in our previous video we dealt with how latent image was converted to visible image by film processing the use of two chemical Solutions called the developer and the fixer placed in a dark room enabled the visibility of the radiolucent and radioopaque structures on the film in this video I'm going to discuss in depth the solutions and steps involved in film processing this radiograph has a latent image that needs to be converted into a visible image to do this it has to undergo a procedure calle
d film processing which is done in a dark room where the processing Solutions are stored before I begin I ensure that the doors are shut to prevent any light from entering this is done because X-ray films are sensitive to light and if exposed they become black with no visible image I remove the film from the film packet and clip it onto a film holder which helps me dip the film into the solution soltions easily so which solution do I insert the film into first a chemical solution called the deve
loper pop [Music] quiz I keep the film in the developer for a specific amount of time this is important because excessive time in the developer will reduce the unexposed silver Hy crystals thereby overdeveloping the film and creating a chemical fog the overall film appears darker with less contrast the developer in this case is maintained at 68° F but one can follow the instructions recommended Ed by the manufacturer if the developer is cold its action will be slow down and the time required for
the full development is unduly long if too warm the image develops quickly and if not careful it could lead to fogging of the film so how does the developer act on the film the developer is made of various components that have different functions these are reduc ucing agent activator preservative restrainer let us discuss them in depth beginning with reducing agents the two reducing agents used here are metol phenidone and hydroquinone as explained in our previous video of the latent image and
visible image formation metol phenidone provides an electron to convert silver ions to metallic silver at the latent image site but this electron transfer converts it into an oxidized form of no further use to prevent this another reducing agent hydroquinon is used to provide an electron that reduces the oxidized phenidone back to its original state this is done so that silver halide grains continue to get reduced to metallic silver the next chemical component is the activator which is sodium hy
droxide or potassium hydroxide it swells up the gelatin in in the film helping the reducing agents to diffuse faster into the Emulsion to reach the silver bromide crystals of the latent sites the activator also ensures the developer is alkaline by maintaining a pH of 10 a low degree of alkalinity slows down the process of development but excessive alkaline pH causes rapid reduction of even the unexposed silver bromide crystals resulting an overall darkening of the image called chemical fog movin
g on the next component is the preservative which is sodium sulfite the preservative acts as an antioxidant preventing the process of oxidation when the developer comes in contact with air this makes the developer solution usable for a longer period let us discuss the next component the restrainer by now you know that the developer converts the silver ions of all the EX exposed silver halight crystals to metallic silver but have you wondered what happens to the unexposed silver halight crystals
restrainers such as potassium bromide or benzo triazol prevent the development of these unexposed crystals prevent excessive fogging and increase the contrast of the film now let us proceed with the next steps of film processing after removing the film from the developer solution I rinse it in water for 30 30 seconds with gentle agitation why because now that the Emulsion is saturated with the developer rinsing it will stop any further interaction between the film and the developer next I place
it in the fixer pop [Music] quiz like the developer the fixer also contains various components such as clearing agent acidifier preservative and hardener the clearing agent ammonium thiosulfate dissolves the unexposed silver halight crystals the next component is the acidifier here acetic acid maintains an acidic pH of the fixer of approximately 4 to 4.5 it also promotes good diffusion of the clearing agent into the Emulsion and the expulsion of the silver thio sulfate complexes another property
of the acidifier is to inactivate any residual developing agents then we have the preservative ammonium thio sulfide which prevents oxidation of the clearing agent ammonium thos fate finally the Hardina is aluminium sulfate which forms a complex with the gelatin and prevents damage to the film Overcoat during subsequent handling the film is placed in the fixer for twice the amount of time is that in the developer let us proceed with the process I washed the process film under running water for
at least 10 minutes to remove all the thio sufate ions and complexes not doing this will stain the radioopaque areas of my image these stains are remnants of any Silver compound or tho sulfate complexes pop [Music] quiz the final step of the film processing is to dry the film using an electric fan or placing it on a drying rack depending on the availability of time this brings us to the end of the procedure let us summarize with this flowchart feel free to take a screenshot we hope you had fun l
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