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1 Dark room by Dr Soumitra Halder

For under and postgraduate students

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1 Dark room by Dr Soumitra Halder

  1. 1. Dr. Soumitra Halder Dept of Radio-diagnosis Medical College,Kolkata DarkRoom
  2. 2.  It is a place where the necessary handling and the processing of the film can be carried out safely and efficiently without the hazard of producing film fogging.  It must exclude all outside light and provide “SAFE” artificial light Dark Room
  4. 4. • Processing Tanks • Warning Light outside room • Lockable Door • Film Bin • Loading Bench • Pass Box • Lights safelight/whitelight • Wash basin • Drying cabinet • Hangers for suspending films Equipments in Darkroom
  5. 5. Location  Centrally sited served with hatch's from adjacent imaging rooms  Away from hot or damp areas  Power And water supply accessibility  Near to viewing/reporting room  Avoid windows Dark Room
  6. 6. Room character • Min 10m sq. • Height 2.5 – 3m Dark Room Walls /ceiling • Wall being Plastered/ thick wall • Light colored to reflect the light-as to use lesser safelight.
  7. 7. Floor • Non-porous • Non-slip • Durable and easy maintaince Dark Room
  8. 8. Ventilation And Heating Satisfactory working conditions for staff .. Good film handling and storage conditions.. Dark Room Maintained by-- • Relative humidity 40-60% • Room Temperature 18-20 °C
  10. 10. Types of Entrance Four designs of entrances 1. Single door system 2. Double door system 3. Labyrinth 4. Rotating door entrance Dark Room
  11. 11. DARKROOM ENTRANCE: SINGLE DOOR Single door entrance Access via single door only Advantage:- - Inexpensive. - Less space used. Disadvantages:- - Not truly lightproof - Poses safety hazard.
  12. 12. DARKROOM ENTRANCE: DOUBLE DOOR Two doors with small vestibule in between. An electrical interlock can be fitted –one door cannot be opened until the other is closed
  14. 14. Labyrinth • It has two parallel passages and a facing wall. • Entire passage and walls are painted black. • Length of passage 3 m • Height of passage 2 m • Each passage width 700 mm • Emergency door Advantages:- Easy and instant accesses.. Continuous darkroom ventilation.. Disadvantage:- Large amount off space occupied ..
  15. 15. DARKROOM ENTRANCE: REVOLVING DOOR Metallic cylinder with Advantages: opening Less space is occupaied at one end for entry & exit.
  17. 17. SafeLighting
  18. 18. SafeLighting The word safe- as brief exposure will not cause significant fogging Functions • Provide sufficient darkroom illumination without any detrimental effect on the sensitive film material. • Helps for inspection of films during processing.
  19. 19. Principle of operation • X Ray film’s are color sensitive- restricted to specfic range of wavelength. • Thus subjecting to non sensitive wavelength and cutting of white light. SafeLighting
  20. 20. SafeLighting Areas where safe light is required • Film loading / unloading areas. • Processor film feed-in points. • Path b/w above two. • At developer tank.
  21. 21. SafeLighting Factors affecting safe lighting performance • Safelight to film distance • Bulb wattage • Number and location of bulbs • Film handling time:
  22. 22. Film handling time: • the length of time the film may be handled in safelight condition with out increase in fog level. • Its around 20 to 45sec. SafeLighting
  23. 23. SafeLighting Recommended standards • Use only the recommended safelight filters • Keep a required film light distance • Keep minimum exposure to safelight s for exposed as well as unexposed films
  24. 24. 7.5 W FILM TRAY 15 W 4 feet 3 feet 25 W 1.2 M SafeLighting
  25. 25. Required for • Inspection & maintenance off cassettes & screens • Cleaning purpose • Servicing off equipment's White light should be • Close to ceiling • Moderate intensity (60W tungsten or 30W fluorescent) • Centrally placed White lighting
  27. 27. Polyester Base..0.2 mm thick Emulsion…Gelatin in silver hyalide crystal generally silver iodobromide Supercoat…Tranparent antistatic
  28. 28. LATENT IMAGE.. DEFINITION MECHANISM OF FORMATION OF LATENT IMAGE: AgBr + X-ray photons = Ag+ + Br- Silver bromide Silver ions Bromine ions The latent image is formed by deposits of free (ionized) silver ions that cannot be seen or detected by any physical test devised as yet. It remains in the emulsion of the X-ray film until it is changed into a visible silver image by chemical processing procedure
  29. 29. Film processing stages… 1.Devolopment 2.Wash ( stop bath ) 3.Fixing 4.Final Washing 5. Dry
  30. 30. Processor Chemistry Overview Developer – converts latent image into manifest image Stop bath -remove excess devolper Fixer – clear the film of unexposed, undeveloped silver bromide crystals, promotes archival quality,image is now stable and unaffected further by light. Wash – rid the film of residual chemicals
  31. 31. (6 Ingredients) 1. Reducing Agent: reduce exposed silver halide to black metallic silver -Hydroquinone (Blacks) -Phenidone (Grays) 2AgBr + Hydroquinone-----2Ag+quinone+2HBr 2. Activator: softens gelatin, maintains alkaline pH (increase pH) -Sodium Carbonate Developer Solution
  32. 32. Developer Solution 3. Hardener: prevents damage to the film from over swelling of gelatin -Gluteraldehyde 4. Preservative: Antioxidant that prevents oxidation of developer -Sodium Sulfite
  33. 33. Developer Solution 5. Restrainer: prevents chemical fog in new developer -Potassium Bromide 6. Solvent: dissolves & ionizes the developer chemicals -Water
  34. 34. (5 Ingredients) 1. Clearing Agent: dissolves undeveloped silver halide - Thiosulfate ( HYPO ) 2. Tanning Agent: shrinks, hardens, preserves emulsion -Aluminum Salt Fixer Solution
  35. 35. Fixer Solution 3. Activator: neutralizes developer, maintains acidic pH (decrease pH) -Acetic Acid 4. Preservative: prevents oxidation, prolongs solution life -Sodium Sulfite 5. Solvent: dissolves other ingredients -Water
  36. 36. Wash  Rid the film of residual chemicals  Residual chemicals on the film will discolor radiograph over time.  Cold water processors are less efficient in removing chemicals – Warm water processors much better.
  37. 37. (Not Washed Off) Fixer Retention
  39. 39. Thank you…