Physical properties of a system for direct acquisition of digital intraoral radiographs

Objective: To determine technical properties for a direct digital intraoral radiographic system, F1 iOX (Fimet Oy, Monninkylä, Finland). Methods: A dose response function was calculated from seven radiographs exposed to a homogenous radiation field. The line spread function (LSF) and the modulation transfer function (MTF) were determined from a radiograph of a test object having a slit. Noise power spectra (NPSs) were determined at three exposures from radiographs exposed to a homogeneous radiation field. Noise equivalent quanta (NEQs) were calculated from NPSs and the MTF. Detective quantum efficiencies (DQEs) were determined from the NEQs and a representative value of the photon fluence. Signal-to-noise ratios (SNRs) were calculated from the NEQs and different signal contrasts. Results: The dose response function was linear and the system relatively sensitive. The maximum NPS was less than 10^-5 mm². NEQs indicate that the system captures a relatively high number of photons. At peaks of about 1 cycle/mm DQEs reached almost 35%. SNRs are relatively high. Conclusion: The technical properties found in this study indicate that the F1 iOX system is suitable for intraoral dental radiography.