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OP 54<br />

Title<br />

THE DESIGN OF FFT FILTERS FOR THE ENHANCEMENT OF DIAGNOSTIC-RELEVANT<br />

STRuCTuRES<br />

Authors<br />

D. bRuELLMANN 1 , S. SANDER 1 , u. zELLER 2 , R. SCHuLzE 1<br />

Affiliations<br />

1 Department of Orla Surgery, University Medical Center, Mainz, GERMANY, 2 orangedental<br />

GmbH & Co. KG, Biberach, GERMANY<br />

Body<br />

Objectives:<br />

The aim of this study is to illustrate the effect of a newly developed filter to enhance endodontic<br />

needles in digital dental radiography.<br />

Methods:<br />

The teeth of the cadaver pork mandibles were accessed. Digital radiographs of these specimens<br />

were obtained using an optical bench. Specimens were then recorded in the exact same position<br />

having had endodontic needles of known size inserted. The resulting images were converted<br />

into their power spectra using a f<strong>as</strong>t Fourier transform to determine the frequencies caused<br />

by the endodontic needles. The encountered frequencies were used to enhance the endodontic<br />

needles. Lengths were me<strong>as</strong>ured in native and filtered images for performance evaluation.<br />

Results:<br />

The encountered frequencies were used for the design of the filter which w<strong>as</strong> programmed<br />

using DelphiXE RAD Studio (Embarcadero Technologies, San Francisco, USA) and tested on 20<br />

radiographs. The software is able to enhance the endodontic needles in the samples and in<br />

similar dental radiographs. Lengths showed a median difference of 0.52 mm (sd 2.76 mm) in<br />

native images and 0.46 mm (sd 2.33 mm) in filtered images, respectively. Pearson’s correlation<br />

test revealed a significant correlation of 0.915 between gauged length and me<strong>as</strong>urement in<br />

native images and 0.97 for filtered images, respectively (p = 0.0001).<br />

Conclusions:<br />

This study shows that we can design filters for every structure, which we can model <strong>as</strong> an<br />

adjunct to digital dental radiographs. The algorithm can be used for automatic detection of<br />

endodontic needles in digital dental radiographs. The technique described <strong>here</strong> could be extended<br />

to simulated carious lesions.<br />

Keywords<br />

F<strong>as</strong>t Fourier Transform, Image Enhancement, Computer Assisted Me<strong>as</strong>urement<br />

62

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