Technical note: an evaluation of a Diamentor based system for estimation of spot film dose-area product values

In the audit of barium studies it is not common to assess the contribution of spot films to the total dose. This study investigates the accuracy with which the number of spot films and associated dose-area product (DAP) may be estimated. The study was undertaken for barium enemas, the swallow part of barium swallow studies, and the abdominal part of barium meal studies on X-ray sets with film-screen radiography, digital fluorography and 100 mm camera fluorography. DAP readings from a Diamentor were input to a computer at a rate of three per second and the difference in successive DAP values calculated. These data were used to assess the number and total DAP from spot films. For Diamentor based systems which sample the DAP values at three times per second the threshold algorithm works well for film-screen radiography of barium meals and enemas. However, the estimated number of spot films is generally in error. For the Diamentor M2 it is unlikely that the sample rate can be increased to a high enough value to provide sufficient accuracy for all barium studies obtained using all spot film modalities, although use of the modified threshold algorithm has the potential to provide some increase in accuracy.