Light source-induced error in computer-assisted image analysis with a video-based system.
OBJECTIVE
We tested the hypothesis that two different light sources, an alternating current fluorescent viewbox and a direct current halogen viewbox, do not differ with respect to their ability to illuminate reproducibly a radiograph during image capture.


METHODS
Two radiographs were taken: one with four hydroxyapatite chips mounted against a dry mandible and one without the chips. They were digitally subtracted with a video-based imaging system. The procedure was repeated at different times.


RESULTS
A statistically significant difference among optical density measurements was found when the alternating current fluorescent viewbox (p < 0.001) was used and was related to light intensity variation. Such effect was not observed with the direct current halogen viewbox (p = 0.873).


CONCLUSIONS
Study design efficiency was increased by 212% with the use of the direct current halogen viewbox so that to detect a specified treatment effect with a given level of statistical confidence, the sample size has to be 2.12 times greater if the alternating current fluorescent viewbox is used.
Stutz
F A
FA
College of Dentistry, Department of Periodontology, University of Florida, Gainesville, USA.
Hefti
A F
AF
Gibbs
C H
CH
D015502:Absorptiometry, Photon; D000704:Analysis of Variance; D016477:Artifacts; D003951:Diagnostic Errors; D006801:Humans; D008027:Light; D008029:Lighting / Q000379:methods*; D008334:Mandible / Q000000981:diagnostic imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D011861:Radiography, Dental / Q000379:methods*; D015203:Reproducibility of Results; D013382:Subtraction Technique / Q000295:instrumentation*; D014741:Video Recording