Avaliação de métodos indiretos de digitalização de radiografias cefalométricas em comparação ao método digital direto

Abstract

Objective: To evaluate the indirect digitization method of cephalometric radiographs in comparison with the direct digital method. Methods: The sample was composed of ten cephalometric radiographs acquired by Orthopantomograph OP100/Orthocef OC100 (GE -Instrumentarium), digital direct. In the Adobe™ Photoshop program, five cephalometric landmarks were set in the images and the impression in transparencies was made. The indirect digitization of the images was performed through the Sony™ DSC-W5 and Canon™ Rebel XT/EOS 350D digital photographic cameras-fixed in a copy stand, at the distances of 25 cm and 60 cm-and through the Hewlett Packard™ Scan Jet 4C scanner. The direct digital images and the indirect ones were inserted and gauged in the Radiocef Studio (Radiomemory™, Brazil) software and the center of the previously marked landmarks was set. The cephalometric computerized analysis generated three angular measurements and four linear ones which were submitted to statistical analysis. Results: The images from the scanner demonstrated small statistically significant alterations, without clinical significance. When digitizing the radiographs at 60 cm, both cameras caused distortions which were statistically significant, but clinically acceptable. At 25 cm, the cameras caused the largest distortions, being more expressive and with clinical significance in the images of Canon™ Rebel XT. Conclusions: The Hewlett Packard™ Scan Jet 4C scanner with transparency reader and the Sony™ DSC-W5 and Canon™ Rebel XT/EOS cameras operating at 60 cm were shown appropriate for the digitization of cephalometric radiographs. In 25 cm, the digital cameras caused distortions in the image which altered the linear measurements with possibilities of jeopardizing the orthodontic diagnosis. Abstract

Radiopacity of endodontic materials using two models for conversion to millimeters of aluminum

“…28 However, X-ray scanners are expensive, time-consuming and not as readily available as digital still cameras. 29 Digital cameras require adjusting of the radiographic and zooming distance 28 of the camera; this can cause distortion of the image, depending on the values chosen for the photographic parameters, such as diaphragm aperture, exposition time and sensor sensibility. 29 In addition, radiographic images obtained by the indirect technique tend to exhibit a higher gray level variation, because the variability of grayscale values depends on the specific characteristics of the scanner 30 or photographic camera used.…”