DARK ROOM

DARKROOM - the dark room is important place in radiology department  of hospital,nursing home,private x-ray clinic in which we develop the latent image into visible image. films of poor quality are far more likely to be due to the incorrect procedure in the darkroom than shortcomings in the tubes , exposure , or radio graphic technique. darkroom is also called processing room.

LOCATION -  the darkroom should be located very near or close to the radio graphic room as its saves lots of time. if there are two or more radio graphic rooms, the darkroom should be located in central position.

SIZE -  the darkroom must be consist of minimum floor area of 10 sq meter and ceiling height of 2.5-3 meter to accommodate all the equipment without overcrowding the size may increase or decrease depending on the department needs.

PROTECTION - As it is present near the radio-graphic room so it is essential for the darkroom to be well protected from the radiation and for this the wall adjacent to radio graphic room should be shielded with correct thickness of lead(1.6 mm lead) which is sufficient to work up to 100 kv

FLOOR - the floor should be durable , slippery , stain proof , chemical resistant  and for this ceramic tiles of porcelain or natural clay are most satisfactory

WALLS COVERING –  the walls of the darkroom do not have to dark. the color chosen should first be judge under safe light illumination as it is  important that there should be maximum reflection of safe light .the walls should be covered by chemical resistant materials such as special paint, concrete or ceramic tiles.

VENTILATION – the darkroom ventilated in such a way that adequate removal of stable humid air and supply of fresh air takes place easily .window should be avoided because they are difficult to render lightproof. Air condition is the ideal solution for the darkroom.

ELECTRIC WIRING – the darkroom Is a place where electric shock can be dangerous because of presence of electric wiring in the proximity of aqueous solution, water pipes, damp floors and wet fingers. It is essential to earth all exposed non current carrying metallic objects.

PASS BOX – the most suitable location for the pass box is near the film loading bench . Typically pass box has two light and x-ray proof doors that are interlocked that both cannot be open at same time. the pass box is divided into two compartments. One is for exposed and other for unexposed films.

ENTRANCE – the simplest type of entrance is a single door which must be made light tight and should have an inside lock to prevent opening while films are processed.  Another type of entrance is small hall with two electrically interlocked doors and revolving doors.

DRY SIDE – various components of dry side of the dark room are loading bench, compartments for cassette, film bin, storage for reserve film, brackets for film hangers and wastepaper receptacle.

WET SIDE – the processing chemicals are available as dry powder or as liquid solutions and made up to the proper volume by the addition of water according to the instructions printed on the labels two stirring paddlers are needed one for developer and one for fixer. The thermometer is used to determine the temperature of the developing solutions and to check the temperature of water used to prepare the solutions

The processing tanks comprise the major equipment's of the wet side of darkroom. The simplest type consists of three compartments tank, one end compartment being used for developing and opposite one for fixing and the middle compartments serves both to rinse and wash the films and should be supplied with running water

FILM DEVELOPMENT -  The process of convert the latent image into visible image by means of developing solution .the film can be process by two methods they are manual and automatic processing

MANUAL FILM PROCESSING – Film processing is the process by which latent images are converted into visible images. In the darkroom the developer tank is in the left side and the rinsing tank is in the middle. The fixing tank is on the right side.  in manual the film are pass though these different procedure separately. The developer can be identified by its soapy feel. The fixer is identified by its vinegary odor and acidic test. The processing process involves several steps, including developing, rinsing, fixing, washing and drying.

AUTOMATIC FILM PROCESSING – In automatic film processing all the process like developing ,fixing ,rinsing and drying are done automatically. The basic mechanism of the automatic processor is a series of rollers which transport the through the various sections. the speed of the transport must be constant to assure correct sojourn of the film in each section. spacing of rollers must be accurate to prevent slipping or jamming of the films

DEVELOPER AND FIXER

DEVELOPER – The developer Hydroquinone is made up of Phenidone or Metol. This creates a sharp image. The developer acts as a reducing agent. It is a benzene ring product, which converts the exposed silver halide into metallic silver halide. Nowadays Phenol is used instead of Metol.

Activator - Alkalize, also called Activator, is used for this, sodium carbonate or  sodium hydroxide whose chemical formula is Na2CO3. It provides alkaline medium benefits in the developing solution. The developer solution works in this alkaline medium and makes gelatin emulsions soft and swells. It attracts silver crystals.

Preservative - In the developer solution, sodium sulfite is used as a preservative. This reduces oxidation of the developer solution, thereby preserving the strength of other chemicals. If this is not done, the strength of other chemicals decreases very rapidly, which causes the solution to be dark colored.

Restrainer - Potassium bromide and potassium iodide are used as a restrainer. It restores or controls the strength of another developing agent. If the retainer is not present in the developing solution, the developing agent also develops the unexposed silver halide, depositing the film as a silver halite fog

FIXER – The function of fixer is to remove the unexposed and undeveloped silver halides and to preserve the film image or to harden the emulsion so that it will not easily damaged.

Fixing agent -  hypo(sodium thiosulphite in powdered fixer :ammonium thiosulphite in liquid fixer)- clear the film by dissolving out the unexposed, undeveloped silver bromide and silver iodide, leaving the  metallic silver in the exposed and developed areas of the film more readily discernible. Without fixation the undeveloped silver halides would leave the radio graph nearly opaque and it would turn into black.

Preservative - Sodium sulfide is used in the fixing solution as a preservative, which prevents the fixing solution from deteriorating.

Hardening agent - Potassium alum (potassium alum) is used as a hardening agent, it shrinks the gelatin and makes it hard.

Acidifier - Acetic acid is used as an Acidifier. This makes the fixer solution acidic medium efficient, as the alum reacts well to the acidic medium, and also inhibits the developing process of the acidic medium developer.

MORE TOPIC RELATED TO DARKROOM CLICK ON THE ABOVE  GIVEN TOPIC TO GET ANSWERS:-

1. film constructions - click here
2. cassette - click here