiographs 3D accuitomo images a small cylinder of information thus enabling high resolution images of specific teeth to be obtained. Voxel size is 0.125mm x 0.125 mm x 0.125mm. Dose of this very low when compared to 3-4 peri apical radiographs.
    183. 183. Indications • Investigation of all conditions affecting the mandible or maxilla including cysts, tumours, giant cells and osseous dysplasia. • Cleft palate assesment • Investigation of maxillary antra • Investigation of TMJ. • Implant assessment . • Orthodontic assessment. • Localisation of unerupted tooth/ odontomes. • Assessment of lower 3rd molars . • Investigation of fractures of mandible or middle 1/3rd of facial skeleton. • For multi planar imaging of a single tooth in terms of peri apical & periodontal tissue with high resolution scanners.
    184. 184. Advantage Disadvantage • Multi planar imaging • and manipulation. • • Low radiation dose • Very fast scanning time. • Inexpensive and affordable. • Used mainly for implant and cephalometric • planning Soft tissue detailing is not possible. Computer derived panoramic image I not comparable with conventional panoramic radiographs- particular are is needed for interpretation. Metallic fillings/objects produce streaks and star artefacts like CT. J of canadian dental association 2006
    185. 185. MRI Principle Radio frequency signal emitted by excited hydrogen atoms in the body (present in any tissue containing water molecules) using energy from an oscillating magnetic field applied at the appropriate resonant frequency. The orientation of the image is controlled by varying the main magnetic field using gradient coils. coils are rapidly switched on and off they create the characteristic repetitive noises of an MRI scan. The contrast between different tissues is determined by rate at which excited atoms return to the equilibrium state, Exogenous contrast agents may be given intravenously, orally or intrarticulary.[ Current science , VOL 67 , No 12, 25 dec 1994
    186. 186. Indications • three-dimensional hard- and soft-tissue imaging of teeth without the use of ionizing radiation. • potential to image minute dental structures within clinically relevant scanning times. • Endodontists-potential method to longitudinally evaluate teeth where pulp and root structures have been regenerated. • Distinguish between various soft tissues and localisation of soft tissue lesions. • Stray field microscope- modification of MRI – can detect canals in tooh for endodontic purposes • Differentiate aglossia from hypoglossia • TMJ displacements and related problems J.endod 2011 Jun;37(6):745-52.
    187. 187. contraindications • Ferromagnestic substance s like pacemaker,shrpnels,etc could be disloged causing complications. • Chromic alloy arch wires, stainless steel crowns. Banda and bonded metals cause artifacts
    188. 188. Ultra sound • Non-invasive investigation which use a very high frequency (7.5-20MHz) pulsed ultrasound beam rather than ionizing radiation. • Produces high resolution images of more superficial structures. Oral surg oral med oral pathol oral radiol 203 june
    189. 189. Which is picked up by the transducer and converted into electrical signal then into real time black , white and grey images Ultrasound travels to the skin Some waves are reflected back by tissues to produce echoes.
    190. 190. • sectional image which represents topographical map of depth of tissue interfaces. • thickness is determined by width of ultra sound beam thus different density in the black /white echo picture is described as hypo echoic(dark) or hyper echoic(light). • A change in the frequency of sound reflected from a moving source allows the detection of arterial and venous blood flow - Doppler effect. Oral surg oral med oral pathol oral raiol 203 june
    191. 191. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Indications :- caries detection, dental fractures soft tissue and periapical lesions maxillofacial fractures periodontal bony defects gingival and muscle thickness Temporomandibular disorders Implant dentistry. Evaluation of the swellings of the neck ,those involving thyroid, cervical lymph nodes, major salivary glands thus to detect solid and cystic soft tissue masses. Detection of salivary gland and duct calculi. Determination of vascularity and vascular structures. Assessment of vascularity of carotids and carotid tumors. Sialolithotripter –to break salivary calculi into 2mm fragments thus avoiding major surgery. Ultra sound guided FNA biopsy.
    192. 192. Advantage • Non ionizing radiation. • • No known harmful effects • • Good differentiation between soft and hard • tissues. • • Widely available and relatively in expensive. Disadvantage Bone absorbs ultrasound thus is not detected. Real time imaging. Technique sensitive Difficult to interpret for inexperienced operator. Oral surg oral med oral pathol oral raiol 203 june
    193. 193. Contrast studies Radiopaque substances alter the density of different parts of patient. Thus certain organs , structures, tissues, invisible by conventional means be seen. Alters the subject contrast.
    194. 194. Different contrast studies Sialography –Salivary glands. Arthrography Angiography Lymphography- Lymph nodes and vessels Urography Barium meal, swallow and enema-GI tract. Computed tomographygeneral enhancement.
    195. 195. Indications To show vascular anatomy and feeder vessels associated with haemangiomas. To show vascular anatomy of arterio venous formation Investigation of suspected sub-arachnoid haemorrhage resulting from an aneurysm in the circle of willis. Investigation of transient ischaemic attacks due to emboli from atheromatous plaques.
    196. 196. Complications • Mild. Eg:-Headache, nausea, warmth/pain, flushing, sneezing, constipation. • Moderate. Eg :-Vomiting , bronchopasm, urticaria and hypotension. • Severe. Eg:-Cardiac arrhythmias, cardiac arrest, convulsions, anaphylactic shock and pulmonary edema. • Fatal.
    197. 197. Patients at risk 1. Very young patients 2. Patients with a history of allergy to contrast media 3. Diabetes, patients suffering from cardiac failure, renal failure, severe pulmonary disorders including asthma Cause of complications • Allergy • Chemotoxicity • Osmolality • Anxiety
    198. 198. Hazards of dental x-rays in oral cavity • da Silva et al have demonstrated that panoramic radiography increases the number of nuclear anomalies (except micronuclei), with significant statistically differences in exfoliated cells from the lateral border of the tongue, • were exposed to a repeat radiograph it induces a genotoxic effect on epithelial gingival cells that increases the frequency of chromosomal damage and nuclear alterations indicative of apoptosis. • The comparison of nuclear changes before and after radiation exposure revealed a statistically higher number of broken eggs, buds, karyorrhexis and binucleate cells 10 days after exposure. D . entomaxillofac Radiol. 2012 March; 41(3): 181–184
    199. 199. • X-ray increased other nuclear alterations closely related to cytotoxicity, such as karyorrhexis, pyknosis and karyolysis. • Digital lateral radiography (cephalometric radiography) obtained on a panoramic radiographic machine showed similar results when compared with conventional radiography in oral mucosa cells. • Yoon et al18 revealed high expression levels of pChk2 and γ-H2AX in oral cells after radiation exposure.indicators of low-dose radiation exposure. Dentomaxillofac Radiol. 2012 March; 41(3): 181–184
    200. 200. • When the effect of dental X-ray exposure in children was investigated, no statistically significant differences were found between micronucleated oral mucosa cells before and after radiation exposure. • radiation did lead to other nuclear alterations closely related to cytotoxicity, including karyorrhexis, pyknosis and karyolysis: there were significant statistically. • CBCT in clinical practice evaluated DNA damage (micronucleus) and cellular death (pyknosis, karyolysis and karyorrhexis) in exfoliated buccal mucosa cells from adults. The effective dose was 12 μSv. Dentomaxillofac Radiol. 2012 March; 41(3): 181–184
    201. 201. RADIATION PROTECTION • Radiation is energy in the form of waves or moving subatomic particles.
    202. 202. TYPES OF RADIATION • NON-IONIZING RADIATION • IONIZING RADIATION • capable for producing ions when interact with matter. PARTICULATE (alpha, beta, neutrons)  ELECTROMAGNETIC (X-Rays, Gamma Rays) 
    203. 203. PATIENT EXPOSURE & DOSE • Patient dose from dental radiography is usually reported as the amount of radiation received by a target organ. • Most common measurements is skin or surface exposure. • Other target organs - Mean active bone marrow, thyroid & gonads.
    204. 204. • The International Commission on Radiological Protection (ICRP) devised a system of dose limitation. Based on following general principles: • No practice shall be adopted unless its introduction produces a positive net benefit. • All exposures shall be kept as low as reasonably achievable (ALARA), taking economic & social factors in account. • The dose equivalent to individuals shall not exceed the limits recommended by the commission.
    205. 205. What is ALARA • ALARA is an acronym for As Low As reasonably Achievable. This is a radiation safety principle for minimizing radiation doses and releases of radioactive materials by employing all reasonable methods. • regulatory requirement for all radiation safety programs • Current radiation safety philosophy is based on the assumption that radiation dose and its • biological effects on living tissues are modeled by a relationship known as the “Linear Hypothesis
    206. 206. Mitigation of External Radiation Exposures The three (3) major principles to assist with maintaining doses ALARA are : 1) TIME – minimizing the time of exposure directly reduces radiation dose. 2) DISTANCE – doubling the distance between your body and the radiation source will divide the radiation exposure by a factor of 4. 3) SHIELDING - using absorber materials such as Plexiglas for beta particles and lead for X-rays and gamma rays is an effective way to reduce radiation exposures
    207. 207. Mitigation of Internal Radiation Exposures 1) Good hygiene techniques that prohibit the consumption of food and drink in the lab and the control of personal gestures that involve “hand-tomouth” contacts. 2) Frequent swipe surveys and lab area monitoring of work areas, refrigerators, hoods, sinks, phones and computer keyboards, etc. 3) Control contamination with absorbent paper and spill trays, properly labeled waste containers, equipment, etc. and prompt decontamination of any detected contamination. 4) Use fume hoods for materials which could become airborne (e.g., vapors, dust, aerosols, etc.) and present an inhalation hazard to workers. 5) Use proper protective equipment (PPE) such as disposable gloves, safety glasses, lab coats, etc. to reduce the possibility of ingestion or absorption of radioactive materials
    208. 208. Maximum Annual Occupational Dose Limits Whole Body …………………… 5000 millirem Extremities ……………………. 50000 millirem Lens of the Eye ……………….. 15000 millirem Fetus ……………………………… 500 millirem* Individuals in the General Public …100 millirem * 500 millirem for the fetus is during the gestation period The ALARA concept imposes lower operational dose limits that are even more restrictive than the maximum legal dose limits in the table above. If a radiation worker’s dose for any calendar quarter (3 months) or calendar year (12 month period) exceeds these values, an investigation is conducted by the RSO to determine if there are reasonable ways to reduce the dose levels and discuss with the worker methods for limiting the potential dose
    209. 209. ICRP divided the population into 3 groups: •PATIENTS •RADIATION WORKERS •GENERAL PUBLIC
    210. 210. PATIENTS • Examination directly associated with illness. • Systemic examinations (periodic health checks) • Examination for occupational, medico-legal insurance purposes. • Medical research.
    211. 211. RADIATION WORKERS • Exposed to radiation during the course of their work. • Divided into 2 subgroups depending on the level of occupational exposure:  CLASSIFIED WORKERS  NON-CLASSIFIED WORKERS
    212. 212. CLASSIFIED WORKERS • Receive high levels of radiation exposure to radiation at work (nuclear power industry) • Require compulsory personal monitoring. • Require compulsory annual health checks.
    213. 213. NON-CLASSIFIED WORKERS • Receive low levels of exposure to radiation at work. • The annual dose limits are 3/10 of the classified worker’s limit. • Personal monitoring is not compulsory. • Annual health checks are not required.
    214. 214. GENERAL PUBLIC • Originally set annual dose limits - 5 mSv. • Current recommendation - 1 mSv.
    218. 218. INTRAORAL IMAGE RECEPTOR • In 1920, regular dental X-ray film – EASTMAN KODAK COMPANY. • Intraoral dental X-ray film – D & E speed. • Speed of E-speed film – 2 times of D-speed film & 50 times of regular dental X-ray film. • E-speed film (Ektaspeed film, Eastman Kodak Company) - 1981.
    219. 219. • Patient dose reductions : – 60% compared with E-speed film. – 77% compared with D-speed film. • Digital Imaging – 50 to 95% reduction in patient exposure.
    220. 220. FILMS/INTENSIFYING SCREENS • Calcium tungstate – emits blue light. • Rare earth elements Gadolinium & Lanthanum – emits green light. • Rare earth screens - – 8 times more sensitive to X-rays. – 55% reduction in patient exposure.
    221. 221. FOCAL SPOT TO FILM DISTANCE • 2 standard FSFDs: – 8 inches (20 cm) – 16 inches (41 cm) • Federation Regulation – Minimum X-ray source-skin distance: – 7 inches (18 cm) X-ray tube operating above 50 kVp. – 4 inches (10 cm) X-ray tube operating below 50 kVp.
    222. 222. • COMPARISION OF 16 INCHES AND 8 INCHES FOCAL SPOT: – 38% decrease in thyroid dose with 90 kVp X-rays. – 45% decrease in thyroid dose with 70 kVp X-rays. • Longer FSFD – 32% reduction in exposed tissue volume.
    223. 223. COLLIMATION • Helps to control the size & shape of X-ray beam. • Recommended beam size – 23/4 inches.
    224. 224. • Decreases radiation exposure. • Minimizes scattered radiation Decreases fogging of film Sharper image & better contrast
    225. 225. • Collimation is done with lead diaphragm within the tube head or at the end of leadlined cylinder. • 2 types : Round & Rectangular.
    228. 228. • Round collimator – 3 times the area necessary to expose the film. • Rectangular collimator reduces patient dose approx 55%.
    229. 229. FILTERATION • Filteration removes the low energy X-ray photons selectively from the X-ray beam. • Filteration is stated in mm of Al.
    230. 230. TYPES OF FILTERATION • INHERENT FILTERATION – 0.5 to 1.0 mm of Al. • ADDED FILTERATION – 0.5 mm of Al. • TOTAL FILTERATION – Inherent + Added filteration
    231. 231. • X-ray beam filtered with 3 mm of Al – surface exposure reduces by 20%.
    232. 232. • Al + rare earth materials like Samariun, Erbium, Yttrium, Niobium, Gadolinium, etc • Selective filteration of low & high energy photons ( X-ray energies most effective in producing image: 35 keV to 55 keV) • Reduces patient exposure by 20% to 80%
    233. 233. POSITION INDICATING DEVICE (PID) • • • • PID - an extension of X-ray tubehead. Direct the X-ray tube. Minimize the volume of tissue irradiated. 3 basic types : – Conical – Rectangular – Round
    234. 234. CONICAL PID
    236. 236. • PIDs are commonly available in 3 lengths : – 8 inches – 12 inches – 16 inches • Long PID is preferred.
    237. 237. FILM HOLDING DEVICE • Helps to stabilize the film position in the mouth.
    238. 238. OFFER PROTECTION TO THE PATIENT : • Reduces frequency of retakes. • External guide to indicate the film position. • Possibility of misalignment of the X-ray tube. • Collimate the beam to the size of film being used. • Reduction in the exposure to patient’s fingers.
    240. 240. LEAD APRONS • A flexible shield of lead placed over the patient chest & lap. • To protect reproductive organs & bone marrow. • Recommended for all intraoral & extraoral radiography. • Protective equivalent – 1/4 mm of Pb.
    241. 241. LEAD APRONS
    242. 242. • Attenuate 98% of scatter radiation to the gonads. • LEADED TORSO (BODY) aprons
    243. 243. THYROID COLLAR • Flexible lead shield placed securly around the patient’s neck. • Protect thyroid gland. • Recommended for intraoral radiographs. • Reduce the thyroid gland exposure by 92%.
    244. 244. CHOICE OF INTRAORAL TECHNIQUE • Bisecting angle technique • Paralleling long cone technique • Rinn XCP instrument / Precision instrument.
    246. 246. KILOVOTAGE (kVp) • X-ray machine : 70 – 90 kVp. • Produce fewer low-energy X-rays. • Gibbs etal (1988) reported that effective dose reduces to 23% - increasing kVp from 70 to 90 kVp. • Constant potential X-ray machine – reduces patient exposure by 20%.
    247. 247. • Higher kVp – periodontal diagnosis. • Low kVp – caries or soft tissue calcification.
    248. 248. MILLLIAMPERE-SCONDS (mAs) • X-ray machine : 8-10 mA. • IMAGE DENSITY – milliamperage & exposure time. • Exposure time – most crucial factor influencing diagnostic quality of radiographs.
    249. 249. TIMER • Timer on the X-ray machine should be electronic. • “dead-end” control. • Calibrated in 60th of sec.
    251. 251. DARKROOM LIGHTING • • • • Kept free from light leaks. Safelight filter – Kodak GBX-2 (red light) 15 watt bulb. Safelight lamps – min of 4 ft from working area.
    252. 252. FULL DEVELOPMENT PROCESSING • Time-temperature processing • Radiation exposure may be decreased by 25%. TEMPERATURE (in OF) 68 70 72 DEVELOPMENT TIME (in min) 5 41/2 4 76 80 3 21/2
    253. 253. PROCESSING SOLUTIONS • • • • Changed regularly Stirred thoroughly twice each day Kept covered to prevent oxidation Not subjected to excessively high temperatures. • Weekly quality control checks. • Chemicals should be replenished according to manufacturer’s instructions.
    254. 254. INTERPRETATION OF RADIOGRAPHS • Viewed in a dimly lit room with a properly functioning illuminator (view-box). • Illuminator with variable intensity.
    255. 255. OPERATOR RADIATION PROTECTION 3 basic methods to reduce occupational exposure: • POSITION • DISTANCE • SHIELDING
    256. 256. DISTANCE RECOMMENDATIONS • 6 feet away from X-ray tubehead during exposure. • When distance is not possible – Protective lead barrier
    257. 257. POSITION RECOMMENDATIONS • 90o to 135o angle to the primary beam. • Never hold a film in place for a patient • Never hold or stabilize the tubehead ………during radiation exposure.
    258. 258. Dystrophic nail changes carcinoma Squamous cell
    259. 259. POSITION DISTANCE RULE “The operator should stand at least 6 feet away from the patient in a safe quadrant at an angle of 90o to 135o to the central ray of X-ray beam.”
    261. 261. ROLLING RADIATION PROTECTION SHIELD • Offers 0.5 mm lead protection. • Measures 24 X 231/2. • Adjusts 36”-56” above the floor.
    262. 262. PROTECTION OF THE ENVIRONMENT • Surrounding environment must be protected from radiation to avoid the exposure of persons in the environment. • Primary beam should never be directed at any one other than the patient. • X-ray beam is aimed at the wall of the room and not through door.
    263. 263. QUALITY ASSURANCE “Any systemic action to ensure that a dental office will produce consistently high-quality images with minimal exposure to patients & personnel.” “Currently some state require dental offices to establish written guidelines for quality assurance & maintain written records of quality assurance test.”
    264. 264. X ray unit Dark room maintenanc e Ancillary instrument maintenan ce Leakage radiation Quality assurance Timer accuracy Collimatio n Stability of tube housing
    265. 265. MONITORING DEVICES AVAILABLE: • ELECTRICAL – Ionization chamber – Thimble chamber – Geiger counter • CHEMICAL – Film – Chemical dosimeter • LIGHT – Scintillation counter – Gerenkov counter • THERMOLUMINESCENCE – Thermoluminescent dosimeter • HEAT – Calorimeter
    267. 267. • Modified version of badge
    268. 268. THERMOLUMINESCENCE DOSIMETER (TLD) • Most common personal monitoring device. • Used for measurements of the actual dose received by the operator.
    269. 269. ELECTRONIC DOSIMETER • 5 to 200 times more sensitive than TLD. • With an audible alarm system.
    270. 270. Unique Considerations for Radiation Exposure in Children in CT scans • There are three unique considerations in children. • Children are considerably more sensitive to radiation than adults, as demonstrated in epidemiologic studies of exposed populations. • longer life expectancy than adults- larger window of opportunity for expressing radiation damage. • The risk for developing a radiation-related cancer can be several times higher for a young child. • The use of more than one scan further increase the radiation dose. • Majority of cases, a single scan should be sufficient during pediatric CT. University of Michigan Children hospital site
    271. 271. Radiation reduction Perform only necessary CT examinations• When appropriate, other modalities such as ultrasound MRI, which do not use ionizing radiation, should be considered. Adjust exposure parameters for pediatric CT based on • • – Child size: guidelines based on individual size / weight parameters should be used. – Region scanned: the region of the body scanned should be limited to the smallest necessary area. – Organ systems scanned: lower mA and/or kVp settings should be considered for skeletal, lung imaging, and some CT angiographic and follow up examinations. Scan resolution: the highest quality images are not always required to make diagnoses. many cases, lower-resolution scans are diagnostic. Providers should be familiar with the multiphase examinations. These result in a considerable increase in dose and are rarely necessary, especially in body (chest and abdomen) imaging. University of Michigan Children hospital site
    272. 272. CONCLUSION Although these radiographic techniques are essential in arriving at a diagnosis, appropriate usage of the right technique in the right time to an apt condition becomes vital to the clinician in guiding to arrive at a conclusion for diagnosis and there by treatment planning “value of a diagnostic procedure depends upon the amount of information that can be derived from it”
    273. 273. References  Principles and Interpretations of Oral Radiology, 5th Edition By Stuart C.WHITE and MICHAEL J.Pharoah.  Essentials of Dental Radiography, 3rd Edition by Haring .  Text Book of dental and maxillofacial Radiology By Frenry R. Karjodkar..  Essentials of Dental radiology and radiology,3rd edition, Eric whites  Text book of Pedodontics (Mc Donald & Avery)  Oral radiology- principles and interpretation; Paul W. Goaz, Stuart C. White  Web Page – Radiographic techniques for pediatric patients (steven Schwartz)  Intra-Oral Radio Graphs for the Pediatric Dental Patient Pedo- fourth molar web page