T.O. 33B-1-1
6-70
6.7.4.1
The following items must be recorded to adequately identify technique charts:
a. Type of unit.
b. Material (type and thickness).
c. Film type.
d. Quality Enhancers (screens).
e. Kilovoltage.
f. Current and exposure time.
g. Source-to-film distance.
h. Film processing factors (temperature, method, etc.).
i. Density of radiograph desired.
6.7.4.2
Step Wedge Radiographs.
A step wedge of the material is usually used as the object to be radiographed. (See Figure 6-35) The wedge may be a
solid block or made up from plates of the material. A radiograph of the step wedge will give a symmetrical shadow
picture of varying densities corresponding to the steps on the wedge. Make a series of radiographs of the step wedge at
different exposures while keeping other radiographic factors constant (including subsequent processing). Preparation
of the technique chart requires the following steps:
a. Select an estimated exposure for the thinnest section of the step wedge based on exposures for similar
material in the middle of the voltage range or a trial exposure on this material. In planning the
exposures pick out a series in an approximate geometrical progression. For example, a series of
120MAS, 220MAS, 320MAS and so on might be chosen.
b. Expose the step wedge under conditions previously selected at the times calculated for the mid-voltage
point.
c. Process the radiographs using fresh solutions according to manufacturer’s directions.
