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Comparison of different commercial FFDM units by means of physical characterization and contrast‐detail analysis
Author(s) -
Rivetti Stefano,
Lanconelli Nico,
Campanini Renato,
Bertolini Marco,
Borasi Gianni,
Nitrosi Andrea,
Danielli Claudio,
Angelini Lidia,
Maggi Stefania
Publication year - 2006
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2358195
Subject(s) - detective quantum efficiency , digital radiography , flat panel detector , imaging phantom , computed radiography , digital mammography , mammography , contrast (vision) , image quality , detector , optical transfer function , tomosynthesis , optics , computer science , materials science , nuclear medicine , radiography , artificial intelligence , physics , medicine , image (mathematics) , cancer , breast cancer , nuclear physics
The purpose of this study was to perform a complete evaluation of three pieces of clinical digital mammography equipment. Image quality was assessed by performing physical characterization and contrast‐detail (CD) analysis. We considered three different FFDM systems: a computed radiography unit (Fuji “FCR 5000 MA”) and two flat‐panel units, the indirect conversion a‐Si based GE “Senographe 2000D” and the direct conversion a‐Se based IMS “Giotto Image MD.” The physical characterization was estimated by measuring the MTF, NNPS, and DQE of the detectors with no antiscatter grid and over the clinical range of exposures. The CD analysis was performed using a CDMAM 3.4 phantom and custom software designed for automatic computation of the contrast‐detail curves. The physical characterization of the three digital systems confirms the excellent MTF properties of the direct conversion flat‐panel detector (FPD). We performed a relative standard deviation (RSD) analysis, for investigating the different components of the noise presented by the three systems. It turned out that the two FPDs show a significant additive component, whereas for the CR system the statistical noise is dominant. The multiplicative factor is a minor constituent for all the systems. The two FPDs demonstrate better DQE, with respect to the CR system, for exposures higher than 70 μ Gy . The CD analysis indicated that the three systems are not statistically different for detail objects with a diameter greater than 0.3 mm . However, the IMS system showed a statistically significant different response for details smaller than 0.3 mm . In this case, the poor response of the a‐Se detector could be attributed to its high‐frequency noise characteristics, since its MTF, NEQ, and DQE are not inferior to those of the other systems. The CD results were independent of exposure level, within the investigated clinical range. We observed slight variations in the CD results, due to the changes in the visualization parameters (window/level and magnification factor). This suggests that radiologists would benefit from viewing images using varied window/level and magnification.