Long cone versus short cone for digital intraoral radiographic imaging

Abstract

<h3>Background</h3> Intraoral radiographs are acquired by one of two methods: the long cone paralleling technique that uses a 30 cm distance from the focal spot to the end of the beam indicating device (BID) versus the short cone technique of 20 cm. The long cone paralleling technique (LCPT) reduces x-ray beam divergence, scatter radiation, penumbra, and magnification as well as entrance skin exposure. LCPT has been recommended for use with digital intraoral radiographic imaging. However, most intraoral generators are supplied with only a short cone BID. <h3>Objective</h3> This research project evaluated image quality of digital radiographs acquired with both long cone and short cone techniques. <h3>Study Design</h3> A series of incrementally increasing exposures of a digital intraoral quality assurance phantom was acquired with both long and short cone methods over a range of exposures from 10 ms to 800 ms to encompass all exposures in the clinical range. Image quality was evaluated using a scientifically validated method that has been published in other research studies on digital intraoral image quality. The image quality parameters assessed were dynamic range, contrast perceptibility, and spatial resolution as specified in ANSI /ADA Standard No. 1094 Quality Assurance for Digital Intra-oral Radiographic Systems. Images were visually evaluated and then objectively evaluated using the NIH ImageJ software for validation. <h3>Results</h3> The results support the use of the LCPT for the acquisition of digital intraoral radiographic images. <h3>Conclusion</h3> The additional purchase of the BID extension is substantiated by the results. <b>Statement of Ethical Review</b> Ethical Review or exemption was not warranted for this study