4-20. EMERGENCY PROCESSING MEASURES
Whenever possible, the x-ray specialist should strictly adhere to the rules of good
processing outlined in the preceding sections. However, emergencies may arise during
which it may be impossible for the x-ray specialist to know all the facts about the
developer and fixer. In such emergencies, the following rules of thumb may be helpful.
a. Sight Development.
(1) Except in cases of extreme emergency, proper time-temperature
processing should be carried out at all times. However, in case the processing timer
should stop working, or if an improperly exposed but badly needed emergency film is
required, it may be necessary for the specialist to estimate visually (sight development)
the appropriate time for terminating development.
(2) Sight development opens avenues of error through which the quality of
the finished radiograph may be impaired. It is a characteristic of x-ray film emulsions
that the silver bromide crystals are packed more closely together than in the usual
photographic emulsion. Depending upon the type of exposure given, the visual
appearance of the developing image may be comparatively different. In radiographs
exposed with intensifying screens, the exposure effect occurs chiefly in the crystals at or
near the surface of the emulsion because the exposure is made chiefly by the
fluorescent light emitted by the intensifying screens. The image appears to flash up
quickly in the developer and the developed crystals at the surface prevent estimation of
the degree of overall development in the body of the emulsion. Therefore, it is largely a
matter of guesswork as to the time that development may be judged complete.
Frequently, the radiograph is removed from the developer before complete development
of the entire image has taken place because the image appears to the eye to possess a
very high density. This results in underdevelopment. In direct exposure of the x-ray
film, the x-rays penetrate the entire emulsion layers fairly equally. Crystals at the
emulsion's surface as well as throughout the layers develop slowly. The developing
image is ill defined at first, gradually building up to the point where the well-
accommodated eye sees what may be construed to be a well-defined image.
Frequently, however, an error in judgment is made and full development is not given.
(3) Sight development requires much experience before proficiency is
attained and, even then; there are physiological factors which hinder the efficiency of
the method. The degree of fatigue of the x-ray specialist is a major factor that lessens
eye acuity in sight development as well as producing poor inherent ocular adaptation.
Passage from a brightly lightly exposure room to the dark processing room requires a
period of adaptation--in some instances, 15 to 30 minutes. The frequent inspection of
the developing radiograph in front of the safelight together with the action of aerial
oxidation frequently fogs the film. To avoid these disadvantages, use a standardized
time-temperature processing procedure and develop films by inspection only when