c. The radiograph developed for three minutes shows more silver deposited, but
the image is still somewhat weak.
d. The radiograph developed for four minutes shows a fairly well defined image.
e. The radiograph developed for five minutes shows all essential details, for the
maximum amount of silver has been deposited on the film. The exposure was such as
to provide a satisfactory radiograph when development times are not sufficient to justify
extension of the development time beyond the basic five-minute period.
3-46. RELATION OF TIME TO ACTIVITY
Development time has a direct relation to the activity of the developer. The
reliability of the recommended normal development intervals for an x-ray film is valid
only as long as the solution has a reasonable measure of its original developing power.
When using the replenisher system, the time should remain the same as long as the
activity is restored by frequent additions of a replenisher solution.
3-47. BASIC TIMES OF DEVELOPMENT
Development time intervals should never be guessed at. There are two basic
times of development for each type of developing solution. One produces an image
with normal speed and contrast, while the other provides maximum speed and contrast.
3-48. EXPOSURE-CONTRAST RELATIONSHIP
The first basic development time provides a short time that is compensated for by
25 percent more x-ray exposure. The second is longer in time, but the x-ray exposure
is 25 percent less than the other. When employing rapid x-ray developer, normal speed
and contrast are obtained by the basic development time of three minutes at 68F. To
obtain maximum contrast, the time is five minutes at 68F. The longer basic
development period will always provide better radiographic quality than the shorter
interval because full development is assured. (See Table 3-3).
3-49. INFLUENCE OF DEVELOPER SOLUTION TEMPERATURE
Chemical reactions are stimulated or retarded by various temperatures. Since
film processing is essentially a series of chemical reactions, the temperature of the
solutions assumes major importance. Variations in temperature require adjustment in
the development time factor so that uniform densities may be maintained.
Temperatures should never be estimated; use a good thermometer. The temperature
should always be checked when development is first begun and at intervals during the
course of the day's work. The optimum temperature as recommended by the American
Standards Association is 68F.