Autoradiography Film Tips

• Autoradiography Film Storage and Handling
• Procedures for Proper Safelighting
• Recommended Exposure Procedures
• Automated Processing
• Manual Processing

Careful film storage and handling is extremely important for high-quality, reproducible results. You should store unopened packages of film in an area properly shielded from penetrating radiations, at temperatures between 50 degrees Fahrenheit and 70 degrees Fahrenheit (10 to 20 degrees C) and a relative humidity between 30% and 50%.

You should store film packages in an upright position. They should not be stacked one-on-top-of-another, because the physical strain caused by weight or pressure on the film sheets can result in creasing, buckling, and friction.

Don't draw film from the box rapidly or handle it in a way that may cause a static discharge. Carefully remove film away from the sample after exposure, to avoid causing static artifacts that may blemish exposed autoradiographs.

Procedures for Proper Safelighting

To obtain high quality autoradiographs, your darkroom should be well secured from light penetrating through the edges of the doorway, walls, ceilings, and windows. You must ensure proper safelight conditions.

The function of a safelight is to provide sufficient illumination in a darkroom while protecting the film from unwanted exposure. Safe illumination in the darkroom depends on:

• The correct lamp, bulb wattage and type of filter
• The distance between the safelight and the photographic material

The word "safe" is a relative term. Most sensitized materials will become fogged if you expose them to a safelight for an extended period of time. Therefore, you should always minimize the exposure of autoradiography and electron microscope films to safelight illumination.

Autoradiography film should be handled under proper safelight conditions using a safelight lamp equipped with a Safelight Filter GBX-2 and 15 W frosted bulb  (other safelights may result in increased background fog and/or unwanted image exposure). The safelight should be positioned a least four feet from the film at all times. Minimize the length of time that the film is exposed to safelight conditions.

Recommended Exposure Procedures for Autoradiography

Direct exposure of the specimen to the emulsion will give the greatest resolution of the image. Using an intensifying screen or fluorography will increase sensitivity but decrease resolution. Conventional intensifying screens are not effective with 3H, 14C, or 35S, because the emissions from these isotopes are not sufficient to penetrate the film and come in contact with the intensifying screen. The BioMax TranScreen LE  intensifying screen is the only intensifying screen available for use with medium- and low-energy radioisotopes such as 3H, 14C, or 35S.

Automated Processing

All BioMax films for autoradiography can be processed in roller transport automatic processors equipment with RP X-Omat Developer/Replenisher and  RP X-Omat LO Fixer/Replenisher.

Manual Processing

There are two different methods to manually process autoradiographs. The difference is primarily in the volume of chemistry used and the method of transferring the films between solutions. The recommended processing chemistry is the same for both methods.

The Deep Tank Method usually includes 5-gallon developer and fixer tanks sitting in a water bath. The water bath controls the temperature of the developer and fixer. The film is moved from tank to tank by hand, using metal film hangers.

The Tray Method includes at least three trays that are two centimeters or more larger than the sheet of film to be processed, and an adequate amount of running water for washing. The film is moved from tray to tray by hand using print tongs.

Maintaining fresh processing chemistry is critical to obtaining high quality autoradiographs. Old developer and fixer will adversely affect the image quality of processed film, even if they are used infrequently. It is recommended that the developer and fixer chemistry be changed every month to ensure optimal processing conditions.

Step I: Developer 

GBX Developer and Replenisher is recommended for developing Carestream Autoradiography Films. Film sheets in metal film hangers should be placed in the developer tank for 5 minutes at a temperature of 20 degrees C. Do not agitate the film in the developer. The rate of replenishment for each 35 x 43 cm film processed is 60 mL of GBX Developer and Replenisher. GBX Developer and Replenisher should be completely replaced every month with fresh developer to assure high quality exposure of Carestream Autoradiography Film.

Step II: Rinse 

Remove film from the developer and place in running water. Wash with continuous, moderate agitation for 30 seconds. Recommended rinse temperature is 16 degrees C to 24 degrees C. GBX Indicator Stop Bath may be also be used to rinse film.

Step III: Fix 

GBX Fixer and Replenisher is recommended for fixing of Autoradiography Films. Remove the film sheet from the rinse and place it in the fixer tank for 5-10 minutes. Recommended fixer temperature is 16 to 24°C. Moderate agitation of film in the fixer is recommended.

The rate of replenishment for each 35 x 43 cm sheet of film processed is 75 mL of Fixer and Replenisher. GBX Fixer and Replenisher should be fully replaced every month with fresh fixer to assure high quality exposure of Carestream Autoradiography Film.

Step IV: Wash 

Remove the film from the fixer and replace it in a running water wash for 5-10 minutes. Running water wash should be 16 to 24 degrees C with a rate of 8 volume changes per hour.

Step V: Dry 

Remove the film from the water wash and hang it with a clip attached to one corner of film sheet in a dust-free area at room temperature, until the film is dry.