Dr Mohd Malik

Format 1. Latent Image Formation 2. Dark Room 3. Processing Solution  Developer  Fixer

Latent Image Formation  Film emulsion largely constitutes Silver Halide Crystals  Free Interstitial Silver Ions  Sulphur compounds – Sensitivity Site  Sensitivity site begin the process of image formation by trapping electrons

Latent Image Formation  X ray Photons  Silver Halide crystals 1. Compton Effect 2. Photoelectric Effect

Latent Image Formation  Removal of an e- from bromide ions  Bromide ion Bromine  Free e- Sensitivity Site  Here e- imparts –ve charge  Silver ion+sensitivity site  Neutral Metallic Atom

Latent Image Formation  Metallic silver at each latent image site renders the crystals sensitive to development and image formation  Larger the aggregate of metallic silver  More sensitive is the film  Developermetallic silverMetallic latent imagesilver grains  Fixer removes unexposed, underdeveloped silver halide crystals

Processing Solution 1. Developer Solution 2. Water Bath 3. Fixer Solution 4. Water Bath

Developer Solution Silver halideMetallic silver  Reduces  Neutral silver ions  Electronscrystalline silver catalyzerions  This is how the reaction process is –  Developer + filmNo reaction (initially)  Developer + film density increases rapidly  Then again the reaction slows down.

Composition Of Developer 1. Developer  Pyrazolone Derivatives(1 – Phenyl 3 Pyrazolidine)  Hydroquinine – it provides an e- to reduce oxidized Phenidone to its original form.  Function/use – Is the main component of developer solution which helps in developing the x ray film 2. Activator – sodium or potassium hydrozide  Developer is active at alkaline pH Function/use – It keeps the developer solution in active state and at alkaline pH as developer gives electrons during x ray film developing

Developer Solution 3. Preservative – Sodium Sulfite.  Function/use –  Prevents developer from getting oxidized  It combines with brown oxidized developer to make it colourless 4. Restrainer – potassium bromide or Benzotriazole Function/Use –  It is more effective in reducing the unexposed silver halide crytals from getting developed  If the film is kept for too long in the developer solution then developer solution can reduce even exposed crystals.

Developer Replenisher (Additioner)  After developing 30 periapical or 5 panoramic films the developer solution becomes weak as all the electrons in the developer solution are used  Hence 8 ounces of fresh developer solution is added per gallon (3.8 liters) of developing solution.  In order to replenish (add) the solution some amount of old solution is to be discarded.  Care should be taken in handling the solutions and proper temperature should be maintained.

Fixer Solution – General Function/Use  Is to dissolve and remove the underdeveloped Silver Halide crystals from film emulsion.  It hardens and shrink the film emulsion.  Unexposed silver halide crystals form opaque film  Unexposed films make a dark and non – diagnostic radiograph

Fixer Composition 1. Clearing Agent – Aquous solution of Ammonium Thiosulphate or Hypo.  Function/Use  It dissolves silver halide grains  It forms stable water soluble substances with silver ions  It does not have a rapid effect on metallic silver grains but excessive fixation results in gradual loss of film density

2. Acidifier – Acetic Acid is used which maintains the fixer solution at 4 – 5 pH  Function/Use  Is required to promote good diffusion (entry) of Thiosulphate (main fixer conponent) into the x ray film emulsion 3. Preservative – Ammonium Sulfite  Function/Use – It prevents oxidation of Thiosulphate solution 4. Hardener – Aluminium Sulfite  Function/Use –  Aluminium complexes with the gelatin during fixing and prevents damage to gelatin during subsequent handling.

WASHING  Is used to ensure the removal of Thiosulphate ions and its compounds.  Washing temperature should be maintained to 600 degrees Fahrenheit below which its efficiency declines  Washing should be done under running water.

Processing Technique  1903 – Edmund KUlls introduced processing tanks  1920 – Reliable film hangers were made available  Requirements Of Processing Tanks:-  They must have a hot and cold running water facility within them to maintain temo. 60o to 75o F  Should be made of non reactive material to the processing solutions and should be easily cleansible

Processing Tank  Master tank – 20 x25 cm (8 x 10 inches)  Function/Use – It serves as a water jacket for two movable inserts to fit inside.  Insert tanks usually hold 1 gallon or 3.8Liters

Processing Tank  Developer insert tank is at left in master tank  Fixer insert tank is at the right in the master tank  Master tank has a cover to protect the solutions from getting oxidized.

Processing Technique 1. Manual  Time Temperature Method  Visualization Method 2. Automatic Processors

Time – Temperature Method  It uses a thermometer which is placed in the developer tank and a stop watch timer which helps to calculate the time for which x ray film should be kept inside the developer and fixer tanks accordingly  Thermometer –  Should be clipped to processing tank  It should contain metal or alcohol to avoid contamination by mercury incase of accidental breakage.  Timer –  An interval timer is needed for controlling developing and fixing time

Time – Temperature Procedure  Once operator enters inside the x ray room he should perform the following actions – 1. Replenish the solution – if the solution was not altered last time 2. Stir solution – with a wooden stick in order to mix all components in the solutions 3. Mount x ray film on hangers 4. Set timer – 68 0 F – 5min…… 80 0 F – 21/2 min 5. Develop 6. Rinse 7. Fix 8. Wash 9. Dry

Visual Method  Here the operator evaluates by visualizing the film under the safe light.  Advantages –  Desired contrast can be obtained  Temperature – time variations can be handled  Operator Satisfaction

 Disadvantages –  Operator sensitive  Manufacture recommended contrast cannot be reached  Operator needs to stand till film develops  Manufacturer cant be questioned for any variations

Automated Film Processors  1910 – Automated film processors  They have light shielded compartment to unwrap the film  the film is passed under rollers

Automated Film Processors  Advantages –  Less time consumption – 4 to 6 min.  Need of specialized dark room eliminated  Portable  Disadvantages –  Dificult to maintain  Roller marks are common  Machine problem in middle  Cost

Radiographic Waste  Silver can be recovered from fixer by  Metallic Replacement ( uses cartridge )  Electroplating Method ( 2 electrodes )  Lead Foil  Countries biohazard team should be contacted for proper disposal.

Recent Advances  Speed F films  Duplicating Films  Self Developing films  Films with suresoft border.

Thank You  Any Questions ?