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PROCESSING OF X RAY FILMS

PROCESSING OF X RAY FILMS. Introduction. Image receptor in dental radiography  film Beam of photons  film  chemical changes Latent image  visible image - Processing. Formation of latent image. Emulsion  photosensitive crystals Imperfections in crystals

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PROCESSING OF X RAY FILMS

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  1. PROCESSING OF X RAY FILMS

  2. Introduction • Image receptor in dental radiography  film • Beam of photons  film  chemical changes • Latent image  visible image - Processing

  3. Formation of latent image • Emulsion  photosensitive crystals • Imperfections in crystals • Free silver ions in between the spaces • Physical distortion due to large sized iodide ions • Addition of sulfur impurities

  4. Formation of latent image • X rays  Silver halide crystals  Compton & Photoelectric effect • Removal of electron from bromide ions • Recoil electrons accumulate at latent image site • Attract Silver ions  metallic Silver atoms

  5. Processing • Immerse film in developer • Rinse the film • Immerse film in fixer • Wash film in running water • Dry film & mount for viewing

  6. Developer solution Reduces all silver ions to metallic silver grains • Developer – Elon / Phenidone & Hydroquinone • Activator – sodium or potassium hydroxide • Preservative – sodium sulfite • Restrainer – potassium bromide / benzotriazole

  7. Developer replenisher • As films are processed  the developer content used / eaten up • Some portion of used solution removed • Each morning – fresh concentrated solution • 8 ounces / gallon

  8. Rinsing • Running water for 30 seconds • Dilutes the residual developer • Removes alkali activator • Not used in automatic processing

  9. Fixing solution Dissolve and remove undeveloped silver halide crystals • Clearing agent – ammonium thiosulfate (“hypo”) • Acidifier – acetic acid • Preservative – ammonium sulfite • Hardener – aluminum sulfate

  10. Washing • Flowing water • Not below 60o F • If not proper discolored stains • Thiosulfate reacting with silver  brown colored silver sulfide

  11. Darkroom equipment • Lightproof • Light tight door / doorless maze • Safelighting • 15 watts bulb  4 feet above working area • Red GBX-2 filter

  12. Processing tanks • Master tank – 20 x 25 cms (8 x 10 inches)  water • 2 removable insert tanks  developing & fixing solutions • Developer – left side • Fixer – right side • Covering lid

  13. Other equipment • Thermometer • Timer • Film hangars • Drying racks • Drying fan or electric heater

  14. Manual processing • Time temperature method • 68o F  5 mins • 70o F  4 ½ mins • 72o F  4 mins • 76o F  3 mins • 80o F  2 ½ mins • Visual method

  15. Rapid processing chemicals • Develop – 15 seconds • Fix – 15 seconds • Room temperature • Higher concentration of Hydroquinone • Endodontics • Emergency situations • After viewing – fix conventionally • Improves contrast • Stable in storage

  16. Self processing films

  17. Automatic processing

  18. Automatic processing • Time saving • Simple & convenient • Less space – no darkroom required • Density & contrast – consistent in all radiographs • Artifacts by rollers • Graininess of image • Expensive – acquisition & maintenance • Frequent cleaning • may break down & needs back up

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