(6) For pneumocystography, the positioning procedure is generally the
same as for cystography. However, AP and PA projections are considered the basic
projections for this examination. The exposure time should be decreased by 40 to 50
percent from that used for cystography because of the radiolucency of the induced
spaced occupied by the injected air. A representative pneumocystogram is shown in
figure 2-36. For double-contrast studies, a special colloidal solution is first introduced
into the bladder and then withdrawn, leaving a residual coating of the substance on the
mucosa. Air is then injected and the pneumocystogram is taken.
Figure 2-36. A representative pneumocystogram.