Radiography in Modern Industry - Kodak

Rapid Access to Processed RadiographsApproximately twelve or fourteen minutes after exposed films are fed into the unit, they emergeprocessed, washed, dried, and ready for interpretation. Conservatively, these operations takeapproximately 1 hour in hand processing. Thus, with a saving of at least 45 minutes in processingtime, the holding time for parts being radiographed is greatly reduced. It follows that more workcan be scheduled for a given period because of the speed of processing and the consequentreduction in space required for holding materials until the radiographs are ready for checking.Uniformity of RadiographsAutomated processing is very closely controlled time-temperature processing. This, combinedwith accurate automatic replenishment of solutions, produces day-after-day uniformity ofradiographs rarely achieved in hand processing. It permits the setting up of exposure techniquesthat can be used with the knowledge that the films will receive optimum processing and be freefrom processing artifacts. Processing variables are virtually eliminated.Small Space RequirementsAutomated processors require only about 10 square feet of floor space. The size of theprocessing room can be reduced because hand tanks and drying facilities are not needed. A filmloading and unloading bench, film storage facilities, plus a small open area in front of theprocessor feed tray are all the space required. The processor, in effect, releases valuable floorspace for other plant activities. If the work load increases to a point where more processors areneeded, they can be added with minimal additional space requirements. Many plants with widelyseparated exposure areas have found that dispersed processing facilities using two or moreprocessors greatly increase the efficiency of operations.Chemistry of Automated ProcessingAutomated processing is not just a mechanization of hand processing, but a system dependingon the interrelation of mechanics, chemicals, and film. A special chemical system is thereforerequired to meet the particular need of automated processing.When, in manual processing, a sheet of x-ray film is immersed in developer solution, the exposedsilver halide grains are converted to metallic silver, but, at the same time, the emulsion layerswells and softens. The fixer solution removes the underdeveloped silver halide grains andshrinks and hardens the emulsion layer. Washing removes the last traces of processingchemicals and swells the film slightly. Drying further hardens and shrinks the emulsion.Therefore, the emulsion changes in thickness and in hardness as the film is moved from one stepto the next in processing. In manual processing, these variations are of no importance becausethe films are supported independently and do not come in contact with other films or any othersurfaces.Automated processing, however, places an additional set of demands on the processingchemicals. Besides developing and fixing the image very quickly, the processing chemicals mustprevent the emulsion from swelling or becoming either slippery, soft, or sticky. Further, they mustprepare the processed film to be washed and dried rapidly.In automated processors, if a film becomes slippery, it could slow down in the transport system,so that films following it could catch up and overlap. Or it might become too sticky to pass comepoint and get stuck or even wrap around a roller. If the emulsion becomes too soft it could bedamaged by the rollers. These occurrences, of course, cannot be tolerated. Therefore,processing solutions used in automated processors must be formulated to control, within narrowlimits, the physical properties of the film. Consequently, the mixing instructions with thesechemicals must be followed exactly.Radiography in Modern Industry 117