Radiographic darkroom Dark room is a place where the necessary handling and processing of films can be carried out safely and efficiently, without the hazard of producing ‘film fog’ by accidental exposure to light or x-rays

Complete blackout is unnecessary. Safe illumination is required to facilitate darkroom procedures. It must exclude all outside light and provide safe artificial light.

Darkroom construction Darkroom illumination Darkroom equipments and its arrangement Health and safety in processing area

LOCATION Centrally located Serviced by hatches from the adjacent imaging room Away from damp or hot areas Accessible in terms of power and water supply Adjoining viewing room Completely light proof – no windows

CENTRALLY LOCATED DARK ROOM

PASS BOX Two light tight and x-ray proof doors Both cannot be opened at the same time.

SIZE Minimum floor area of 10 sq m Ceiling height of 2.7 – 3.3 m Size may be increased depending upon the department needs

RADIATION PROTECTION Walls adjacent to the radiographic rooms should be shielded with correct thickness of the lead - 1.6 – 2 mm lead or its equivalent 25mm high quality barium plaster 225 mm thick single brick wall 150 mm thick concrete

X-ray apparatus in the adjacent room should be properly placed – primary beam never be directed at the darkroom wall. Radioactive materials should be stored as remotely as possible from the darkroom.

FLOOR Non-porous Non-slippery Chemical resistant Stain proof Durable & easy to maintain Light coloured (low-light working conditions)

Asphalt tiles Porcelain tiles Clay tiles Plastic tiles may be used in the dry dark-rooms Walls adjacent to the sinks and wet processing equipment should be protected to 1.3 m height

WALLS & CEILING Light in colour to reflect as much light as possible onto the working surface A glossy cream or white paint(to obtain as much as reflected light as possible). Good quality paint, non-flaking Easy to wipe or clean Covered with chemical resistant materials Special paints, varnish, ceramic or plastic wall

Ceiling should be at least 2.7 m high Non-flaking emulsion paint Any water pipes, electric cables or AC ducts to be enclosed above a false ceiling

VENTILATION AND HEATING Satisfactory working conditions for the staff Adequate processing conditions Efficient automatic processor performance Adequate removal of stale humid air and supply of fresh air Intake and extract fans can be used

Relative humidity is maintained at around 40-60 % Room temperature maintained between 18-20 degree celsius A minimum of 5 - 10 air changes per hour Minimum of 1000 cu.ft. airspace/person

All of these conditions can be achieved by using a good air-conditioning system Exhaust fan if used are provided with a cowl on the outside – light proof and protect against wind pressures

TYPE OF ENTRANCE Single door system Double door system Maze and Labyrinth Revolving door system

SINGLE DOOR ENTRANCE Latch or lock from inside Capable of releasing the lock from outside in case of emergency Emergency exit Ideally no one should work alone in a dark room

DOUBLE DOOR ENTRANCE

Double door plan with interlocked doors

MAZE TYPE ENTRANCE M A Z E

LABYRINTH TYPE ENTRANCE Light is reflected at least 3 times. Intensity is reduced to a harmless level. Black paint for the interior of the passages Matt black paint Vertical height- 2m Length – not less than 3 m Width – not more than 700mm Safelamps fitted along the passageway

Advantages of labyrinth: Easy and instant access to dark room No hazard to single-handed operator Allows for fresh air to come in

REVOLVING DOOR ENTRANCE 3 feet in diameter. Extends about 15” into each adjoining room. Lightproof access to the room.

DARK ROOM ILLUMINATION White lighting Safelighting

WHITE LIGHTING For inspection & maintenance of cassettes & screens Cleaning of work surfaces Servicing of equipment, changing solutions

Sited close to the ceiling ; Preferably centrally placed Moderate in intensity (60w tungsten, 30w fluorescent )

SAFE LIGHTING A source of light which will not fog the films and still provide adequate illumination under processing conditions. Consists of a lamp fixture in which a pearl bulb of 25 W is used with a colored filter placed in front of the bulb However no safe light is completely safe – depends on wavelength /color , intensity of light and duration of exposure.

How does a safelight work ?

Color of the filter depends upon the sensitivity of the x-ray film Eg: Kodak GS-1filter with green sensitive Ortho-G film Usually brown or olive-green lighting is used – represents region of the spectrum for which we have greatest visual sensitivity at low levels of illumination

Two types : Direct safe lighting Indirect safe lighting

SAFE-LIGHT LAMP Direct safe lighting : light from safe lamp directly falls onto the work surface Minimum distance of 1.2 m (4 feet) from the working surface Best for loading & unloading areas

DIRECT SAFE LIGHT

Indirect safe lighting : directs the light towards the ceiling which reflects light back into the room Is intended to provide general illumination of the dark room Suspended atleast 2.1 m above floor level One for every 6.5 m2 of floor space

Safe lamp for both direct & indirect illumination Filters on both upper and lower surface

Combination Safelight Combination Safelight is a unique two-compartment unit features a safelight at the bottom and a normal room light at the top

SAFE LIGHT FILTERS Sheet of gelatin dyed to the appropriate colour and sandwiched between two sheets of glass for protection Used in conjunction with a 25 W lamp Extremes of heat and moisture deteriorates the filter gelatin Should be cleaned periodically

TESTING FOR THE SAFETY OF SAFELIGHT WHEN IS TESTING REQUIRED ? Darkroom is a new one Safelights have been changed New method or technique If a particular lamp is suspect as causing fogging

Film is subjected to very small exposure, just enough to cause graying In the darkroom, one half is covered with black paper and other half exposed in the safelight Film is processed If uncovered portion is darker, darkroom lighting is not safe.

DARK ROOM EQUIPMENTS AND LAYOUT

Darkroom equipment With automatic processing With manual processing unit Manual processing unit Loading bench For film storage – hopper/drawers/ cupboards. Cassette racks Cassette hatches Darkroom sink Hangers for suspending film Processing chemicals + storage place. Drier Automatic processor Loading bench For film storage – hopper/drawers/ cupboards. Cassette racks Cassette hatches

PROCESSING APPARATUS 1. MANUAL PROCESSING 2.AUTOMATIC PROCESSING

AUTOMATIC PROCESSOR Through the wall position for an automatic processor

MANUAL PROCESSING UNIT MATERIAL – PVC /Stainless steel ARRAY OF TANKS FOR MANUAL PROCESSING

The loading bench: Long enough to allow 3–4 cassettes to be placed side by side. Min length 2.5m per operator 600 mm min width Min 900 mm high Top – hard wood – teak covered with linoleum ( easy to clean, hard wearing, anti-static) Formica is not recommended.

Film hopper: Stores the unexposed films intended for immediate use Under the loading bench Cone shaped drawer hinged at the lower edge Inside is painted black Prominent WARNING should be written on outside that it should not be opened in white light Instead drawers and cupboards can also be used to store unused films

FILM HOPPER FOR THE STORAGE OF UNEXPOSED FILMS

Cassette hatch : Two light tight and x-ray proof doors Should open on the loading bench. Interlocking device to prevent both doors from being opened simultaneously Light proof Must also be proof against x-rays Two compartments – labelled ‘exposed’ and ‘unexposed’ on either side

DARK ROOM DRY BENCH SYSTEM Cassette rack : Stores the loaded cassettes.

Hanger storage Stored on metal wall brackets Each one projects about 230 mm from the wall and can hold max 12 hangers Two brackets should be placed 100 mm apart from each other Height of about 750 mm from the workbench

Hangers used for suspending films during processing DIFFERENT TYPES Channel hangers Tension hangers Hanger bars and clips Tension hangers

Channel hangers

The darkroom sink Placed adjacent to the processing unit Sink should be about 250 mm deep, and 750 x 450 mm in its other dimensions. Hot and cold water should be supplied Taps should be at least 400 mm above the sink Cupboards under the sink for storage of equipments and chemical stocks

Film Drier Films are hung in their hangers Fan for circulating air Heater elements to warm the air Drip tray is provided beneath Interior safelight Thermal film bin

A well planned darkroom should have following characteristics: Separation of dry and wet sections. Orderly sequence of events. Neat layout of the equipment. Clear ‘traffic lanes’ for the technicians. Dry bench Processing unit Sink Drier Door

HEALTH AND SAFETY IN THE PROCESSING AREA

ELECTRICAL SAFETY GENERAL SAFETY CHEMICAL SAFETY

ELECTRICAL SAFETY All electrical equipments to be sited well away from sinks & manual processing units Adequate earthing of all electrical appliances No trailing cables from appliances Pull-cord switching for lights

GENERAL SAFETY MEASURES The maximum level of safelighting consistent with film sensitivity Adequate ventilation Second exits for fire safety Staff should be advised to read product labels & mixing instructions before handling solutions

Thank you !

Safelight tests