3-43. DEVELOPER CONTRAST
The type of developer solution used produces a degree of image contrast that is
considered optimum by the manufacturer. Therefore, developer contrast may be
considered a contrast when the solution is used according to the directions outlined by
its manufacturer. Full advantage of this constant is usually obtained when complete
development of the image takes place.
3-44. TIME-TEMPERATURE PROCESSING
a. General. The chemical reactions involved in the processing procedure occur
within a limited time and temperature range for optimum results. The effects of
overexposure may be easily observed and the best in exposure technique obtained.
Although the latitude of the film will compensate in a measure for some errors in
exposure, good quality radiographs cannot be consistently secured if processing is not
b. Radiographic Uniformity. Uniformity in radiographic densities between
comparative films is obtained only by the use of the standard time-temperature method
of development. With this method and with both time and temperature at optimum, films
lacking density are the result of underexposure, not underdevelopment, and those
having excessive density are the result of overexposure, not over development. Results
of this nature make possible changes in the exposure factors so that good quality
radiographs can be obtained.
3-45. INFLUENCE OF DEVELOPMENT TIME
The time of development given to an exposed x-ray film materially affects the
amount of silver deposited on the radiograph. As the time development increases up to
a certain point, the amount of silver increases. In general, the time required to develop
a film in a given developer depends upon the emulsion and its thickness. To assure
accurate timing of all processing procedures, it is necessary to use a properly
functioning interval timer. A series of correctly exposed hand radiographs was made
using identical x-ray exposure factors, but each film was developed for a different period
of time at temperature of 68F.
a. The radiograph developed for one minute shows only slight traces of silver
deposit. Image detail is lacking and the contrast is low. The streaked background
density is characteristic of the underdeveloped radiograph.
b. The radiograph developed for two minutes shows some of the important
features of the image and a greater overall deposit of silver (B, figure 3-8). Image detail
and contrast are somewhat improved.