Some special imaging process


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Some special imaging process

  1. 1. 1- Xeroradiography 2- Copying Radiography 3- Subtraction
  2. 2. Xerography An image-recoding process in which the sensitive material is a plate carrying an electrical charge on its surface. When light falls on the surface the charge is released. The plate is dusted with a special powder and image is formed by the powder being attracted and retained in charged area.
  3. 3. 1- Xeroradography Xeroradiography is not a process requiring any specialized x-ray equipment; it is only a different method of recording an x-ray image. It depends upon the photoconductive behaviour of a selenium plate and substitutes a photoelectric process for photochemical one associated with the use of a film.
  4. 4. Photoelectric and photochemical responses
  5. 5. Selenium Plate Is an insulator in the dark, become conductive when exposed to light or x-ray. If the plate is given a superficial electric charge, it is capable of remaining of retaining this charge for a period of hours. In charged condition, expos of the plate to light or xrays effect conduction in exposed area.
  6. 6. Two machines are necessary for xergraphy 1- conditioner
  7. 7. The main features of the conditioner A – a storage box containing xergraphic plate. B, C- a plate (B) passes form storage box through a small oven (C) which removes any residual charge; the plate then to storage elevator (D). E- insertion of an empty cassette initiates the charging process. F- an ionizing device which charges the surface of the plate after it leaves the storage elevator and before it enters the open cassette.
  8. 8. 2- processor
  9. 9. •I – a rotating brush which cleans the plate before H- a third ionizing device which loosens any powder remaining on the plate after transfer. it enters a storage box. •J – the paper passes through an oven (J) which fuses the power image to the paper
  10. 10. The main features of the processor for xergraphy A- the cassette containing the exposed plate. B- the plate is transported to a development chamber, where developer powder (toner) is sprayed on its surface. C- D paper is removed from the paper tray (C) to a position (D) for contact with powder plate. F- an ion- emitting device, the effect of which is to loosen the powder on the plate, preparatory to its transfer. G- another ionizing device which gives the reverse side of the paper a charge of opposite polarity.
  11. 11. Xeroradiograph of female breast
  12. 12. Copying Radiograph To copy radiograph is produce a second from the first; It may be Smaller in size than the first (miniaturized) The same size (facsimiles) large in size (enlargement)
  13. 13. Duplicate film (copy film): Is single emulsion film that is exposed to ultraviolet light or blue light through existing radiograph to produce a copy. Duplicate film is direct positive film.
  14. 14. Subtraction film Used in angiography, although with the increasing application of digital fluoroscopy, its use is declining. Subtraction film single emulsion, and there are generally two types; (a) One type to prepare the subtraction mask. (b) One to accommodates the superimposed image of the original radiograph and subtraction mask. Subtraction film has high contrast to enhance existing subject contrast
  15. 15. conventional subtraction
  16. 16. The plain film
  17. 17. The subtraction mask.
  18. 18. The angiogram The subtraction mask
  19. 19. The plain film The subtraction mask
  20. 20. The angiogram The subtracted image
  21. 21. Digital subtraction angiography Coronary artery
  22. 22. Digital imaging technology (cont) The technique of digital subtraction angiography (DSA), based on digital image processing, allows enhanced visualization of blood vessels by electronically subtracting unwanted parts of the image.
  23. 23. Thank you