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Digital imaging


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Digital imaging

  1. 1. Digital imaging Islam Kassem Level 6
  2. 2. Digital Radiography• Advances in digital technology have led to a unique “filmless” imaging system known as digital radiography.• Introduced in 1987, digital radiography has influenced both how dental disease is recognized and how it is diagnosed.• In the last 2 years, the use of digital radiography is rapidly increasing in both general and specialty dental practices.• Numerous companies are producing digital radiography systems.
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  4. 4. The Basics of Digital Radiography• Digital radiography uses a sensor to capture a radiographic image, breaking it into electronic pieces and storing the image in a computer.• The patient is exposed to less x-radiation than with conventional radiography.• The image is displayed on a computer screen rather than on film.• The term image (not radiograph) is used to describe the pictures that are produced.
  5. 5. The Basics of Digital Radiography- cont’d• The x-ray beam strikes the sensor.• An electronic charge is produced on the surface of the sensor, and this electronic signal is digitized.• The digital sensor in turn transmits this information to the computer.• Software in the computer is used to store the image electronically.
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  8. 8. Radiation Exposure• Digital radiography requires much less x- radiation than conventional radiography because the sensor is more sensitive to x-rays than to conventional film.• Exposure times for digital radiography are 50% to 80% less than that required for radiography using conventional film.• With less radiation, the absorbed dose to the patient is significantly lower.
  9. 9. Equipment• For digital radiography, special equipment is required. The essential components include: • Dental x-ray unit • Intraoral sensor • Computer
  10. 10. Types of Digital Imaging• Direct digital imaging• Indirect digital imaging• Storage phosphor imaging• The difference between each method is in how the image is obtained and in what size the receptor plates are available (e.g., panoramic).
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  12. 12. Digital RadiographyDigital dental radiography comes in twoforms:• Direct : that connect directly to the computer via USB and provides immediate images• Indirect : (photostimulable phosphor plates, or PSP) which uses plates that are radiated and then digitally scanned.
  13. 13. Indirect Digital radiography• Indirect digital imaging utilizes a reusable plate in place of the film. After X-ray exposure the plate (sheet) is placed in a special scanner where the latent formed image is retrieved point by point and digitized, using laser light scanning.
  14. 14. Direct Digital Radiography• There are two main types of digital sensors available• One is based on charge coupled device technology and the other consists of phosphor storage plates
  15. 15. Charge Coupled Device (CCD(• Is a device for the movement of electrical chargeusually from within the device to an area where the charge can be manipulated .for example conversion into a digital valueThis is achieved by shifting the signals between stages within the device one at a time CCDs move charge between capacitive bins in the device with the shift allowing for the transfer of charge between bins
  16. 16. PSP systemPSP or Phosphor Storage Plate systemsThe X-ray image is captured using a PSP. PSPs are wireless. Since they are not directly connected to the computer, adevice is required to read or extract the data from the PSP and send the image data to a computer.
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  18. 18. Advantages of digital imagingDose reduction• Dose reductions of up to 90 per cent compared to E-speed filmin the diagnosis of caries.
  19. 19. Image manipulation• This is perhaps the greatest advantage of digital imaging over conventional film.• Contrast enhancement.• Measurements. Digital callipers, rulers and protractors are some of the many tools available for image analysis.• 3-D reconstruction. This application can be theoretically used to reconstruct intra- and extra-oral images• Filtration. The addition of filters to the airspace around the face can clarify the soft tissue
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  22. 22. .Time• Much time is gained especially with the CCD system where the image is displayed at the chair side immediately post exposure.
  23. 23. Storage• Now a CD ROM can hold over 30,000 images. This means that images can be stored cheaply and indefinitely.
  24. 24. .Teleradiology• The digital image file can be further reduced in size by compression techniques, and sent via a modem and telephone line to colleagues for review.Environmentally friendly• No processing chemicals are used or disposed of. Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures.
  25. 25. Disadvantages of digital imaging The majority of the disadvantages are associated with the CCD system. Cost • Currently, the cost of converting from intra-oral film to digital imaging is approximately 6600 Euros.
  26. 26. Sensor dimensions• These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires.Cross-infection control• Each intra-oral sensor and plate must be covered by a plastic bag, and this bag is changed between patients. However, if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense.
  27. 27. .Medicolegal• Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes. Manufacturers of software programmes have installed ‘audit trails’, which can track down and recover the original image.
  28. 28. Extra-oral digital imaging• Extra-oral digital imaging is available using both systems.• The larger CCD sensors are extremely expensive and usually requires the purchase of new X-ray generators• These constrictions effectively mean that the PSP method is the one most commonly used.
  29. 29. Panoramic radiography• The PSP method of panoramic digital imaging is very similar to conventional film. The film and intensifying screen are replaced by a storage phosphor plate.• The plate is scanned after exposure, which can take up to 3 minutes or longer depending on the product used.• The resolution of these systems is greater than 4 LP/mm.
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  32. 32. Cephalometric radiography• The effect of dose reduction obtained with PSP on the identification of cephalometric landmarks did not effect the localization of cephalometric landmarks.• It is also worth noting that with CCD sensors the image is acquired over 15 seconds as the sensor and narrow X-ray beam move up the facial bones and could lead to an increase in the incidence of movement artefact.
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  34. 34. Applications of Digital radiographs in DentistryIn Periodontics :• to evaluate the level and condition of the alveolar ridge• to search for factors which may influence periodontal disease such as calculus, overhangs, etc.,• to prepare treatment plans and finally to evaluate the results of treatment.• comparison of images of the same teeth taken “before” and “after” treatment
  35. 35. In Fixed Prosthodontics :• With digital radiography you will be able to check the fit of new crowns, bridges, posts, and implant impression copings and abutments and also verfication of proper seating of the restoration without increase in cement space as in cases of post and core .• Gives information about the changes within the periodontium of the abutments in partial fixed prosthesis , if there is any recurrent caries under restoration and if there is any periapical lesion following improper post and core restoration .
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  37. 37. In Endodontics :Canal Length Measurement by Digital RadiographyThe canal length is measured from the radiographic apex to a reference point on the crown. Studies of periapical healing after endodontic treatment have shown the importance of confining endodontic instrumentation and obturation within the root.
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  39. 39. In Orthodontics :• They offer higher-resolution images within the mouth – enabling the orthodontist to diagnosis and correct problems with greater accuracy.• The digital cephalometric radiograph can be analyzed more precisely using dedicated software.• These digital tools are very important in the studies of the growth and development of the stomatognathic system
  40. 40. In Implantology :• used to plan the placement of endosseous dental implants using three-dimensional computed tomography images obtained with commercial software.• uses digital subtraction radiography to assess longitudinal bony change around dental implants.
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  42. 42. In TMJ :• Plain films are used primarily to evaluate for bone disease such as osteoarthritis and traumatic injuries. Digital radiography improve diagnosis by providing helpful tools such as: image sharpening, contrast and brightness enhancement, zooming, color coding, iso density and spotlight, angle and length measurement• CBCT “tomography” used for the measurement of the angle of the long axis of the condylar heads
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  44. 44. In Diagnosis of Pathological lesions :• Many developmental lesions and anomalies can be detected in earlier stage with digital systems than with conventional methods• The possibilities to vary the brightness of an image is often of great diagnostic value. the same physical brightness difference e.g. between a pathological lesion and its background, is easier perceived against a darker background that against a light one .
  45. 45. As this radiograph gradually getsdarker, the lesions at the apices of the first molar become more visible
  46. 46. In Surgery: • X-ray based imaging is routinely used for preoperative diagnosis and planning, for intraoperative guidance and control, and for the postoperative evaluation of computer-assisted surgery (CAS) in the majority of its applications • Possibility to locate impacted molars and cuspids and to measure the dimensions of the alveolar bone with great accuracy.• identify potential pathologies and structural abnormalities with unprecedented accuracy
  47. 47. • You can get the lecture on•
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