(3) Figure 4-12, part C, shows the same object projected by a vertical CR.
This illustrates a violation of the basic rule with respect to the constant horizontal CR. In
a strict sense, no fluid level as such is demonstrated by the use of a vertical CR.
Projections of this nature are sometimes used; however, to supplement regular fluid-
level projections for purposes of comparison with previous or subsequent radiographs
or to demonstrate certain aspects pertaining to the collection, dispersion, or
characteristic behavior of free fluid.
Figure 4-12. Schematic representation of fluid-level radiography with a drinking glass
partially filled with barium sulfate suspension demonstrated in steps A, B