DR Mammography에서 평균유선선량 감소를 위한 방안

The Study for Average Glandular Dose Reduction in Digital Mammography

Purpose : In digital mammography, Exposure condition was automatically chosen using by measurement breast thickness and the density of mammary gland. It may cause a lack of recognition about an appropriate exposure condition and total exposure dose which would be high through the more increase dose and the image quality was better. For search a minimum dose at diagnosis and find a minimum scan parameter, in our study using an authorization standard breast phantom from ACR(American collage of radiology). Materials and methods : AOP mode of Digital mammography(Senographe DS) used with Standard, Contrast, Dose mode take every 3 times and archived 9 images for reproducibility in same parameters. In Manual mode, kVp was fixed 29 and mAs was changed from 40 to 4 in 11steps, it take every 3 times and archived 33 images for reproducibility in same parameters. Phantom image was evaluated and analze by SPSS program with mAs, phantom scoring, evaluation of false region, image quality, SNR and average glandular dose. Results : Average glandular dose is revealed the highest dose in contrast mode, the lowest dose in dose mode out of AOP mode. The scoring of false region was passed on ACR quality control standard, it was above 0.58mGy at average glandular dose(59% of standard mode) and 25mAs(61% of standard mode). It has a right statistical correlation. Do evaluations of false region with the naked eye, the order of correlation with average glandular dose was such as following speck, fiber, mass. It has a right statistical correlation. Also evaluation of image quality was above score 3(good) which more than 0.92mGy(93% of standard mode) and 40mAs(98% of standard mode). It has a right statistical correlation. SNR was satisfied with standard score, more than 0.58mGy average glandular dose(63% of standard mode), and 25mAs(61% of standard mode). It has a right statistical correlation, too. Conclusion : The image quality of possibly diagnosis could maintain by low average glandular dose and mAs by Manual mode which less than AOP mode parameters of the existing digital mammography. Also it could reduce average glandular dose. Also it could change minimum parameters accompany with a shape of lesion. This method is innovative plan of reduction of patient dose about unnecessary radiation exposure by using a AOP mode but Manual mode with previous reference parameters when follow-up study and post operation patient exam.