ON THE DYNAMIC-RANGE OF DIFFERENT X-RAY PHOTON DETECTORS IN INTRAORALRADIOGRAPHY - A COMPARISON OF IMAGE QUALITY IN FILM, CHARGE-COUPLED-DEVICE AND STORAGE PHOSPHOR SYSTEMS

Objectives. To compare film for intra-oral radiography with two charge -coupled device (CCD) and one storage phosphor system for digital imag ing in respect of subj ective image quality, detectability of small ma ss differences and appearance of burn-out effects and blooming phenome na at various exposure times. Methods. Dried mandibles with teeth from different areas were radiographed at exposures covering a relative ra nge from 1 to 100. Image quality was subjectively evaluated after imag e processing, when applicable, using a visual grading scale from 0 to 10. The number of visible holes in an aluminium block was used to meas ure the detectability of small mass differences. Burn-out effects and blooming were evaluated by measuring widths of roots and of aluminium and plastic cylinders. Results. Radiographs with the storage phosphor system achieved image quality scores similar to those of film but over a larger exposure range, while CCD images were rated lower and over a smaller range. All holes in the aluminium block were only detected wi th the storage phosphor system. While the widths of roots were strongl y affected by sensor saturation in CCD images and by burn-out in film images, smaller effects were seen with the storage phosphor system. Si milar results were obtained with aluminium and plastic cylinders. Conc lusions. Higher image quality was achieved over a much wider exposure range with the storage phosphor system than with either film or the CC D systems.