The Comparative Research Of Image Quality And Dose In Mammography

Objective To compare the imaging quality and imparted dose between digital mammography and conventional screen-film mammography.And to confirm the connection between image quality and average glandular dose(AGD) through systematic research on each kind of mammography system.Material and method one kind of screen-film mammography system,DR mammography system and three kinds of CR mammography systems were selected. The AGDs were calculated according to the imaging exposure parameters.The trend of image quality with AGD changes and the image quality for all systems on the same AGD were analyzed.Results The trend of image quality with AGD changes:the comprehensive evaluation results of details in TORMAX phantom images of both SFM and CR systems are similar with the changes of AGD in the setting dose scope.However the image quality will be improved with the dose increasing in CDMAM phantom images of all digital mammography systems although the changes are not significant,and to DR, the image quality keep consistent as the AGD changing between 2.01mGy and 2.31mGy,to Fuji CR,the AGD between 2.00mGy to 2.36mGy,to Konica CR,the AGD between 1.70 mGy to 2.40mGy.To SFM,the image quality improves with the increasing of AGD at the low dose stage and decrease with the increasing of AGD as the dose at the high dose stage.However there is an optimized dose level as the AGD near to 2.4mGy.Comparison of image quality between all systems at the same AGD level:the high contrast resolution will be up to 13 lp/mm in SFM and can be near to the theoretic value in digital systems.The IQF of SFM is less than Fuji CR,Konica CR and PCM but more than DR.In CR systems,the difference of IQF between Fuji CR, Konica CR and PCM is less than 5.the IQF of Kodak CR is the largest.Conclusion the comprehensive image quality of SFM is similar with such CR systems as Fuji CR,Konica CR which IP pixel are 50μm.However the image quality is poor as the IP pixel is 100μm.The image quality of PCM which is a phase-contrast CR system is better than the image quality of SFM systems and conventional CR systems.The image quality of DR is the best in all systems.The image quality of all of the mammography systems will be improved with the increasing of radiation dose in a setting dose scope and a inflexion,which delegate the optimized dose point,must exist in each of the curve of image quality trend.The inflexion is most significant in SFM image quality curve.As a whole,the better image quality can be acquired as the AGD between 1.8mGy to 2.5mGy.to DR system,the latitude is better than SFM and CR systems and can acquire better image quality in the whole using dose scope.The SFM system takes the advantage in resolution which will not change as the dose increase,however the digital systems is similar or better in the density resolution and threshold contrast detail.In fact that the imaging ability of CR systems in resolution and threshold contrast detail depends on IP pixel.There is an advantage that AEC is used,however the AEC mode is not perfect in current clinic application especially in CR systems.It is important for clinic mammography that exposure parameters are set reasonably in AEC mode according to the beam quality.