Abstract:

Objective To compare the effect of different digital mammography exposure modes on the image quality and radiation dose of the breast phantom,and to provide the basis for diagnosis of breast cancer. Methods A breast phantom was exposed by using automatic exposure mode and manual exposure mode,respectively.There were three automatic exposure modes including DOSE,STD,and CNT.About manual exposure mode,at first,the tube voltage was changed,such as 25,26,27,28,29,30,32,34,36,38,and 40 kV,when the tube loading was 32 mAs.Then the tube loading was changes,such as 20,32,40,45,56,63,80,100,125,160,and 200 mAs,when the tube voltage was 29 kV. According to American College of Radiology (ACR) criteria,the average glandular dose (AGD) and image quality score were recorded for each image. Results Among the three automatic exposure modes,there were no statistical difference of the quality score of images of the simulated specks and the simulated masses (P=0.37),while there was statistical difference of the quality score of images of the simulated fibers (P=0.00).When exposuring with the manual mode,there were statistical differences of the quality scores of images of three simulated lesions (P=0.00).However,there were different trend changes in the quality scores of images of three simulated lesions.The imaging of simulated fibers was most susceptible by changing of tube voltage or tube loading,while the imaging of simulated specks was least susceptible by changing of tube voltage or tube loading.AGD value will be increasd with the increasing of tube voltage or tube loading,whenever the automatic exposure mode or manual exposure mode. Conclusion When digital mammography being,it must be executed to the breast cancer screened with the low dose model of automatic exposure.And the manual mode can effectively reduce the radiation dose without sacrifice image quality.

Key words: phantom, tube loading, tube voltage, radiation dosage