Radiology

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Radiology

  1. 1. dr.ESLAM MOSAAD
  2. 2. History History History X-ray X-rays were first discovered in 1895 by Wilhelm Conrad Roentgen, the professor of physics and director of the physics institute at the University of Wurzburg in Bavaria. Hence the term ROENTGEN RAYS, often applied to mechanically generated x-rays. He won a Noble prize for his discovery of X-ray. Roentgen called them X-rays after the mathematical symbol X for unknown. dr.ESLAM MOSAAD
  3. 3. History History History X-ray of Bertha Roentgens Hand Roentgen soon found that photographic plates were sensitive to the newly discovered rays. He convinced his wife to participate in an experiment. Roentgen placed her hand on a cassette loaded with a photographic plate. He then aimed the activated cathode ray tube at her hand for fifteen minutes. When the image was developed, the bones of her hand and the two rings she wore were clearly visible. dr.ESLAM MOSAAD
  4. 4. History History History Early x-ray machine. Arrow points to “live” electrical wire. dr.ESLAM MOSAAD
  5. 5. Specialized radiography.• Panoramic radiography.• Computed Tomography.• Sialography.• Ultrasonography.• Magnetic resonance image.• Nuclear medicine. (Radio nuclide imaging )• Digital imaging.• Arthrography.• Electronic thermography.• Endoscopy. dr.ESLAM MOSAAD
  6. 6. Panoramic radiographyrotational radiography, or curved surface tomography It is a radiographic technique forproducing a single image of the facialstructures that includes both maxillary andmandibular arches and their supportingstructures. dr.ESLAM MOSAAD
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  8. 8. As Tomographic principles, the x-raytube and film cassette rotate in oppositedirections around the patient’s head toproduce a specific curved image of themaxilla and mandible on the film. dr.ESLAM MOSAAD
  9. 9. dr.ESLAM MOSAAD
  10. 10. • In panoramic technique, during exposure, the x-ray source moves in one direction while the film moves in the opposite direction• The area of the object in the center of this movement will appears in focus and very sharp on the resultant radiograph as its shadow.• All other structures will appears blurred or out of focus dr.ESLAM MOSAAD
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  13. 13. Diagnostic imaging and techniques, help develop and implement a cohesive and comprehensive treatment plan to the implant patient.Diagnostic Imaging objectives depend on a number of factors including :• The amount and type of information required• The time period of the treatment rendered. dr.ESLAM MOSAAD
  14. 14. Imaging modalities• Depend on the patient clinical needs.• The imaging modality should yield the necessary diagnostic information versus the least radiologic risk.• Examinations that are known to produce this result are not necessarily those that cost the least.• Basically the dentist should use the modality that provides the standard of proper care . dr.ESLAM MOSAAD
  15. 15. Imaging modalities can be described as 1-Analogue-2 dimensional systems-use x-ray films or intensifying screens dr.ESLAM MOSAAD
  16. 16. 2-Digital• Two dimensions : described by an image matrix that has an individual picture elements called (pixels)(width X height)• Three dimensions: described by an image matrix that has an individual picture elements called(voxels) (width X height X depththickness) dr.ESLAM MOSAAD
  17. 17. The decision of when to image along with whichmodality to use depends on the integration of theprevious factors and can be organized into threephases: dr.ESLAM MOSAAD
  18. 18. Phase one :preprosthetic implant imaging dr.ESLAM MOSAAD
  19. 19. Global objectives• Develop and implement a treatment plan for the patient that enables restoration of the patient’s function and esthetics. dr.ESLAM MOSAAD
  20. 20. Specific Objectives:• identify disease.• determine bone quality.• determine bone quantity.• Determine implant position.• Determine implant orientation. dr.ESLAM MOSAAD
  21. 21. Imaging modalities 1-analog imaging modalities.• -periapical radiography.• -panoramic radiography.• -occlusal radiography.• -cephalometric radoigraphy. dr.ESLAM MOSAAD
  22. 22. 2-three dimensional imaging modalities-computed tomography-magnetic resonance imaging-interactive computed tomography. dr.ESLAM MOSAAD
  23. 23. 1-periapical radiographsThese are images of a limited region of the mandibular and maxillary alveolus.• Common technique used: long cone paralleling technique,to eliminate and to limit the magnification distortion to less than 10%.• Film used :commonly among our clinics is no.2 size dental film which provides (25-mm X 40-mm)view of the jaws. dr.ESLAM MOSAAD
  24. 24. In terms of objectives of preprosthetic imaging• Useful high –yield modality for ruling out local bone and dental disease.• Of value in identifying critical structures but of little use in depicting the relationship between the proposed implant site and those structures.• Limited value in determining quantity because the image is magnified and does not depict the third dimension of bone width. dr.ESLAM MOSAAD
  25. 25. • Limited value bone density or mineralization(the lateral cortical plates prevents accurate interpretation and cannot differentiate the subtrabecular bone changes. These films most often are used for single- tooth implants in region of abundant bone width. dr.ESLAM MOSAAD
  26. 26. 2-Occlusal radiographsCommon technique used :placing the film intraorally parallel to the occlusal plane with the central X-ray beam 1)oblique usually 45degrees for the maxillary images ,this is why the images are inherently distorted. dr.ESLAM MOSAAD
  27. 27. 2) perpendicular to the film for the mandibular image ,which is usually less distorted than the maxillary image ,but the mandibular alveolus generally flares anteriorly and demonstrates lingual inclination in the posterior region, producing an oblique and a distorted image .• As a result occlusal radiographs rarely are indicated for preprosthetic phases in implant patient. dr.ESLAM MOSAAD
  28. 28. 3-cephalometric radiographs.• These films usually provide useful information for the 1-cortical thickness , 2-height and 3-width of the alveolar ridge at the mid line ,as well as the 4-skeletal relationship between the maxilla and the mandible and 5-facial profile.• Their use in implant patient is limited to structures at the mid line , with minimal usefulness for other areas of the jaws. dr.ESLAM MOSAAD
  29. 29. A cephalometric film. dr.ESLAM MOSAAD
  30. 30. 4-panoramic radiography.Curved plane tomographic radiographic technique used to depict the body of the mandible , maxilla and the lower half of the maxillary sinuses in a single images. dr.ESLAM MOSAAD
  31. 31. Advantages of panoramic radiographs• Opposing land marks are easily identified .• The vertical height of bone initially can be assessed.• Convenient ,easy and speed procedure that can be carried in most dental offices.• Gross anatomy of the jaws and related pathologic findings can be evaluated.• Popular and widely available technique in dentistry. dr.ESLAM MOSAAD
  32. 32. disadvantages• Does not demonstrate bone quality minerlaization.• Misleading because of magnification and third dimensional cross sectional view is abscent.• Does not depict the spatial relation between the structures and dimensional quantitation of the implant site. dr.ESLAM MOSAAD
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  34. 34. • Diagnostic templates that have 5-mm ball bearings or wires are incorporated around the curvatureof the dental arch and worn by the patient ,to enable the dentist to evaluate the magnification in the radiograph. dr.ESLAM MOSAAD
  35. 35. • Recently a modification of the panoramic x-ray machine developed that has the ability of making cross sectional image of the jaws.• These devices use limited angle linear tomography (zonography) and means of positioning the patient.• Tomographic layer of 5mm.• This technique enables correlation between spatial structures and implant sites and quantification of the geometry of the implant site. dr.ESLAM MOSAAD
  36. 36. 5-Tomgraphy• This is a generic term formed from greek words tomo (slice) and graphy (picture).• It describes all forms of body sectoin radiography.• It is a special X-ray technique that enables visualization of a section of the patient anatomy by blurring regions of the patient’s anatomy. dr.ESLAM MOSAAD
  37. 37. • In conventional tomography the X-ray source and the film are connected and rotate around a fixed point(fulcrum)usually performing simple ( linear )or complex (elliptic or hypocycloidal)tomographic motions.• Structures that are in the plane (focal area)of rotation do not move in realtion to the tube and the film and thus are depicted in the sharp focus .• Structures outside the plane of rotation are blurred progrssively depending on their distance from the focal plane. dr.ESLAM MOSAAD
  38. 38. Advantages :with proper patient seating• Generates a true cross section of the alveolar ridge.• Provide diagnostic information of the cortical thikness , trabecular density , height and width of the alveolus and location of vital anatomic structures.• Imaged structures are predictably magnified , so measurments made of tomograms can be adjusted to provide accurate angular and linear assesments. dr.ESLAM MOSAAD
  39. 39. • Dose is limited as the area of the jaw imaged is limited• Useful during the placement of a single or few implants. dr.ESLAM MOSAAD
  40. 40. Disadvantages• Equipment requires familiarity with the image acquissaton.• Image interpretation is some times challenging . especially when the anatomy of the jaws are altered because of traumatic extractions , alveolar ridge resorption , and other conditions. dr.ESLAM MOSAAD
  41. 41. • The progressive blurring of structures outside the focal plane does not allow sharply defined tomographic slices , the prominent opaque structures can cast ( ghost ) shadows and complicate the images.• Generated images are created once a time ,so patient has to be repositioned each time dr.ESLAM MOSAAD
  42. 42. 6-Computed tomography(CT)• CT was invented by sir Hounsfield in1972.• CT enabled differentiation and quantification of soft and hard tissues.• The individual element of the CT is called a voxel , which has a value referred to in Hounsfield units,that describes the denisty of the CT image at each point .• Each voxel contains 12bits of data and ranges from -1000 (air) to +3000 (enamel /dental materials)and 0 for water. dr.ESLAM MOSAAD
  43. 43. • A thin fan-beam of X-rays rotates around the patient to generate in one revolution a thin(0.5-1.00mm wide)axial slice of the area of interest.• Multiple overlapping axial slices are obtained by several revolutions of the X-ray beam until the whole area of interest is covered.• The image detector is Gaseous or solid state ,producing electronic signals that serve as input data for a dedicated computer .• The computer processes the data using back –projection fourier algorithm techniques. dr.ESLAM MOSAAD
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  47. 47. • A three dimensional digital map of the jaws are constructed,and a specialized software can be used to generate approprite views that can depict the dimensions of the jaws and the location of the important anatomic structures.• Typical dental views obtained from a CT scan include axial ,panoramic,and cross- sectionalviews of the jaws. dr.ESLAM MOSAAD
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  50. 50. Advantages• True cross sections offer a precise and detailed evaluation of the height and width of the alveolar ridge.• The images can be adjusted and printed without magnification. , facilitating measurments directly from the prints or films . with standard rulers not magnified.• Anatomic structures can be visualized and analyzed at all three coordinate axes.• Bone and soft tissue contrast and resolution are excellent for the diagnostic task. dr.ESLAM MOSAAD
  51. 51. Disadvantages• requires specialized equipment.(expensive)• High radiation dose compared to other modalities.• Metallic restorations cause ring artifacts. dr.ESLAM MOSAAD
  52. 52. Dentascan imaging• Provides programmed reformation , organization , and display of the imaging study.• The radiologist determines the curvatures of the maxillary or the mandibular arch and the computer is programmed to determine referenced cross sectional and tangentialpanoramic images of the alveolus along with three dimensional images of the arch.• The cross sectional and panoramic images are spaced 1mm apart and enable accurate pre prosthetic treatment planning. dr.ESLAM MOSAAD
  53. 53. Denta scan images ofreformated andreorganized CT images dr.ESLAM MOSAAD
  54. 54. Limitations• May Not be true in size ,and require compensation for magnification .usually a diagnostic template is required to take full advantage of the technique.• The diagnostic template usually contains lead balls of known diameter ,to calculate the magnification. dr.ESLAM MOSAAD
  55. 55. 7-Cone beam computed tomography• CBCT scanners generates a cone shaped X-ray beam in contrast to the fan shaped beam produced by CT scanners.• Images are generated in 1- degree increments, at the end of a single rotation 360 images are created.• Computer then uses these images to create a 3-D map of the face.• Multiplanar reconstructions of sections of variable thickness can be reconstructed as the CT scan. dr.ESLAM MOSAAD
  56. 56. • CBCT offers the same advantages and disadvantages of CT, with only few differences.The most important difference is that• CBCT delivers a radiation dose which is similar to full mouth x-ray, this is 50-100 times less the radiation dose deliverefor CT.d dr.ESLAM MOSAAD
  57. 57. Interactive computed tomography• A technique that was developed to bridge the gap in information transfer between the radiologist and the practitioner.• Dentist’s computer becomes a radiologic workstation with tools to measure the length and the width of the alveolus,measure bone quality,and change the window and level of the grayscale of the study to enhance the perception of the critical structures. dr.ESLAM MOSAAD
  58. 58. • Electronic surgery(ES) can be performed by the dentist and the radiologist .• By selecting arbitrary –size cylinders that simulates root form implants in the images .• With appropriate diagnostic template ,ES can be performed to develop the patient’s treatment plan electronically in three dimensions. dr.ESLAM MOSAAD
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  60. 60. Advantages• Three dimensional treatment plan that is integrated with the patient’s anatomy and can be visualized before surgery.• Enables the determination of bone quality adjacent to the prospective implant sites. Limitations• Refinement and exact orientation (parallelism of the electronic implants is difficult dr.ESLAM MOSAAD
  61. 61. 8-Magnetic resonance imagingTechnique :• Imaging protons of the body using magnetic field ,radio frequancies,and electromagnetic detectors and computers . dr.ESLAM MOSAAD
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  64. 64. Usage :• When complex tomography fails to differentiate inferior alveolar canal in about 60 % of cases and CT fails to differentiate the inferior alveolar canal in about 2% of the cases.• MRI visualizes the fat in the trabecular bone and differentiates the inferior alveolar canaland neuro vascular bundle from adjacent trabecualr bone. dr.ESLAM MOSAAD
  65. 65. Limitations• Not useful in characterizing bone mineralization or as a high-yield technique for identifying bone or dental disease. dr.ESLAM MOSAAD
  66. 66. Diagnostic templates• Purpose :is to incorporate the patient proposed treatment plan into the radiographic examination• The pre prosthetic imaging procedure enables evaluationof the proposed implant site at the ideal position and orientation identified by radiographic markers incorporated into the template. dr.ESLAM MOSAAD
  67. 67. Several types for diagnostic templates to be effective and more precise1-clear acryl and radio opaque denture teeth.2-acryl and the restoration sites is covered by barium sulfate and filling a hole drilled through the occlusal plane with guttta percha..• N.B : do not use metal markers if CT or CBCT is going to be carried. dr.ESLAM MOSAAD
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  69. 69. Surgical templates: dr.ESLAM MOSAAD
  70. 70. CAD-CAM STEREOTACTIC SURGICAL TEMPLATES• Depends on producing a three dimensional model of the patient’s alveolar anatomy using a computer aided manufacturing (CAD-CAM) and rapid proto typing procedure.• Derived from the model by aligning cylinders at the implant sites which just accommodate pilot drill.• Used to establish pilot drilling up to 10mm then the template is removed and the osteotomies Are completed. dr.ESLAM MOSAAD
  71. 71. Phase two surgical and interventional implant imaging• Involves imaging the patient during and immediately after surgery.Purpose:• Evaluation of depth of implant placement.• Position and orientation implant osteotomies.• Evaluation of graft sites. dr.ESLAM MOSAAD
  72. 72. • This is usually carried at the dentist’s office this is why it is usually the periapical and the panoramic radiography.• Digital radiography software facilitated the process. dr.ESLAM MOSAAD
  73. 73. Advantages of digital radiography for the implant surgery.• Fast• Low radiation.• Calibration.• Magnification.• Excellent quality.• Measures depth,density, and neighbouring structures.• Patient stays in surgical setting• Keeps aseptic setting dr.ESLAM MOSAAD
  74. 74. Phase three post prosthetic implant imagingPurpose:• Evaluate status and prognosis of the dental implants.• Evaluate bone adjacent to the implant for changes in mineralization or bone volume. dr.ESLAM MOSAAD
  75. 75. Peripaical radiography: Produces high resolution planer images of the dental implant and the alveolar bone adjacent to the implant. dr.ESLAM MOSAAD
  76. 76. Bite-wing radiographsPurpose :• Evaluate crestal bone loss around the implants.• In this image the superior third of the implant is the region of interest.• A vertical bitewing film is ideal once prosthesis is in place.• Quality periapical and bitewing radiographs should be parallel to the implant body with the central ray of source oriented perpendicular to the film enable sequential radiographs for crestal and periimplant bone loss. dr.ESLAM MOSAAD
  77. 77. Temporal subtraction radiography:• (SR) is a radiographic technique that enables two radiographs made at different points of time and of the same anatomical region to be subtracted resulting in an image of the difference of the two original radiographs.• Needs to be standardized to account for changes in exposure and processing between each radiograph then they can be digitalized registered and subtracted with a resulting subtraction image. dr.ESLAM MOSAAD
  78. 78. a. Immediately after tooth extraction a. Immediately after tooth extraction b. At 12b. At 12 months after tooth months after tooth extractionextraction Blue region = ROC, Red region = ROIBlue region = ROC, Red region = ROI Blue figures 1-6 = reference pointsBlue figures 1-6 = reference points d. Resulting subtraction imagec. Resulting subtraction image Blue area in ROI = Bone gain Red area in ROI = Bone loss dr.ESLAM MOSAAD
  79. 79. Advantages:• More accurate than periapical in depicting the changes in bone mineralization and bone volume.Limitations :• Difficulty to obtain a reproducible radiograph. dr.ESLAM MOSAAD
  80. 80. Computed tomography• Unlike the conventional imaging techniques the resolution ,, spatial discrimination ,and three dimensional imaging capabilities of CT enable• precise evaluation of the position of the dental implant relative to critical structures .• failing implants characterized by trabecular and crestal demineralization,resorption ofbone implant interface,cortical plate fenestrations and perforation of the inferior alveolar canal. dr.ESLAM MOSAAD
  81. 81. conclusion• Many radiographic projections are available for the evaluation of implant placment. each with advantages and disadvantages . the clinician must follow sequential steps inpatient evaluation, and radiography is an essential diagnostic tool for implant patient . selection of appropriate radiographic modalities will provide the maximum diagnostic information , help avoid unwanted complications and maximizes treatment outcome while delivering as low as reasonably achievable(ALARA) radiation dose to the patient. dr.ESLAM MOSAAD
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