Chapter 11

TheX-ray

Darkroom

General Darkroom Layout If you are hand developing there

should be a film handling area and a processing area to minimize the possibility of solutions contaminating the film and the intensifying screens.

If space is limited extreme caution should be taken.

General Darkroom Layout

When using an automatic processor a much smaller room can be used.

Today many x-ray rooms are set up so that the automatic processor is positioned in the x-ray room.

Lightproofing the Darkroom Obviously the darkroom must be

lightproof. This is best tested by the use of

dental film, half-covered, placed in various parts of the room for a period of time, three to five times the normal film handling time, and then developed.

Lightproofing the Darkroom Any fog in the portion that was not

covered indicates light leaks. The use of half-covered film eliminates film fogging from other sources.

A baffle entrance is more lightproof than a door (and permits better ventilation).

If you have your automatic processor in the x-ray room, this room, of course, will have to be light proof.

X-ray Proofing the Darkroom

The darkroom must be x-ray proof or radiation entering can fog the film being processed or, even more important, the larger amount of film being stored in the room.

This is more important when using non-screen film, however, screen film is also sensitive to x-ray.

X-ray Proofing the Darkroom

A leaded film bin will be needed if you are processing in the x-ray room.

The position of the x-ray unit is important (the primary beam should be focused away from the darkroom).

Additionally, the darkroom walls should be lead lined (see state specifications for specifics).

X-ray Proofing the Darkroom

The amount of lead needed is determined by room size, material of walls, types of x-rays, film/screens used, tube placement, placement of x-ray room within the building, and the x-ray machines capability.

X-ray Proofing the Darkroom

The adequacy of such protection can be checked by leaving a loaded cassette with a few coins or keys on top in the darkroom for a considerable number of exposures. Any exposure occurring can be attributed to x-ray leakage.

Darkroom Color The color of the darkroom need not

be a black or dull, dark color. If the safelight is "safe" all the

reflected light will be too. Colors suggested are light green

for use with a green safelight or beige for use with a red or yellow safelight.

Darkroom Cleanliness The darkroom and all the equipment

and accessories should be kept spotless.

Dust can cause artifacts on the film. Chemical dust from spills can stain

film and screens. The solutions should be covered

when not in use.

Darkroom Cleanliness A contaminant or scratch on the

cassette will also leave a reproducible artifact on the film until it is cleaned or replaced.

When changing solutions the tanks should be cleansed with Clorox before refilling.

Scouring powder should never be used as it leaves a gritty dust behind.

Darkroom Temperature If you are hand developing, the

darkroom temperature should be maintained as close to 68 degrees as is possible as should the developer.

In addition to influencing the temperature of the developer and fixer, excess heat can fog the film stored.

Darkroom Temperature The film bin should be as far

away from the heat source in the room.

Some means of controlling the temperature of the solutions should also be available.

Safelight Illumination Wratten 6B (yellow) or Series 2

(red) can be used with a ten watt bulb and should not be directed at the film being handled.

The film should be at least 4 feet from the safelight at all times.

The length of time of exposure to the safelight is also a factor.

Safelight Illumination Loading a cassette or putting a

film onto a developing hanger should take a matter of seconds.

To test just how "safe" your safelight is, first make a radiograph in the usual manner.

Safelight Illumination Then unload the cassette in the

darkroom and cover half of it with black paper and expose the uncovered portion of the film to the safelight for a period usually used in film handling.

Develop the film for the normal length of time and examine it for any fogging in the uncovered portion.

Safelight Illumination This is the same procedure in x-ray

proofing. The covering of half the film

eliminates mistaking fogging from any other source for safelight fogging.

We should used exposed film because film exposed to x-rays and light from the intensifying screens is more sensitive than unexposed film.

Darkroom Ventilation Noxious fumes may present

with use of today's auto processors. Therefore, ventilation near the processor is needed.

Make sure that the ventilation system is lightproof.

Darkroom Set-up When setting up a darkroom,

preplan. Installation of drains, a sink,

and proper power sources should be considered initially as it is costly to add these necessities at a later date.

Darkroom Tidbits For proper quality control (QC)

you’ll need a sensitometer (controls the amount of each exposure & makes the same exposure in each given shot) & a densitometer (checks contrast, speed & fog).

You need to keep track of re-shoots & log why.