Sensitometric effects of varying the intensifying screens used with Agfa Dentus ST8G and RP6 panoramic radiographic films.
OBJECTIVE
To compare the sensitometric effects and information yield of varying the intensifying screens used with both Dentus ST8G and RP6 Agfa Gevaert, Dormagen, Germany panoramic radiographic films.


METHODS
Four screen-film combinations were employed for each of the two film types. The screens used were blue fluorescing PX-III (Kasei Optonix, Tokyo, Japan) and Special (Siemens AG, Bensheim, Germany), as well as green fluorescing Lanex Regular (Eastman Kodak, Rochester, NY, USA) and Trimax T16 (3M, Mineapolis, Minnesota, USA). The density response for each screen-film combination was evaluated using the characteristic curves generated. Information yield, as determined by the radiographic detection of defects in an aluminium test object, was evaluated by nine observers.


RESULTS
The characteristic curves for ST8G were different when green and blue fluorescing screens were used; however, those for RP6 varied little irrespective of the choice of intensifying screens. Observers were able to perceive defects at significantly lower radiation exposures for ST8G combined with green fluorescing screens compared with blue emitting screens. RP6 with all screen combinations provided similar image detail perceptibility at comparable exposures with ST8G with green-fluorescing screens.


CONCLUSIONS
RP6 is suitable for use with either the spectrally matched blue emitting screens or green-emitting screens. ST8G radiographic film should always be matched to rare earth screens.
Wakoh
M
M
Department of Oral and Maxillofacial Radiology, Tokyo Dental College, Chiba, Japan.
Farman
A G
AG
Scarfe
W C
WC
Kitagawa
H
H
Kuroyanagi
K
K
D000704:Analysis of Variance; D003116:Color; D015588:Observer Variation; D011857:Radiographic Image Interpretation, Computer-Assisted; D011861:Radiography, Dental / Q000295:instrumentation; D011862:Radiography, Panoramic / Q000295:instrumentation*; D011874:Radiometry; D018709:Statistics, Nonparametric; D014962:X-Ray Film; D014963:X-Ray Intensifying Screens