The Research On The Quality Assurance Of Digital Mammography

Mammography is the major and preferred means to detect mammary cancer, its efficiency of dectecting the mammary diseases can reach 84.3%-90.5%. According to the findings by AJCC and NCI, mammography can detect the earlier period of cancer 2 years earlier than the most experienced doctors. Compared with the traditional screen-film technique, digital mammography can get the images and computer-assisted diagnostic results more conveniently, the techniques of image transmission, searches and storage is more advanced, and within the accuracy of diagnosis, dose is lower.However, as the facts show, because of the false negative or false positive cases, there are still some misdiagnoses. The elements that related to the misdiagnoses by mammography is as follows: the performance of the operating machine, the quliaty of the image, the position of the projection, patient's age and density of breasts. Moreover, the overdose by the accumulated dose from X-ray itself is the dangerous cause of cancer. Therefore, in order to stablize the performance of the machine, to optimize the quality of image, to increase the ability to detect cancer, and to ensure the safety of the patient, the quality control of mammography is very important.The thesis uses GE Senographe DS mammography as the example to study how to improve the quality of mammography. Three aspects are mainly mentioned:1. The guarantee of the performance and operating state of the machine: beam quality assessment; breast entrance exposure,average glandular dose and reproducibility; kVp Accuracy and Reproducibility; radiation output; evaluation of focal spot performance; collimation assessment; Mammographic unit assembly evaluation.2. Image quality assurance: Flat field test; phantom image quality on AWS and printer test;CNR and MTF measurement; AOP mode and SNR check; monitor calibration; artifact evaluation and flat field uniformity; RWS monitor calibration3. The assurance of the criteria of mammography techniques; relation between galactophore types and exposure conditions; photographed-position; application of compressor; repeat analysis.The thesis systematically puts forth the view of advancing the quality of digital mammography, elaborates on the methods of measuring for every parameter as well as some requisite items while photograhying, thus attempts to estabilish a system of feasible methods for the quality assurance towards digital mammography.