Limitations of retarded (bisulfite) x-ray film processing Page: 5 of 8
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The characteristic curves derived from films exposed at 17.5 and at 25.3
keV and developed under standard processing conditions agreed well with the
curve obtained at 17.5-keV by Leipelt and SIivinsky* and with our earlier
(unreported) curve at 25.3 keV, respectively.
We also analyzed the results obtained by bisulfite processing. We
normalized the exposure-vs-energy results of an earlier comprehensive
calibration of Type-M film developed using standard processing to the 17.5-
and 25.3-keV bisulfite-processed data. These results were used to calibrate
spectra generated by the bent-crystal spectrometer, and we found large
discrepancies between these spectra and consensus spectra from other
experiments. This disagreement, prompted us to initiate a re-examination of
the retarded processing technique.
About 10 weeks after the first set (Set 1) had been processed, a second
set of Type-M film (Set 2) was exposed at 25.3 keV. Five exposures of Set 2
were developed using the standard processing procedures, 9 were set aside
undeveloped, and the remaining 20 were processed for either 4.5, 6.0, or 3.0
min using bisulfite developer solution of the same formulation and prepared
under the same conditions as Mix 1, which was used to develop Set 1. The four
samples retained from Set 1 were also included in the second processing (two
at 4.5 and two at 8.0 min).
Density values from the average characteristic density-vs-exposure curve
(derived from the two exposure sets at 25.3 keV using standard processing)
agreed within +7% at any given exposure. Similar comparisons of the results
for two exposure sets developed under bisulfite processing, however, revealed
that, for the 8.0-min processing period, the densities of the film samples
processed with Mix 1 differed from those of Mix 2 by factors of 2.5 or more
(Fig. 2a). For the 4.5 a.id 5.0-min processing periods, the density variations
between exposure sets was even greater (Figs. 2b and 2c). (For the 4.5-min
period, the comparison is not as straightforward since the characteristic
curves derived from the Mix 2 processing still lie in the nonlinear region of
the density-vs-exposure curve). The results obtained for film samples from
both Sets 1 and 2, which were processed with Mix 2, all fall on the same curve
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Stoering, J.P. & Dittmore, C. Limitations of retarded (bisulfite) x-ray film processing, report, October 16, 1979; Livermore, California. (https://digital.library.unt.edu/ark:/67531/metadc1092201/m1/5/: accessed March 23, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.