Evaluation of image quality and radiation dose in maramography: a comparison among digital radiography, computed radiography and film-screen systems

Objective To compare the image quality, radiation dose and diagnostic accuracy on film-screen, digital radiography (DR) and computed radiography (CR) mammography. Methods Three different kinds of mammography machines (film-screen, DR and CR) were tested to make sure they were qualified and comparable. Radiographies were taken on Mammo-152 phantom and ACR phantom using filmscreen, DR and CR systems with the same radiation dose. Next, radiographies were taken on two phantoms using DR and CR systems with classic mode or AEC and the radiation dose was recorded. The images were numbered and scored by eight independent experienced radiologists under the same reading condition according to ACR method. Statistics was performed with the randomized complete-block design variance analysis. The diagnostic accuracy of three kinds of mammography methods were compared with Kappa test in clinical cases who had pathologic results. Results The spacial resolution of film-screen system was the highest (7.0-8.0 Lp/mm) and that of CR was the lowest (2.5 Lp/mm). When the radiation dose was increased (27. 0%-30. 0% ), the resolution was improved with DR ( +11. 0% ) but almost no change with CR ( +1.5%). The radiation dose of DR was the lowest on ACR phantom. The delineation of mass was better on film-screen than on CR, but the delineation of fibers and speck was better on CR. When the radiation dose of CR was increased (25. 0% ), the delineation of fibers and speck on CR was similar to that on DR and the delineation of mass was similar to that on film-screen. There was a good correlation between the mammography diagnosis and pathological results (film-screen is 50/56, DR is 83/90 and CR is 61/69,P 0. 75) . The diagnostic accuracy of three mammography systems had no statistical difference [film-screen 89. 3% (50/56), DR 92. 2% (83/90) and CR 88. 4% (61/69),Pearson X 2=0. 722 ,P =0. 697]. Conclusion Film/screen system has the highest space resolution and DR has the lowest radiation dose. Three mammography systems have the same diagnostic accuracy for breast disease. Key words: Mammography;  Radiation dosage;  Diagnostic techniques and procedures;  Image quality of simulated fabrics