AN EVALUATION OF A DIAMENTOR BASED SYSTEM FOR ESTIMATION OF SPOT FILMDOSE-AREA PRODUCT VALUES

In the audit of barium studies it is not common to assess the contribu tion of spot films to the total dose. This study investigates the accu racy with which the number of spot films and associated dose-area prod uct (DAP) may be estimated. The study was undertaken for barium enemas , the swallow part of barium swallow studies, and the abdominal part o f barium meal studies on X-ray sets with film-screen radiography, digi tal fluorography and 100 mm camera fluorography. DAP readings from a D iamentor were input to a computer at a rate of three per second and th e difference in successive DAP values calculated. These data were used to assess the number and total DAP from spot films. For Diamentor bas ed systems which sample the DAP values at three times per second the t hreshold algorithm works well for him-screen radiography of barium mea ls and enemas. However, the estimated number of spot films is generall y in error. For the Diamentor M2 it is unlikely that the sample rate c an be increased to a high enough value to provide sufficient accuracy for all barium studies obtained using all spot him modalities, althoug h use of the modified threshold algorithm has the potential to provide some increase in accuracy.