Abstract
Purpose: This study aimed to evaluate the quality performance of digital mammographic systems based on the national survey data in Taiwan. Methods: On-site inspections were conducted on 120 mammographic units during 2014 survey in Taiwan. Quality performance of digital mammographic systems evaluated by DIGIMAM phantom (Artinis) complied with the European guidelines for quality assurance program were performed on 56 digital units, including 35 CR and 21 DR systems. The phantom was exposed with clinical techniques on-site for further investigate geometric distortions, contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) with for-processing images, and dynamic range and chest wall missed tissue with for-presentation images. Results: Geometric distortion ranged from 0.3%∼12.5% for chest wall-anterior and from 0.8%∼14.1% for left-right direction. Mean CNR for 0.1 mm and 0.2 mm Al were 0.06±0.02 and 0.11±0.04, respectively. SNRs for DR may deviate from systems of different manufacturer/model and had a mean value of 69.87±15.02. As for CR systems, larger SNR variations were found between different manufacturers as compared to DR ones. For investigating the dynamic range in the low contrast inserts within fatty, normal and dense tissue, only 4 of 10 Hologic systems failed to distinguish the inserts for all the three test patterns. Evaluations of missed tissue at chest wall side showed that most DR systems had missed tissue less than 5 mm with the exception of 2 Hologic systems. Total pass rate according to European guidelines for chest wall missed tissue was 84.78%. Conclusion: Feasibility for quality survey using commercialized digital phantom were investigated in this study. Further analysis may be performed and more systems may be included in the survey in the future. The results may provide as a reference for digital mammography quality assurance program established in Taiwan.
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