IMAGE QUALITY ASSESSMENT OF DIGITAL DENTAL RADIOGRAPHY SYSTEMS WITH SPECIFICALLY DEVELOPED PHANTOM AND SOFTWARE

摘要

The purpose of this work is to assess the image quality of dental digital systems with computed radiography (phosphor plate) and direct radiography (charge-coupled-device sensor), by developing a specific dental phantom named RADEN and software to analyze the phantom image automatically. The phantom developed to evaluate the image quality of dental radio-graphic equipment has specific test objects of contrast-detail combinations appropriated for the resolution of the dental digital systems. The image quality is evaluated by using contrast-detail curves and an image quality index. The phantom was made of a square aluminum block 7.5 × 7.5 cm that has a lodge of size 3.2 × 3.2 cm for fixing the sensor of the digital dental system, and it contains specific test objects of contrast-detailrncombinations that are cylindrical holes. The diameters of the holes ranged from 0.3 to 1.6 mm, and the depths ranged from 0.14 to 1.28mm; these ranges for the diameters and depths are suitable for resolution of the dental digital systems and the contrast attenuation curves of the X-radiation, and the results are sensitive to the operating conditions of the dental radio-graphic system.rnWe have also developed specific software to analyze the RADEN phantom image automatically obtained by the digital radiographic equipment. The algorithms are based on digital image processing techniques, and they have been implemented in a user-friendly tool with a graphical interface.