Optimization of image quality and radiation dose in CR ammography

Objective To investigate the difference of image quality between automatic exposure control(AEC) and manual exposure in CR digital mammography,and to observe the effect of image post-processing on improvement of image quality and dose reduction.Methods CDMAM 3.4 phantom and TORMAM phantom were selected and exposed in a CR system in 5 different phantom thickness.Under each thickness there were 4 dose levels(once automatic and 3 times manual exposures,which corresponded to 80%,60% and 40% dose).Three observers interpreted all the images.Each image was scored twice with unprocessed images and post-processed image.The differences of image quality were compared between 3 lower dose images and 100% dose image.Results The results of image quality figure(IQF) of CDMAM phantom showed the image quality of post-processed images were higher than unprocessed images.Part of the lower dose images exceeded AEC dose image in image quality through post-processing.The dose decreased from 20% to 60% through image post-processing in different equivalent breast thickness.From the results of TORMAM phantom,for the detection of filament details and circular details,the scores increased after post-processing(P0.001).However for the partical details,the effect of image post-processing on image quality was not obvious(P=0.74).Conclusion In CR digital mammography,the image quality can be improved through image post-processing.Radiation dosage can decrease through the image post-processing without reduce of image quality.